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hiosilver
01-16-2006, 12:11 PM
I just purchased my SVT and have a question about engine managment. It appears that the engine does not want to come down in RPM when I let off the gas. When I shift gears there is practacally no drop in RPM when I let off and push the clutch in. When I slow down for a light, the RPM's will drop to around 1400 and then after several seconds drops to around 850. All other functions are normal. I have checked for a physical obstruction in the linkage but it appears as if the computer is controlling the fuel injection to allow the RPM's to drop slowly. Perhaps this is a normal function to comply with emission requirements but it is annoying. Does everyone else's car do this too? Thanks for a great forum and I hope someone can help.

Pat

AirForce1
01-16-2006, 01:23 PM
No, it should not do that...... it can be the computer in the car.

I would take it to a performance shop and let them reset the rpm on the chip.

Or it could be the throttle control sensor on the throttle body is bad. If that is the case you can take it to the ford dealer and have them order a new one and have them put it on.

Good luck let us know.:thumbsup:

hiosilver
01-16-2006, 06:44 PM
Thanks for your reply, I appreciate your suggestions. I am very much a do-it-yourselfer and would like to fix this on my own. I found online a very detailed discription of OBDII engine managment and it lists the checks I can make to test the throttle position sensor and some of the other sensors that effect idle. I do have a OBDII scanner but it did not set any trouble codes. I am going to find another person with a manual transmission and see if it does the same thing. You would never notice this problem with an automatic. I will let you know what I find.

Thanks again Airforce1

cobrabitn
01-16-2006, 07:07 PM
Don't bother trying to fix it on your own as there is a TSB on that problem from Ford. Take it to the dealership and they will reflash the computer to solve the idle issue. I would ask them first but I'm 99% sure there is a TSB on it.

:D

ausie
01-17-2006, 07:00 AM
That does not sound good, I had the same problem with my 01 for a short time. What I found was that the throttle stop was not where it should be (throttle would stay slightly open ocassionally). Punching the gas would correct the issue. The throttle would not always return to the closed position. Look for varnish buildup at the bottom of the throttle plate interface. I eventually took off the throttle body and cleaned it by hand with solvents as well as removing the upper plenum plate due to the amount of gunk in it. The build up may be in the shaft of the throttle and not on the plate itself. Before I did this, I replaced the IAC since it threw a code but replacing the IAC did not fix the issue and it repeated itself. Even after cleaning the throttle plate assembly did improve some of the issues but did not completely cure it. On a long shot, I decided to replace the EGR valve and bingo problem solved. However, replacing the EGR may not fix what you are experiencing plus it is expensive for a long shot. I did have other issues (pinging and carbon buildup which were probably related to each other) but after replacing the EGR valve it performed better than it did when I took it home from the dealership. I would not doubt that it may be code related so definately have a check on the TSB's from the ford dealer.

hiosilver
01-17-2006, 06:19 PM
Thanks guys, I went out today and took the intake boot off and looked at the throttle plates and intake runners. They were fairly clean and the plates seem to come back to the same place each time. I also checked the EGR valve vacuum hosing and they all look good. The car only has 39K miles but it does not mean the EGR isn't bad. I looked for a TSB that covered the idle system and could not find one online but will talk to the Ford dealer tomorrow. I think you are right cobrabitn, the computer appears to need re-programming because when I first start the car, the RPM's go up to about 2K without me putting my foot on the gas pedal and then slowly comes back to idle.

I sure am learning a lot about engine managment and OBDII.

Pat

ausie
01-18-2006, 07:02 AM
Pat, There is one thing to know about the TSB's, some are not published to the general public. Ford may have some issued but not released.

It may be code related so having the computer reflashed for the idle issue would be a good thing. This may also be the same TSB for the stalling issue too.

hiosilver
01-19-2006, 09:37 AM
Thanks Ausie, I went down to the Ford dealer and looked up TSB's for idle issues and could not find any. If I had a number, it would be easier but he was going to talk with the regional manager and get back to me today. He said he would reflash the computer memory, if he could find a TSB that was close. I did not mention a stalling problem because mine doesn't stall but maybe the two complaints are related in one TSB, so will mention it to him today. He did say that he was not an SVT dealer so did not have anyone who knew them real well so I may have to go into Seattle to find a dealer who knows the SVT engine.

I worked for the FAA in Allentown for four years--sorry but I could not wait to get back to Seattle.

Thanks for your help

Pat

ausie
01-20-2006, 06:34 AM
Pat, I am not sure what FAA is (Federal Aviation Authority?) If the dealer does reflash the chip and the problem returns I still have a hunch that it is related to the throttle body.

