Engine/Transmission (1994 - 1998) Low RPM @ Idle

[whistleman]

Friend has 98 (yes a 12 valve) Engine rpm is low at idle and oil pressure drops and check engine light comes on. Any help is appreciated.

 

[JConley]

I have had the same problem, and it seems others with the 98 12 Valve have had this too. I think it is a problem with the sending unit. I just turned up my idle another 100RPM, and it doesnt happen anymore.

 

[Andy Redmond]

Whistleman:



I confer, see if its better without the a/c. You might find the tach is not too accurate at lower rpm's. Mine if off about a 100 rpm in this range, according to a Scanner. However, by 1500 its dead on.



Good luck



Andy

 

[Missouri Mule]

Definitely adjust the idle rpm up.



Automatics 750 to 800 rpm with trans in drive and a/c on.



Manauls 780 rpm with trans in neutral and a/c on.



If it is already set at respective rpms set idle up 50 to 100 rpm.



Mine runs around 825 to 850 rpm at idle.

 

[DieselDoghouse]

Another 2¢, if the idle adjust is OK and the oil sender is not going south, I have been told that the fuel pressure bypass in the Banjo at the front of the P7100 may become thermobaric (how the Heck did I remember that one??) as it heats. If this seems to be a hot-engine problem or the idle drops alot from cold-->hot this might be suspect. Replacing the bypass unit in the banjo will prevent it becoming softer when hot.