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98 cobra
02-19-2007, 07:43 PM
Hey guys and girls,
Can someone help me out with this problem I am having with my 29,000 mile 98 cobra? Let me start with the occasional grey smoke at start then when it warms up it hiccups at idle and enough to shake the car. I have taken it to the dealership and they could not find a thing wrong with it. On the third time they told me it was a leaky valve guide so I pulled out the plugs and replaced them and there was no oil build up and they all looked the same. I had the fuel filter changed along with the pump and the fuel system cleaned and it still remains the same. My back is against the wall on this car and any help would be thankful. My mods which I don't belielive have anything to do with it are cold air, pulleys, gears, off road H-pipe with mils and magnaflows.

Thanks
Kasey

blk04cobra1
02-19-2007, 10:14 PM
Hey guys and girls,
Can someone help me out with this problem I am having with my 29,000 mile 98 cobra? Let me start with the occasional grey smoke at start then when it warms up it hiccups at idle and enough to shake the car. I have taken it to the dealership and they could not find a thing wrong with it. On the third time they told me it was a leaky valve guide so I pulled out the plugs and replaced them and there was no oil build up and they all looked the same. I had the fuel filter changed along with the pump and the fuel system cleaned and it still remains the same. My back is against the wall on this car and any help would be thankful. My mods which I don't belielive have anything to do with it are cold air, pulleys, gears, off road H-pipe with mils and magnaflows.

Thanks
Kasey
The grey smoke from startup could just be that you're running a little on the rich side. So long as you're not getting a lot of blow by, I would think your valve guides would be fine, but there's no way to tell w/out doing a leakdown and compression test. I would start with a new idle air control sensor/valve, these have a tendency to fail and you can replace this on your own. I believe the part # is F65E-9F715BB, but double check with your parts counter. If this doesnt help, let me know and i'll give you a few other things to look for :thumbsup:

ausie
02-20-2007, 06:22 AM
rough idle and hesitation could be related to several things. A sticky IAC valve can cause this as mentioned by blk04cobra1. If you had more than 29k miles on the clock I would begin to suspect the O2 sensors. When they become slow in response the engine would bog down under hard acceleration since the fuel ratio may begin to richen out. A gummed up PCV valve can also create some problems that are similar. MAF sensors also may create some issues if they become dirty either from oil vapors exiting through the breather line after shutting off the car, or from some air filters if there is too much oil on them. It is okay if the filter is just tacky but if saturated that could find its way into the MAF sensor under acceleration. A dirty throttle plate along with IAC valve may also lead to some slight problems. Most of the contaminants inside the intake plenum are provided by the EGR valve along with oil vapors or oil mist that gets drawn into the intake through the PCV valve. If you remove the IAC valve an notice carbon/varnish build up, chances are that the back side of the throttle plate of the throttle body will be in the same condition. Both of these can be cleaned with throttle body cleaner. These are just suggestions and may not be a fix for the issue at hand.

98 cobra
02-20-2007, 06:19 PM
Thanks for all the advice. The O2 sensors have been taken out a couple of times so that might be the problem, but it has been doing this for about two years now about 10,000 miles and is getting worse. I also keep the K&N kind of oily. I will check all the parts listed in your comments and let you know if it helps. Thanks again.

cobrabitn
02-20-2007, 09:43 PM
You just hit the nail on the head. If you are putting too much oil on your K and N filter, you probably over saturated it and now the oil is blowing through to your sensor in your cold air kit. This will create a rough idle as your sensor is sending the wrong signal to the computer.

Personally, if it were me, I'd clean the air flow sensor and throw that K and N filter away. Several people laughed at a guy who replaced his K&N filter everytime it got dirty. I didn't laugh at him, I change mine too and forgo the oiling. Those filters are factory oiled and they are given just the right amount of oil in them. No way anyone would ever make me believe they could match the exact machine amount. Most people tend to over oil them so my advice is to go and spend a few more bucks and get a new filter. JMHO for what it is worth.. :)

98 cobra
02-20-2007, 10:37 PM
The car has more of a hiccup that vibrates the car at warm idle.
I will try the filter as I had no idea about the oil, along with all the other great suggestions in this thread. I really appreciate the help and will post when I get results from these ideas or not.

