Has anyone ever had there idle go crazy ?

When cold and the auto choke is on and everything is fine, as soon as the engine warms up and the choke switches off my idle bounce's from 400rpm upto the standard 900rpm then drops back down, the whole car vibrates and if my lights are on they dim. It feels like it will stall any minute, but so far it has not. The strange thing is, it does not always do it ? I guess I just need a new idle, but I thought I would ask first, someone may have had this happen before ?

cheers

Elliot

 

If your car is a MY99/00, then it's quite possible that your MAF sensor needs replacing. It's a common fault.

Do a search for MAF, and you'll find out all you need to know

 

Ha ha - auto choke My first car, a 1.6GL Vauxhall Cavalier, had one of those. Major pain in the ****, damn thing was always flooding the engine.

Thank God for fuel injection and computerised engine management, makes cold starts so much simpler.

Anyway as mentioned it's probably MAF related (esp. MY99/00), £75 from your friendly dealership and a ten minute job to change. Failing that could be lambda sensor or the idle control valve. Have a search as suggested.

 

This has just happened to mine.

On idle, ranging from 1100 rpm to 1700 rpm and smoking when pulling away from traffic lights or if I've been sat in traffic for a minute or two.

Luckily, I've got a PFC commander so (with a little help from a couple of people) the faults could be diagnosed and monitored fairly easily.

I've replaced the MAF, which stopped mine overfuelling but didn't sort out the tickover, so I borrowed an idle control valve off a mate and hey presto.. tickover back to normal. As it happens, it looks like my lambda is broken too!!

I have just got an ICV from Grade A in Hadfield... £35 + vat
The MAF cost me £68 + vat from ProSport and I've got a lambda off a mate for £40

Jeff

BTW:

Before you replace you ICV, try cleaning it with some white spirit to see if it's just a bit of dirt stopping the valve from working correctly.

 

I think I need a new MAF as identical symptoms but hav'nt time to replace for a couple of weeks. Any tips on how to avoid engine damage while driving with dodgy MAF sensor.

 

Don't boot it?

 

Buy my Maf sensor!!! Still got a brand new one for a 99/00UK car from before I sold my scoob, bought by mistake when I had a problem with it so never used! £50 inc p+p to you sir (Think they are £68 from Subaru)!.

 

If it is the MAf what other, if any symptoms would you get ? so far all I have noticed is the idle doing what ever it wants, I have not noticed any smoke and it still seems to go ok ? may just be the idle control valve ? ill book it in to my local Scoob mechanic. Problem is I need the car, so I might just get him to order a idle control valve and see if it does the job or not ? I have heard that a dodgy maf may cause the car to smell (burning oil sort of smell) any truth in this ?

cheers for all your feed back

 

Well mine smelt of unburnt fuel because it was overfuelling and that was what the black smoke was. Basically, it thought there was more air coming into the system at idle and was dumping extra fuel in as it thought it was on boost. The tickover has been sorted by replacing the ICV. In other words, two different problems but they are kind of related.

However, I don't think it's a really common fault that the ICV's actually fail, so I would suggest cleaning it first. I have an Apexi ecu, which I have been reliably informed is very agressive in the way it controls idle and has contributed to it going pear.

The £35 + vat that I paid for the ICV, was from Grade A Subaru, IE secondhand. I haven't a clue how much a main dealer would try robbing off you for a new one LOL

Why not do what I did, borrow one off someone to see if it cures the problem before you go buy one? Its a 2 minute job (2 screws) to swap the ICV.

 

classic signs of a maff sensor! if not get someone to check ya alternator.