Needing help got a 99 grand original motor quit after #4 piston cracked in half bought a used 4.0l motor 2003 jeep grand and installed it on start up eng. Revs up to 5k rpm and stays new timing chain trottle body sensors new cam sensor new crankshaft sensor. New ecm comupter No noticable vaccuum leak or air intake this gots me stumped on whats next to try.
99 grand cheeroke extreme high idle 5k rpm
- Thread starter Rsnyder22
- Start date
JPNinPA
Well-known member
A vacuum leak is most likely. At the cylinder or the throttle bottle even a crack away from the engine. Like the vac resivoir under the battery. Second a bad or dirty IAC on the TB.
Is there any sputtering or popping? If so it could be at a cylinder like the intake not married or bent or the gasket leaking from exhaust to intake. Even the or ing gaskets on the injectors.
Regards,
JPNinPA
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Is there any sputtering or popping? If so it could be at a cylinder like the intake not married or bent or the gasket leaking from exhaust to intake. Even the or ing gaskets on the injectors.
Regards,
JPNinPA
Sent using TapTalk
OK this is a replacement engine - in a 1999 GC,
WHat ECM is installed the 99 or a 03?
What codes are showing?
What sensors and why?
Wil eng start with TB closed?
As mentioned knee jerk would be a vacuum leak - throttle stuck open..
NOW you mention - Having TB open this suggest over fueling - check inj wiring - easy test with noid light or test light KOEO. Also heck fuel pressure regulator for fuel in vacuum line.
WHat ECM is installed the 99 or a 03?
What codes are showing?
What sensors and why?
Wil eng start with TB closed?
As mentioned knee jerk would be a vacuum leak - throttle stuck open..
NOW you mention - Having TB open this suggest over fueling - check inj wiring - easy test with noid light or test light KOEO. Also heck fuel pressure regulator for fuel in vacuum line.
JPNinPA
Well-known member
I take it you mean the TPS and IAC.
I think the TB is closed on start. The IAC controls the airflow at idle.
If you stall at idle with the TB closed your IAC is not connected properly, dirty or stuck.
JPNinPA
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Jeeprancher
New member
I had that happen after spraying down the engine for its annual cleaning . Moisture in a plug connection . Took the ones around the throttle body apart , sprayed them with contact cleaner , let them dry , plugged them all back up . Problem solved .
Also was already mentioned , the IAC is maybe stuck . They carbon up . Spray cleaner in the port . Most time you don't even need to take the untit out to clean it . There's just enough build up in there to make it stick . It might need more but I'd try that first .
Also was already mentioned , the IAC is maybe stuck . They carbon up . Spray cleaner in the port . Most time you don't even need to take the untit out to clean it . There's just enough build up in there to make it stick . It might need more but I'd try that first .
No stall
