nord

Hi everyone!
Got this strange problem with my car..
When i try to start, it start but revs right up to about 3k then dies.
I can be able to keep it running but i have to pump on my accelerator pedal and keep it at a high rpm.
Any ideas where i should start troubleshooting..?


Thanks.

WallyP

The first step is to tell us what the model year, USA/RoW, transmission, etc., specs are for your car.

Lots of differences between a '79 and a '95...

It's also nice to know who you are.

nord

Hi Wally!
Guess i was a bit tierd this morning.. :
My name is Ron and i'm from Norway..owned my porsche about 3 years now and it's been a troublefree relationship.

Done some minor things like gts mirrors,clear turnsignals and removed the cat's by using a kit from 928gt.com.

Her is a pic of the car.It's a 1988 model us spec 928 s4 with manual transmisson : http://i195.photobucket.com/albums/z...976/div044.jpg

Thanks Ron.

w3lfd

Just off the cuff, I would say check all of your intakes seals and vacuum lines, it could be pulling a large amount of unmetered air, and giving it throttle is "making up" for the extra air... just a guess.

killav

Un-plug the MAF connector and see if it will start and idle on its own.

smudaaar

I had the same problem with my land rover. It turned out to be a bad fuel pump.

nord

Hi!
When i un-plugg MAF it starts and idles about 2000 rpm.
Sometimes around 1000 rpm but extremley rough and
does not respond well too throttle.

Looked in some old receipt's and the fuel pump and LH-unit was changded 5-6years ago so i guess they should be o.k.
I can hear the fuel-pump buzzing but havent checked the fuel pressure.
Knock-sensors,idle-stabileser,seals/gaskets and vakum-lines (everything under the manifoild) was changed about 3 years ago.

The car has been "harder" too start and i've felt some small hesitation when driving at low rpm the last berfore it became like it's now.

Ron.

nord

Could it be a MAF problem...?

docmirror

Yeah, this sounds fuel metering or vacuum related. I don't suppose there is another car around you that you could swap MAFs with? Also potentials are the aux air regulator and the temp II sensor. Check for vacuum leaks carefully with a can of aerosol carb cleaner or fuel injector cleaner for the purists.

docmirror

Testing of the LH starts on WSM 24-109 or there-about. If you follow the guide, it's pretty good. You will need at least an ohmmeter, and if you have access to an Oscilloscope, that would be better. Your computer with sound card, and a simple home made probe will work with this downloaded software and a simple Oscilloscope. It's not fancy, but will perform the tests we need to troubleshoot.

http://www.zelscope.com/

killav

Hop up onto the engine and look down at the MAF boot. Look and see if the rubber hose on the right of the MAF boot is still plugged in. This hose runs to the ISV (Idle Stabilation Valve). When mine popped off, the car would not run on its own without adding throttle as you describe. Mine idled perfectly once I un-plugged the MAF connector, so you more than likely have a vacume issue as well (mentioned above).

nord

Hi!
No other car around her that i can borrow parts from.
Going to check for any vacume leaks.
I've tried to disconnecte the MAF on my car one time before when i had some trouble with unstabile idle.
It did not act anything like it does now.

Ron.

docmirror

Ron, do you have work shop manuals either in print or the CD? Much of the LH troubleshooting in there is good stuff. If not, we'll get you through it.

Mike Frye

Check this out:

https://rennlist.com/forums/showthre...ferrerid=45339

nord

Hi!,thanks for your help guys!
No,manual...
Thanks,for the link..i'll try to see what i can find out
Can not find any tubes that has fallen out.
Will try buying some aerosol and search for vakuum issues...not sure i'll be able to find any with the engine running @ 2500-3000 rpm at idle with maf disconnected.
Tried putting my hand over the MAF when engine running @ 2500 rpm blocking for air in to the motor.
Did not notice any change in rpm will blocking air intake so that suggest a air leak i guess...felt some sucksion.

Ron.