Surging Idle - Need some help
12-20-12, 08:18 AM
#1
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Surging Idle - Need some help
Hi all, I haven't introduced myself though I have made a few posts to the forum.
I have a '99 Harrier that I bought a couple of months ago and I have a curious problem. I have done several searches and can't seem to find a solution.
Some background info:
I bought the car with the CEL on. Error code P1155 - air fuel sensor.
I have been driving it and wasting fuel until I can get the sensor shipped.
Prior to my buying it, the PO changed the timing belt and water pump and unknown to me didn't change the tensioner or tensioner pulley.
Two weeks ago, the tensioner failed and snapped the belt. I towed it to my mechanic and we changed the belt tensioner and pulley.
She started up just fine, revved all the way out, had no noticeable power loss.
The problem is once the engine comes up to operating temp, the idle drops and surges from 500rpm to 1200rpm on a very predictable pattern.
I've cleaned the IACV (the Lexmex way), the MAF and cleaned out the throttle body.
The throttle response got better but once warm, the surging won't stop! Help!!
I have a '99 Harrier that I bought a couple of months ago and I have a curious problem. I have done several searches and can't seem to find a solution.
Some background info:
I bought the car with the CEL on. Error code P1155 - air fuel sensor.
I have been driving it and wasting fuel until I can get the sensor shipped.
Prior to my buying it, the PO changed the timing belt and water pump and unknown to me didn't change the tensioner or tensioner pulley.
Two weeks ago, the tensioner failed and snapped the belt. I towed it to my mechanic and we changed the belt tensioner and pulley.
She started up just fine, revved all the way out, had no noticeable power loss.
The problem is once the engine comes up to operating temp, the idle drops and surges from 500rpm to 1200rpm on a very predictable pattern.
I've cleaned the IACV (the Lexmex way), the MAF and cleaned out the throttle body.
The throttle response got better but once warm, the surging won't stop! Help!!
12-20-12, 12:00 PM
#3
Pole Position
If its surging from 500 to 1200 rpm it sounds like it might be confused about its operating temperature. Have you checked the IAT and THW sensors for proper operation? If these are not functioning properly they might be telling the ECU that the engine is cold when it is not and the ECU would then increase the idle rpm.
12-20-12, 01:06 PM
#4
Driver School Candidate
I don't think it would hurt to also make sure that all vacuum hoses are plugged in and that there are no vacuum leaks. I've had multiple occasions on friends' cars that came to me with bouncing idles and it was simply because some vacuum lines weren't hooked up.
Daniel
Daniel
12-21-12, 03:36 AM
#6
Super Moderator
It was many years ago since I visited Jamaica, https://www.clublexus.com/forums/rx-...er-emblem.html but it sure was a blast. Went to Bert's in Kingston to get that emblem.
If that A/F sensor isn't in there yet, get used to some issues. One thing that could help a bit would a bottle fuel injector cleaner in your tank. It won't erase that code, but clogged injectors can be a source of issues with idle (and it's good maintenance nonetheless).
Even with everything okay, I have experienced issues with idle on startup and warming up (both here in Florida and also in Mexico), where I can get a bit of surging.
If that A/F sensor isn't in there yet, get used to some issues. One thing that could help a bit would a bottle fuel injector cleaner in your tank. It won't erase that code, but clogged injectors can be a source of issues with idle (and it's good maintenance nonetheless).
Even with everything okay, I have experienced issues with idle on startup and warming up (both here in Florida and also in Mexico), where I can get a bit of surging.
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02-28-13, 06:27 PM
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So... today I serviced the RX .I haven't been able to work on my it before as I was away.
I replaced the A/F sensor, changed the plugs ( the LexMex way), oil and filter and air filter.
The car started up just fine and ran like a champ.
No surge was there on that test drive. I shut it off to put on the engine cover and when I started it again, the surge was back!
Any ideas guys?
I replaced the A/F sensor, changed the plugs ( the LexMex way), oil and filter and air filter.
The car started up just fine and ran like a champ.
No surge was there on that test drive. I shut it off to put on the engine cover and when I started it again, the surge was back!
Any ideas guys?
02-28-13, 07:42 PM
#10
Moderator
Surging idle is most likely a vacuum problem.
