Warm idle drops intermittently

[disclee]

On occasions, but only when the engine has warmed up or just warmed up, the car surges forward when idling. Doesn't happen when moving, eg slowly. The surges are actually due to a drop in the idling speed when the ECU detects and corrects but overdoes it a little. So why does the idle drop? Have cleaned both the MAF and carb throttle flap several times. Runs very well otherwise so cannot be a fuel blockage although I have tried, twice, REDEX additive. Am at loss as it is intermittent in the sence that I don't know quite when it is going to happen during a journey. Yesterday, the ECU failed to correct in time and the engine died but I was able to restart immediately. The overall effect is like watching a learner at lights struggling with cluth control but I have an automatic. Could it be the fuel filter?

 

[d4hwt]

Check spark plugs/HT leads????

 

[bigasotonuk]

hi,
wot car is it? if c class check below could also apply to other models to:-
similar problem on my c230k replaced maf sensor ok now
look on e-bay have number to hand should be able to replace for about £50-£100. Also could be throttle body they are both weaknesses.

 

[disclee]

Sorry, the car's a 1997 C200 auto. The tendency is to point to the MAF. I wonder if it can take so much cleaning (4 times) and then it's time to replace?

 

[supercooper188]

What turned out to be your problem?

 

[disclee]

Problem solved

Sorry to be so late in replying and closing off my thread.

The problem was the MAF. Had it diagnosed clearly by Mercaid. Now perfect.