Clutch Problem?

[HISSIN50]

The EEC can't figure out what's going on because the IAC keeps being changed but it doesn't know about it. The surging will probably continue to come and go.

You can get 511 if you have a chip or a device on the J3 port.

 

[maximos]

So basically the code reader is worthless since I've had a chip burned? Am I just going to have to live with the surging idle at this point?

 

[HISSIN50]

No, a code reader is fine. It's just that a chip can be the reason you get a 511 (and your EEC isn't screwed up).

The fix for the surging is out there but it might be tough to find. E.g., This time of year people start getting more surging because they use the AC more, for instance. It's not really a new issue, but it's being discovered or re-discovered.

 

[maximos]

Perhaps I was too hasty in returning the new IAC I bought a couple days ago? I didn't really give the computer time to reset by unplugging the battery. I also haven't checked the TPS yet. Do you think the TPS could be causing the surging?

 

[HISSIN50]

I doubt it's a TPS issue. If it was, the IAC would not have had an effect. And for two components (IAC and TPS) to both go wonky would be too weird.

 

[str8stang036]

Go back to square one. When did it begin? Did you modify anything before this began?

 

[revhead347]

The surging is totally normal. The computer does command a rolling idle when the clutch is pushed in, but the car is still rolling. On a stock engine, it's only about 1300 rpms, so it's not very noticable. With a camshaft, it can come up higher, because the manifold pressure is higher. You can fix this by fine tuning the computer, but it's only an issue if it bothers you. The engine should stall out when you disconnect the IAC. If it doesn't stall out, then the idle screw on your throttle body is out of adjustment.

If the car continues to drive itself, then there is a clutch adjustment issue. I'd go under the car and check the fork to make sure it is properly adjusted. Sometimes the auto adjuster on the pedal wears out. Did you get a replacement clutch quadrant when you did the clutch? If not, I would start with that.

The squealing and burning is a seperate issue. That's usually a pulley in the serpentine somewhere that has worn out. If it stopped squealing, then I guess it wore a groove.

Kurt

 

[maximos]

Go back to square one. When did it begin? Did you modify anything before this began?

I noticed the problem about three weeks ago. No changes to the car had been made prior to the car starting the problems. Several separate issues seemed to come up at the same time. 1) AC came through defroster - found the vacuum leak and fixed it 2) clutch started to squeal and slip - I had a new clutch, throwout bearing, and an adjustable clutch cable and quadrant installed 3) surging idle and the car started driving itself

At this point all that is left is the hovering idle and and the car driving itself. I've cleaned the MAF, IAC, TPS, and the throttle body.

The surging is totally normal.

Surging is normal to a certain extent, but when you come to a complete stop and your RPMs are staying at 1800 for 5-10 seconds then something is wrong somewhere.

If the car continues to drive itself, then there is a clutch adjustment issue. I'd go under the car and check the fork to make sure it is properly adjusted. Sometimes the auto adjuster on the pedal wears out. Did you get a replacement clutch quadrant when you did the clutch? If not, I would start with that.

I had a new clutch, throwout bearing, and an adjustable clutch cable and quadrant installed. The shop I had my car at is among the best in Central Ohio and I believe would have noticed if something was out of place knowing how experienced they are.

The squealing and burning was the clutch. A burning clutch has a distinctive smell.

 

[revhead347]

Well, then there is something definately something up with that clutch. Not much I can say but get in there and figure out why it's sticking. I've seen a few stangs hold the rpm 5 to 20 seconds after coming to a stop. Does it go back to a normal idle after that 10 seconds, or is it like a rough idle.

Kurt

 

[HISSIN50]

I assume from what you said earlier that the car driving itself happens when you're in gear and not pushing on the gas or brake. Because the RPMs stay up, it wants to keep cruising while you've got it in gear. Is this correct? If so, the issue is not your clutch so don't tear it out. Once you find the reason for the high rolling idle, then the issue should abate.

 

[revhead347]

I thought I read that the car kept going when he pushed in the clutch.

Kurt

 

[maximos]

Sorry for any confusion...The car drives itself only when it is IN GEAR. If I push the clutch in, the RPMs hover around 2k on the tach. I did just learn something interesting though. Apparently there are different calibration codes for IACs on our cars. So the IAC I picked up from Advance Auto was given to me based on the fact that it was a 5.0 Mustang and nohing else. I think I may invest in a Genuine Ford IAC with the right calibration code and see if that fixes my problem. I can't really think of anything else except for maybe a vacuum leak that is not easily accessible.

