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View Full Version : Happy camper, awesome new cobra but one problem


cobrawannabe
05-30-2007, 08:34 PM
Got my cobra from Orlando and the only problem I see is that the engine dies sometimes while idling. It also kinda misses while accelerating slowly but not when hammering on it. The guy before me took off the catalytic converters (probably has nothing to do with the problem I'm having) and the Check engine light is on and ford told me with their computer that, that was caused by the cats being taken off. Could it be the O2 sensors or the Idle air control valve? Can anybody help me, I don't know if this is the right place to put this but let me know. The compression check came back and she is putting 439 hp to the wheels, just fyi. Thanks for any help fellows, I'm new so don't beat me up to bad! One more thing, I changed the oil and the engine took 8 quarts to fill the crankcase!

cobrabitn
05-30-2007, 08:47 PM
Your off road pipe is causing the light to trip and for your car to ide rough. Your car needs a tune where they can turn off the MIL light and can make the car idle smoothly.

Your Cobra does not take 8 quarts to fill up. It should be 6.5 quarts so your crank case is over full. You might want to drain some of the oil out.

Congrats on the purchase! :thumbsup:

cobrawannabe
05-30-2007, 09:45 PM
not up to speed on a "tune". what do I need to do to get a "tune"? If I put my catalytic converters back on, will my car quit sputtering at slow acceleration and decelleration? I appreciate any help!

red04svtcobra
05-30-2007, 11:33 PM
congrats on the purchase bro. As Tony was saying it should not be 8 quarts to fill up. I put 6 in mine as the manual says. I would drain some out before you drive it anymore.

red04svtcobra
05-30-2007, 11:35 PM
not up to speed on a "tune". what do I need to do to get a "tune"? If I put my catalytic converters back on, will my car quit sputtering at slow acceleration and decelleration? I appreciate any help!What you need is a dyno tune (best) or a handheld tune. this way your car is not lean at WOT and safe!!

Pro-Dyno
05-31-2007, 02:28 AM
The cats being gone are probably affecting back pressure and causing the car to die at idle the other issue is ford had an issue with staling on the 03's it should be able to be fixed with a tune

;)

JROC
05-31-2007, 04:01 AM
Congrats on the Cobra. :thumbsup:

ausie
05-31-2007, 06:22 AM
Congrats on the new ride. I would agree that the 8 quarts is a bit too much. The 4.6L block takes only 6 quarts. Considering the cost of the catted mid pipe (unless you got the original with the purchase) I would go with a high flow arrangement from Bassani. Definately have a tune (in order to correct the idle and low engine operation as well as verify that the A/F ratio is where it should be). Best to have it done after installing the catted mid pipe or at the same time. Also you may want to check or replace the sparkplugs since that can cause issues if they are old (electrods could be worn down or depostis may be causing the sputter or miss).

cobrawannabe
05-31-2007, 03:03 PM
Where do I go for a tune? I live in Louisiana so there are not many places in my rural area?

XCOBRAX
05-31-2007, 03:30 PM
One source for a location that can do a tune is to look for places in your area that have a dyno. Then.. ask around about the quality of their tunes.

Here is a link to locations that have Mustang Dynos.
http://www.mustangdyne.com/locator.htm

spincobra03
05-31-2007, 04:26 PM
I had great service with pro-dyno, they can do a mail order tune for you. All you have to do is give dan a call and he can explain everything. Those guys not only did a great job on my car but they explained what they were doing and I learned alot about my car during the process. You wont be disappointed. His number is 1-704-651-3807 :)

spincobra03
05-31-2007, 04:30 PM
[QUOTE=cobrawannabe]Where do I go for a tune? I live in Louisiana so there are not many places in my rural area?

Just so you know they are out of South Carolina but I live in Boston Massacusetts and they got my car running great and its never left boston, All you have to do is find a shop that has a dyno and access to a computer and they will take care of the rest.

cobrawannabe
05-31-2007, 05:15 PM
sorry for all the questions but how much can I expect to spend for a tune and should I put the cats back on before I do the tune?

blk04cobra1
05-31-2007, 07:15 PM
Great advice from the above posts...like many said, drain some of that oil out...also, the stall at idle could also be your IAC going bad...very easy to replace to see if that fixes your problem...as for the sputtering, you probably do need a tune...one more thing, you said the compression check came back and it put down 439rwhp, do you have the graph or numbers from the compression test? If it put down 439rwhp, then it shouldnt be sputtering (if it were tuned properly).