It could be binding in the throttle calbe..... With the car off, apply the throttle on the gas pedal a few times but slowly. Lift off the gas pedal slowly and then inspect the throttle linkage at the throttle body. If you can pull the linkage towards the closed position, chances are the cable may be binding (most likely at the gas pedal attachment area). If you look under the dash where the throttle cable enters the firewall, there is a ball end on a plastic sleeve that feeds throught the top of the gas pedal.

hiosilver
01-20-2006, 08:51 AM
The FAA is the Federal Aviation Administration. I was an aircraft safety inspector. We tried to make sure the airplanes you fly on were safe and well maintained. I worked out at the ABE airport.

You may be right about the cable, I have always run the throttle plate by hand right at the engine side so bypassed the cable completely. I did measure the throttle position sensor with an ohmeter and it appears to react normally. I haven't heard back from the Ford service manager yet, perhaps today. Meanwhile I will check the cable too.

Thanks, Ausie I do appreciate the help.

Pat

AirForce1
01-20-2006, 11:11 AM
:thumbsup: The FAA is the Federal Aviation Administration. I was an aircraft safety inspector. We tried to make sure the airplanes you fly on were safe and well maintained. I worked out at the ABE airport.

You may be right about the cable, I have always run the throttle plate by hand right at the engine side so bypassed the cable completely. I did measure the throttle position sensor with an ohmeter and it appears to react normally. I haven't heard back from the Ford service manager yet, perhaps today. Meanwhile I will check the cable too.

Thanks, Ausie I do appreciate the help.

Pat You were an FAA safty inspector? My dad and I are private pilots.:thumbsup:

I earned my license in March of 2003. I have my private and I am working on my instrument and ATP.:eek: I am only 22 and I have about 500 hours, and my dad has about 5,500 hours. (give or take a hundred)

I also flew T-38's in AirForce ROTC.

I hope you get everything settled :thumbsup:

flynfink
01-20-2006, 01:11 PM
:thumbsup:
You were a FAA safty inspector?

My dad and I are private pilots.:thumbsup:

I got my license in march of 2003. I have my private and i am working on my instroment and ATP.:eek: and i am only 22. I have about 500 hours and my dad has 5,500 hours.

I also flew T-38's for the AirForce ROTC.

I hope you get every thing settled :thumbsup:

OK, please work on your typing skills.... :doubt:

AirForce1
01-20-2006, 07:56 PM
OK, please work on your typing skills.... :doubt:Sorry i was in a hurry.:eek: I am about to fix it.:thumbsup:

hiosilver
01-21-2006, 09:09 AM
Airforce1:

The idea came across just fine--I am not an English teacher. I am a private pilot too and so is my son. He is just about to take the CFI flight test and has all of the other ratings including multi-engine. I worked for NASA in California for 15 years but never got to fly any of the T-38's. Aviation is a small world, nice to know we have the same taste in cars too.

I did the tests that Ausie suggested and the throttle comes back to the same place every time. I measured the resistance of the throttle position sensor and it is smooth and even. I still believe I have a computer problem but the Ford dealer has not been able to get in touch with the regional rep yet. I may have to take it to one of the larger dealers in Seattle.

Sorry to take some of the bandwith for non-Cobra related stuff.

Pat

ausie
01-21-2006, 10:47 AM
Pat, The 01 Coupe had a few problems that ford was unable to fix (they kept telling me there was nothing wrong with it). Most of the issues I was able to fix on my own including the throttle issue you described. The RPM used to stay at the point when the clutch was put in. If I shifted at 5000RPM the engine would stay running at 5000RPM with no throttle input (foot off the gas pedal). IF for any reason the engine speed races to the fuel shut off point, more than likely there is and obstruction on the gas pedal. I do not believe it is getting stuck at WOT since it is not banging the redline as was the case with my 04 when the throttle got stuck by the carpet.

On the flip side, if for any reason the engine is running lean after accelerating (getting more air than it should for the amount of applied fuel) it will tend to respond to some degree in the same manner. That would either mean that there is an issue with the A/F curves or a bug in the chip. Or a vacuum leak allowing for unmetered air to enter the intake (Do you get any pinging under hard acceleration when the motor is at operating temperature?), or excessive EGR from a stuck EGR valve or faulty O2 sensors.

IT may be probable that the IAC is not functioning properly. Since the IAC is nothing more than a solenoid (where as some manufactures use stepper motors) it is possible that the pintle of the IAC is dirty, dirt on the valve seat, or a weak return spring. This component can be cleaned, but if not done properly may cause damage to the coil of the IAC valve but that would result in a check engine light (only if the throttle position sensor is indicating a closed throttle position).

