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Idle trouble - not the IAC

S

schmiedel

NAXJA Forum User
Location
Mexico (Querétaro)
I just replaced the IAC valve thinking this was the problem, but it's not there.

My XJ starts immediately in normal situations, but the engine just stalls everytime I stop unless I slowly (very slowly) deaccelerate. It does it more when I turn it off and then, after one or two hours start driving again.

Sometimes, it will turn off and it is a PITA to start the engine again, I get alot of gasoline smell and the best way to start the engine is to wait for about 10 minutes.

Recently replaced:

filters, spark plugs, spark plug cables, rotor, distributor cap, IAC valve; inyectors were also cleaned properly.

Any thoughts?

It's a 1988 4.0 Renix XJ.
 
Just a shot but my son had the same problem. What it was the little white resistor on the front drivers fender. take the two wires off and hook them together and see what happens. the part was only $6 from Jeep and was a very easy fix. Hope this helps.
 
But where is that resistor? I only found a kind of relay that has two vacuum connections and two wires, but nothing like a ceramic resistor. Any pictures? What's the exact name of this part?
 
ballast resistor.

do a search, there have been many threads that have the picture. yours may have been already bypassed. off the top of my head, the wires to the ballast resistor are orange on my 89.
 
Well, I found the resistor, it was under the airbox (not screwed to the fender like on the picture I found). However, the engine still stalls, I read a little bit more on this resistor, and I don't think it's the cause.

In my case the engine starts smoothly, no trouble at all, but specially when stopping, the engine just goes off, rpms drop too low and then it just dies.

Normally it will start fine after that, but on some strange cases, the engine just won't turn on and the muffler will have a strong gas smell with some smoke (the running engine doesn't visibly smoke).

Any other thoughts?
 
Do you have a catalytic converter? If you don't, the exhaust will smell like gas no matter what.

Although it could be flooding the system with gas. Check your pressure, your fuel pressure regulator might be shot.
 
Pull the vacuum line to the EGR and plug it. If that doesnt help, then id check the fuel pressure at the rail. I had the stalling problem too.
 
check for a large vacuum leak, I had an escort that would do that, it had a hole rubbed in a vacuum hose.

it might also be an electrical problem, have you had the alternator/battery tested?

for sure check the fuel pressure, but low fuel pressure would be more apparent at high rpms rather than low.

you'll also want to take a very good look at the EGR system.
an EGR valve that's stuck open would let in exhaust gasses
 
Solution was simple. Some time ago I was fixing some vacuum hoses as they were old, so I checked everything. I found the EGR valve disconnected, so I just connected it.

The XJ had dirty injectors / tps, so the engine was behaving like crap. When it was serviced, it improved alot, but with the problem I statet before.

So, seeing the advice to check the EGR system, I found that it was exactly the valve I had connected, however, my XJ has no cat converter, so there's the problem; cancelled the vacuum line again and everything is normal.

The odd thing is that the XJ passes every year's inspection without any trouble...

Regards
 
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