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Stalling problems, after seafoam

CRJeepin

NAXJA Forum User
Location
York, PA
Hey guys,
I posted this on JU too so I apologize if you've already seen it, not trying to spam up the interweb with this but I'm really out of ideas and thought I might give it a shot over here.

Problem is the '88 XJ 4.0L has begun stalling randomly, it first did it about a week ago the day after I did a SeaFoam treatment into the intake manifold. I replaced the TPS and IAC as both were original to the jeep and I had planned to replace them soon anyway, and I ran it at 2500 rpm for another 15-min stretch thinking maybe I still had some seafoam in there. It ran good for 3 days of around-town driving but then last night died on the highway after about 15 minutes of driving.

I bought this jeep about 2 months ago and have replaced:
-IAC & TPS (as mentioned above)
-plugs, wires, cap, rotor
-CPS
-fuel pump & filter
-CCV lines
-starter, alternator
-converted from closed to open cooling system (about 3 days before the seafoam, so it's possible this is related). Used a 1981 Corvette Temp Sensor as detailed on Lunghd's site.
-Oxygen sensor
-removed and cleaned throttle body
-removed and cleaned valve cover
-fuel injectors (one was leaking....FoMoCo 19# replacements)
-and the battery is 1 yr old according to date sticker on it (from PO).


At this point, I'm out of ideas. I don't know what can cause this type of apparently random stalling, it does seem slightly more likely to stall when accessories are running so I'm thinking it might be electrical but the voltmeter is fine when it dies and there's no symptoms of low power (the alternator failed about a month ago so I'm familiar w/the slow blinker, dim lights, etc common when there's an alternator problem). I guess it's also worth mentioning that the alternator I bought to replace the OE one failed about 1 week after I replaced it, so I'm on the second alternator. However, this one has been fine so far.

The really strange thing is that the stalling started right after the seafoam. I had driven it about 3000 miles of highway and city driving before the seafoam and it drove decent, except for the alternator failing but it was a real old alternator so that wasn't too suprising.

I'm going to clean all the grounds for the battery cables and replace them with 2-gauge. But other than that or replacing the CPS and the 02 sensor again, I don't know what to try. However, the jeep runs fine when it runs (idles perfect, no mis-fire, no stumble, etc) so it seems strange the 02 sensor could be to blame here.

Jeep does not backfire, the cat converter is new about a month before I bought the jeep (have the receipt from the PO). Oh, and I did pull 3 plugs to inspect them after seafoam but they looked good, and again no stumbling or mis-fires are happening...just stallin'.

ANY SUGGESTIONS VERY MUCH APPRECIATED! Pulling my hair out here, and the worst part is this was gonna be the winter beater for the wife but she's so gun-shy from the stalling problems I don't know if she'll ever want to drive it.
 
You seem to have touched every part in the engine bay in a short amount of time. There is no telling what you have moved or damaged through the internet.

One thing to check... When you changed the CPS, did you secure the weather-pak connector away from the exhaust manifold? It can easily fall onto the exhaust manifold and melt. This can result in the situation you are in.
 
Thanks for the comments. I gave up and brought it to a real good shop for diagnostic work, I don't have a fuel pressure gauge (need to get one) but that's a good point to check.

Jess - yes I have power after the stall, it doesn't seem to be electrical.

bottleworks - yes I secured the connector (and wiring) to the clips as the factory one was secured. I agree I've done a lot of stuff quickly, and it's a tough one to diagnose! Appreciate the suggestions.

The shop seemed curious about the Advance Auto alternator and said they'd probably want to bench test that or swap it with a known good one temporarily in case it was causing interference or some sort of goofy harmonic. Anyway, they seemed very meticulous and I think they'll get it figured out.....I hate bringing it into a shop but these guys were highly recommended for their diagnostic work and I'm pretty optimistic. I just can't spend any more on parts, and to be honest am starting to get pretty defeated by this one! Figure it's a good one to let the professionals (with their professional quality diagnostic tools!) take a crack at it.

Will definitely post up what ends up with it....thanks again all.

CR
 
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