hunting on idle ??

[chris52]

Picked up my griff yesterday and drove her the 200 miles home its a 1995 500 , she drove absolutley sweet with no real issues temps were 90 sat in traffic and 70 on the motorway (was raining very hard and wow that was scary lol)

Only issue i had was every now and then the engine would start hunting and evetually stall on idle, this did not happen all the time and as long as the revs were kept up it would settle down and start idleing at a steady 1000rpm, it wasn't down to the wet as the car was doing it before it started raining.

The only fuel station i could get to was a BP so i used there 97 octane, so maybe it was that??

any help would be great

cheers chris

[Colin RedGriff]

Hi Chris

welcome to the wonderful world of TVR ownership. Firest thing to check would be the stepper motor. It tends to get a dirty and needs to be cleaned. Simple enough job.

http://www.thegriffithpages.com/modifications/engi...

Colin

[chris52]

Cheers Colin

Chris

[blitzracing]

Colin RedGriff said:

Hi Chris

welcome to the wonderful world of TVR ownership. Firest thing to check would be the stepper motor. It tends to get a dirty and needs to be cleaned. Simple enough job.

http://www.thegriffithpages.com/modifications/engi...

Colin

Problem with that method is it does not clean the keyway under the spring where the carbon really mucks things up. To do the job properly, you wind the stepper motor almost all the way out on its thread, then start the car with the stepper connected. It will rev up to about 2500 rpm, and the ECU will wind the cone out much further than normal to try and reduce the tickover (assumming its not stuck). After about 20 seconds , or if the engine RPM drops, disconnect the stepper (engine still running), and then switch the engine off and finaly remove the stepper. It should now be possible to move the spring out of the way with the shaft extended and clean the keyway with a needle or small screw driver. Once its clean, then reconnect the stepper and cycle the ignition on / off and the stepper should wind fully home, as the ignition goes off. It is possible to get the cone out completely if you take the stepper out of its housing, and hold it in your hand, and get someone to start the car(its 2500 rpm time again). The ECU will just keep winding until the cone and spring drops out, so be ready to catch it and it may take 20-30 seconds. The tricky bit here is getting the shaft back in, as it has to be wound in, and the keyway has to be aligned with the small plastic key in the motor housing, and then the ignition cycled on off with the stepper connected to get it to wind full home.

[Ballistic Banana]

Agree Blitz although I have never heard of it being done like that before, and with your permission would happily add that to the article.. But also remember we arent all spanner monkeys and the way explained is quite simple and relatively quick, And if it cures the problem then maybe yes go the whole hog and take it out again and clean the rest as you describe so that its all clean.

BB

ETA Mines gone so will never have that problem again

Edited by Ballistic Banana on Sunday 18th January 21:56

[JKY]

blitzracing cleaned mine using his method and works fine now.

[ButtonIt]

I had a problem with bad statrting (lumpy) excessive hunting on idle and regular stalls on idle. I cleaned the stepper motor following the instructions above (I didn't take the stepper all the way out though) and it's cleared up the stall issue. It also appears to have alleviated it running lumpy on cold start. But, the idle is still very low and it's hunting.

I've also noticed a load of black crap coming out the exhaust and terrible smelling fumes, so I think it might be running rich.

Any suggestions please?

[Barreti]

To the OP

Give the car another go in the dry and see if you still have a problem.
When I drive my car for a while in really bad weather the speedo stops working sometimes and the idle is all over the place.
It only happens when I've been driving in very bad rain though.

[spend]

If its since you've had the top end re-assembled, check for air leaks, it doesn't take much un-metered air to screw up the idle control (even a bad plenum seal can make them horrible).