88 xj Choking

The O2 sensor is under recall.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: N>

Plug wires, spark plugs, distributor cap, rotor? Which engine?

Earle

I replaced all of them when I first got the Jeep so I knew what I've got. Its the 4.0l and a 5speed.

Well the previous owner replaced it and gave me a spare one so I'll try that in a couple hours.

It would be worth checking them again. The parts stores have mis matched rotor and caps for the 4.2 engine on the shelves. I don't know if they also have bad 4.0 ones out there, but the same crappy company makes them...

The rotors are too short so they arc out all over the place.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: N>

A customer of mine came in and had the same problem. Ended up being the knock sensor on the right side of the engine screwed into the block right near the seam of the oil pan and block.

Jesse

The thing is I had the distributor off 2 days ago because I was told that they rust up a little this time of year because of the humidity here. I replaced the distributor, rotor, plugs, and plug wires less than three months ago and replaced the ignition coil 2 days ago.

Good point. What fuel is in it? My 4.2 engine bogs bad on alcohol mixes and my owners manual for my 88 XJ warns of possible engine bog or loss of power when using a 10% alcohol mix.

The knock sensor is supposed to help with that...

The OP can hit on the manifold with a hammer of the warmed engine to see if the engine gives a little stumble. If it does, the knock sensor is working. Another test is to use a timing light when you hit it. The mark on the crank pulley will move.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: N>

Did he get the right O2 sensor? The originals are defective. You can phone Chrysler and give them your VIN to find out if the recall has been performed. If it hasn't, it wouldn't hurt to have them do it.

Mike

AWantz wrote:

How did it look? If you shine a bright light inside and see anything that looks like spider web marks, you have a spark jump.

Mike

AWantz wrote:

It was a little rusty since I replaced the distributor cap without replacing the rotor at the same time. But it was clean besides that.

Before I wasted any more time, I would put a new rotor in it....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: N>

I did that and it didn't effect it at all. The O2 sensor didn't either when I replaced it.

I would next suggest taking a multi meter and check the resistance on the TPS with the engine off. If you put the meter on ohms and then hand move the throttle linkage, the meter reading should change nice and smooth all the way to wide open. If it has a jump in there, it is either dirty or worn out.

The plug and socket on the TPS can get corroded easily too, but that usually gives stalls after a first start and high first idle rpm.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: N>

Well the fuel problems was a cracked fuel line. Its always some stupid thing that breaks. But it still won't start sometimes. I will start one time and not the next. It turns over fine but its like its not getting gas or any spark. Do you have any suggestions.

I would be cleaning the connection on the CPS which is on the drivers side bell housing just above the exhaust manifold.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

Mike Romain did pass the time by typing:

Also check to see if your getting spark. Pull the primary off the distributor and have someone hold it close to the block while the engine is cranked. Just keep the primary closer to the block than your hands or your gonna get one hell of a shock. I generally stick a sparkplug in the boot and ground it with a jumper wire.

Not sure of the 88, but in later computers if the car doesn't get a crank sensor signal in a couple of revs it cuts power to the coil.

That and all the fuses.

The other thing is to check the coil for any melty spots and the rotor for a burnthrough. Sometimes the rotor burns through right were it sits over the distributor shaft. Real pain in the ass to diagnose.

Oh Yea.. and one other thing.. run a heavy jumper cable between the engine block and the frame. If you have a rotten engine ground strap it will never start.