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MG MGF Technical - Idle high, intermittant .... #3,

Hi all,

I used the same header cause this is the third update since May on the high idle and revs getting down slowly in failure case.

Last appearance of the silly idle (@1500 revs) was August 4th.
31 May 2003 /14 June 2003 /04 August 2003

Yesterday it played up again all the day. I did app. 1000 miles since it happened the last time in August.
http://www.mgfcar.de/high_revs

It started already early in the morning when the engine was warmed up.
Went on all the day while I did about 400km down to the *Treffeners* over with Rob as co-driver to the dealer and later back home.
I don't know how often I reset the stepper. LOL... I've got a high-skilled *resetter* and can do it already while driving (the car just rolls, of course, with pushed clutch and ignition off).

Rob said *Never seen such mad speedo*. MS ideas tend to changing the inlet temp sensor when we got back and Rob explained the problem.
But why should that fail every 3000km or in 1 to 2 Month distance ?

However, this morning... nothing....
The car drives as if there's never been anything wrong with it and the only modification to the ride on Monday was different contend of the boot. (Cloth instead of tools). Did the 300km to works without any problem, the same weather, the same speeds (high of course)

Anyway, I've no sence what more to look for. This should end up in a Testbook session in next month.

Regards
Dieter
Dieter K.

Good luck Dieter - hope that something shows up.

I wonder though (and I am sure that you've checked this already) whether your GM throttle body throttle valve is seating correctly after opening? Mind you, with engine speeds as high as 3000rpm and only slowly coming back down to a fast idle 1300rpm still does not make any sense...

Hope that this problem gets solved soon!
Rob Bell

Dieter, have you cleaned the throttle control body?
Mine was sticking once.
Ddraig

While the engine is idling high, try pinching off the hose to the Idle Air Controller. If this drops your idle to normal (or if the engine is cold, stops it entirely) then you could have a faulty or dirty Idle Controller Valve.

I experienced these symptoms (also intermittently) and replacing the valve fixed the problem. I also learned that a gate valve or restrictor in the tubing to the IACV improved drivability substantially, and I have continued to use this trick. The car is much more responsive to throttle input and much smoother to drive.
Grant Vowles

Dd, you reffer to the IACV (stepper motor), do you ?
This is next on the list. I have to do oil change and will dismantle the Stepper then. (seen how to in last year).

btw. done again nearly 1000km since the 8th. Nothing bad again since that funny ride.

Anyway, I have now left only 5 more 300km rides to Dormagen and back until I move... counting :)
Statto calculation:
I had app 185 weekend rides (600km each) between Hersfeld and Dormagen. This means 110k km.
therein about 20.000 km with the crashed BRG
about 70.000 km with the current (almost with 200km/h and very low brake wear)
and another 25.000 with the crap winter car (Fiesta).

HEF-MG96 will soon get a real fun car with low mileage per year :)
... sometimes with idle high, who cares.

Dieter

Dieter K.

Hi all,

I've been at a Testbook Session..
:)
Things come clear(er).
The ECU had two failures stored.

No 1. Circuit Vacuumsystem failed (This is OK for me, cause I know I played with it pulling off hoses, like Grant said)

No 2. :))))))) CIRCUIT COOLANT TEMPERATURE SENSOR FAILED ...
Blame me. I had it in my mind, who cares.
I never removed the connector since I own the car.

http://www.mgfcar.de/throttle/testbook02176.jpg
'Nicht OK' means 'failure'

New theory regarding the intermittant occurance discussed with a MGR mechanic leads to intermittant connection problems or sensor failure itself. We think this intermittant failure plays up the ECU 'failure memory' and may be at any time the ECU has enough with it and switches to fail save mode (idle high).

I bought a new MEK100060 brown coloured coolant sensor for prehibiton and will see for a *final repair* tomorrow. I'd bet its the well known connector corrosion only. However, I will pull the connector and see what the front fan and idle does.

Some more researches and a webside promised.

Regards
Dieter
PS. MGCC Safety Fast readers should see for the MGF section in issue 47. Dave L report included with some hints on the damn sensor.

Dieter K.

Intermittent failure of the temp sensor? Well, at least this is a simple thing to fix Dieter - and let's hope that it does the job! :o)
Rob Bell

IntermittEnt, *g* ... I take it to my dictionary ;)

Anyway, took off the connector and did some detail pix. Hmmm, there's nothing to complain from first view. I think I'll put it back after cleaning and application of some 'battery-grease'.
Dieter K.

Fingers crossed that that will do the trick! :o)
Rob Bell

This thread was discussed between 09/09/2003 and 22/09/2003

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