Thanks

cobrabitn
02-21-2007, 12:31 AM
Pull the sensor out and gently wipe it off with a Q-tip! :thumbsup:

ausie
02-22-2007, 06:42 AM
Typically I will clean the throttle body, IAC, MAF sensor and PCV valve at every other oil change. Sometimes I let it go even farther. Keeping the intake parts clean keeps every thing in check and reduced the chance of issues if not done. Spark plugs only get pulled once a year (usually in spring).

If the MAF gets dirty, the acceleration will less responsive. Isopropol alcholol can be used with the qtip, try not to leave any fibers from the qtip on the sensor. I typically use the MAF cleaner which works, I have also used Berrymans B-12 chem tool also since it does not leave oil like the throttle body cleaners will. The small parts of the MAF sensor that hand down in the small tube are a hot wire type component. As air flow passes over the element, it cools down and the current changes. Once they get contaminated with oil and other stuff, that tends to slow the response of the sensor down and the wire coil on the sensor will not cool down as much which will result in reduced throttle response. As for the cleanable filters, I may use them but typically may only clean them once before replacing them. You have to let them air dry completely after washing and after you coat them with oil, so I usually install the paper filter (that I still have from the factory) when the cleanable filter was removed for cleaning and reoiling.

Considering the issue you are having, I would check the plugs and measure the spark gap. For a standard plug the gap should be around 0.040" +/- 0.005". The gap should be printed on the catalyst sticker found in the engine bay (either on the bottom side of the hood, or on the radiator cover). As for the gray smoke, if it smells normal (no strong odors of oil, and does not smell like a wet bee nest) it could just be condensate from humidity in the air. That should clear up shortly after the engine warms up. If it continues there may be something else contributing like a small head gasket leak, or that your mufflers are saturated with water since most of the glass fiber insulation typically used tends to act like a sponge during the cool down of the exhaust.

98 cobra
02-22-2007, 08:12 PM
I have not been able to look at anything yet due to 15 hour days at work, but am getting right on it Saturday. You mentioned the throttle response and I do believe the response has gotten worse. I sure hope it is this simple. The only reason I replaced the plugs is because the dealership who I thought I could trust told me they were bad. They also are the same ones that told me I needed a valve job, but none of the plugs that came out of my car had oil build up on them and the compresion tests came out good.
Have you ever heard of only taking your cobra to an authorized SVT dealership for repairs? I was told that after Billingsly ford in Lawton Oklahoma had no clue as to properly diagnos my car and had to wait for a tech that had worked on cobras to come back to work. It sounded like they did not know a thing about cobras. Just wondering.

Thanks again

ausie
02-24-2007, 10:40 AM
That used to be the way it was in 2004. There were specific SVT dealerships that had a few trained technicians for the SVT products. Often times the SVT rep would get involved in the repair or service. The engines and drive line are not the same run of the mill parts found on other products. The only other vehicles I can think of that may have similar components and training are the Lincolin dealers. Even though Lincolin's are not the same as the SVT, they require special training for repair. You may want to locate one of the SVT dealers in your area if the valve guides do need to be replaced, or if there is an isssue with the secondary ports IMRC's (Intake Manifold Runner Control) which I belive is on the 98 model. It may be hard to locate the old SVT dealerships since they no longer use the SVT banner. It would not hurt to ask around.

The IMRC's are one component that I have yet to deal with since my first SVT was a 2001 Cobra. The November issue of 5.0 magazine had a really good 4 valve 4.6L head guide that compared all of the SVT heads used on the 4.6L SVT Cobra. Your engine has the swirl port heads, B cast. Since the secondary ports shut off at RPM level below 3250 and do have a tendency to develope carbon buildup. If they get too gummed up they may cause some issues in the low RPM range. Some have been able to clean the secondary runners with Seafoam and that is great since you do not have to remove the intake plenum to clean them. If for any reason the secondary ports do not close completely, more air will enter the combustion chamber when it is not supposed too. This may cause a lean condition at idle resulting in a miss fire.

