new porblem...90 xj 4.0...cranks, fires once in a while, has weak spark then no spark then good spark and tries to start then no spark again. tested cps...replaced cps...fuel pressure ok...i read about testing cam sensor but im lost. i know my slave cylinder is leaking and the old cps had oil all over it. if its dirty on the part the cps reads on (the flywheel i assume) will it give it a bad signal and keep it from strarting? im almost done with these peices of crap. i have 2 xjs that i have owned for about 2 months and i havnt had a problem free week yet. the best i got was 3 days. thanks

 

the old cps read 194 ohms, as does the new one and the one in my running xj. i checked as it was cranking with my meter on vac as it said to do and i read .2... so did the one i took out and the one in my running xj.... the testing procedure says replace if lower than .5 but i have one reading .2 and it still runs....please help! im tired of working on this! im going to just swap parts off of my running xj till i find the issue or til neither work and then im pushing them both into the lake! just kidding! i am desperate to get this fixed

 

CPS controls fuel injector pulse, Distributor has cam sensor that controls ignition timing...
Have you checked coil also?

 

i just traded coils (coil from running xj into nonrunning...coil from nonrunning into running) no chnge. im gonna trade dist. now

 

http://www.lunghd.com/Tech_Articles/...iagnostics.htm

 

ive looked through those pages and i did all those test but no luck! i changed the ecm and no change to the nonrunning but now the running one isnt running well. backfiring missing and so on! off to the lake with them!

 

ok so im an idiot! i did not bolt the coil back down on the running xj so its running fine again! now the bigggest bonehead move! i completely passed over the spark plugs as the issue!! i cant believe i went through 2 days of diagnostics and it was $12 worth of spark plugs!!! no wonder everything i checked wasfine! thanks to the guys who helped out! i forgot to keep it simple!