misfire/distributor problem

X

xj_redneck

NAXJA Forum User
Location
Hanover, Pa
My 99 cherokee has been having a misfire issue sundeck got it. Just a mild one, so I got spark plugs and rotor, that's all it needed everything else was new before. Did an oil change, trany flush, trany filter change, both rears fluids changed, radio Bezel replaced. Went to start after everything and still had that mild misfire. Checked top dead center and the rotor was off by a 2 teeth. Moved it over and fired it up and had a major misfire moved it back the 2 teeth and now it won't run for sh*t. Please help.
 
xj_redneck said:
My 99 cherokee has been having a misfire issue sundeck got it. Just a mild one, so I got spark plugs and rotor, that's all it needed everything else was new before. Did an oil change, trany flush, trany filter change, both rears fluids changed, radio Bezel replaced. Went to start after everything and still had that mild misfire. Checked top dead center and the rotor was off by a 2 teeth. Moved it over and fired it up and had a major misfire moved it back the 2 teeth and now it won't run for sh*t. Please help.
Click to expand...

What do you mean the rotor was off by 2 teeth?

Assuming you know how to find TDC compression on #1 cylinder and align the crankshaft damper index mark at 0 degrees on the timing chain cover timing index.

If so do it.

You should see the rotor at approximately this position (#1 Cylinder).

RotorPosition_0DegonTimingMarks.jpg


And you should be able to insert a 3/16" pin punch or drill through the alignment hole in the pulse ring down through the mating access hole in the distributor housing, like this.

3_16PinInstalledat0DegTimingMark.jpg


If your distributor timing is off the pin/drill will not drop down through the alignment hole and acess hole in the distributor housing, and the rotor won't be in the position shown.
 
Thank you sidewinder cc that's what I needed to see someone with the same distributor as mine and showing me true line up thank God. I looked and looked and all I could find was older Gens. Nothing like mine. Finally progress. Haha. I'll let ya know how it goes in a little while.
 
Alright it fires and runs now it sputters and cuts in and out alot it also back fires some too. It drives fine but as soon as you put it in gears it misses and cuts in and out as you give it throttle.
 
xj_redneck said:
Alright it fires and runs now it sputters and cuts in and out alot it also back fires some too. It drives fine but as soon as you put it in gears it misses and cuts in and out as you give it throttle.
Click to expand...

Check Engine light on? Even if it isn't, you should use a code reader or scanner to see if there are any active codes or pending codes.

How long has your Throttle Position Sensor been installed?
 
Firing order is good. My code reader took a poop so I'll go to AutoZone up the street tomorrow and have them run them. I put it in 3 weeks ago. I've tested the tps but it tests bad bud I've replaced it 5 times now. It tests at 1.02 fully closed can't remember wide open. But they all have tested the same. I know it's high, there supposed to be .5 at close. But everyone has tested exactly the same. Replaced the throttle body and got no difference. I traced the wiring and nothing wrong anywhere.

Does anyone have a schematic on all ground locations in the engine bay. I know grounds are important. The kid who owned it before slaughter the fuse box. I got all that fixed back right. And yes it's done right I have been a mechanic for 4 years but been destroying and fixing cars for 8 yrs
 
Alright well redid the grounds in all 4 gauge wire and brand new ends. Put a new distributor in it. New cap new rotor, returned all the plugs and got all new ones encase one was fouled. Replaced the throttle body, the map sensor, crank sensor, tps, iac, pcm.

Does the exhaust have a ground like a lot of GMs do?

And any other ideas, I tested the tps as soon as I put it in and still tested 1.02 idk any more what else am I missing bout to drop the tank and get a new fuel pump.
 
This is the best way I can explain how it's acting right now. 9 out of 10 times it idles smooth as silk, some times it will bubble a little or have the idle fluctuate some. Then you put it in gear normally with very little fuel will ease it's way down the road about 1/2 throttle it's can't get out of it's own way, misses back fires, put puts, acts like a bi*chy h*r. Sometimes 3/4 throttle will run awesome but then once it hits 3k RPMs it's starts it all over again. Then full throttle with get and go but as soon as it's shifts it misses some but keeps trucking. I also feel like it doesn't like to shift from over drive down to 3rd it bucks the vehicle at low RPMs. Idk.
 
Since you have tested and replaced almost everything; some things more than once.... Have you tested the engines fuel pressure and what the fuel pressure is when you operate the throttle?
You can do a search to verify what normal pressure is for your year XJ. This has been posted numerous times.....
Could be a bad fuel pump, pressure regulator or dirty fuel filter.....
 
Hard and fast rule at our shop:

ALL driveability issues you start with the battery and charging system. Load test the battery. Clean cable ends and check static and running voltages, and voltage drop tests on the cables. About 15-20 minutes time and has paid off time and time again.
 
All ground are brand new just remade them all in 4 gauge wire positives have all been replaced with 2 gauge wire and alternator wire has been replaced with 4 gauge wire. Everything is brand new copper ends all connections were cleaned and battery terminals are all cleaned as well. I'll do tonight the battery test tonight and run the codes and see what's all wrong. I team them last night and got the front O2 sensor and high voltage and low voltage at tps.
 
The front--pre-CAT o2 sensor will affect driveability as it's input is used by the PCM whereas the post-CAT o2 sensors only monitor CAT efficiency and only trigger codes.
 
xj_redneck said:
Fixed, bad brand new set of spark wires and fuel pump have shot.
Click to expand...

Second rule of XJ-Club:

You have to share details of how you figured out your problem, that way others down the road can benefit from your blood, sweat, and tears. :cheers:
 
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