More common rough idle issue may be related to a vacuum leak or improperly sized PCV valve or dirty PCV valve. You may want to replace the PCV valve (relatively low cost item) and see if that cures the idle issue. In some cases, the EGR valve may also be leaking and not closing properly. I found replacing the EGR in my 01 cured the pinging issue I had with it at 16k miles. As it turns out, the diaphram was not pulling in the EGR pintle valve. Along with the pinging issue I had, the IAC was generating a code for high idle speed. Even after replacing the IAC valve, the problem persisted until I replaced the EGR valve. In other words, the diaphram of the EGR valve was the vacuum leak source.

To test for bad or leaking valve guides or seals, you need to perform a compression test which I think is different than a leak down test. I found this when doing a search on valve guide testing. Hopefully it will help you diagnose the issue you are having. :cool:

http://www.aa1car.com/random-misfire/

98 cobra
02-24-2007, 10:54 AM
Thanks. So far I have cleaned the MAF with a alcohol and it seemed to tone it down a little bit, but the hiccup is still there. I guess I will move on to IAC, PCV and EGR just as soon as I get to the dealership and talk to the tech that diagnosed my car with bad quides and almost cost me $2700. I had two other mechanics look at my pulled plugs and told me there was no oil build up or burn on them. I guess this is how the dealerships keep there shops open.

ausie
02-24-2007, 11:19 AM
One thing to keep in mind, if there is oil consumption present, it could be from the PCV valve as the source since it is common for oil to enter the intake through the PCV system (breather or pcv valve vacuum feed). Many owners install a PCV filter to reduce the amount of oil drawn in by the engine vacuum. More than likely the source of oil if found in the intake and combustion chamber is from the PCV lines. I will not say the tech is wrong about the valve guides but the issue with the PCV systems (lacking baffles and overhead cams) tends to complicate a good diagnosis for the actual source of oil in the combustion chamber. After I installed a PCV filter I noticed that the plastic separator bowl would fill up after 50 miles of driving which is a considerable amount of oil that was prevented from entering the intake plenum. Keep that in mind. However, if there is considerable amount of miles on the odometer, the valve guides or seals may be the probable cause. In my opinion, if you have to have the heads removed due to valve guide issues, you may as well find a suitable shop that will clean, port and polish the ports at the same time. At least that way they will inspect the valve springs, seals and valve seats, etc.... I would check around for the cost and compare that to the $2700 they want for head removal and valve guide replacement. Ford service will send out the heads for the job anyways since they do not typically do that in house.

98 cobra
02-24-2007, 08:24 PM
The odometer reads 29,688. I stopped and talked to another shop that builds and races fox body's out here and is respected as one of the top dogs and he is convinced that I have a pitted bearing in one of my injectors due to it sitting that is causing the warm idle hiccup. The problem is to find out witch one is bad. There seems to be alot of things that could be causing this problem. I started with cleaning the MAF and I am working my way down to the injectors as they are the hardest and most expensive. The PCV is next and then all the other listed in this thread as they won't break the bank. I will keep posting when I go through this to let you all know what cures this pain in my a**. Thanks again for the helpfull info.

ausie
02-25-2007, 08:55 AM
If you find the issue elusive, which it can be at times, the best approach is the basic one that you are following. If the issue is a vacuum leak, it could be as simple as a rubber hose or even the gromet on the valve cover as they tend to dry out over time. If the breather connector or PCV is loose in the existing gromet, it will not cost too much to replace it.

When you decide to tackle the injectors, the best advise I can give you is to get replacement "O" rings from your local ford parts dealer. Package of 16 will cost around $12. Never reuse the old O rings since they can rip easily when removing the injector rails. Before reassembly, lubricate top and bottom O rings with some oil before inserting onto the injector and into the port. The fuel rail should assemble easily. Make sure that you have retrieved all of the old O rings from the port and the fuel rail since they can stick inside the holes and not come out with the injector.

