Engine Surging
Thread Starter
1st Gear
Joined: Mar 2011
Posts: 1
Likes: 0
From: Texas
Engine Surging
Engine Revs surge between 650 and 1100 while in neutral or when at a stop. Have replaced a number of sensors and the ECU. Did 3 vacuum tests and checked the EGR valve. There are no codes except for the computor seeking the proper rev info. Anyone have any ideas??
Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17
my vote was gonna be for the EGR, may be somethig that uses vacume, like the cruise control servo, an 02 sensor that is doin g something called 'hunting'. if you give the year of your car others will step in faster cause its probably happened to them
Le Mans Master
Joined: Jul 2009
Posts: 6,381
Likes: 66
From: SF bay area C.A.
C4 of the Year Finalist
Sounds like the IAC to me. Same thing happen on my Grand Prix SE, changed the IAC and it was fixed. BTW buy it at pep boys for about 30 bucks, others charge up to 200.
Safety Car
Joined: Jun 2009
Posts: 4,738
Likes: 15
From: OC Calif
St. Jude Donor '10
Also found out the Temp Sensor can be reading temp correctly, but not signalling the ECM correctly. Fuel is constantly trying to adjust due to faulty temp reading to the ECM.
A scanner told me this, but no code because it wasn't completely malfunctioning.
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Burning Brakes
Joined: Dec 2008
Posts: 1,021
Likes: 7
From: Morgan Hill and Marina California
That was my problem, only just the plug to the IAC. Check the plug first, unplug it, clean it, try it again.
Also found out the Temp Sensor can be reading temp correctly, but not signalling the ECM correctly. Fuel is constantly trying to adjust due to faulty temp reading to the ECM.
A scanner told me this, but no code because it wasn't completely malfunctioning.
Also found out the Temp Sensor can be reading temp correctly, but not signalling the ECM correctly. Fuel is constantly trying to adjust due to faulty temp reading to the ECM.
A scanner told me this, but no code because it wasn't completely malfunctioning.
sensors. One feeds the gauge on the instrument
panel, the other feeds the ECM, which makes emission
decisions based on the info, and triggers the low
temp fan (with dual fans the high temp fan has a
third on/off sensor).
My '01 Nissan Pathfinder is the same way (except
no two-fan option).