EGR problem or something else

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Jun 8, 2006 | 01:35 PM

dkatz

Thread Starter

New User

Joined: Jun 2006

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EGR problem or something else

High guys. My 94 Lightning is plagued by idle surging and stalling these are the symptons:

On start up with the engine cold there is no problem. The idle seems to be consistent if a little high.
As the engine becomes warmer the she seems to be running a little rich with a pronounced smell of petrol.
When the engine is warm the idle will surge quite violently and when in the down cycle will thow black smoke out the exhaust.
Soon after that the vehicle will stall and have trouble starting. It seeems to be very rich.

All indications point to a stuck EGR valve. Would you guys agree?

Jun 8, 2006 | 01:55 PM

fordf150guy

Tuned

Joined: Jun 2006

Posts: 420

Likes: 3

have you checked your air filter? do you know if you have any codes? i'm not an expert on efi stuff, but check if your O2 sensor is still plugged in. it sounds like some sort of sensor fault because your motor runs fine when its cold. its in a loop mode untill it gets warmed up, then once its warm the ecu takes information from all your sensors in order to make your motor run its best. if one of t hese sensors are out of range, or not plugged in, the motor will most likely run like crap. i hope someone with more knowlage will chime in and point you in a specific direction. good luck.

Jun 8, 2006 | 02:25 PM

ksdunlap

Freshman User

Joined: Jun 2006

Posts: 28

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From: Ennis, Texas

it may be the temp sensor for the computer if it is reading -40 degrees it will run rich also pull the vacume line off the fuel pressure regulator and see it if there is fuel in it from a bad regulater, if thats dont help pull codes

Jun 8, 2006 | 04:25 PM

subford

Fleet Owner

Joined: Aug 2005

Posts: 23,666

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From: Easton,Ks

As fordf150guy said, check your codes, post them and we will get back with you.

Jun 8, 2006 | 06:57 PM

Popa Tim

Posting Guru

Joined: Jun 2004

Posts: 1,781

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From: Central NY

If your check engine light is not on, then I doubt the EGR is stuck. The egr valve has a position sensor on it...

The rich running could be many things, best advice has already been given: pull those codes

Jun 11, 2006 | 03:59 AM

dkatz

Thread Starter

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Joined: Jun 2006

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vacuum

I changed my oxgen sensor yesterday as a friend pulled codes a few weeks back and it apparently showed poor O2 sensor. THIS did not help.

While I was checking the EGR I found that the vaccum to it was weak and erratic. Will this make any differece to the idle. Wen I pull the hose it makes no difference to idle.

Jun 11, 2006 | 05:35 AM

subford

Fleet Owner

Joined: Aug 2005

Posts: 23,666

Likes: 301

From: Easton,Ks

Quote:

Originally Posted by dkatz

While I was checking the EGR I found that the vaccum to it was weak and erratic. Will this make any differece to the idle. Wen I pull the hose it makes no difference to idle.

When the engine is at idle, cold and WOT you will have no vacuum to the EGR Valve and it should be closed. The vacuum is controlled by the PCM.

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Jun 12, 2006 | 06:56 AM

tim73

Mountain Pass

Joined: Feb 2003

Posts: 136

Likes: 3

Vacuum to the egr, has to go through either two or three solenoids, which are controlled by the ECM. To check the EGR itself though, you can hook a vacuum gauge/gun to the egr itself, then take the reading(Resistance) from the EVP sensor as you apply vacuum. There are alot of vacuum lines/trees going to the EGR, via the solenoids, so there are lots of potential areas for cracks/breaks.

Also, have you checked the Engine Coolant Temp Sensor? If it is stuck showing cold, then the engine will think that it is cold, when its really hot, and wont lean out like it should, to componsate.