One thing I amost overlooked,,,,,, If it gets difficult to shift when the RPMS are hanging while moving, the clutch cable may need some adjustment. When the clutch and pressure plate expand with increase in temperature, and if the pressure plate does not open up far enought, the slightest friction between the clutch and pressure plate will hold up the RPM. Almost as if there was a very heavy flywheel on the crankshaft. The mass of the steel flywheel on the 99-01 Cobra's is much greater than that on the 03/04's. If there was a way to find out if the clutch was replaced, it may be the total mass of the pressure plate and flywheel is more than it should be. That is one big difference I noticed with the 04, the RPM drops like a dead fly when shifting when compared to the 2001 which seemed a bit slow in RPM response.

The last thing if not mentioned previously, check the PCV valve. Pull if off of the valve cover while the engine is running at idle and put your finger at the bottom of the PCV valve. if you do not feel any suction or vacuum, there may be an obstruction in the PCV valve, PCV line or in the Plenum channel. If there is no vacuum, it is possible that the intake will pull in air throught the brealther line (but your throttle body would not be very clean).

Also, another issue relating to vacuum leaks. If the intake plenum was taken apart (upper housing removed). It is probable it was not put back on correctly. If it was not carefully installed, there may be a nick in the rubber seal. It is almost fool proof since the seal is mounted in a plastic spacer. However if there is a crack in the plastic, or if the rubber seal was damaged it will cause excessive air to enter the intake. It may not be present on a cold engine but once it heats up and expands you may get some issues similar.

The last bit, dump the EEPROM. Disconnect the battery neg cable for a minimum of 1/2 hour. Just resetting the codes or clearing them with a scan tool will not erase any data stored in the EEPROM. By dumping the EEPROM the ECU will have to relearn the operating parameters it uses to adjust or compensate for variances in the sensors and or other aspects of the motor. The code may be the same for all the ECU's but there are differences in the motors. Since it is a self learning program it may have collected data that no longer applies if the air filter , spark plugs, or other related components were changed.

Hopefully this is not one of those mystery issues that nobody can solve.

ausie
01-22-2006, 10:40 AM
oops, that sounded a bit general, in other words; my 01 Cobra had isssues. And the dealership I went to was an SVT authorized dealership.

hiosilver
01-23-2006, 05:34 PM
Ausie:


It took a while to read all of that but I understood it all. I am not sure if the plugs have ever been changed but I know the intake has never been off. The car never pings even on hard acceleration. The engine is very clean and there appears to be no vacuum leaks anywhere. The idle is very smooth (when it finally gets there) and the gas pedal is not sticking. The one thing I did notice is that if the RPMS are fairly low, less than 2500 when I shift, the RPM will drop some, but if I wind it out to 4 or 5K it just seems to stay there and only drops because the car is in a higher gear when I let the clutch out. Speaking of the clutch, the car only has 39K on it so the clutch has not been changed and seems to work nicely. I will try to reset the EEPROM by disconnecting the battery for half an hour and see if that changes anything.

I still have not heard back from the Ford dealer but I did find a TSB that deals with this same problem but on the 3.8L V6.

Thanks again, I appreciate your staying with this.

Pat

ausie
01-24-2006, 06:59 AM
this may be of interest: it appears when I changed my IAC and replaced the gasket, the hole size may have been smaller than the original. When I found this in modular fords, it may be of help.....


http://www.modularfords.com/forums/mustang-gt/slow-dropping-hanging-rpm-fix-2v-and-4v-27761.html?highlight=hanging+rpm

hiosilver
01-24-2006, 08:49 AM
Ausie:

What a find! I am an aircraft mechanic and can make one of those plates easily. I had to put brakes on all the way around but when I finish that, I will try the restrictor plate. I have never seen a car wear out the rear brakes in 40K miles, perhaps the previous owner drove with the parking brake on for a while.

Thanks for finding the perfect solution, or so it seems.

Pat

Bartman01
01-24-2006, 02:23 PM
Ausie:
I have never seen a car wear out the rear brakes in 40K miles, perhaps the previous owner drove with the parking brake on for a while.
Pat

A couple of track events will do that too. Between two track events (one 1 day and one 2 day), and 37k of street driving my rear brakes were getting pretty low.

ausie
01-25-2006, 06:19 AM
The stock brake pads should probably last a minimum of 4 years (if not longer) for street driving. The stock brake pads are great but cost far more than the aftermarket cheapo's found at Pep Boys or autozone. I made the mistake on the second year of ownership to replace all of the pads on the 01 (having been a ford owner for some time now I was used to replacing brake pads yearly on my explorer, and Escort GT). The difference between new and the 2 year old pads was not even noticable. Do you still have the stock solid surface rotors? Cross drilled or slotted rotors will cut down the pads quicker. From what I read about non-stock, the slotted rotors are not worth the money. As for the cross drilled, some are better than others but they can crack over time or hard use. They are good but you need to inspect them on a regular basis to prevent failure if they get cracks between the holes.

