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slight surge at idle

2K views 15 replies 10 participants last post by  gmanEA 
#1 ·
Put ya thinkin' cap on guys ;)

EA CFI 3.9

When I have to sit and idle for more than about 30 seconds the engine will sort of "surge" every now and then, but it ONLY happens when I have the airconditioning on and I am in Drive, other than that the car runs fine, fuel economy is good, doesnt get hot etc
Any ideas what could be up? it had never done it before the Timing chain was replaced a week ago....
 
#2 ·
I would say that it is the air con compressor coming in and going off again.

Maybe the beasty idles better so that you can notice the surge?
 
#3 ·
hehe nah I dont think it is that as I can hear that happen at different times.....its a fairly decent sized surge.....like it wants to stall then it picks up again
 
G
#6 ·
just having a shot in the dark,putting a new timing belt on wouldn't that alter the timing ,i mean with the old timing chain streaching longing and longer over 13 years i am sure the timing has aletered, my 2 cents worth
 
#7 ·
Yeah thats what I was thinking...I have played around with the timing a little and the car runs beautifully...just does this surge when the air is on at idle......if I pull up and let it idle say...through maccas drive thru...it wont start doing it until when your collecting your food so to speak....so it only happens when it has been idling in drive for a certain period of time.
 
#8 ·
I had a similar problem to this at one stage. My car would get a bit shuddery at lights and stuff. but mine was due to the engine running way too rich. It was starting to flood. I can't remember whether it was my tps or the isc motor that was causing the problem though. Have you tried resetting the idle?
 
#11 ·
how do I play around with the idle on these things? might give it a go and see what happens...I have actually noticed it is using a little more fuel than it used to..so I will defintely check the timing as well and I may even replace the thermostat next service ( never hurts )
When u say reset the idle Clutterz...do u mean disconnect the battery leads and reset the computer?
 
#12 ·
If you have just have the timing chain replaced was it by a mechanic ? If so I would be contacting them and asking if they have put the ECU (Electronic Control Unit) through its relearn process. This involves putting the ECU in diagnostic mode and preforming a series of tasks, such as turning the steering wheel lock to lock. One of the things that is adjusted during this process is the base idle speed. If they havent done this then I would be taking it back as it is a recognised part of any major work on an EFI vehicle. Further to that you need to have the ECU in diagnostic mode to adjust the timing on a CFI EA.

If that all fails have a look at the TPS (Throttle Position Sensor)if this is faulty the ECU thinks the throttle is moving and adjusts fuel flow to suit, but if your butterfly isnt moving youll run rich and flood

Hidden Soul

EA CFI Series I Wagon Just finshed installing Dual Batteries, Dickie Seat and Headlight flasher unit. Am now in need of Money for a new engine as I cracked the Head last week typical EA
 
#15 ·
Here is the sequence for EF, if that is any help

Run engine until operating temperature is reached and thermostat opens
The engine should be idled for 1 minute in each of the following conditions (total idling time approx. 4 mins.
1. Neutral with all electrical loads off
2. Neutral with air conditioning on
3. Drive with all electrical loads off
4. Drive with air conditioning on

Note: Do not touch accelerator during any period of adaptive process.
When selecting drive apply both hand and foot brakes.

That's it.
Or you could do what I do, and put it in neutral if idling for any length of time, less strain on the trans.
 
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