Car starts, then shuts off after cold start
#1
Car starts, then shuts off after cold start
I need some help. I have a 86 s4 N/A whenever I start the car and it comes off the high idle cold start the engine shakes violently then shuts off , if I keep my foot on the gas it at anything higher than 1k rpm it will run smoothly. I checked the tps even cut out the plug and hard wired it. I've been told it can be the primary injectors or the thermowax sensor. I'm thinking of changing the injectors. What could it be ? Any help would be much appreciated. Thanks
#8
Ok so a bit of an update. I changed the primary injectors and the leaky secondary one. It appears that the non leaking secondary injector was clogged with debris. The car comes off the cold start and idles perfect now. Now when I hold the rpms higher and let it go the engine starts to shake violently and hunts for idle, then shuts off. While I had the upper intake manifold off I checked the vacuum hoses and they seem fine.
#9
Sharp Claws
iTrader: (30)
still got vacuum leaks.
just because everything looks ok doesn't mean much. a 25 year old vacuum line looks like a brand new line when it is installed, doesn't mean it is ok.
most leaks are at cracks in vacuum line bends unnoticeable til you bend them, or at the old and brittle injector lower seals, or at the old wobbly tired 5/6th port shaft seals, or at some hacked up lower intake gasket install leaving chunks of the old gasket still in place, or the same for lower intake to block... many places leaks can hide.
you could likely offset it by richening the variable resistor, i do it on customer cars where it is obvious the owner's don't want to spend $500 sorting out their intake system. but it only works for relatively small leaks due to age, not someone else's filthy paws being in there and messing with poor gasket replacements for example.
just because everything looks ok doesn't mean much. a 25 year old vacuum line looks like a brand new line when it is installed, doesn't mean it is ok.
most leaks are at cracks in vacuum line bends unnoticeable til you bend them, or at the old and brittle injector lower seals, or at the old wobbly tired 5/6th port shaft seals, or at some hacked up lower intake gasket install leaving chunks of the old gasket still in place, or the same for lower intake to block... many places leaks can hide.
you could likely offset it by richening the variable resistor, i do it on customer cars where it is obvious the owner's don't want to spend $500 sorting out their intake system. but it only works for relatively small leaks due to age, not someone else's filthy paws being in there and messing with poor gasket replacements for example.
Last edited by RotaryEvolution; 09-20-15 at 07:38 PM.
#12
i figured i should update the status on the car. after removing the manifold and pulling the injectors i found that they were blocked up with what i can only assume is rust/dirt(look and felt like coffee ground). after seeing that i pulled the tank, filled with the same dirt/rust/coffee ground looking substance so i sent the tank out to get cleaned, changed the fuel filter, cleaned out the injectors and i also changed the tps ,then started her up. everything seems to be working properly, idles perfect. ill keep looking through my vacuum system. thanks alot for your help guys.
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
07-01-23 04:40 PM
sherff
Adaptronic Engine Mgmt - AUS
9
02-24-19 12:09 PM