One question, does the idle surge? if it is just a sputter it may be a missfire of the injector so your mechanic may be on the money. One other thing to check when the engine is running at idle would be the battery voltage. You should have around 14vdc at idle and 12vdc with the engine off. A weak or close to dead battery may also cause issues with the PCM and sensor voltages as well as the injector pulse voltage. I think there was another thread regarding a similar issue a few months back.
http://www.svtcobraclub.com/forums/showthread.php?t=12153

ausie
02-25-2007, 09:54 AM
Since you are in the gotta find the idle issue fix, If you pulled the plugs, make sure they are all of the same type. Also inspect the coil packs to see if one has been replaced. In some cases, a cold plug will cause issues with the coil packs. This is more of an issue with the 99+ that use the coil on plug arrangement. It may also be related to a bad spark plug wire. Best to check or inspect the boots on the coil packs as a loose fitting will cause issues.

98 cobra
02-25-2007, 05:01 PM
It is more of a sputter that will shake the car, but not near as bad as that thread of the supercharger. One more thing is that my gas milage has dropped.

ausie
02-26-2007, 05:19 AM
That could be related to a few things, primarily the O2 sensors. Typical replacement interval is 30k to 60k miles. They can go bad eventually which would result in poor driving characteristics. The engine will buck and bog down under hard acceleration. Had this problem with my 96 Explorer. Had a similar situation with Idle but acceleration and driveability issues indicated bad plugs as well as the OBDII codes. Worn electrodes was the fault, shortly after new plugs. That cured most of the issues for a week until performance and drivability increasingly got worse with a Check Engine light indication. Code indicated one of the O2 Sensors. I replaced all three (not dual exhaust) and every thing was great.
Cost of O2 sensor is around $56 each (depends on where you buy them).
O2 sensor replacement will be one of the items on my 04 Cobra this year as preventive measure. Even though they are operating within the specified range, why wait for them to fail. Since you mentioned that you had yours out on several ocassions, that could be one of the issues. They are one component that cannot be cleaned. Since fuel delivery or adjustment of fuel ratio is controlled by the O2 sensors as well as air temperature, mass air flow and load, if one component (primarily the O2 sensor) is off or slow in response the fuel consumtion will increase. The worse it gets, the system will no longer function in closed loop and finally it will operate with a fixed fuel ratio which is running rich. If you noticed a decline in power as well as poor fuel milage that could be the O2 sensors. What is nice about some scan tools is that they have an emissions test mode that allows you to monitor the system. If all is up to snuff, you get a simple pass, but if there is one component out of whack you will either get a slow response bank #x position y.

98 cobra
02-26-2007, 08:15 PM
That might be what I check next. The O2 sensors have been out about three times in the past six months and now I am running mils for my off road h-pipe.
It always sputtered a little, but about two months ago I started my car and noticed that a puff of smoke came out and when I get on it (hard accel) the smoke comes out again like I am running rich. so many things....LOL. I am back to a fifteen hour a day work week so it will have to wait until the weekend, but I think I will replace the O2 before anything else seeing how it can't hurt. Thanks again Ausie...

ausie
02-27-2007, 06:47 AM
If it was caused by the mills you would know it by the check engine light. I would almost suspect that the remianing O2's if at fault would have set off the check engine light. If it is the O2 sensors, perhaps the mill eliminators are masking the issue. My thoughts on your issue still leans towards a vacuum leak or bad plug wire or a leaking EGR valve.

When you get on it, does it bog down and sputter like the engine is being choked off? When the O2 system is running on open loop that is what will happen. Another trick would be to dump the EPROM memory that the PCM modifies to correct operating parameters used for fuel ratio corrections and other things like the load table and so on. All you need to do is to disconnect the battery for more than 1/2 hour. If you are going to replace the O2 sensors, that would be the time to dump the EPROM memory so it can recalculate all of the runnig parameters instead of operate off of old data. I am sure that there is a solution to your problem but may take some time to discover it.