Remove the cover and see if the problem goes away ... if it does then check the vacuum plumbing and see how it gets aggravated by the cover.
Salim
Remove the cover and see if the problem goes away ... if it does then check the vacuum plumbing and see how it gets aggravated by the cover.
Salim
03-07-13, 05:44 PM
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Hi guys, time for an update. I took the car for a long run with the A/C on and spirited driving. I got 20 mpg!!
However, even though I have removed and thoroughly cleaned the IACV the car surges sometimes.
In fact each startup is a 50-50 chance of surging. Whenever it happens I restart the car and it goes away.
The only constant is that the surging occurs only when the engine is warm. What gives??
However, even though I have removed and thoroughly cleaned the IACV the car surges sometimes.
In fact each startup is a 50-50 chance of surging. Whenever it happens I restart the car and it goes away.
The only constant is that the surging occurs only when the engine is warm. What gives??
03-08-13, 10:59 AM
#12
Super Moderator
Hi guys, time for an update. I took the car for a long run with the A/C on and spirited driving. I got 20 mpg!!
However, even though I have removed and thoroughly cleaned the IACV the car surges sometimes.
In fact each startup is a 50-50 chance of surging. Whenever it happens I restart the car and it goes away.
The only constant is that the surging occurs only when the engine is warm. What gives??
However, even though I have removed and thoroughly cleaned the IACV the car surges sometimes.
In fact each startup is a 50-50 chance of surging. Whenever it happens I restart the car and it goes away.
The only constant is that the surging occurs only when the engine is warm. What gives??
Where I've seen the issue most often is where there is a sudden temperature change (either the weather or because I went from being on a highway for a while and then going to city (happened a lot in Mexico) or vice-versa. After cleaning the IACV, I generally pull the EFI fuse or the battery cable to reset the system.
eep in mind that unless you have the crankcase ventilation system plugged (or going to an oil catch can), vapor from the crankcase will find it's way into the combustion cycle and also to your IACV. That's the way the system was designed emissions wise (as are most vehicles) and the IACV needs cleaning.
03-08-13, 11:38 AM
#13
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I have had surging idle when it is cooler (and denser air).
Where I've seen the issue most often is where there is a sudden temperature change (either the weather or because I went from being on a highway for a while and then going to city (happened a lot in Mexico) or vice-versa. After cleaning the IACV, I generally pull the EFI fuse or the battery cable to reset the system.
eep in mind that unless you have the crankcase ventilation system plugged (or going to an oil catch can), vapor from the crankcase will find it's way into the combustion cycle and also to your IACV. That's the way the system was designed emissions wise (as are most vehicles) and the IACV needs cleaning.
Where I've seen the issue most often is where there is a sudden temperature change (either the weather or because I went from being on a highway for a while and then going to city (happened a lot in Mexico) or vice-versa. After cleaning the IACV, I generally pull the EFI fuse or the battery cable to reset the system.
eep in mind that unless you have the crankcase ventilation system plugged (or going to an oil catch can), vapor from the crankcase will find it's way into the combustion cycle and also to your IACV. That's the way the system was designed emissions wise (as are most vehicles) and the IACV needs cleaning.
03-08-13, 05:55 PM
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Baetke, there was oil vapor in the intake bellows. I replaced the PCV as well (it broke when I was changing the spark plugs). So i will check the hose next.
Tell me though, since the surge is very predictable, 6 seconds proper idle, 1 second surge, 6 seconds proper idle, 1 second surge......... could vent vapors cause this?
I'm thinking ECU. Anyone has a spare i could try?
Tell me though, since the surge is very predictable, 6 seconds proper idle, 1 second surge, 6 seconds proper idle, 1 second surge......... could vent vapors cause this?
I'm thinking ECU. Anyone has a spare i could try?
03-08-13, 08:00 PM
#15
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Plugged PCV's have resulted in some very strange symptoms including excessive oil consumption and unexpected "compression braking". I haven't been able to explain why but since it is a simple and inexpensive fix and it has helped others, when you have that obvious symptom, its a good place to start. Let us know if it helps. This is just one of many systems that interact with the induction system so it's worth eliminating quickly.