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Still running like a dog

1K views 14 replies 5 participants last post by  89Saharagreen 
#1 ·
guys i installed a new tps on my daughters jeep, was having the problem of the rpms randomly going up and down.how ever after the tps swap out, now we are getting black smut on the ground from the tail pipe and the gas millage is crazy bad from what it was. any ideas. i dont have testing equipment so not sure what to do.
thanks
michael
 
#2 ·
What's your year? Engine? Trans?

Pull a spark plug and post a pic of the electrode. Also you really should get a fuel pressure gauge to read the fuel pressure.
 
#4 ·
Pull a plug and post a photo of the electrode.
 
#6 ·
Idle air control valve can have issues too. doesn't explain the toast spark plug though. could have more than one issue. idle air control valve is cheap though and mine was definitely bad and would have idle all over the place, especially at start up. Mine is an 89 2.5l. You could be getting blow by too with a motor that old. I found my EGR valve almost completely clogged. Check all vacuum lines going through the back of the motor and over to the cannister.
 
#7 ·
Alot of things could be going on... if you do not have the test equipment like you said you have two choices go buy the equipment and learn how to use all of it over the next 2 years to fix the issue and other issues that pop up or take it to a good reliable reputable mechanic not a part swapper....this will cost money either way......

Is it Fuel Injection or Carb?

Timing could be off fuel injectors could be misfiring fuel pump could be bad EGR could very well be bad, catalytic converter could be plugged, plug wires could be fried on the inside. Engine could be blown, head gasket could be cooked.....did the vehicle overheat?

you are obviously running very rich with plugs like that and the bad gas mileage is the exhaust just black or does it have a blue tint to it?


Chief
 
#11 ·
TBI 2.5L. The intake is off of an XJ apparently, and OP cannot find any replacement sensors that fit his pigtails.

I've had lots of guesses but the current one is that the intake manifold was swapped and the sensors are not reading correctly.

I find this odd because the TBI has a WOT switch which is only supposedly found in YJs. So a YJ TBI on an XJ manifold.
EDIT: both YJs and XJs use the same TBI and ISA. The part numbers for the ISA are the same. The parts diagram does not list the WOT switch for XJs, only YJs. Yet the 88 XJ FSM lists the WOT switch as an integral part of the ISA...

My next suggestion would be to get the PCM number to see if it's off an XJ or YJ, and try to make the system 100% XJ or 100% YJ.
 
#13 ·
Ok so today we checked the timing, I think it may be off. I got #1 at tdc and took off the dist cap, the rotor button is not pointing at #1, it's past #1 by a good bit. In the picture my right finger is pointing at #1 and my left finger is where the rotor button is at. What's yall's thoughts?
 

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#14 ·
That is not that far off depending on where your timing marks are on the Harmonic balancer take a pic of the timing marks on the Harmonic Balancer when you are at TDC and show us that also.

Also I know you said "black smut" on the ground but I did not see any mention of exhaust upgrades or changes especially your Catalytic converter if that has gone bad it could be causing an issue for you...Lastly show us a pic of your exhaust pipe were it connects to your exhaust manifold.

Chief
 
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