Rough and high idle with eaton swapped Cobra

[agent-orange]

Hi guys

I have an eaton swapped 2001 cobra, I did a eaton swap several years ago and I never had big problems so far.

I have several "problems" with my Cobra, which are annoying me. I replaced the clutch and flywheel 2 years ago and since then I had the problem, that the car has a very high idle. I thought it's because I installed an aluminium lightweight flywheel so I never cared really about it. But always when I press the clutch while I'm driving, the idle goes up to around 1800-1900rpm for about 20-30seconds and then comes slowly down. Is that normal?
I dont have any shifting problems or so. Just when I press the clutch, the RPM goes up and comes down as soon as I shift or wait long enough

The other problem is when I start the engine, the RPMs are also around 1800-2000 for about 1min and then goes down to around 1100-1200rpm. The engine is also quite shacking, when its idling at 1100-1200rpm.

I recently read, that the idle of the car should be around 700-900rpm So I connected my SCT and read the DTC codes, it shows me P0135 & P0155 which should be the upstreams O2-sensors. I already checked the fuse, it's OK. So I ordered new O2-sensors, but didnt receive them so far. I also ordered a new MAF, cause I'm using still the 01 stock MAF. I also checked the IAC, but when I disconnect the IAC shuts off immediately. So I guess the IAC is working, specially cause I dont see any other error codes. Is it possible that the O2-sensors cause all this problems, that I have? A vacuum leak would produce other error codes or?

Another thing is, that when I shut the engine off, I hear a strange whistling sound from engine for about 20-30sec. I dont know if that is normal.

I uploaded 2 videos on youtube:

High idle:

Whistling sound:

I'm thankful for any help

 

[01yellercobra]

You probably have a vacuum leak somewhere. When I set the idle I usually have the throttle blade open enough so the engine will idle without the IAC plugged in. A vacuum leak won't set codes. And usually only one O2 sensor goes out. It's extremely rare for both to go out.

Did you plug the hole at the bottom of the lower intake when you installed the eaton?

 

[Snk-Byet01]

You should use the IAT2 port, not the IAT. Block that off. Also, the 90MM MAF is a requirement. Get one for a Lightning or Terminator.

Edit: You will need a tune after installing the 90MM MAF.

 

[agent-orange]

I never set the idle after I installed the the throttle body. Is that necessary? But when I unplug the IAC, wont the car automatically die or do I have to pull the throttle body open manully a bit?

The best way to check if I have a vacuum leak, would be a smoke test or? Yes, I installed the hose on the plug on the lower intake. I when I installed the lower intake I had to remove it again, cause the plug wasnt screwed in enough and was hitting the block. It is possible that the hose came lose or so, but wouldnt the car running much rougher in this case?

About the O2 sensors, the other thing would be that I have a problem with the wiring, cause I replaced the fuse altough it was ok.

 

[agent-orange]

@snk-Byte01 is the 90mm MAF really required? I thougt I still can use the 80mm MAF and do a tune with it? My car was tuned btw about 2-3 years ago by Brooks Speed Tuning Support.

When I remember it correct, I used the IAT and extended it so that I install on the IAT2 sensor on the blower.

 

[01yellercobra]

The lower fitting is notorious for causing issues in 03/04's. The elbow goes bad and causes a big vacuum leak.

Personally I wouldn't want the engine to die as soon as the IAC is unplugged. What happens if the IAC goes bad and you're no where near home? Plus if you set the duty cycle where it should be (around 30%) the throttle blade will be opened a tad.

From what I've see the smoke test is the best way to go.

As for the MAF, it really depends on how close you are to pegging the 80mm. If you have some head room the 90mm really isn't necessary. But I can't see you having much room even with a low boost set up.

 

[agent-orange]

Ok, I will check how I can do a smoke test by myself. When the lower fitting would cause a vacuum leak, I should see it. Hopefully not, it's pain in the ass to remove all that stuff :O

Whats the best way to set the correct duty cycle?

So you would suggest, that I should go for a 90mm MAF? I dont want to put the maximum RWHPs out of the, I'm happy with the performance actually

 

[01yellercobra]

There should be plenty of videos on YouTube about how to smoke test an engine. I'm not sure what being by yourself gas to do with it. You'll be watching it under the hood anyway. That would be why I deleted mine when I went whipple.

