87 XJ 4.0 EGR problems

[WagoneerXJ]

So just before I parked my 87 Xj last year, it ran like complete crap. Would fire up and run for about 30 seconds on it`s own, after that it needed my foot on the throttle to stay running.

This happened right after I replaced the AC compressor with an idler pulley from a base model XJ. I changed all the sensors I could think of with spares ( TPS, IAC, Oxygen, MAP ) After fiddling around today I noticed the small vacuum line going onto the EGR valve on the side of the intake, was cracked and obviously leaking.

I removed the line from the valve and started it up. Voila! it runs perfectly fine on it`s own now, goes into gear without stalling etc... When you put the line back on, it goes back to running like crap. I`m going to replace the cracked line later tonite and see if that helps it. If not, would that mean the EGR valve is toast, or just plugged. Can I harm the engine running with the EGR unhooked...

Thanks for any help!

[TL-Iguana]

With the EGR unhooked you may throw a code, (not sure how computerized the 87's are) but it shouldn't harm anything other than the environment. It does need to get fixed to run properly, but driving around as is should not harm the jeep in any way.

[JENSSEN]

With the EGR unhooked you may throw a code, (not sure how computerized the 87's are) but it shouldn't harm anything other than the environment. It does need to get fixed to run properly, but driving around as is should not harm the jeep in any way.

My 89 has been bypassed for years, no CEL ever

[WagoneerXJ]

Good to know, thanks fellas! On the other hand I have a spare intake with an EGR valve on it. Is it even worth my time to try and replace it?

[cLAY]

No, pull the hoses and cap the lines. I ran my '89 for a long time like that and it never hurt anything. In fact most vehicles run better without it. Its just there to <slightly> clean up the exhaust. It doesn't even come into play when you are past about half throttle.

[WagoneerXJ]

No, pull the hoses and cap the lines. I ran my '89 for a long time like that and it never hurt anything. In fact most vehicles run better without it. Its just there to <slightly> clean up the exhaust. It doesn't even come into play when you are past about half throttle.

10-4, thanks Clay!

[mike s]

EGR's can be critical in controlling detonation, or pinging under medium throttle and high load conditions (wheeling), best to repair it, of fuel/timing changes may be required. 87 is obd 1 and as stupid as an atari  or Vic-20. EGR won't likely set a code. Egr=cheap, melted pistons = expensive

[morerpmfred]

The egr only works on startup for emission purposes. Once they start leaking then the o2 sender can not keep up unless you have a wideband aftermarket sensor. I had one that only leaked at high load and rpm intermittently. So at high rpm it would leak , lean out and melt a piston. But it would only leak like once a year. So every year or so I would put a new moter in for like four years. Tough one to figure out as well as expensive. The lucky part is the detonation  never took out the block or head. And running a performance , er noisy exhaust you would never hear it till you lost power.

[WagoneerXJ]

Well it won't be driven much, so it's capped off for now. It's just to move it around the yard and into the shop

[cLAY]

The EGR system works all the time.  On an older Jeep like yours works solely off of a vacuum signal, no computer involved. The stronger the signal the more exhaust gas you recirculate. At idle you have your strongest vacuum. By 1/2 throttle the EGR is closing and by 3/4 throttle there isn't enough vacuum for it to overcome the spring holding it closed and cause it  to open so it stays closed and no exhaust is recirculated.

A malfunctioning EGR could stick open and let hot exhaust gases into the engine and cause damage. A capped off system won't ever let exhaust gases in unless the EGR is damaged and the spring won't hold it closed. Or if you have a blockage in your exhaust such as a crushed pipe or plugged cat the high pressure in teh ehaust system could force EGR to open. On my '89 XJ the EGR melted out before opening when the cat plugged up.

I spent $200 replacing the EGR on my '89 XJ only to have it melt out again right away due to a plugged cat. The cat got removed and replaced with a straight pipe and the egr got capped off.

If you are really worried about it replace the EGR with a block off plate. You can buy them or make your own.

[JENSSEN]

As clay stated , it's aok with no egr,... If I am wrong my engine should of blown years ago,.. My race jeeps revs and is abused all the time, if a 4.0 should of blown it would of been the big jeep,....

[WagoneerXJ]

Yea I'm certainly not worried after hearing some first hand experience, from some knowledgeable people. Especially since they own the exact same vehicle.

My 87 hasn't had a Cat for years, and I just cut off the junk muffler and put a Flo Pro muffler on tonite. Sounds and runs alot better!