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chapter 6000

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byrinxx74

NAXJA Forum User
Location
oakland
Ok so i have posted my problems a ton of times. My 1996 jeep 4.0 is having a shake at idle, no rpm flux just shake. Here is what i have done to it.
Check comp 120 all the way down
New iac
New tps
Cleaned throttle body
New plugs,wires,cap,rotor,
New fuel filter.
Check fuel pressure.
Check fuel injectors.
Put new seals on fuel injectors
So when i drive there is no slack in driving or slugsh ness. No hick-ups. Just at idle it seems to miss a little. Any idea's would be great. Ooh also there are no codes, no codes pending either.:soapbox::flamemad:
 
1. Your fuel injectors are still a bit of a wildcard here. You can't really check them unless they are tested for flow with precision equipment.

2. What brand plugs are you using? There have been a few reports of misfires with both Bosch and E3 specialty plugs. Champion coppers best for your application. Be sure gap is at .035
 
Is the shaking a problem, does it stall ? The Jeep is 16 years old, some loss of that "new Jeep" smoothness should be expected. The In-Line 6 cylinder engine isn't exactly known for its smooth idling.
 
I have champion plugs. I checked fuel injectors with the little light. Also checked them by taking them out and starting the car. They all squirt the way they should.
 
All the light is going to tell you is whether or not your injectors are getting the signal to fire, not anything about how well they are performing.
 
so you checked with a noid light..and you have a pulsed the injector out of the manifold to see if the stream is good. have you measured the volume of fuel coming from each injector? also measuring the type of stream coming from each injector?

like said above it does take special equipment and they match each injector....not knocking you or anything but i dont want you to spend a fortune replacing parts that simply aren't at fault...if it's more of an annoyance then by all means i can understand but if this were me i'd give it the ole "if it ain't broke don't fix it"

the I6 again stated above are not the smoothest running especially with years put on them at idle but it sure as hell will run for ever....good luck with the search but i think your going to be going around circles just trying it to idle smoother

by the way have you checked your motor mounts?
 
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No i do understand what you are getting at. I will have to try taking it to a shop that has the tools to do that. I understand as well what you mean about the jeep shaking. Its just something now that i have noticed and i cant let go. lol Its so weird you can feel it in the steering and at your feet, it will shake semi hard then try to correct it self. Im wanting to spend alot of money into fixing her up and making a good offroader, im just afraid of doing that and then having the motor go poop, because of me ignoring the signs?:puke:I mean if you all think its normal or can be something that can be ignored then maybe. Or maybe its just my jeep and something she just does.
 
I also forgot to mention when doing the comp test i only did it dry, and it red 120-122, Is that normal or is that pretty low? All cylinders the same though.
 
It was all the same 120 every time i would crank the motor. No difference. Acually come to think of it. The fifth cylnder first crank was at 90, then after that it went to 122. I tried it four different times and stayed at 122
 
Have you had it SMOGed lately? If so, what are he numbers? The print-out will indicate fuel mixture at idle and cruise. A lean idling engine can shake a little; especially if the motor mounts have hardened.
 
My 98 had the same issues. I swapped in an extra map sensor and changed motor mounts and shes fine.

I think my map was going anyway (it was the original and had about 225k on it lol). But those two things fixed it right up.

I had just a tiny miss intermittantly at idle, and the jeep had good power and ran beautifully except that little miss.

I think the mounts were the key. Under the hood if I revved the motor at all it would twist like a biotch.
 
I agree with the motor mounts. Have someone watch your motor while you put the vehicle in drive and then to reverse with your foot on the brake. You may be suprised with what you see. Even if the mounts appear ok they could be alot more flexible than they were at earlier times. If they appear good or you replace them and the shake is still there. I'd do a vaccuum test as well. There are symptoms of problems in the top end of the motor that can be picked up by observing the vaccuum readings that cannot (or at least as not easily with a compression test.
 
Yeah i have tried the foot on brake, test for the jeep, though there was barley any moviment if none at all. You put your hand on the back exhaust and you could feel it putt every couple of sec?:soapbox:
 
Sounds like you have a bit of a misfire judging from the putt from the exhaust. What is your long term fuel trim like? Have you checked/replaced the O2 sensor? What about the MAP sensor and coolant temp sensor?
 
Talyn said:
Sounds like you have a bit of a misfire judging from the putt from the exhaust. What is your long term fuel trim like? Have you checked/replaced the O2 sensor? What about the MAP sensor and coolant temp sensor?
Click to expand...

Talyn, it seems that the MAP made a huge difference on my rig. Is it plausible that as they age they leak a little air through and messes up the readings and allows a small puff of air into the system causing a misfire?

Or would it just be the circuitry? It doesnt matter much Im just curious.
 
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