Let me know if it works. It does not look like a difficult part to make and I could probably mill one out for myself if needed. So far I have not had any issues with the 04 in that area. The only problems I ever had were the clutch quadrant and the sticking gas pedal from the carpet (one of the worse things to find when at the dragway, especially at the end of the track :eek: ).

hiosilver
01-25-2006, 10:04 AM
It's a miracle--the car has been transformed. Who knew a small plate could make that much difference. I did not reset the computer after I installed the plate and the idle did some weird stuff but after I let it sit with the battery disconnected for half and hour, all is fine. I will know more when I get a chance to drive the car for a while longer. Thanks to the guys at modularford.com and thank you Ausie, for finding it for me.

As for the brakes, I mic'd the rotors and they were well within specifications and they are the stock solid rotors. I used ceramic Raybestos pads all around and it appears that this is the first time they have been changed. I don't do any track racing but I sure like the way the big brakes stop the car. I'm not sure who the first owner was but he tried his best to make it look like a Honda Accord. Had some weird tail lights and put some 18" wheels that sort of look stock but aren't really. I can't afford to change them now but will eventually. He also put on a shifter made by Steeda that seems to transmit every little noise that happens in the transmission into the cockpit. I like mechanical sounds but I hear every syncro spinning up or down. I put a small strip of insulation between the shifter handle and the shifter box and that helped a little. Too bad he did not keep all the stock parts, cost me a pretty penny just to find Cobra tail lights.

Thanks again, this is a great forum

Pat

ausie
01-26-2006, 06:45 AM
I am glad that it worked for you. :thumbsup: Since you dumped the EEPROM, It may take a while for the idle to adjust itself. If the check engine light comes on it may be indicating an IAC fault or out of range idle condition. If you have a scan tool or programmer you can read the codes and it should display what the error is. If it does happen to be IAC related, just open up one of the holes a bit and try again. If I knew it was that simple I would have done it myself when I had the 01. The worse thing that could happen is a stall if the opennings are too small. I know I will apply the same thing to the 04 if I have a similar problem. So far the engine runs flawlessly.

hiosilver
01-26-2006, 09:45 AM
My daughter had to take my car to work yesterday and she said it worked just fine except it did stall one time at a light. I used a 9/32 hole to start with so I may take it out to 5/16. So far I have no check engine light but I did put the scanner on it just to see if it stored any codes and there were none present. She also said the the brakes were wonderful. She drives an 05 with a V6 and automatic so is quite a difference.


Pat

allandwysmuller
02-21-2006, 07:39 PM
Pat, there is a setting in the programming called the "dashpot" setting. The drop from 1400 rpm when you come to a stop is controlled by that setting. The fix is to get into the computer programming and alter the % of reduction of the dashpot. I just went through this while setting up an SCT Excalibrator II for my '96 Cobra. You need to retain a small amount so as to prevent the car from stalling when you come to a stop. All this was accomplished when the car was on a dyno and the re-flashing was bein done. I strongly suggest that you do NOT just buy a preset diablo, sct or any other flash device with out it being set up for your particular car, rather than the generic programs from the suppliers. I went through a 7 month ordeal trying to cure just what you are talking of and finally got it straight with the dyno tune. Good luck.

hiosilver
02-22-2006, 09:22 AM
Allan (sorry, I shortened your name)

Seems like you are really into the tuning side of our engines. I was thinking of re-programing the chip but there are so many different ones out there. I saw a program on the speed channel where they took a Mustang and re-programed it with the Xcalibrator II and they could change just about any perameter that they wanted. They were looking for more horsepower and jumped it by 80HP. Impressive to say the least. It was on a 04 Cobra with the supercharger but I'm sure it would work on my normally aspirated engine too. The cost is pretty high on the unit ($380) and that was keeping me from buying one. It is too bad we can't find a place that will rent them. The dyno shops charge just about the same as the cost of the unit to set your car up. I am very happy with the power I have, and the idle plate I put in helped some but the computer is now trying to compensate for the plate being there and is causing the idle to do the same thing. The dashpot control makes a lot of sense--on older carbureted engines the dashpot was on the linkage to bring the engine back to idle slowly. Perhaps I will work some overtime or have a garage sale. Thanks a bunch for your help.

Pat