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GTA TECH Want to discuss technical topics about your GTA.... engine tuning, mechanical upgrades, problem areas, etc.? Then post it HERE!

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Old 02-17-2010   #1
BigBadGTA
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GTA Year: 1988
GTA Engine: 350 TPI Automatic
Cold starting issue.

Well ever since I got my GTA its never liked to have the throttle touched when the engine is below 130 F. When I start it up its idles fine, shakes the car a bit but it is smooth. BUT if I give it any gas it sounds like its knocking bad, and it hessitates. After it warms up though, it runs and drives like a brand new car, no knocking at all, and super smooth like a kitten. My friend reccomended gapping the plugs about 5 thousands over what they are at now and see what happens. He said if that doesnt do anything, I should try to put in a hotter set of plugs. Its not crappy gas I put in either, because it always gets premium. Does any one else have any theories on why its acting like it is? Anything to try?
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Old 02-17-2010   #2
89-5.7GTA
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GTA Year: 1989
GTA Engine: 350 TPI Automatic
Re: Cold starting issue.

I am no expert and I hope someone chimes in, but I would suspect a sensor is defective cold, but the values come into range when it warms up. I doubt re-gapping the plugs will cause any dramatic change except for busting up your knuckles.
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Old 02-17-2010   #3
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GTA Year: 1987
GTA Engine: 350 TPI Automatic
Re: Cold starting issue.

Id start with the things like the TPS voltage, IAC, base timing and MAF test before Id go in pulling plugs and gapping them. If your engine is stock the factory recomended gap is fine.
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Old 02-17-2010   #4
BigBadGTA
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GTA Year: 1988
GTA Engine: 350 TPI Automatic
Re: Cold starting issue.

Yes the engine is stock, and the MAF on the car is a reman unit only about a year old. The car doesnt throw any codes either, that's why im stumped..
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Old 02-17-2010   #5
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GTA Year: 1988
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Re: Cold starting issue.

I did change the coolant temp sensor in an effort to fix the problem about a month ago with no success... thanks for the help guys.
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Old 02-18-2010   #6
Corp Z
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GTA Year: 1987
GTA Engine: 350 TPI Automatic
Re: Cold starting issue.

Perhaps the IAC is all carboned up. Remove the throttle body and remove the IAC and clean it all up with some cleaner and a toothbrush. If the pintle isnt moving properly due to age or gunk, it may cause the condition u described. You MAF could have been bad fromt he get go. Bang on it with a rubber mallet or something when its running and see if the engine reacts.
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Old 02-19-2010   #7
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GTA Year: 1988
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Re: Cold starting issue.

Ok I will try it and see what the deal is. I hope its that simple.
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Old 02-19-2010   #8
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GTA Year: 1988
GTA Engine: 350 TPI Automatic
Re: Cold starting issue.

It could be the Cold Start Fuel Injector Switch located rite next to the Coolant Temp Sensor.
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Old 02-21-2010   #9
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GTA Year: 1988
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Re: Cold starting issue.

What exactly does a cold start injector do? And I forgot to say, every once in a while right when I turn the car on cold it will start to run ruff, and sound like it's going to die, but it never has. And its only once in a while id say about 1 outta 10 starts or so. When it starts doing that it lasts for about 4-5 secs then its fine.
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Old 02-22-2010   #10
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Re: Cold starting issue.

Quote:
Originally Posted by BigBadGTA View Post
What exactly does a cold start injector do? And I forgot to say, every once in a while right when I turn the car on cold it will start to run ruff, and sound like it's going to die, but it never has. And its only once in a while id say about 1 outta 10 starts or so. When it starts doing that it lasts for about 4-5 secs then its fine.
The cold start injector, also known as the 9th injector, sprays some extra fuel during startup. It is located on the left side of the engine. It is mounted in the runners between #3 and #5 cylinders.
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Old 02-23-2010   #11
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Re: Cold starting issue.

...and it's whitish.
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Old 02-24-2010   #12
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Re: Cold starting issue.

so hows the start up ?
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