'88 hiccups at idle

I need help with my '88 xj. It has 151 thousand miles and has problems with misfiring at idle and low RPM's. It also dies if the gas is let off too quickly, regardless of wether it is warm or not. We have cleaned and checked the injectors, replaced the regulator, replaced plugs, wires, cap, and rotor to no avail. I finally just readjusted the accelerator linkage to keep it from dying, but the misfire problem is still there. What should I do?

This should be in oem tech. I would check your tps, iat, and all other sensors. The FSM has procedures on checking them with a volt meter.

sorry about that, thanks though

Maybe post this on the main board. I have this exact symptom creeping up on me. I started to noticed it a month ago (was subtle), but now it is getting to the point where it dies and happens any time it is at idle. Not sure myself. I cleaned the throttle body, replaced the gasket, cleaned out holes, recalibrated the TPS, and not much change. I am questioning the fuel pump, idle control valve, or TPS. It only happens at idle, any time giving it gas--it is smooth and responsive.

Please post your findings!!!

Thanks.

I would really check the TPS. I have the same problem every once in a while when my TPS works out of adjustmant. I have an adapted sensor to work with an HO TB so it gets way out of adjustment sometimes. I would check to see if its faulty. You get a similar symptom if you disconnect it all together.

A cool thing to do is to find someone with a scope who can watch to see if you have a secondary ignition issue as far as misfire is concerned, or an issue somewhere else. Usually, you can tell by secondary ignition if a cyl is rich or lean, and if the shop has the capability to take exhaust readings pre-cat, you can tell if you have a lean misfire or not.

If you don't have any hookups with the above machine, try everything else as far as testing sensors and such. If all else fails, you can go to the u-pull-it in Lynnwood and put all kinds of sensors and stuff for really cheap, then swap them in and see.

Steve

Stumbling like you've described was attributed on my rig to the TPS finally starting to go and a dirty Idle Air Control motor in the throttle body. It would stick not regulating the idle correctly, allowing it to die at stop signs and in low idle situations.

Do you have a lot of oil in your air filter? If so, I would look first at the throttle body and yank it off, then look to see how dirty it is and the condition of the IAC motor. The oil gets in there and bakes causing the device to stick.