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Dying on Cold Start

9

93dangerranger

CEG'er
Joined
Mar 29, 2011
Messages
187
Location
Crossville, TN
Lately my 2000 SVT has been acting up when starting. It will instantly die. If you catch it soon enough and rev the engine it will continue to run, but if you release the throttle too soon it will die again. Just started this a week or so ago, but has done it multiple times. After it is warm, it don't do it. Doesn't matter if it has a full tank of fuel or low on fuel. IAC need to be cleaned? Any other suggestions? All help is appreciated. Thanks.
 
mines doing pretty much the same thing. i went over all , my vacuum lines and i cant find a leak. have you checked yours or scanned it looking for any data?
 
i checked fuel pressure. i started with that because its the original pump as far as i know with 130k but i got 45 running. seems fine. i am lean like plus 20 percent ish, i thought it was abnormal and i started looking for vaccum leaks and cant find any except i have low vacuum especially when cold about 14 psi. no codes for me, just acting pretty weird in this cold weather.

aic, you mean idle ait control valve IAC? mines new.

any further thoughts?
 
svtfixer said:
i checked fuel pressure. i started with that because its the original pump as far as i know with 130k but i got 45 running. seems fine. i am lean like plus 20 percent ish, i thought it was abnormal and i started looking for vaccum leaks and cant find any except i have low vacuum especially when cold about 14 psi. no codes for me, just acting pretty weird in this cold weather.

aic, you mean idle ait control valve IAC? mines new.

any further thoughts?
Click to expand...

Might be a throttlebody/intake clog with carbon. Fords are known to carbon up easily. Pull the TB and clean it. Also check UIM/LIM vacuum leaks at the gaskets.

I had a Mazda 3 that was doing the same thing, (they use a variation of the Duratec) and I ended up cleaning the TB which was plugged with carbon and it ran fine afterwards.
 
i know the tb and intake is pretty clean. i also checked the pcv system for clogs and leaks and it seems good. i smoke tested it twice i cant find the leak if it is one and its driving me nuts. the data itself when im looking at it live on the code scanner looks like a vacuum leak. i may have a slight exhaust leak but i have to investigate that further. i know the flanges off the headers to the y pipe come slightly loose once in a while. whatevers going on is pretty sneaky. ive been looking pretty hard. i missing like 3-4 psi of vacuum somewhere which is screaming vacuum leak.
 
svtfixer said:
i know the tb and intake is pretty clean. i also checked the pcv system for clogs and leaks and it seems good. i smoke tested it twice i cant find the leak if it is one and its driving me nuts. the data itself when im looking at it live on the code scanner looks like a vacuum leak. i may have a slight exhaust leak but i have to investigate that further. i know the flanges off the headers to the y pipe come slightly loose once in a while. whatevers going on is pretty sneaky. ive been looking pretty hard. i missing like 3-4 psi of vacuum somewhere which is screaming vacuum leak.
Click to expand...

Vacuum leaks can be hidden quite well and smoke tests won't always spot the. I have the smoke tester and sometimes I can't hit on the leak with it.

Sometimes the vacuum leaks occur in the HVAC system.
 
Just now able to get back on here and see the replies. Haven't checked anything yet. Thanks for all the tips. If I find something, I will post it and let you guys know. Thanks again.
 
I had that issue, and I replaced my IAC and nothing changed. I ran some STP Fuel system cleaner and the issue was fixed. It could be gummed up fuel injectors thanks to the cold, but check the iac too.

Edit: didn't realize your IAC was new, sorry
 
If motor has high mileage (100-125K+) you can easily lose 3-4 inches of vacuum and run normally. Loss of ring and valve seal.

Look at O2 sensor output, if not switching right it will back up vacuum leak theory. Like said before anything that affects the closed throttle air flow there will affect cold start running, plugged pcv valve, IAC or TB aircrack. I often fix the cold start die with TB aircrack cleaning. May be like zetecs and show a hot idle issue from vacuum leak faster than at cold start, at least every one I've ever fixed of vacuum leak did that. The cold fuel added is more than the hot at closed loop and hot running will show idle issues before cold does. The hot idle trim hits limit before the cold does.

If anyone has messed with the absolute TB aircrack setting to throw off the IAC default running position, well, that can do it too. IAC takes a second or so to stabilize, if aircrack too small the motor will die in that. Older engines do not pull vacuum as hard, I correct cold idle dying on higher mileage car by slightly increasing the TB air by maybe 1/3-1/2 turn more to increase the amount a miniscule amount. You commonly end up doing that on oldschool non-PCM cars as well to do same thing. The loss of engine seal again, they don't last forever. Less sealed engines need more idle crack because vacuum has dropped, pretty much all engines do that.
 
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