Grif 4.3 fluctuating engine when cold

[HVGRIFF430]

Hello there,

Over the winter i started on the suspenion, bushes,Gaz pro's, new bigger brakes....... I disconnected the battery.
I first drove the car yesterday, en now the engine rpm's are fluctuating but only when driving between cold and hot.
Cold start ,the engine goes to 2000 rpm and then quickly falls to 950 so this is ok. When i start driving and approach a junction, the rpm's are fluctuating between 1500 and 2000 rpm's. When the engine comes hot, everything is ok.
I did nothing on the engine ,and before the engine was so smooth (last year new spark plugs,act induction elbow). Is the ECU learning or is there something that i can do ?

Thanks for the help

[blitzracing]

Make sure you have not introduced an air leak anywhere from the AFM to the plenum or the surrounding hoses / stepper motor etc. Try unplugging the stepper with the engine running if it continues to idle correctly as you drive it? If the idle is poor because the mixture is weak due to an air leak or the engine is misfiring the idle will be unstable.

[Steve_D]

HVGRIFF430 said:

........ Is the ECU learning or is there something that i can do?.......

If the ECU is the 14CUX then it 'learns' within just a few minutes.

Steve

[HVGRIFF430]

It is the 14CUX , mine is old and slow then :-) Like i said , idle is fine with in a minute. When i start driving and aproach a junction, rpm's are fluctuating with cold engine. Warm is ok. Before i started working on the suspension and disconnected the battery, everything was fine. I try again this evening with the fine weather in Belgium. i hope after some cycles, it adjust himself.

[HVGRIFF430]

Picture is always nice isn't it?

[porterpainter]

Nice looking car!

[spitfire4v8]

Does your 430 have cats and lambda (it's an export so might have) but if not it won't learn anything fuelling related.

[PeteGriff]

Have you cleaned the stepper motor (idle valve)? If not take it out, clean all carbon or other deposits with fine nylon brush (I use iso-propyl alcohol-IPA) , also use a round brush to clean inside plenum orifice. I need to do this at least once a year on my 430 to keep idle stable. Worth a try.

[TarquinMX5]

A bit late to the party and if cleaning the stepper motor (my first thought) doesn't work, it might be worth looking at for info:

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Symptoms are slightly different in that your revs are rising, rather than falling/stalling and I don't know which gearbox/diff/cats etc you have.

[HVGRIFF430]

Thank you guys for the reply. Stepper was new last year ,also the speedotransducer new. And it still has the lambda's and cats.
Took it for a ride saturdaymorning and all became fine. I think it was the ECu who was still searching the right setting.

[Teamred]

If you can get access to the Roverguage software you can reset the stepper motor from there, which will sort it out if you get a reoccurrance.