94 xj idle rough and stumbling

[nickxj94]

Well I've Google searched for about 6 hrs. Not really finding any answers.
My 94 xj sport 4.0 auto 219k miles.
Started two weeks ago I filled up with 100% gas like I do every week at the same station. Was running perfectly. Drove home about 20miles, killed it for about 30 mins. Then headed back to town for dinner. About 10 miles or so it started running rough on acceleration, let off runs better shift to neutral rev up it clears up. So I figured maybe bad gas? I stop by autozone get a bottle of Lucas fuel treatment. Drove it about 10 mins clears up.

Now a week later I fill up again and same thing bam its running worse and now popping and backfireing under acceleration. Kinda stumbles while idle too. I got some more fuel treatment tonight on the way home and gas at a different station and no change.
Different forums say
Tps
Cps
Fuel pump
Tune up
Fuel filter
Grounds
IAC

Well I've replaced
Fuel filter
Tps
Tune up plugs,wires,cap,rotor
Cleaned the grounds and battery

All in the last 3-9 months

Now my cps and fuel pump is about 3 yrs old.

Anyone got any other input?

I'm going to take my cps off tomorrow and get it warrentied out and try that first.
And clean the IAC out its been a year since that also.

[4.3LXJ]

I think you are on the right track with the CPS. Backfiring is an indication that fuel is not igniting and then being burned in the cat. What brand of CPS. Many of them do not last unless they are the Chrysler brand

[nickxj94]

No cat on mine.

Oreally brand

[cantab27]

injector's all good .....no cat awesome get banned for that on other forums ,,just saying ha ha ........sound better with out em anyways

[nickxj94]

injector's all good .....no cat awesome get banned for that on other forums ,,just saying ha ha ........sound better with out em anyways
Not sure if injector went bad or going bad.. Going to start with the cheap parts first get them all warrantied out. I'm not going to spend anymore money on this jeep.

I am looking for a new to me xj 96-99 in a few months I almost got enough saved up. Lol

[nickxj94]

Well update.

This morning I go out to the garage pull the cps and tps, took them to the part store got them warrentied out. Come back home put them on.
Disconnected battery for a bit touched the terminal together, cleaned the post and terminals up. Hook it back up start it. Fired right up! (Usually have to leave key on for 15 secs)
Let it idle and warm up for 30 mins, never did it idle rough or stumbled.

Took it on a test drive about 10 mins to town and back, no rough acceleration or popping/back firing..
So hopefully it was the cps.
Will see what it does tomorrow morning on the way to work.

[nickxj94]

Well started doing again today.

Checked fuel pressure, got 32 psi at idle, 45 psi with the vac line off the regulator.

Pulled cap on distributor... And it is corroded with blue corrosion and had moisture inside the cap.
Lifetime warranty on them so new ones are on there way to my work..

I put the new cap and rotor on and no change.... It has seem to idle better now, just cutting out and stumbling on acceleration now.
Won't cut out if ease in throttle

Anyone know why there is corrosion on the contacts?

[nickxj94]

Another update..replaced the injectors with 5.0 mustang yellow injectors. Stumble and hesitation went away. I had two stock injectors going bad.

[cantab27]

Well started doing again today.

Checked fuel pressure, got 32 psi at idle, 45 psi with the vac line off the regulator.

Pulled cap on distributor... And it is corroded with blue corrosion and had moisture inside the cap.
Lifetime warranty on them so new ones are on there way to my work..

I put the new cap and rotor on and no change.... It has seem to idle better now, just cutting out and stumbling on acceleration now.
Won't cut out if ease in throttle

Anyone know why there is corrosion on the contacts?

moisture =corrosion....:D....mine hates it but part of the clean down after a big comp or wheeling trip....can pressurise em same as diffs and trans

[nickxj94]

I got a new distributior lol

[cantab27]

I cant afford that new shit nick lol

[nickxj94]

I cant afford that new shit nick lol
Me either! It come out of the two door engine 😂

[nickxj94]

Well resurrecting this post..

My jeep started to have a slight miss Tuesday evening.
Wednesday it was doing same thing on the drive to work, lunch it ran fine,filled gas up, after work wouldn't start..
Checked all the obvious. Grounds,swapped out CPS,Swapped out coil, swapped out PCM. Brought out the test light. Checked every fuse under hood and under dash, checked power to coil and have none. Checked cel codes..come up with 54 and 11.. Distributior pickup.

Do they just go out like that? I figured the codes popped up since I've been trying to figure out what is wrong. I did replace the entire distributior a few months ago with a used one from a running engine.

Guess i will eliminate it with a brand new one.

[4.3LXJ]

The magnetic switch can start to wear out. So yes, it can give you fits.

[nickxj94]

Or could ignition switch on column cause no power to coil? Remember it does turn over.

[4.3LXJ]

No power at all. Did you check for voltage at the plug? Coil was new?

[nickxj94]

The magnetic switch can start to wear out. So yes, it can give you fits.
The 93 distributor didn't look that old when i installed it from the other engine.

[nickxj94]

No power at all. Did you check for voltage at the plug? Coil was new?
Yes no power from plug with key on or off and while turning over. Tested with a test light. I don't have a voltage meter.

[4.3LXJ]

It should get power directly from the ignition switch. You might check other things like the ASD and see if it gets power from the ignition switch too. Back later

[nickxj94]

It should get power directly from the ignition switch. You might check other things like the ASD and see if it gets power from the ignition switch too. Back later
I've swapped asd relay with fuel pump relay. Fuel pump is working.

I have a new ignition switch on my other column I'm headed home to get it and go back to work and install it. Will check back in a hour or so when i get it in.

[nickxj94]

It was the magnet. Good call and thanks for the help. Brand new Duralast gold dizzy in running perfect.

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