cobrawannabe
05-31-2007, 07:34 PM
I have the graph from the dyno. No numbers from compression check. Can the Idle air control valve cause her to sputter at constant speed?

red04svtcobra
05-31-2007, 07:34 PM
I had great service with pro-dyno, they can do a mail order tune for you. All you have to do is give dan a call and he can explain everything. Those guys not only did a great job on my car but they explained what they were doing and I learned alot about my car during the process. You wont be disappointed. His number is 1-704-651-3807 :)I too have had great services with Pro-Dyno. They tune my Lightning :).

red04svtcobra
05-31-2007, 07:37 PM
sorry for all the questions but how much can I expect to spend for a tune and should I put the cats back on before I do the tune?Your best bet would be to call a tuner. You will need to buy a handheld tuner and they will put a tune in it for you and flash the computer. Look at spending roughly $400-500 for a handheld device with tune.

cobrawannabe
05-31-2007, 08:45 PM
Just found out that the dealership put 5W-30 in my cobra instead 5w-20. I think probably not but is that why he had to put 8 quarts to fill? The dip stick shows right at max on the dip stick not over. I have not driven it since I changed the oil so I will drain some out before I drive again.

red04svtcobra
06-01-2007, 01:15 AM
Just found out that the dealership put 5W-30 in my cobra instead 5w-20. I think probably not but is that why he had to put 8 quarts to fill? The dip stick shows right at max on the dip stick not over. I have not driven it since I changed the oil so I will drain some out before I drive again.
putting a diffent oil weight doesn't mean it needs more or less. This is why I do my own oil changes. don't go by the dipstick because it may have a diffent one in there. put what the manual says and then mark the dipstick where it hits. My lightning shows that I need to add oil but it has the proper amount. hope this helps, Chris

ausie
06-01-2007, 06:42 AM
two things, Chris may be on to something there if the dip stick is not original or if the guide tube was removed and or replaced at some time (removing headers may require removal of dip stick tube). Check to see if the stock exhaust is still in place (cast iron exhaust manifold) when you look down around the heads. If you see headers instead of the cast iron exhaust that may explain a few things at least in terms of the dip stick issue. Assuming the dip stick guide has not been removed, the factory dip stick should be a stainless braided wire with a cast metal end (should not be flat ribbon steel). The mechanic could have used mechanic's quarts, or if the mechanic was really sloppy when adding the oil. 6 quarts will show on the dip stick end as being 3/4' of the way up on the cast end.

The second issue could be if the oil pan was replaced with a larger capacity pan. This is just speculation but plausible if any work was done on the engine by the original owner.

Sometimes sputtering can be related to the spark plugs (depending on the gap or condition of the plugs).

blk04cobra1
06-01-2007, 09:12 AM
I have the graph from the dyno. No numbers from compression check. Can the Idle air control valve cause her to sputter at constant speed?
no, but like Ausie said your plugs could if they've been fouled...sounds like the there's something in the tune that definitely needs to be fixed, but it could also be partly mechanical...I know you said you live in Louisiana, but there has to be a performance or general repair place near by...

Ram77mus
06-01-2007, 05:28 PM
If you would like to see if the idle air valve is the shutter your talking about unplug it and drive the car. Now the car will no longer try to idle on it's own but you can drive it just fine. I would change the plugs in it(NGK tr-6 gapped @.32-.34)If your check engine light is on from the cat's then you can put MIL eliminators inline and that should make the light stay off.

ausie
06-02-2007, 08:11 AM
My hunch is on the 02 sensors since it has flagged an error. I had a similar issue with my explorer that had a bad 02 sensor. When accelerating slowly everything was fine but attempting to get the vehicle out of its own way would cause severe hesitation and stumbling. If the check engine light is on, I would take it to a local auto parts shop that will read the codes for you. Once the computer detects an error with the 02 sensors it will operate in open loop and run very rich which is not good if the extra fuel washes off the oil film on the cylinder walls. That sounds like something you need to have checked out. Once corrected it will probably make more power at the wheels.

red04svtcobra
06-02-2007, 03:01 PM
I have learned alot from just reading and posting in this thread. Something I did not know about with the o2 sensors.

blueblazes
06-03-2007, 12:35 AM
was this the car you posted about week or 2 ago about buying? If so you said it had longtubes and I would be willing to bet that the person who put them on didnt take car to make sure the dipstick was reinstalled properly.

