90 Xj Tps

Been reading all the threads about low idle, this has been happening to my 90 as well, It wants to stall when I come to a stop. So far I have replaced the 02 sensor, cat converter, muffler, a couple of vacume lines, the valve cover gasket, dist. cap and rotor, plug wires, I have low oil pressure at idle, around 40 PSI or less and it to takes forever to warm to operating temp and sometimes it never gets there. I have no water in my oil or oil in my water. any thing else I have missed? I have read posts that TPS's are out there for around $30 dollars......WHERE? I have only found them for around $70+. HELP ! :doh:

On my three Renix XJs, I've found that the TPS doesn't do much to idle speed; however, others will disagree but you can prove it for yourself by manipulting it while the engine is running. Have you cleaned the throttle body? Idle speed is controlled by the ECU which in turn controls the IAC gizzmo. Make sure the IAC and it associated passage are clean. Has the idle port on the left side of the throttle body been readjusted? You can tell by checking to see if the soft metal plug is missing on the left side of the TB. Two significant ECU inputs that impact idle speed are CPS and MAP. If the CPS is bad, the engine won't run. I know that the idle speed will be high if the MAP is telling the ECU that vacuum is high so I assume the opposite would happen if the MAP was telling the ECU that vacuum is low.

90 Xj low idle

The Renix XJs (up to 1990) use an Exhaust Gas Recirculation Valve (EGR) on both the 4.0 and 2.5 engines. When it quits working, it sticks open, letting too much exhasut back into the engine at low rpms. The result is low idle and frequent stalls at idle, but runs OK once you raise the rpms. My 1990 with 4.0 is on its third EGR since new. My daughter's, also 1990 4.0, currently has the EGR blocked (pull the vacuum line from the round part going to the valve itself and plug it)- until I put in a new one. Don't leave it that way- we have to breath air and it keeps emissions down, plus it also helps keep combustion temperatures down a bit (important if driven hard or hot). As above, I would clean the throttle body using spray cleaner through the top, cleaning the butterfly and Idle Air control (take this one out and clean the passages- don't touch the TPS unless you want to go through the adjustment procedure (no need to remove it, anyway)., then try blocking the EGR line. This will tell you if the EGR is the problem. They're easy to replace (remove the air box for access), and not too expensive. 4xBob