Older '87 question

A family member of mine has a '87 JC with the 4.0L, auto and it keeps hesitating or dying out completely when taking off only. They have replaced a lot of parts(what exactly I am not sure) but I was wondering what could possibly causing this older TBI to be doing this? I was thinking possibly the TPS. Are there anything else sensor wise that could be bad?? And also is there a way to get any engine codes to find out what might be possibly wrong?

within 5 seconds, turn your jeep ON-OFF-ON-OFF-ON... then count the flashes of the Check Engine light. (i.e. two flashes, a pause, then one flash would be 21.

Then check out the stickied thread about computer codes.


Perhaps the CPS? (seems to be a lot of that going around...)

Got an 87 and the on-off-on thing will not work.

you could try testing the MAP sensor since it will cause this. But the CPS is the one sensor that cause 90% of the problems on these.

You can try the autozone.com website to retrieve testing procedures for you Jeep. Then you can test each to find the problem.

Try here for the MAP sensor: http://www.autozone.com/az/cds/en_us/0900823d/80/15/23/34/0900823d80152334/repairInfoPages.htm

and here for the TPS: http://www.autozone.com/az/cds/en_us/0900823d/80/15/23/08/0900823d80152308/repairInfoPages.htm#hd1-1-2

It could also be a fuel injector or spark plug or plug wires.

OK, I am not sure if this is the case with this particular vehicle but I know on some vehicles you can do a quick MAP sensor test while engine is running disconnect it, if it stalls then usually it is a sign the MAP sensor is ok. I did this and it stalled, so i take it for granted that the MAP sensor is good.
They claim they had replaced the TPS with a new one, what I seen looked like one that came from a junkyard though. So, my thoughts are leaning towards this. Also wondering about the air temp sensor, will this cause issues such as I described? Knock sensor or any other that may be present, I am not sure of all the sensors that this is equipped with but Autozone claims it does have a knock sensor and they said it can also cause the same problems. It only cuts out when applying the gas, like right after you start moving if you don't gun it then it stalls.

Change the TPS. Buy one from Advance or Auto Zone and put it in, adjust it correctly... If its fixed, there ya go, if not, return it and get your $ back. Simple.

(Adjusting it is important. - http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm -4th one down.) -Get a volt/ohm meter if you haven't got one.

Thanks for that llink citizen@large. I will try doing this when I get a chance.

certainly... what are JEEP friends for anyway, waving? let us know what you come up with.

So far, I have came up with the O2 sensor, TPS and one other sensor that ATM has slipped my mind(thinking air charge temp sensor, could be thinking of my JGC though) that are bad. I can not convince my father-in-law to by new ones, he says that ones from a junk yard will do just as good. I was thinking TPS could be from a faulty ground though, I get inconclusive read outs each time I tested it. So, before I buy one I will run an extra ground or trace down where it might possibly be bad at and try retesting. I have been doing work on my JGC as well and not putting a lot of time in on this jeep. Might be a while before I am able to get it squared away. They had talked about just getting rid of it (trading) and getting another used vehicle, I think I talked them out of that. I told them Jeeps are popular, run forever if MAINTAINED PROPERLY, this one is deceit on gas even with this problem, parts are easy to find, and it is paid for.
Which they also have the "Death Wobble" problem we are going to tackle after getting it to run good. That really is no biggy cause it hardly ever gets above 35 MPH due to the roads here in the part of WV we live in, lol.
I told them I would do all work for free and once they spend a little money on the jeep it will probably better than getting another vehicle they would have no idea anything about except trusting the person they get it off of.
I say about $400 and this jeep will be as good as new.

I have seen a lot of problems with the egr valves on the old xj's.They usually hesitate real bad from a stop but run great after that.You can unplug the vacuum hose from the egr and see how it runs

Any more progress to report msdz?

Any more progress to report msdz?

No more progress as of yet. Had other prolems I needed to do with my '(4 JGC and then my mother-in-laws Cherokee's rear brake line busted and I had to repair that. The more I think of it, I am starting to wonder if it might not of been better for her to trade it off cause she is nickle and diming her money into this Jeep.
I am sure I will get all squared away with it though with about $400-$500.

No more progress as of yet, cause she is nickle and diming her money into this Jeep.
I am sure I will get all squared away with it though with about $400-$500.
Solution: Buy it from them, inve$t 1/2 (-the work you've already done!) that much she can owe, sell her to a happy new owner...x2!!! It's like selling religion/politics... Simple, not necessarily easy... You know. Scrap the good parts at least! ru with me here?

Thought about trying to get it off her. I would raise it and make it into a ridge runner if I had her Jeep. My Jeep Grand Cherokee is a limited and just don't think it would look right raised with 33's on it like the Cherokee would(plus the JGC is our family grocery getter).
Just something to play in the mud with and if I did tear it up, I'd sell what I could and then crush the rest.
I do have another question though....Will the 4.0L engine in the '87 work in a newer model Cherokee like a '97 or '98 model?? Found one REALLY, REALLY cheap, almost a give away with excellent body and no engine thought they looked a lot alike but not sure if I could replace sensors with newer ones and make it work if all was about the same. Also wondering if tranny will work?

You should be able to use the 87 engine, if you swap out the computer also you should not have change any sensors. even if change the sensors you may need to change out the computer, since some of the new sensors use three wires where the 87 sensors use only two, i.e. MAP sensor & Crank sensor.