One other thing to consider, if your temp guage is sitting on the low side, check your coolant level. If you are low in coolant that may cause the engine temperature sending unit to misread the actual engine temp. Why check this? The PCM also makes use of the engine temperature to adjust fuel ratio. If the coolant is fine, it could be the electrical connector on the temperature sending unit that may be loose.

98 cobra
02-28-2007, 05:06 PM
It does not boug down at all, but smokes a little when I get on it like it is burning rich. There is also a rich smell after first start up and sometimes hesitates or dies when first starting.
I will check the wires out since the new plugs did not really fix the problem and will price out the EGR valve.
I Pulled off the battery cables to see if that helps also. I would think after three tries at the dealership they would have found a vaccum leak if there was one.
It is strange that it has always had a little sputter than two or three months ago it got a little worse and also started to run rich all at the same time.

I am about to let it go and buy an 03-04 as that is really what I want, but mama says differently and seems to put the pants on a liitle faster than me in the morning.

ausie
03-01-2007, 06:58 AM
The EGR valve may contribute to the rough idel but will not cause it to run rich. A faulty EGR will create a leaning out condition if it is leaking. If you do not get any pinging (due to lean A/F) it may not be the EGR causing the problem. What I have noticed with the EGR on the 01 and 04 if operating properly, it will cycle on and off every one to two minutes after start up. With the hood up, you will hear it click (just as loud as the AC compressor clutch activating).

The issue with the O2 sensor should only happen after warm up since the Emissions system runs in open loop when cold (on the rich side). If it runs rich when at operating temperature, Emissions system is operating in closed loop and is regulating the A/F mixture it may be a slow response on the O2 sensor. If it fails, the check engine light should come on, or there should be a pending code on the O2 sensors. At that point, the engine would bogg when accelerating under WOT but would operate fine with slow advance on the throttle. There could also be an issue with timming as well. Sometimes the crank shaft position sensor may be at fault and the ignition timming gets out of whack. That is not a cheap part to replace. If for any reason timming gets too far advanced or retarded, would result in incomplete burning of the fuel mixure and loss of power. That is one part I do not think of often.

98 cobra
03-01-2007, 07:46 AM
The battery test did not help. It still runs the same after unpluuging it for an hour. I am going to replace the wires and regap the plugs this weekend to X out that factor. I do hear a metalic click from the engine compartment cycling every 15-20 seconds until warm up. I believe this thing is going to nickel and dime to the ground to find this problem.
If I can't find the problem I will take it to another ford dealership in VA when I go there in a couple a weeks, but will check to see if they have techs that have done work on these cars first as that was the case here in Oklahoma. I will keep posting as this progress goes on.
Thanks

98 cobra
03-02-2007, 06:59 PM
I recently took the EGR valve off and cleaned it with B22 and regapped the plugs and it still continues to sputter. God only knows why this car is doing this to me.

ausie
03-03-2007, 10:11 AM
That clicking noise should be the EGR diaphram valve which is normal. If you did not hear it turn on and off during the warm up cycle of the engine then you could suspect an issue with the EGR valve. At this point, you could probably rule out a vacuum leak since that would result in RPM surge which causes the engine to run lean and the RPM speeds up as a result since it is getting more air than it should for steady idle speed.

If you have cleaned the MAF, checked the plugs and regapped them, inspected wires along with everything else. Dumping the EPROM memory would cause the PCM to re-calibrate all of the running parameters and with most cases it would correct any bad data it collected previously unless there is an issue that is allowing the A/F to run rich. This could point to several components. For starters, what is the condition of the Air filter? You mentioned earlier that you had a K&N filter. Try removing the filter and then start up the car. It could be that simple if the filter is either saturated or clogged and getting a replacement would be the fix. I would doubt that is the problem. It could be related to a faulty fuel pressure regulator which would also contribute to the rich idle and poor off the line acceleration.

