Rough idle that smooths out in time.

[Guest]

[rusty105]

Hey Joel....

I haven't pulled codes yet, but I have a question? I just picked up a 86 Mustang GT, the previous owner said the previous owner, to him, had the engine rebuilt. Now the  guy I bought it from hasn't had in on the road in over 2 years, so lack of running may be my issue, but let me describe it. When cold it will start and run Really rough, rough to the point of dieing, sounds like it has a mild cam as well. Anyway, after about 4-5 minutes it will all of a sudden smooth out. It is still a speed/density setup. I am thinking there is a thermostatic switch that does something as soon as it reaches a temp? I'll pull codes this weekend and see what comes up. Any specific tests to run?


Thanks

[Joel5.0]

Run the DIY KOEO/KOER self tests = http://sbftech.com/index.php/topic,2471.0.html

Then.... you may want to:

1. Clean that TB with carb cleaner and a nylon brush.
2. Check/recondition those salt and pepper connectors = http://fordfuelinjection.com/index.php?p=85
3. Perform a base idle reset = http://sbftech.com/index.php/topic,1031.0.html

LUK

[David Claflin]

Once it gets where it is making corrections with the O2 signals is probably what you're seeing, do as Joel suggests, I'd be checking for a vacuum leak as well.

[rusty105]

Once it gets where it is making corrections with the O2 signals is probably what you're seeing, do as Joel suggests, I'd be checking for a vacuum leak as well.

Yeah, I have to check everything, I think the engine was thrown together by a hack. I think it also has a fuel delivery problem. When it stalls it will refire for a fraction of a second, then die. BUT as long as it is running it is fine, so far. I only have about 20 minutes of seat time in it, so I am sure I will find more 'issues'

[rusty105]

OK
KOEO codes:

67
84
(flashed both 2x)

flashed a 1

then flashed 34 (2x)

from my Haynes

67= "Neutral Drive Switch"
84= "EGR Control Circuit"

34= "EVP voltage above closed unit"

I tried to get KOER codes, but nothing came up



I did the base idle reset, .90 volts on the TPS.

It still has the issue, and it happens on every start, cold or hot. I will post a video later.

[liljoe07]

Code 67 may be contributing to the bad idle. That's plus there may be some codes in the KOER test also. But code 67 will not allow that test to run.

Try and run the KOER test again. But this time hold the clutch through the remainder of the test. See if the codes flash then.

[Joel5.0]

.... + disconnect the EVP sensor connector and leave it disconnected, clear codes and make sure code 31 is the one that shows. If so, make sure the EGR valve is not staying partially opened.... causing an exhaust leak into the intake + code 34 to show.

[rusty105]

Thanks for the info, I'll look into it tomorrow, but for now here is the video.

http://www.youtube.com/watch?v=Sv5WI6hcVZs

Warning, the accessory drive makes a horrible noise! The A/C clutch bearing is shot, and the power steering whines. I'll get to those soon enough. Anyway, around 1:10 in the video, it stumbles, then runs much better. Not great, but better. I am not sure you can see on the vac gauge, but it goes from bouncing 5-12 to an almost steady 16-17. This happens EVERY time I start the engine, doesn't matter if hot or cold, every time. It also doesn't always clear up, at that magic point in time it either dies, or clears up. Make for an interesting drive. 

Thanks!!

[rusty105]

Oh, and disregard the "fuel delivery" problem I mentioned in post #3. It had a bad ignition switch. It was making intermittent contact. 

I pick up the car last week, and I know it had issues, guess I got my work cut out for me.

[Joel5.0]

Make sure you do not have vacuum going to the EGR valve, disconnect and plug the vacuum line to the valve. LUK

[rusty105]

OK, I pulled the connector to the sensor on the EGR, car wont stay running, but code "31" does show up now.

But you mentioned this

Make sure you do not have vacuum going to the EGR valve, disconnect and plug the vacuum line to the valve. LUK

I pulled the vac line going to the EGR valve, and plugged it, MUCH better. Idle still rolls . Crappy tach says about 850-1050RPM, BUT a separate tach says about 250 RPM lower. (The instrument cluster is not original to the car,    ,I also found out gray is not the real interior color  )

Any benefit to deleting the EGR?

[Joel5.0]

Aside a cleaner engine bay and cooler air flowing through the intake..... nope.

[Uhvnutn]

I am having the same issue with my 93 lx. It was originally a 4 cyl car that I converted. When I start it up it runs fine for a minute then runs like crap. I starts to run rough/flat and has now power. After another minute or so it clears up. I can be driving while it is doing it and all of a sudden its like a switch if flipped and it runs great.

I have ran the codes and the only ones I am getting are from the egr being deleted. I have been dealing with and trouble shooting this issue for some time now and haven't had any luck. I also know a few other people that have the same problem. If someone can shed some light on this issue that would be great.

[Joel5.0]

I am having the same issue with my 93 lx. It was originally a 4 cyl car that I converted. When I start it up it runs fine for a minute then runs like crap. I starts to run rough/flat and has now power. After another minute or so it clears up. I can be driving while it is doing it and all of a sudden its like a switch if flipped and it runs great.

I have ran the codes and the only ones I am getting are from the egr being deleted. I have been dealing with and trouble shooting this issue for some time now and haven't had any luck. I also know a few other people that have the same problem. If someone can shed some light on this issue that would be great.

There is no "one solution will solve all the cases" situation. You need to go through the procedures to ID, isolate and correct the specific cause(s) for your particular setup. A partial list of "possible causes" or recommended procedures based on the cases I've worked for years are:

- 10-pin connectors reconditioning.
- Base Idle reset.
- Check for vacuum leaks, make sure no unmetered air conditions are present (open breather with PCV valve and/or PCV valve is installed correctly).
- MAF sensor elements reconditioning.
- O2 sensors heater power and ground circuits verification.
- Main and EEC grounds voltage drop test.
- Make sure EEC electrolytic capacitors on the board are not leaking/faulty.
- Check/confirm valve train is not under excessive lifters preload condition.
- Alternator ripple test (AC noise in system will cause EEC system to misbehave).
- Wiring harnesses problems.
- Wiring connectors contact problems.