syncview

oh well.

as the title says,
my cherokee upon first start in the morning idles very rough and shuts off if I let off the accelerator. So, now if I keep my foot on the accelerator for about 5 to 6 mins, and let off it then the engine will not stop but still idle very rough. I have changed the plugs, the wires look fine, every cylinder is firing, where to look now?

Also before this happened, I used to keep it at about 1500 rpms and let go of the accelerator slowly, then it would stay at normal 800 - 900 rpms smoothly. But now, it idles rough and is hard to keep the engine running when started in the morning. regardless of the engine temperature, if it reaches 100 Celcius, it won't stop the rough idle. I can smell the rich smoke coming out the of the exhaust, now I want to know that from where should I start?

got2lovethexj

did it just start idling rough or did u change something and then it started?

syncview

changed nothing man. I put in a new (used) fuel pump along with a new in-tank fuel filter and the outer fuel filter. It was running smooth and after a few weeks it suddenly started this.

gintaras

You said you didnt change anything, but I had a similar problem with mine, it never died but t ran rough, I ahd a combination of problems, I had an intake manifold leak as well as a bad O2 sensor.

claygrassmann

try replacing your iac and tps

goalpost95

my guess is the crankshaft position sensor, i had a similar problem and i put in a new cps and it seems to be running fine. I literally just put the new one in today and haven't done much driving but I haven't had a startup issue yet. I got a new one from autozone for about $34 if i remember right but the bolts to get the old one off are a little challenging to get to . . .

krkx93

check both the sensors on the throttle body and also try tightening up all the manifold bolts. they are notorious for leaking. another thing to check is make sure u dont have any vacuum leaks anywheres and make sure all vacuum hoses are still good

syncview

Okay, I cleaned the throttle body using a spray cleaner, then I found a pipe that was going from the valve cover to the intake manifold, that was cracked at the joint, I taped it well and reconnected it. Then I started the thing up, it was smooothh! YAYYY! rpms at 800 and going smooth and soft.


Then I drove it around the block and when under heavy throttle (while driving only) I experienced something strange (again). Like a fuel cut-off or something and a buckk sound and the car jerks bad and keeps on going. At this very time the CHECK ENGINE came on, I did the ignition trick to read the code and they were 21 and 24. 21 is for oxygen sensor and 24 shows that TPS voltage is over 4.96. Now what?

Rich exhaust must be due to the o2 sensor NOT BEING present at all. Because mine is shot and I have disconnected it for now. TPS? Should I replace the TPS? Would this random jerky cut-off like thingy be because of the TPS? ALso the transmission is shifting weird too. And since this has happened, the JEEP stays at 1500 RPMS idle. no matter what.


I tried re-setting the computer, then drove again. under light throttle it is fine, as soon as I push it, it bucks and jerks and the check engine light comes on. What should I do now?

Also note that when trans in P or N, no matter how much I rev the engine, it is smooth, no jerks or kinda cut-offs. But when driving, as soon as I push the throttle it jerks and shift wierd and the engine bogs down and bucks with rich smoke coming out of the exhaust. Keep in mind that it was running fine before even with out the o2. of course the exhaust was rich but not this much.

syncview

Any ideas?

phillyxj570

i had the same exact problem with my xj it was a combo of things, crankshaft sensor, cam sensor and my fuel pump.

syncview

could it be because of the distributor? :s how to check the distributor?