Cold start stumble for couple seconds and then everything is fine
10-01-2009, 11:15 AM
#31
Three Wheelin'
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I have the same problem....I am leaning towards a Vacuum leak also....Or possibly the cold start valve...Testing the MAF tonight..I have heard that the Barn door gets out of whack and this can also cause the problem...My car is running VERY rich..I can smell it even when its all warmed up...
I have heard that if you suspect a vacuum leak, the trick is to take Carb Cleaner and spray at the various vacuum line connections and see if you notice a difference while spraying..
And I dont suspect anything Emissions related because I have removed everything and anything that has to do with emissions and the car ran SO MUCH better for over 2 years, and about 2 months ago this problem started...
DAmian
I have heard that if you suspect a vacuum leak, the trick is to take Carb Cleaner and spray at the various vacuum line connections and see if you notice a difference while spraying..
And I dont suspect anything Emissions related because I have removed everything and anything that has to do with emissions and the car ran SO MUCH better for over 2 years, and about 2 months ago this problem started...
DAmian
10-01-2009, 07:07 PM
#33
Racer
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supes6, I have done all of the same things you have and have had my injectors rebuilt. The only thing I haven't done was the check valve. I am not loosing coolant and have checked my plugs and no signs of antifreeze. I am at a loss. I was hoping you would come and say that it fixed your problem.
My car starts rough and normally will die, restart and it runs perfectly fine with exception of being very slugish until warm. I have checked compression and leak down all comes back great, I loose less than 1/4 quart of oil each oil change. I can't figure it out.
My car starts rough and normally will die, restart and it runs perfectly fine with exception of being very slugish until warm. I have checked compression and leak down all comes back great, I loose less than 1/4 quart of oil each oil change. I can't figure it out.
Whoever mentioned the hissing noise - it's probably coming from your AFM. I noticed it while adjusting the idle air screw - there's a threshold where you start to hear a hiss, which is just air entering the intake through that small opening. You can get rid of it by closing the screw, but I think it's probably audible when you have it adjusted right.
10-02-2009, 04:35 PM
#34
Rennlist Member
944 Ross my car has 102000 and I had the compression and leak downs done perfessionally recently. My engine is very healthy and it put down 246 wheel horsepower at 15 psi boost. I think there is something else causing the problem.
10-02-2009, 09:23 PM
#35
Track Day
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Chased the exact same problem for a year. You must remove your AFM, open it up, clean the contact and bent the contact. (Search on AFM fix and you'll see the procedure. Also on Clarks Garage.) You really can do it. I did a lot of much more difficult stuff before this fixed it.
10-02-2009, 11:31 PM
#36
Racer
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Chased the exact same problem for a year. You must remove your AFM, open it up, clean the contact and bent the contact. (Search on AFM fix and you'll see the procedure. Also on Clarks Garage.) You really can do it. I did a lot of much more difficult stuff before this fixed it.
10-05-2009, 05:55 AM
#38
RL Community Team
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I have done the AFM fix. I tried both "north" and "south" versions. It did not help.
What if I run the car to when it smooths out, then completely suck all the coolant out of the system, then let it sit over night and then finally start it. If it still stumbles, it rules out coolant leaking into the cylinders right?
I really don't want it to be a HG leak. I can't deal with a HG issue on my back-up car. My main car (93) is already inches away from needing a rebuild, and my 95 just got a rebuild last year. I'm getting broker by the minute!
My wishful theory is that a problem with the computer is making the open-loop functionality WAY too rich. How do I check for rich/lean, again?
What if I run the car to when it smooths out, then completely suck all the coolant out of the system, then let it sit over night and then finally start it. If it still stumbles, it rules out coolant leaking into the cylinders right?
I really don't want it to be a HG leak. I can't deal with a HG issue on my back-up car. My main car (93) is already inches away from needing a rebuild, and my 95 just got a rebuild last year. I'm getting broker by the minute!
My wishful theory is that a problem with the computer is making the open-loop functionality WAY too rich. How do I check for rich/lean, again?
10-05-2009, 12:13 PM
#39
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10-07-2009, 02:58 PM
#40
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Hate to be the bearer of bad news.. but I am now about 99% sure my problem is a leaking headgasket. On my drive to work this morning I noticed the temp gauge getting high - just past the 2nd mark, before it goes in the red. I've been suspecting the temp sensor / wiring as it seems to read erratically, but the high speed fans were also running. I let the car cool off and checked the reservoir tank, but realized I couldn't even find the water level because the plastic is so discolored. Well I added some water... and then added some more water - 2 liters to be exact. So, the headgasket is definitely leaking water into the cylinders when the car is cold... because there are no external water leaks. After topping off the reservoir, I was able to drive it home without the temp going past halfway. But obviously I've found the problem. What bugs me the most is that I asked my mechanic if this could be the problem and he shot it down saying there would be smoke on startup. 
10-07-2009, 03:50 PM
#41
Rennlist Member
I have the same issue. My car has a mysterious coolant leak as well so I believe it is the head gasket. I will do my head gasket over the next couple weeks and report back with my results.
10-07-2009, 04:42 PM
#42
Rennlist Member
Mine definetely is not a head gasket, no loss of antifreeze at all and all test (including pulling the plugs on cold startup) come back with no signs of headgasket. I am at a loss on mine.
10-07-2009, 06:07 PM
#43
Rennlist Member
Hate to be the bearer of bad news.. but I am now about 99% sure my problem is a leaking headgasket. On my drive to work this morning I noticed the temp gauge getting high - just past the 2nd mark, before it goes in the red. I've been suspecting the temp sensor / wiring as it seems to read erratically, but the high speed fans were also running. I let the car cool off and checked the reservoir tank, but realized I couldn't even find the water level because the plastic is so discolored. Well I added some water... and then added some more water - 2 liters to be exact. So, the headgasket is definitely leaking water into the cylinders when the car is cold... because there are no external water leaks. After topping off the reservoir, I was able to drive it home without the temp going past halfway. But obviously I've found the problem. What bugs me the most is that I asked my mechanic if this could be the problem and he shot it down saying there would be smoke on startup.
Also, you can be losing coolant through a bad head gasket without smoke, but you would have milkshake in your oil.
One last thing - how is your coolant reservoir cap? If its beat, you'll also lose coolant, and you just may not have noticed it. Now its low enough that you aren't losing any more (well, until you refilled it).
10-07-2009, 06:51 PM
#44
RL Community Team
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My car eats about a quart of coolant every 6-7k miles. Does this correlate with your coolant loss Karl?
Well there is a brightside. When we take the head off, we will find clean shiny combustion chambers and pistons thanks to the steamcleaning it gets every morning.... lol.
Well there is a brightside. When we take the head off, we will find clean shiny combustion chambers and pistons thanks to the steamcleaning it gets every morning.... lol.
10-07-2009, 06:53 PM
#45
Rennlist Member
I couple of things that may or may not help - you can be leaking coolant without it ending up on the ground. Check all of your hoses for crusty stuff around them. If you haven't checked your coolant for a few months and find it low, it's entirely possible this is the cause, and has nothing to do with the head gasket.
Also, you can be losing coolant through a bad head gasket without smoke, but you would have milkshake in your oil.
One last thing - how is your coolant reservoir cap? If its beat, you'll also lose coolant, and you just may not have noticed it. Now its low enough that you aren't losing any more (well, until you refilled it).
Also, you can be losing coolant through a bad head gasket without smoke, but you would have milkshake in your oil.
One last thing - how is your coolant reservoir cap? If its beat, you'll also lose coolant, and you just may not have noticed it. Now its low enough that you aren't losing any more (well, until you refilled it).