98 cobra
03-04-2007, 10:46 AM
That clicking is coming from below the air compressor, but is not the compressor. I recently took it to another shop for free advice and they think it is a fuel system or injector problem. I think you are right and saying that it will probably be a time consuming process to find this issue.

ausie
03-04-2007, 12:41 PM
That clicking is coming from below the air compressor, but is not the compressor. I recently took it to another shop for free advice and they think it is a fuel system or injector problem. I think you are right and saying that it will probably be a time consuming process to find this issue.
:eek: that is odd. I hope the noise is not from your water pump. Since you are running a mid pipe with no cats, at least you do not have to worry about them getting clogged up from the rich condition. I would check coolant level if you have not done so yet. Also a good idea to locate both temperature sending units (one is for the guage and the other for the PCM, may be closer to the water pump). Check the wire connectors to each. Sometimes they can become loose which would result in low temperature readings. IF the PCM temperature sending unit is not working properly or has a loose connection to it the engine would appear to be operating cold which would also increase the amount of fuel. Also if the thermostat is stuck open this will also cause the engine from reaching operating temperature along with some other issues like overheating if you are on a long drive.

If it turns out to just be the fuel pressure regulator, the cost should not be that much to have replaced. Hopefully that is all it is.

Rons98SVT
03-04-2007, 08:49 PM
Have you checked the fuel filter ?

ausie
03-05-2007, 06:32 AM
Dirty MAF TSB. Found this today. Describes the condition of a dirty or contaminated MAF sensor.

http://www.ford-trucks.com/tsb/fulltext/show_article.php?tsb=98-23-10

Rons98SVT
03-05-2007, 07:06 AM
Great info. :thumbsup:

98 cobra
03-07-2007, 08:43 AM
For some reason or other the hiccup has quieted down a little after I put 93 octane in, but still there. I went out to start it yeaterday and right after I started it it surged up to 1300 rpm them died. Then when I started it it fired right up. Strange huh. It does this once in awhile. So far the plugs have been replaced and regapped, the AIC was taken off and cleaned with b22, filter and pump replaced 10,000 miles ago. Don't get me wrong, the car drives great, but has this annoying attitude that I would like to get rid of.

I went and talked to the tech that worked on my car at the track last weekend and he said that the compression and fuel pressure is all great, but won't rule out the regulator. Everyone I talk to just scratch their heads at my car. I was encouraged to get a programmer and get a dyno tune to see if that will work out any iregularities from the small amount of mods I did to the car. SBCT ot diablo?

As far as the coolant level, I am getting it flushed this week and all fluids flushed for this 1400 mile trip to Virginia.

99cobra~
03-27-2007, 10:18 PM
egr bad???

98 cobra
04-24-2007, 04:00 PM
I was told the EGR valve was working just fine by another tech here in VA. were I had to bring the car for a class I am taking. ( about 1500 miles from home).

I will tell you that after driving for about eight hours straight the issue got worse and when there was a load on the engine like the air being on it pretty much stopped at idle.

I found an IAC valve off a wrecked low milage cobra (ten bucks)that I a will be throwing on in a couple of weeks to see if that is the issue. If not, I will slapping in a new EGR Valve when I find one that won't cost me 150 bucks.

I haven't given up yet...LOL

Thanks for all the help.

ausie
04-25-2007, 07:20 AM
If everything checks out fine, and you cannot find a leaky vacuum line, you may want to inspect the throttle body shaft since that can also be a source for leaks (where the springs and throttle arm are attached). Also, it could be related to either tune (in regards to timming) , or crankshaft position sensor. I would check the alternator output to make sure it is operating within spec as well as check the battery for bad cells. If the battery is on the way out, it will load the electrical system to some degree which pulls the 5 volt supply down too. Once the voltage of the regulated 5 volt suppy drops, all of the reference voltages will also decrease resulting in out of whack measurements from the various sensors. Just something to consider but may not be the cause.

