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renix missing issue

043500

NAXJA Forum User
Location
Ocala, FL USA
yes I searched. :)

1990 XJ renix 4.0 auto 4wd

Have done a fair bit of work to it. It had a stalling issue which a TPS fixed.

Here is list of everything else that has been done:

plugs
wires
cap
rotor
injectors (ford 19 lb)
changed MAP (went back to original as it did not help)
changed manifold temp sensor (went back to original as it did not help)
changed ECU (went back to original as it did not help)
IAC (did not help)
all new gaskets EXCEPT head gasket

EGR is not a factor as it is not hooked up at all. There are no detectable vacuum leaks...and I've looked hard for them.

None of these things listed made it better or worse. It does not high or low idle at all. Sits right where it should even with the miss.

It began as an intermittent miss. It would run smooth as silk a few days and then out of the blue it would miss slightly. It would do this for a couple days and then be gone. It cycled like that for a couple months and then began to miss more frequently. Now it is constant.

It's a slight miss...seems like 1 cylinder only. It has great power/acceleration. Cruises just fine and shows no other signs of any problem.

When I disconnect the #3 Cylinder either at the injector or the plug it does not get worse...BUT it does get worse if I disco ANY other cylinder.

It does it whether it's hot or cold...and it is just barely noticeable when cruising but is more apparent at idle.

I know I need to do a compression check but I am wondering why it would be intermittent for so long if it was a compression issue...?

Often times before it became constant I could floor it up to about 60 MPH and then the miss would clear like that. But that doesn't work any more. It's been missing constantly for about 2 weeks or so now.

Any ideas would be helpful thanks!
 
If the injectors were used, run a can of BG44k through the fuel. Injectors that run dry tend to get gummy and sticky. Both sets of Ford Injectors I put in my stroker had the same issue.
 
I will try that Old Man. Can you get it at most local parts stores? (IE advance, auto zone, napa...?)

A compression check is definitely in order. I am thinking/hoping that's not an issue but I know it needs to be looked at.

The new injectors did not change the problem in one way or the other.

I didn't list it but the fuel filter was changed within the last 1500 +- miles.

Thanks everyone.
 
BG 44K is generally sold at auto repair shops. Great stuff.

If you wiggle the injector connector on #3 can you duplicate the miss?

No. I can disco #3 at the injector or the plug and nothing changes. I have even 'squeezed' the wires for #3 all the way into the harness as far as I can to see if there is a bad spot somewhere but nothing really jumped at me.
 
The plug is fine and getting spark.

I am leaning toward the injector, the injector connector, or the cylinder is going bad.
 
THe plug looks normal and is virtually idnetical to the other plugs.

I tried an experiment tonight and swapped the #3 injector but it did no good.

I traced the #3 injector wires back as far as I could short of removing them altogether from the harness but saw/felt nothing that would indicate a probelm there.


Tomorrow we're going to do a compression check on 3 and go from there.

Not sure where to go if compression is good as then it seems it must be an electrical issue. Sad thing is back when the miss was just intermittent...when it was NOT missing it ran perfect. I've owned 3 late model HO's and it ran just as well as they did (and one of those I bought new)...until this miss became a permanent thing.
 
We'll be rechecking that today but months ago when we did check things over it was getting power.
 
I'm not one to be hard on my vehicles but on my way to church this morning I drove it HARD all the way. By the time I got to church it was running perfect again...first time 3 weeks or so.

Went to my friend's house afterwards and it checked out just fine with everything we can check.

I guess I'll drive it and see how it does this week.

I did put a bottle of water remover into the fuel tank to see if that does anything. What the hell right?
 
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