Classic idling problem.
 

Hi guys
Need a little help / some suggestions with an issue I'm having with my 2000 P1.
When warm the idle is very low only 300-400rpm, when it drops to low the engine then starts to hunt with the revs rising (to stop the stall) then dropping down again, it will do this 3 or 4 times then the car will stall. Starts again fine.
It's been doing this on and of for a few years now. Car has had new spark plugs recently (ngk), which may have made the problem worse.
Car is running large injectors and upgraded fuel pump, has since I've had it, so don't think this is the problem.
Anybody any ideas what might be causing this?
Does the EJ20 have an idle control valve if so are they prone failure?
Cheers for looking.

The symptoms you quote are usually showing MAF failure.
You need to get a known working one to check. DO NOT try the "unplug it" trick, it does nothing.

Has the car been mapped for the changes already made?

And yes, the car has an ICV, they are prone to getting dirty.

Edited to say: stay off boost until the problem has been diagnosed and a map applied unless already done.;)

If it's running bigger injectors without remap then the injector scale will be out.

Thanks for the replies, sorry I should have added that the car is running a separate ECU but as far as I'm aware it's never been on a rolling road. I. Eli's said as well it has the MAF removed but I will need to check this.
i will also check the ICV as well, where can this be found?
regards
D

Sorry for spelling on an I phone.

Is this a new issue ?
id still find a set of rollers and give it a health check.

If it only does it when warm and you have no MAF it could be the O2 sensor. If its slow or showing 0V (normal fail mode) then you get ECU injecting lots of extra fuel and it could bog down and behave like that.

Idle control valve is worth cleaning out if not done in 18 years. They get pretty filthy and become non-linear due to the gunk so ECU has trouble finding correct spot to get nice idle. Also most aftermarket ECUs are generally worse at idle control than the original - but presumably it used to be fine?

Presumably no engine management light been seen?

If you had the original ECU you would probably have seen fault code and could rectify as per http://www.scoobypedia.co.uk/index.p...eadingECUCodes or if you have a VAG Com OBD2 cable and Rom Raider/Ecuexplorer etc you can see real-time values for sensors, and you'd be able to see which one is faulty. Aftermarket ECUs tend to be harder to diagnose without the right tools.

Thanks TJnet
i will clean out the ICV and see if I can replace the O2 sensor ( I'm assuming it has one as the car is de catted).
Thanks
D

I guess it might not have (or use) the O2 sensor. They are quite expensive for genuine so you might want to try free things (ICV clean) first and try and see if it is dead before you buy another. People warn you need a new gasket to remove and clean ICV (but I've done it before without).

Multimeter on the signal wire should see oscillations between 0.3 and 0.7 volts. Stuck at 0.9V or 0.0V when warm idle is indication of failure. Unfortunately its hard to prove for sure, as if the ECU ignoring it and chucking in far to little or too much fuel it might also do similar.)

So I've gone out cleaned up the icv, warmed it up took it out for a drive and the idle is a lot better now sitting on or about 1000 rpm, I will see if my morning drive is ok.
Thanks to everybody who posted I appreciate your comments and the time spent answering.
Regards
D

Bump update, so idle much better, apart from this morning when the temp was very low and it was very lumpy. My issue is now there seams to be some issue with the engine temp. Previously the temp gauge would sit midway no fluctuations, now the temp gauge is wandering all over the place, especially if I'm sat in traffic. Worried now that the I might wreck the engine. Have I knackered the 'O'ring? Otherwise Idle is OK.
Cheers
D

temperature gauge might indicate hg failure, get a sniff test done asap.

Hi Alcazar thanks for the response, its just strange that this has occurred just after doing the ICV, when previously never had a temp issue.