One more coughing Griff

[matts]

Hi there, Sweden calling

Looking for some advice. I have problem with my Griff 500 ´94, pre serpentine. It started a sunny day (of course) when flooring it. Suddenly it started coughing, and still do, very frequently under 3000 rpm. Over 3000 it´s a rocket as usual, but I beleive the cough is still in the background. The idle speed turns 150 rpm up and down and it fails the emission tests.

I got it diagnosed and was indicated that the Air flow meter was the problem. Another meter was tested, but the problem was the same.

There is a high-frequency sound when idling , EVEN when running good! Could the cough be consequence of this? Where should I start looking? The vacuum has been measured, and was very low. How much should it be? I couldn´t find it in the bible.

Among a lot of other things; The AC is out of order, I have a new fuel filter, good spark plugs and leads, new coil amplifier and nice helpful friends and I am still in good mood.

Fuel, electrical or vacuum problem?

Very thankful for your advice!

[seasider]

Hi Matts,

If you have uneven idle (and haven't cleaned it already)it could be the "stepper motor"
Do a search in the Forums Tvr(all) and give it a clean. It's also covered in the bible...

It might well help with the bad running at low revs as well...



>> Edited by seasider on Tuesday 9th November 22:41

[GreenV8S]

Not sure what you mean by 'low' vacuum, but I would expect roughly half a bar in the manifold at tick over. If the idle is eratic I would clean the stepper first (because this is SO often the culpret), check for air leaks, especially in the vac lines to the fuel regulator and distributor, and check the vacuum capsule on the dizzy is not leaking.

[matts]

Thank you for your very fast reply!
I have cleaned the stepper motor once, but will do it again to be shure and I will check for air leaks where you suggest. It takes probably three weeks before I can let you know how I succeded.

Regards
Matts

[Dgbroadhurst]

I have a Griffith 1993 500 that has the same issue. My garage could not diagnose either. I have relocated the ignition amplifier so far but Also need to clean or replace idle stepper motor and check pipes. Most of mine were replaced on cam replacement recently. David

[ESDavey]

I’ve had previous issues with the Air Flow Meter. It works by taking readings from a hot wire which can get contaminated.

To isolate the AFM, simple disconnect and see if you get smooth running.