Spread5150

Spread5150

AHHHHH !!!!!!

After a few phone calls and some digging I was able to get ahold of the previous owner. (I purchased the vehicle from a car flipper who didn't know much about its maintenance schedule.)

Here is what he told me.

Did the timing belt 3 thousand miles ago (water pump at this time)
New various parts.

But he did say that one day he went out to start the vehicle and found it would not start. He researched a bunch of things and found when he disconnected the EGR as pictured that it would run. When plugged back in it would idle rough. Does this sound like the EGR needs replacement or some other component.

RJR

It sounds like the EGR valve isn't closing when it's supposed to. The engine won't run well or at all at idle with a lot of exhaust gas coming back into the intake, so normally the EGR valve is closed when the engine is idling (or when it is cold).

The cause of an open EGR valve could be a stuck EGR valve, a faulty vacuum modulator, a faulty vacuum switch, or a bad electrical connection from the ECU to the vacuum switch. Or it could be another vacuum line in the EGR system that is disconnected and/or misrouted. You won't know until you test those parts.

The fact that the engine runs with the vacuum line disconnected from the EGR valve (the big valve) suggests that the EGR valve itself is NOT the problem. It's closing when the vacuum is removed from its control port. Rather, the problem is in the upstream control system for the main valve.

Try the attached file and see if you can load it. It will give you some tests to run to figure out where the failure is. (This is the same FSM manual section scope103 referenced.)

scope103

Could also be a straight vacuum leak. But that would (likely) be through the EGR valve.

This is just a guess; ;don't go replacing parts until you run the diagnostics.

Spread5150

Well the shop I take all my vehicles to called and advised it is in fact the EGR Valve. Its getting swapped and I hope to be back on the road in a few. Since I have only had the vehicle for about 100 miles I really started going through much of it this week. Found a Hayes Repair book in the jack space ! score !

scope103

Toby Hayes lived down the street from his much more successful neighbor John Harold Haynes. https://en.wikipedia.org/wiki/Haynes_Manual

A Hayes Repair book, of course, is MUCH rarer.

Spread5150

o yes ... haha

Spread5150

Dang ! SO IT CAME BACK ON ! After swapping the EGR and about 50 miles it came back on. I will have to return to the shop. Same code coming back. He is the thing. It ran like poo if you hooked up the old EGR. Unhook and it worked well. Now it runs great with it hooked up and the new EGR but its throwing again. I read the other posts about common fixes. Here we go.....

Spread5150

Thinking it may be the sensor or as I have read it may be a build up down the line.

Merklecr

I'm not sure what everyone's opinion of EGR block off plates are, but they worked great on my '94 3.0. You can get the entire EGR block off kit from LC Engineering, and there are many extensive write ups on this site and others. It can be a PITA to remove the lower bolts due to rust and hard to reach, but it worked great on my non working EGR system.

Spread5150

Merklecr

Power and acceleration feel the same to me after deleting the EGR. My check engine light went away, again using all of the supplied parts in the kit. I also used Sea Foam in the engine to clean out some of the sludge and buildup. My rig has 230k miles, but I'm doing my best to keep it alive.