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Urgent help with Misfire!!

Jay 964rs Rep

Well-known member
Joined
3 Jul 2007
Messages
47
Hi All,
Just polished the car & went to get soem Vmax. On way home, car started misfiring at various revs. Came home on a light throttle & checked the distributer leads to make sure non come had come off.
Car had vent kit & belt changed on thursday along with oil change.
Any suggestions????
I really want to take the car to Ragley Hall tomorrow because Jasmine Porschalink want to display it on the stand.
:cry:
 
obvious check for the DME Relay, sounds like it is (?) which is an easy fix
 

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Ahhhh!!!
I replaced the DME & the misfire remains. Thoughts are dirty fuel or water in fuel. An engineering friend suggests running current tank down & re filling to see what happens.
Anybody else experience something similar?
 
Jay 964rs Rep said:
Ahhhh!!!
I replaced the DME & the misfire remains. Thoughts are dirty fuel or water in fuel. An engineering friend suggests running current tank down & re filling to see what happens.
Anybody else experience something similar?

When a problem occurs immediately after doing something, I always work on the premise that what I've done must have caused it so:

Have you used Vmax petrol before? Personally I don't use it because the car was designed at a time when only 95 ron was available. Vmax contains additives including ethanol (I believe) and I wonder whether our cars can cope with it. So if you've not used it before try sticking some normal unleaded in.

Did it not have the vent kit installed until now? If not try unplugging the hose and see if the misfire goes.

Finally, a broken distributor belt can lead to a misfire. As this has been changed, I wonder if it was not put on correctly and broken?
 
based on the fact that the DME relay answer didnt work, boxsey should take all the credit for the earlier answer 8)

the only problem with running the tank down is that you may capture all the dirt at the bottom of you tank (?) but it's kind of catch 22 as you need to flush out all of the fuel particles
 
Hi,
I've run on vmax since the rebuild with no issues.
the distributer belt was replaced when the vent kit was put on.
I'll take the vent pipe off & see what happens.
by the way sundeep, lovely car! I spotted it at Ragley as you were opposite the jasmine porschalink stand.
(sigh) one day!
 
18K miles in the 964 on optimax in the last year and no issues so unlikely that is the cause.

If the distributor belt has just been replaced that has to be the number one candidate for the misfire. It might have slipped or broken.

Did you buy reconditioned distributors from Porsche (only official recommended method - no surprise there!) or have them refurbished by someone?

Ian.
 
Hi Ian,
the distributers were not replaced, just the belt as a precaution.
The car is now at Steve Bull & hopefully thay can find the problem & resolve it.
fingers crossed it's going to be simple (& inexpensive!)
 
Just a thought- might some damp have gotten in where its not wanted from when you were washing it initially?
 
Boxsey said:
Ian, out of interest do you know what the price of a reconditioned dizzy is?

No sorry. Thinking from memory not that outrageous but could be completely wrong.
 
Problem Solved :D
A wire was not connected properly when the distributers were refitted. Steve Bull found the loose connection & sorted it.
The noisy ***** is now running well again.
Thanks for everyones advice. This is a great forum for help.
 
Sundeep said:
obvious check for the DME Relay, sounds like it is (?) which is an easy fix

O/T - My DME relay is in a different place....? Does it change dependant on year? (1990 in my case)
 

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