Porsche Enthusiasts Club Forum

Fresh from me saying how well the car was running ( I think she heard me) I have had a breakdown and been recovered by the AA!

Cars was running perfectly and was doing about 40mph when there was a sudden loss of power and it stalled.
Car re-starts ok. Temp and oil pressure are normal and she ticks over but as you apply revs the engine dies. Fumes from exhaust suggest no fuel problem at all - smells like its running very rich. Symptoms are almost like its sucking a huge amount of air when accelerator depressed?

Car has been running perfectly since fitting new MAF and belts/water pump done in the last couple of weeks. Difficult to be absolutely sure in the dark but oil seems fine and no trace of oil in coolant.

Any ideas/thoughts much appreciated.

Hi Paul

Assuming a large amount of air, I would guess a major air leak...

Maf has been changed so assuming its still DOWN in the collar...it probably isnt that...

My best guess would be the throttle body...look THROUGH the spider legs from the passenger side and look at the rubber neck that seats the plenum chamber ONTO the throttle body....there are 2 giant jubilee clips that hold the plenum and the body together...with a rubber collar in the middle (around 3 inches deep)

The top one holds the plenum to the rubber neck, the bottom one holds the neck to the body...

IF ITS popped off (it can happen)...then do this...

REMOVE the air filter top casing and air filter and them remove the bottom casing and MAF..

Then get a LONG (AT LEAST 12 INCH) FLAT blade screwdriver and stick your hand at the back of the plenum (where the MAF was before you removed it) and the screwdriver will just fit under the spider legs to check those 2 jubilee clips....

DO this in daylight, as it makes it much easier to see...

Hope this helps


All the best Brett

I hope it's an easy fix Paul.

I'll check it out thanks

Me too

Sorry to hear about that Paul. And after you'd spent all that money on it lately.

What did the man from the A.A. say about it? (Or did he just tow you?)

We chatted about all the possible faults and I convinced him that none were likely to be fixed at the side of the road in the dark so he ordered me a low- loader which got me back home about 9.40pm

oh b*gger, hope its an easy fix like a pipe off or split

Sorry to hear this Paul - your S2 has been very mischievous lately!

Could just be a coincidence that this has happened so soon after the MAF and timing belt but I'm suspicious.

The symptoms could be another MAF problem (JDS may have let a rogue one through) or a massive vac leak created by not seating the MAF in elbow correctly. Have you tried unplugging MAF connector to see if it still dies when revved?

Kind of unrelated to the recent work but a possible consequence is a failure of the crank speed sensor (another match for the symptoms). I'm out of my depth here as I know a bit about them on S4s but not on your S2 (assuming it has one!). If it's present it's on top of the bell housing under and behind airbox. On S4s the signal wire from the sensor is routed in MAF area so this old wiring may have been disturbed when MAF changed. Could now be intermittent or the sensor itself is iffy. How does tacho behave when it stalls? If there's a crank sensor problem the needle will drop instantly to zero just before the stall. If the EZK doesn't get this signal then the fuel pump does not run.

Hi Paul,

I know it not the same intake arrangement but i had a very similar problem with my 944 last year ....starts but would not rev freely and smell of unburnt fuel from the exhaust etc.

Took a while to diagnose but it was a intake pipe failure (see pic) which lead to huge air leak post ISCV & AIR METER.....Hope you get on ok...i have a S2 as a project car ,i've got a lot K-JETRONIC info if you are interested ..let me know

Cheers

Derrick

That's interesting Derrick and possibly very relevant to Paul's 928.

Paul is there any chance that you didn't tighten the clamp securing MAF to throttle body sufficiently, or perhaps it wasn't square and has since shifted off the rubber elbow?

When you removed and replaced the MAF was it a struggle or did you have to place little stress on the rubber throttle body elbow? Derrick's post set me thinking that if the elbow and hose connections to it were in poor condition then manipulating it when removing/replacing MAF may have dislodged or damaged a hose (when I did the intake refurb I found the old plastic connectors which attach hoses to the throttle body were a loose fit in the old rubber. The new ones are tight as a duck's...)

PS spot both nice references to 928s in April's 911 and Porsche World, including the founder PCGB member who described an S2 as the nicest Porsche he ever owned.

Thanks for all the ideas - I'm just waiting for the weekend and a chance to get under the bonnet and take a good look at everything in daylight.

I'll let you know how I get on

Finished early today so I had a chance to look at the beastie.Took the airbox off and the MAF was not seated properly

Re-seated and popped the airbox back on - started up and ran perfectly. Took it for a short spin without incident so it looks as though that was the problem.

Glad to hear it was an easy fix and she's running again.

It's great when it's simple, cheap fix! Wish it was like that all the time Well done for sorting it!