Before you drive the car anymore I would strongly recommend draining all the oil from the car and putting 6qts back in it. UNLESS you look under the car and see an aftermarket oil pan such as canton. Its usually not hard to tell alot of times they are bright silver <aluminum color> or goldish in color. Then it is most likely a 7qt pan. Either way you should drain the oil and refill it with either 6 or 7qts of oil, depending on which oil pan you have.

As others have said the check engine light coming on is from the rear o2 sensors, its a common issue when putting on an xpipe and not having a tune to cut the rear o2's off. You can purchase a set of mil-eliminators or if you get the car tuned they can turn them off then.

The stall is known problem with 03 cobras take it to local ford dealer and see if they will reflash the pcm with the stall fix. They may not if its out of warranty, if they wont then best bet would be to just have the car tuned and a tuner can use the most update flash for the pcm.

Also can you post up the graph of where the car was on the dyno? When it was dyno'ed did they measure the a/f ratio? What was the a/f like? It should be around 14.6 idling <this is stoich for gas> and then under wot should be less than 12.0 to 1. If its on stock tune then it should get really fat as rpm increases.

Was this a dyno shop you went to and got it dyno'ed or did the person selling you the car just give you a graph?


Like dan said earlier get you some ngk tr6's should be no more than 13-18 bucks at local parts store and gap them to about .035. Dont use those cheap circular gapping tools find you a little set of feeler gauges shouldnt be more than few bucks and use that to gap your plugs out.

Hope that helps

ausie
06-03-2007, 10:01 AM
Yep, once the O2 sensors become sluggish in response time the performance will suffer to some degree. The primary O2 sensors are what regulate A/F ratio and the secondary O2 sensors are used for fine adjustments and probably EGR control. O2 sensors work like a thrermopyle since they generate a low voltage when in the presence of Oxygen and heat. They will not work when cold so your engine operates in open loop during warm up. Once hot, they will generate a milivolt signal (0.23v up to 0.85v or higher) depending on the level of oxygen in the exhaust. Excessive heat, carbon deposits, and moisture will damage the O2 sensor over time. They do have a replacement life of around 60k miles. In my opinion, if you have moderate milage and you want a tune, best to replace the O2 sensors with new ones to eliminate issues with degraded parts since they are used to monitor and regualte the A/F ratio. There is a ton of information on the web on how O2 sensors work, how they fail, and so forth.

When adding long tube headers, the increase in scavaging will change the A/F ratio to some degree and would be a good idea to have the A/F checked or tuned to compensate. Backpressure of the existing factory setup will reduce the amount of fresh air/fuel charge that gets pulled out from the exhaust valve before it closes (the essence of scavaging which draws out all of the burned fuel and some fresh unburned fuel). The amount of scavaging is also in relation to the cam overlap as well but since they optimized the lobes of the cams for use with forced induction, the overlap is not as great as it would be for a NA application. There is also more info on the net if you did a search on exhaust scavaging. The size of the primary tubes and shape of collector also plays an important role in scavaging.

red04svtcobra
06-03-2007, 03:40 PM
Yep, once the O2 sensors become sluggish in response time the performance will suffer to some degree. The primary O2 sensors are what regulate A/F ratio and the secondary O2 sensors are used for fine adjustments and probably EGR control. O2 sensors work like a thrermopyle since they generate a low voltage when in the presence of Oxygen and heat. They will not work when cold so your engine operates in open loop during warm up. Once hot, they will generate a milivolt signal (0.23v up to 0.85v or higher) depending on the level of oxygen in the exhaust. Excessive heat, carbon deposits, and moisture will damage the O2 sensor over time. They do have a replacement life of around 60k miles. In my opinion, if you have moderate milage and you want a tune, best to replace the O2 sensors with new ones to eliminate issues with degraded parts since they are used to monitor and regualte the A/F ratio. There is a ton of information on the web on how O2 sensors work, how they fail, and so forth.

When adding long tube headers, the increase in scavaging will change the A/F ratio to some degree and would be a good idea to have the A/F checked or tuned to compensate. Backpressure of the existing factory setup will reduce the amount of fresh air/fuel charge that gets pulled out from the exhaust valve before it closes (the essence of scavaging which draws out all of the burned fuel and some fresh unburned fuel). The amount of scavaging is also in relation to the cam overlap as well but since they optimized the lobes of the cams for use with forced induction, the overlap is not as great as it would be for a NA application. There is also more info on the net if you did a search on exhaust scavaging. The size of the primary tubes and shape of collector also plays an important role in scavaging.WOW, great post. Didn't realize there was that much to learn about O2 sensors.