MK1 GTI Idling Problem

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guy
New Member
Posts: 2
Joined: Thu May 03, 2007 6:08 pm
Location: Netherlands

MK1 GTI Idling Problem

Post by guy »

Hi all,

Over the past few months my 1987 MK1 GTI 16V has developed an idling problem as follows:

When I am driving around town, or stuck in traffic jams for any length of time, the idle speed starts to drop from the correct 800/850 to 650 or less, and becomes erratic and eventually the engine will stall each time I stop if this style of driving continues for any length of time.

Under normal usage for me, cold start, long motorway drive then simple end of journey conditions for about 15 minutes there is no problem.

In addition, during the last couple of weeks it has become a bit jumpy when accelerating from very low revs (less than 1100) whereas before it was a lovely smooth beast.

All other indications/behaviour are normal.

I was going to change the spark plugs, but they were only put in 9000 kms ago, so well within recommended life. It seems to me that the symptom is almost like it is overfueling when it is at idle for a long time.

Anybody had a similar problem, or has a suggestion?

Thanks,

Guy

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AndersDK
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Posts: 537
Joined: Sat Jul 23, 2005 4:41 pm
Location: Denmark West

Post by AndersDK »

The throttle endstop switch is a likely problem candidate. Can be checked with ohm meter or testlamp.
C U / Anders - '90red16riBreak - '91GrisDolment16meteor - Project'88red19trsBreak
dead cars : '89white 16RS - '89antrasitTRDturboEst - '90white19triBreak

prm
BXpert
Posts: 192
Joined: Tue May 01, 2007 7:54 pm
Location: Surrey

Post by prm »

Hi Guy

It does sound from your description that it could indicate a fuel to air metering problem, possibly temperature related - at low revs, tied into the throttle position switch requires resetting as Anders has indicated.

Check the connections and readings on the coolant temperature switch, on the engine block. Should indicate approx, 2.3- 2.8k ohms at 20degrees C. 1.0 – 1.5k ohms at 40C.
Are the fan/s running when the engine revs start to drop off??. Is the idle rpm remaining at 6-700 or oscillating between the 6-900 mark??. Any air con?.

Remove the AFM multi pin plug, and gently close up the female connectors, as these can make an intermittent fault due to low rev vibration, also check to see if the air control flap inside is moving freely. Also maybe worth checking and cleaning the connections to the CAS and plug/socket connections on the ECU loom in the engine bay.

Inspect the throttle cable to see if there is a small amount of slack when fully closed, and you are able to rotate the throttle body quadrant a fraction further, when the throttle pedal is fully depressed. Less any mats and carpet. If you’ve got a heavy foot!!

guy
New Member
Posts: 2
Joined: Thu May 03, 2007 6:08 pm
Location: Netherlands

Post by guy »

Thanks for the info lads, I will get on and examine the items mentioned and see what I find. Will give you the results as feedback is always useful for the future (still an engineer at heart!)