Usually when I'm setting duty cycle I use something to datalog so I can see what's happening as I'm doing it. I let the engine idle while adjusting the stop. When the duty cycle is where I want it I lock everything down and double check the TPS voltage.

Like I said, you need to know how close you are to pegging your current MAF. I would think if you were close before your tuner would have said something.

 

[hotcobra03]

Your codes say pinched wire.

Work done on car.

Clutch is causing the shake at idle

Pinched wire is common being harness is in the way of bolts


Chilton Library

Scroll down for link in.

Has full pc/ed section for codes.

Pinpoint test H fuel control.


Can’t do a copy and paste. Site changes the format to where you cannot understand it.

 

[agent-orange]

Thx hotcobra, I will check that site.

About the clutch, do you think that my car dude installed the clutch not correctly?

 

[agent-orange]

I probably found the vacuum leak, the plug which is connected to the EGR. I gonna buy a "new" one at ebay, in this case I have at least a spare one.

I will also check the TPS voltage and will adjust it if necessary. I also saw that, that the throttle body set screw is screwed out quite a lot.

 

[hotcobra03]

I probably found the vacuum leak, the plug which is connected to the EGR. I gonna buy a "new" one at ebay, in this case I have at least a spare one.

I will also check the TPS voltage and will adjust it if necessary. I also saw that, that the throttle body set screw is screwed out quite a lot.

That connection is a pick and pull part.

Use a large cup of boiling water and soak it for a few. Than it will pull off green hose without breaking the hose.


Can’t answer any on what might be up on clutch other than it can cause a vibration at idle when it’s not right.

Both install or just the part not balanced properly

Installing old parts back is only way to confirm.

 

[agent-orange]

I will test that, thx.

I just checked what kind of clutch and flywheel I've ordered. IT's a Mcleod Racing 463408 8 Bolt Steel Flywheel and a McLeod Racing 75204 Mustang V8 10 Spline Super Street Pro Clutch Kit. The flywheel should be zero balanced. But my car dude installed it, I thought he knows what to do back then.

 

[hotcobra03]

This could be it.

What was wrong with oem.

Aluminum flywheel with steel insert

I had changed my oem clutch with an oem

At 365k it still had a lot of life left.

 

[01yellercobra]

This could be it.

What was wrong with oem.

Aluminum flywheel with steel insert

I had changed my oem clutch with an oem

At 365k it still had a lot of life left.

01 Cobras don't have aluminum flywheels stock. They come with steel from the factory. The 03/04's are the only ones that came with the aluminum I believe.

 

[bobbystang]

01 Cobras don't have aluminum flywheels stock. They come with steel from the factory. The 03/04's are the only ones that came with the aluminum I believe.

It’s a common problem on our mustangs it just literally happened to me today again. Typically you have to get the throttle position sensor voltage between .97 and 1 V it’s tricky to do not difficult but I’m in the same issue myself right now..... always ends up coming back at least once every couple years


Sent from my iPhone using the svtperformance.com mobile app

 

[agent-orange]

So I have some news guys. As I mentioned before, I've ordered some spare parts incl. new MAF and ignition coils. Those things arrived today, so installed them this afternoon. So I removed the ignition coil cover and saw that one plug wasnt connected with the coil

I installed the new coils and connected all of them. There is a noticeable difference now and car doesn't shake anymore at idle. When I start the car now, it still goes up to 2k rpm but comes much faster down to 1200 and when the engine is warm, the idle is around 1000rpm. But I still have the feeling something is wrong with the clutch. Anyway I will bring the car to a car guy which is specialized for "older" cars. He will also take a look at the O2-sensors.

 

[Arthur]

smoke the engine for the air leak then if the same I would look at your iac and your throttle body itself including position sensor.

 

[agent-orange]

The car now at the car shop, the guy with take a look at it. I dont know what happens when both upstream O2 sensors are not working. What I can say, that the car didnt have this problem before the clutch and flywheel was replaced.

 

[hotcobra03]

Have you read thru pin test H fuel control?

All about o2 sensor codes.

1 sensor may have as many as 8 codes.
Each telling what happened to set it.

Be a step ahead of your mechanic