I have an 89 xj Laredo and I noticed when my engine is warming up not at operating temp it seems to idle at around 800 rpm but then suddenly it will drop to 300 rpm and almost die but it doesn't and then back up to 800 and then back down anyone have an idea what this could be? Any help will be very much appreciated!

 

1. Clean the throttle body and idle air control
2. Ensure that all tuneup hardware is fresh (plugs, wires, cap, rotor)
3. Test your "throttle position sensor" and be sure it is in ADJUSTMENT. Yours is adjustable

 

I dont know how to do any of that kinda new to these things can you kinda give me an idea?

 

does your jeep get driven often? and atleast 20 miles?


so, when the engine is cold, your pistons have the highest gap between cylinder wall and piston (rings). This allows for H20-gasoline, and oil to wash down into the crank case. This reduced combustion efficency combined with the lowest HP out put (cold: highest piston gap= lowest HP) creates a stumbling rough idle sometimes. if you turn your heater on rite away, not only is it robbing the engine of heat, but it is also creating increased resistance on the engine and reduction of alternator/battery charge. mine will do something similar when its cold and I shift into Rev. or really crank on the wheel so the power steer has to work harder. if a car is not routinely driven atleast 20-30 mile long trip once a week, the constant short stop trips add more and more h2o condensation, gasoline, and oil into the crank case... compounding the problem. on a long drive, all the H20 evaporates, along with the gasoline.

 

Yes I drive it almost everyday but it's just to school and back maybe 6 miles a day or sometimes more but I only notice it when I just start it up and I'm not driving like just idling I'n park

 

I think that is a plausable explanation. try running a fuel injector cleaner in your tank and take her out for a nice ~hour drive. Then take note of how it all runs the next time. 6miles will not allow the vehicle to obtain running temperatures that the engine needs to avoid wear

 

Well thank you very much for the valuable info now what is injector cleaner stuff? Where can I find that and how does it work just curious?

 

you go to an auto parts store, or sometimes a super market will have it in the auto section, if they have one.
there are additives in every gasoline to protect against wear, and clean the engine. there are injector cleaning additives.

the fuel injector cleaner is sold in a bottle, you pour it in your gas tank just before fueling so it mixes. then try and get a longer drive~30 miles in.

Gas has a life of about 30 days before the vapors, and additives break down and affect combustion (Diesel-90 days)

i think all of these factors could be the problem.

 

Alright I will try that