Hello i have an xj sport that i just put the 4.0 l back in. I start it up and it wants to idle at 2000-2200rps i checked the timing as far as being 5 degrees before TDC. But still not luck i changed the tps sensor and iac sensor located on the throttlebody but still no luck i run the engine and then disconnect the tps and plug it back in and it has no effect on the performance on the engine what so ever. i dont have an OBD1 reader to check for codes neither does oriellys auto parts. so i cant check the codes. im thinking it maybe could be the intake manifold gasket there might be a vacuum leak that would be my only other guess but before taking that off again i would like some advice before i tackle that again. pls sincerly 92 xj sport 4.0l driver. thank you.
06-24-2013 09:56 AM
Definately sounds like a vacuum leak to me, check all your hoses. I did the intake gaskets on a 3.1 grand am once and forgot to connect one measly hose. First start up, it idled at 3300 rpm:o
06-24-2013 09:44 PM
Hey I looked thru the vacuum hoses still couldn't find anything but I think it might be a bad ecu because my tps has no change I checked the codes with obd1 it shows no errors but if I turn the key on and off three times I can get codes thru the check engine light I sprayed carb cleaner around the intake manifold and no leaks we're found so I'm stumped right now it could be bad computer that's my guess any more input would be greatly appreciated.
06-27-2013 11:33 AM
Is the throttle plate completely closed while attempting to get it to idle? Starting fluid is better for trying to find a vacuum leak.But it could flare up on a hot engine. Did you do ANYTHING before this problem started or did the problem start on its own?
06-28-2013 10:19 AM
Hey ron I pulled the engine and when I hooked everything back up it happened it ran great before pulled could it be a map sensor? And thanks for replying.
06-28-2013 01:44 PM
If all is hooked up correctly id still say vacuum leak. Did you take the manifolds off? The fuel rail ( lots of o-rings) to lose. Try strarting fluid to find the leak.