My 2.8 Cherokee is grumpy

15

Asked by Nov 19, 2016 at 03:45 PM about the 1986 Jeep Cherokee 2 Dr Pioneer

Question type: Maintenance & Repair

The time light shows an erratic crazy timing and the car pops and idles rough

23 Answers

57,155

The timing chain may be stretched out.

1 out of 1 people think this is helpful.
57,155

If the distributor bushings are worn the timing may be erratic.

1 out of 1 people think this is helpful.
15

You mean the rotor? Replaced, still same, could be the map sensor? I have replaced alot of parts but not successful, replaced chain, rebuild carb, redone throttle shaft, alot alot, what does the fire timing regulations, the map or something else?, I bought a maintenance book also.

57,155

Not the rotor but the internal parts to the distributor. Depending on what type of ignition system you have, the bushings being worn can cause the timing to jump all over the place. You may want to get a new distrubutor.

1 out of 1 people think this is helpful.
57,155

If you replaced the timing chain did you replace the gears?

1 out of 1 people think this is helpful.
Best Answer
15

If I disconnect the 4pin connection to the distributor tha engine idles ok

15

I will try to do that with the distributor thanks, let you know

57,155

Try to wiggle the rotor around. If there is any play side to side then the bushings are worn.

1 out of 1 people think this is helpful.
15

I 've checked the voltage of the O2 sensor and comes out 0,2 it should fluctuate, id does but a little, the timing is way too advanced, if I unplug the air mix solenoid in my carburettor the voltage goes to 0.5 where should be, if I unplug the map sensor hose the timing goes closer to the 6' btdc os so, I will check the right voltages of the throttle position sensor and the MAP, check other sensors, but it could be the PCM? I need to take it out and check the connections, it became a Nightmare, or the most challenging yet. I will figure it out, but at what cost!!!

15

The timing is set to factory spec with the 4 pin wire off 6 bdtc, but when I accelerate seems okay, with or without wires I think also the o2 sensor value fluctuates, unless I keep steady RPM then it shakes a bit, drops to .2 volts , I connect and disconnect things to try timing and O2 voltage, I read that .5 volt is the right value range for a correct carb emission value, I was wondering if the MAP sensor if at fault for everything.

15

I've replaced the engine with a used one, did compression tests, the old one was mixing water with oil, kind of low compression on a cylinder and had a little knock, junk. The new one starts easier but still similar misbehaving good cold or warm but as soon it gets to temp. op. condition it idles porly, I bought a special sensor tester, and noticed that the idle misfiring is due to a lean/timing condition, the timing goes way over the max gauge, and 1 inch over to the left of the pulley mark. The electric air/gas mix gets activated and lean condition occurs, I think. After all the work that I've done to it, it is so frustrating, my wife sais that if does not go we can junk it. I can start buying pmc, map, cat, etc etc, basically it is not gonna happen, not funds to waste on it, the car over all is in good condition, everything works well, does not leak anything, because I fixed everything. The timing is always advanced, I'm sure that someone that had the same problem knows what is the part that is failing to report the right info to the PMC. or the PMC is fried or so, I was thinking about the MAP sensor to be at fault and sending erratic info about timing, but what about the air/gas solenoid, before it did not do that I think, because the carburetor throttle shaft was super loose, and I bought a throttle shaft rebuilding kit and fix it, nothing, should do better but no, that solenoid has to be activated all the time, before I think it used to be on an off as needed.

15

I live in California, the worst of the "smog States", I understand that is important to keep cars smog safe, but in this State you cannot do too many modifications, not different carbs, would not pass the visual, I'm going true the manual and check the all sensors system and start to rule out one thing at the time. unplug the pmc and check for faults, I believe that there is a reason for it to behave like this. And then, after I found the problem I'll let you know, also I will get 1/2 gal of gas and burn it. Easier and cheaper to get a new one, this time fuel injected. My grandfather sold mopeds, and one day a guy came to his store to buy a new moped because he got fed up of his old one, he got stranded for too many times and too many time he had to call the mechanic to fix it, so a way he did not have to deal with it, he got a ride to the gas station to buy a qt of gas and burn it.

15

Sometimes you get and sometimes you loose. Probably the moped needed some gas, but in the tank.

15

the other day I was a little frustrated, When I unplug the hose from the MAP the timing goes to specs

15

I've checked the voltage fluctuation of the o2 sensor, at idle is very low voltage, about 0.2 if I rev the engine the voltage goes up, and I was able to use the gas idle adjusting screw, not the air, on the carburetor, the voltage reading goes up, but not enough, should be around 0.45 or so, so I'm thinking, or there is air that goes in somewhere,or the EGR does not open at idle as it should, oxygen going in from a pump on the exhaust, but why the mixture solenoid gets activated, The PMC? Mhhhh!! more investigation is needed, I do not want to continue buying things without results, I was checking on those internet forums and I did found some, but not answer.

15

I was reading that at idle the mixture solenoid is activated, I've accessed the idle mixture screw, and backed up a little and the overall thing gets better, the car does not have too much power now, like I remember, I'm not sure, because, I've been driving a Saab 220hp so I cannot compare it, Today I will play a little with it and see, feels like something in the carb got plugged, I've disassembled the carb too many time now.

15

Could it be the EGR?

15

I've checked, cleaned, but you imagine, if it is that, it sounds right, the symptoms are the one described. But when I disconnect the vacuum line for it, the car still idles poorly, I need to investigate more.

15

Funny part, I've taken the car to smog and it seems that it went well, the only thing that did not go was the visual inspection, a hose was plugged up and it was not supposed to be, going back wednesday, hope everything goes well

15

EGR checked clean and good, my worry was the exhaust, but that seemed not the issue, I guess that"s how those run. It does not have much power, is okay, maybe because Ive been driving a Saab 2.3 turbo 220 hp

15

Lowered the idle rich mixture (I've cut the base plate to access it), that sounded better, but let see this Wednesday!!

15

I love how the Saab runs, lots of power and when you need it, the turbo doesn't make it too quick to response, but it is a beast. There are 3 steel lines coming from the gas tank, one is the gas, one is the vapor, and one should be the return, maybe someone substitute an electric pump and there is a return line? When I first got it I've felt a gas smell, and realize that was coming from that hose, and I plugged up, now it backfired on me. I have two choices, take it out, or connect it to a spare something or so, i"ve connected to plugged steel line for the transmission, I believe. There was a recall for the timing of 6 BTDC but the technician said that it supposed to be 10 BTDC, I've set it to 8, he said that is okay, hope I do not get catch up on mistakes

15

The technician sent me to a referee to check if the extra hose that comes from the tank is pluggable or something else. I think that my jeep has to have a mechanical pump, and someone swap an electric one, without return line, so the extra hose should be the return line, it comes from the tank!! Now I have 10 days to figure it out, the engine seems to not have the mounting for a mechanical pump. Franco

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