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Discussion Starter #1
We finally got some good weather again!! So good in fact I'm taking tomorrow off to do a couple of jobs on the old Girl.

I have a very high Idle speed, around 1200 revs, and when I try to adjust it, the screw is in as far as it can go!! If you place your finger over the hole where the screw is, it gets sucked in!! Is this right, or is something amiss?

Lee from middlehurst has been a complete star, and advised on the problem,stating it could be an air leak,idle valve incorrectly adjusted, or butterflies letting too much air in.

have any of you experienced similar problems with your cars, and what was the cure?? Is something probably blocked? is the Idle valve clean-outable?

I realise that I'm probably asking a daft question, but if say...10.. of you have had a stuck idle valve, then theres a good chance that it could be that. The car's done 56,000km's, and hasn't been thrashed at all since 29,000km's.

What is a PCM valve? It's on the left hand inner wing, and has two hoses on it. I pulled one of the hoses off, and tried to suck and blow through it, but it was completely solid,maybe it's supposed to be like that????????

Sorry about all the questions AGAIN!!!!!!!!!!! I am grateful for your help.....honest!!

Regards:(
 

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Sounds to me like an air leak. If it is, you'll be running lean at idle. Get yourself to a local MOT type garage and get an emissions check done... this will help.

I don't know the arrangement of the idle adjustment screws, but, I'm 100% certain that your finger should not be sucked in... that means that air is being drawn into the system that is a) unmetered and b) unfiltered. This could well be the cause of the problem. Try turning the screw out, small amounts at a time, and see what difference it makes.

Jon
 

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Maybe the idle screw should have an O-ring seal?

Check every rubber air hose for leaks - very easy for 10 year old rubber tubes to have barely visible splits and cracks.
 

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Discussion Starter #4
Yep, the screw has an O ring on it, which looks a little perished. I refitted the screw with a little grease, as a temporary measure, and it made no real difference to the idle speed.

I've had a good look round all the pipes, and cant find anything obvious, although I would like to know how the idle valve comes off?? It feels as though it's bolted to the bottom of the intake plenum, but it must be fitted to something on the other side of the butterflies, or it wouldn't do anything!!

I'm beginning to think the plenum and inlet manifold are going to have to come off!! I've ordered new gaskets today just in case.

Thanks for more help in anticipation:confused:
 

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Nigel,
Have you tried cleaning the electrical connections on the AFM's and the TPS ?

Maybe worth tryign the ECU reset too. (disconnect battery / stand on brakes / reconnect battery)
 

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I just don't agree with this whole disconnect the battery/stand on brakes thing.

Standing on the brakes will do precisely nothing. If you disconnect the battery, the brakes are not grounded, therefore there is no circuit, therefore it makes no difference whatsoever. It's fairly elementary electronics.
 

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LOL, You're right too :D

It should read, Disconnect the battery / connect earth lead between chassis and true earth / Stand on Brakes / Reconnect battery.
 

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Remove the rubber hose on the idle valve and block it.
Start up and if the idle rpm is still high then this check
bypasses the idle valve.

If this check helps lower the idle rpm then there is a brass screw hidden
above the idle screw u have to remove plastic to get at it.
Screw the brass screw in and readjust the idle screw.

If rpm is still high and ur sure all is well and there are no air leaks it will
be easier to adjust each throttle butterfly return stop screw.

Don't get too hung up on the idle control valve, its only real
function is to help maintain a steady idle rpm when u have the lights
on,or put a loading on the battery..etc.
 

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Discussion Starter #10
Thanx charlie. I'll try running through this process tomorrow.

Should this be done with the engine cold, or hot? Do you mean the 15mm bore hose that comes from the bottom of the plenum?

I have noticed that the idle speed is the same when the engine is cold as when its been left running for 10 mins or more! In fact doesn't that mean that the idle valve isn't working?

I'm not really worried about the idle valve,as such, but I really do want to sort the fast idle problem!!

Thanx again for your advice.........any more????????



:smokin:
 

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Discussion Starter #11
Thanks again Charlie. I carried out the process you described on your last post, and nothing happened. there was a slight reduction when the hose was plugged, but only about 50rpm according to the tacho.

I removed the idle valve, four 6mm bolts (10mm head) on the side of it,one wiring connector and a rubber hose, and cleaned it out. This didn't seem to make any difference either!!

I think I'll have to wait for the new gaskets to arrive from Middlehurst, and get stripping. I think I'll take photo's along the way, and make this the first part of the "Haynes" type manual I'm gonna put together for each job done on the car.

It's at this stage that I'll check to see the butterflies are fully closing. I have found out that they should form a seal, rather than have the old style setting, up a small gap between the butterfly and bore.

I've also noticed that there is only one idle adjustment screw on my car, on the middle section of the manifold.

I'll keep you posted on what i find.

Regards
 
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