 

[HGFireHazard]

If you decide to purchase a new IAC make sure you disconnect the negative battery terminal. To speed the process and to clear the KAM I like to pull the headlight switch to drain the residual energy.

I suggest you go through that big write-up I copied for you on the first page and re-dial in/verify your idle. If you purchase a new Ford IAC, do those steps, give the computer a bit of time to re-learn the idle, and it still continues to do this, we can continue further.

If you have a meter it wouldn't hurt to test the TPS just to see, but Hissin is likely correct that it isn't the problem. However, ruling out one item never hurts.

Thinking out loud, what lets the PCM know that the vehicle is moving in order to correctly initiate and remove the high idle, the vehicle speed sensors?

I still think we're in the neighborhood of a previously bad IAC, vacuum leak, and/or throttle body problem.

 

[maximos]

I suggest you go through that big write-up I copied for you on the first page and re-dial in/verify your idle. If you purchase a new Ford IAC, do those steps, give the computer a bit of time to re-learn the idle, and it still continues to do this, we can continue further.

The new IAC should be here Friday. If that doesn't work, I've been planning on following the procedure you posted for resetting the idle on Saturday afternoon when I can devote a good chunk of time to it.

 

[HGFireHazard]

The new IAC should be here Friday. If that doesn't work, I've been planning on following the procedure you posted for resetting the idle on Saturday afternoon when I can devote a good chunk of time to it.

That sounds like a solid plan.

Good luck, and I hope you can get this fixed cheaply and quickly.

 

[HISSIN50]

Thinking out loud, what lets the PCM know that the vehicle is moving in order to correctly initiate and remove the high idle, the vehicle speed sensors?

I still think we're in the neighborhood of a previously bad IAC, vacuum leak, and/or throttle body problem.

Spot-on on both counts.

The VSS input (and IAC) also command the dashpot (so the car doesn't stall while shifting).

I still think he might find a vac leak.
If you have a gauge, toss it on. Stock you should see about 20" hg at idle.

 

[maximos]

I still think he might find a vac leak.

I think I may have found something...I heard what sounded like air coming out of a small hole behind my upper intake and I sprayed some carb cleaner back there and the car rev'd a little bit. After a bit of searching with my fingers to see if anything would change the sound, I think I've narrowed it down to the gasket between my upper intake manifold and the phenolic spacer separating the upper and lower manifolds. I tightened down the upper a little more but I know a piece of the gasket broke off when my fingers ran over it so I'm not sure if the leak is still there. As of now I can't hear that sound anymore. Any thoughts?


Side note - I unplugged the battery to reset the computer and I installed the new IAC. After I turned the car on, it appeared to be working perfectly. I let it sit and idle for about 5 minutes. During that time I rev'd the engine and it didn't surge at all. I took it down the street and it appeared to be misbehaving again which is what ultimately led me to discover the phenolic spacer issue.

 

[HISSIN50]

Be careful with over-torquing the plenum (upper).

There's a test to check for an intake leak but it's a lot of work - it would be more trouble than it's worth. And it might not be too revealing, given how small this leak should be.

I'd get a new gasket [if possible] and just start over. The stock gasket is like 5 bucks but I don't know about a gasket for your set-up. I'd check both mating surfaces for true when you have the upper off.

 

[maximos]

I'd get a new gasket [if possible] and just start over. The stock gasket is like 5 bucks but I don't know about a gasket for your set-up. I'd check both mating surfaces for true when you have the upper off.

Jeg's has the Edelbrock gasket for $10 - I'm going to go pick one up tomorrow. Do you think if I just put some RTV sealant all along the where the gasket is that it could plug up whatever space there is?

Do you think this could be the cause of my problem?

 

[HISSIN50]

Jeg's has the Edelbrock gasket for $10 - I'm going to go pick one up tomorrow. Do you think if I just put some RTV sealant all along the where the gasket is that it could plug up whatever space there is?

Do you think this could be the cause of my problem?

It's tough to say without seeing it. I'm not big on using RTV in a situation like that but you can. You could try to goober some over that area (where the gasket chipped off) to see if it idles differently.

Or just throw some duct tape over the area, simply to see if the issue changes. If it does, you know you're on the right track and need to fix that sealing surface.