Stalling and 15mpg

[salmon]

Has anyone else had problems with bouncing revs, and stalling? Read some where this might be the dump valve?

Also is 15mpg normal around the doors?

(91 S2 coupe, de-cat otherwise standard)

[Greg_S]

clean your maf in the first instance, if the revs are cycling up and down it could also be your lamda.

im sure others on here will have a more definitive answer

[S2central.net]

Has anyone else had problems with bouncing revs, and stalling? Read some where this might be the dump valve?

Also is 15mpg normal around the doors?

(91 S2 coupe, de-cat otherwise standard)

Pull fault codes, but I'd suspect, air leak, MAF, or lambda problem. Would go for lambda first - but confirm it with fault codes.

May also be ISV, thermostat or MFTS causing the 3B ECU to think the engine is colder than reality...


Paul

[salmon]

I know I'm going to sound thick now, but I'm not that technically minded, Whats that mean in layman's terms. Is this somthing I can do myself, or a garage job.

[Greg_S]

much of this you can do yourself with a few tools.

the lamda probe measures AF in the exhaust and it mounted in the exhaust down pipe.

the MAF is the mass air flow sensor and measures the amount of air going into the engine, this is between the air box and turbo.

the ISV is for idle stablisation
and is a bypass around your throttle body for the ECU to control the tickover.

MFTS is a temperature sensor telling the ECU what temp the air is, i dont know much on this one.

The lamda takes about 10mins to change and you can take you MAF off and look at it to see if its all sooted up.

Greg

[S2central.net]

Just for clarity - the MFTS (sorry to use all these acronyms but they do save finger time) is the Multi-function temp sensor. It sends coolant/water temp info and a high temp alarm to the instrument cluster and ECU on the car.

The intake air temp sensor (IAT) sits on top of the intake manifold and measures uhhhhhhh air temperature. If faulty this can also cause dicky running.

Checkout S2central.net for lots more info and how to pull fault codes without a computer.


Paul

[salmon]

Cheers, Much appriciate the advice.

Would this affect the performance as I've had the car over a yer now and I never been blown away by it (i have a rolling road print out from a 2 years ago at 238bhp), and I seem to get pasted by the mates impreza sti running at 260bhp evry time?

[S2central.net]

If the rolling road was accurate, then 238bhp is on the money for a healthy de-CATT'd 3B. I strongly suggest it is now sick if you can't give a scooby a run for its money. If you want ~270bhp and ~410Nm of torque in your car, then send me a PM about an ECU upgrade. This will NOT fix the ailments with your car, but when its fixed you will have a lot more ooomf on tap !


Paul

[salmon]

If the rolling road was accurate, then 238bhp is on the money for a healthy de-CATT'd 3B. I strongly suggest it is now sick if you can't give a scooby a run for its money. If you want ~270bhp and ~410Nm of torque in your car, then send me a PM about an ECU upgrade. This will NOT fix the ailments with your car, but when its fixed you will have a lot more ooomf on tap !


Paul

270bhp sounds good to me, knowing my luck my current 15mpg will drop to 5mpg....

Think I'll be happy when its running properly though..