98 cobra
12-20-2007, 09:31 AM
Thanks for all the advice. I finally found the issue and wow what an expensive one. I have a bad cam and not sure which one so looks like it is time for a cam wap.:( I am looking and would take any advice on a good set that would make it a good street, but a little more aggresive. Something that will compliment a later application KB.


Thanks

ProfChaos
12-27-2007, 11:48 PM
Thanks for all the advice. I finally found the issue and wow what an expensive one. I have a bad cam and not sure which one so looks like it is time for a cam wap.:( I am looking and would take any advice on a good set that would make it a good street, but a little more aggresive. Something that will compliment a later application KB.


Thanks


Sean Hyland Motorsports offers a cam re-grinding service for 4.6L DOHC Camshafts (http://www.seanhylandmotorsport.com/online/product_info.php?cPath=103_98_28&products_id=127).

Unless you make other arrangements ahead of time, there is a core fee charged to your credit card until the camshaft core exchange takes place, but Sean Hyland Motorsports will grind camshafts to suit your tastes, as specified on the page at the above link.

cheers,
--Professor Chaos

brkntrxn
01-01-2008, 10:33 AM
How was "a bad cam" diagnosed and by whom? Did they pull the valve coves off and physically spec the cam with a micrometer? If you have a cam that is going bad, something is causing it.

Something that I did not see mentioned and I may have missed it. Did you try clocking the mass air meter?

98 cobra
01-12-2008, 08:01 PM
There was never a tear down to inspect, but all the techs I talked to ran the car on diagnostics and all three tell be it is mechanical and 99% sure it was a bad cam. It only hiccups and misses at warm idle and the rpms jump around from 650 - 725. I hear so much good advice on this website and am trying everything mentioned, but nothing is locating this hiccup. I am curious about this clocking of the mas air meter. What is it?

This cobra only has 38,000 miles and has had this issue since I bought it with only 17,000 miles, but got worse as I added mods. wierd huh.....



Kasey

blk04cobra1
01-13-2008, 11:24 AM
I am curious about this clocking of the mas air meter. What is it

Kasey
sometimes if the MAF gets moved, it can throw off your tune. sometimes MAF's like to be positioned a certain way and by "clocking" it slightly can help. If you've taken it to several tech's and they've said bad cam, then just pull it and put in a nice new set of cams and springs :thumbsup:

brkntrxn
01-13-2008, 01:32 PM
In my opinion (take it for what it is worth), if a cam was causing the issue it would happen at all times, not just warm idle. I'd also be suspect of a bad cam diagnosis without the valve covers coming off the car.

As Torrey explained, as the air tumbles and flows through the MAF, the MAF can be sensitive to where it is phsyically placed in the flow of the air stream. By clocking it (physically rotating it counter- or clock-wise) within the related tubing, you can change where it is phsyically sampling in the air stream. This commonly happens after a cold air intake is added to a car.

98 cobra
01-13-2008, 02:10 PM
I have never heard of that and will give it a try. No one has ever mentioned that to me before. As you can read from this long lasting thread that this issue has been a probablem for a long time and I am pretty sure I have tryed everything except that. New plugs, wires, coils, compresion test, fuel system check and flush, IAC and nothing yet has found it and when monitored they just can't isolate it. Pretty confusing and telling me it is cams might just be a cop out for them not being able to find. :mad:

I'll give it a try and thanks again......

Kasey

brkntrxn
01-14-2008, 11:37 AM
No problem. Just rotate it a bit at a time and see if it affects the idle quality.

For instance, we had to rotate the MAF on Torrey's car (the twin turbo in his sig) about 1/4 turn to play with the idle quality so I could drive it to a car show one day right after the build was complete.

On my 99, we had to play with the clocking after I redid all of the blower piping and went from an old Pro-M Univer to a C&L housing with an 03 MAF card.

While it is not overly common, it is far from rare as being the culprit to the issue you described. No promises, hopefully it will do the trick for you.

Shoot me a PM if you need more info and I can point you to a few reading sources.