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Old 01-13-2010, 08:44 PM
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87 gm tbi hard to start when cold

hello all, i have a 87 truck it is hard to cold start i have to feather the gas pedal until it warms up a few minutes.. after that it runs really good but when its cold i have to let it warm up at least 5 minutes of stepin on the gas to put it in gear and drivin off without drying or running really crappy no other fuel injected vehicle ive ever driven did this im more of a carberator guy with a choke...

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Old 01-13-2010, 10:58 PM
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Is the heater from the exhaust manifold to the air cleaner still intact? If not the problem is likely throttle blade icing. The moisture is entering the throttle body at such a high velocity the moisture in the air sticks to the butterflies and forms ice.
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Old 01-14-2010, 01:14 AM
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DoubleVision made a good point imho. You may also want to clean your IAC (idle stepper motor) and make sure your CTS (coolant temp sensor) is alright.
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Old 01-14-2010, 12:51 PM
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Janus is likely on it with the IAC. Very common issue with GM tbi units. If the cleaning does not correct the issue, and a new IAC does not as well, the driver in the ECM is likley fried. Another common issue.
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Old 01-14-2010, 04:14 PM
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Quote:
Originally Posted by chevyAL
hello all, i have a 87 truck it is hard to cold start i have to feather the gas pedal until it warms up a few minutes.. after that it runs really good but when its cold i have to let it warm up at least 5 minutes of stepin on the gas to put it in gear and drivin off without drying or running really crappy no other fuel injected vehicle ive ever driven did this im more of a carberator guy with a choke...
Either the IAC is out of adjustment or dysfunctional. This is a linear motor that opens an air bypass for engine idle. Or the temperature sender to the computer has failed. This device is on or close to the thermostat housing. It furnishes engine coolant temp data to the computer, when engine temp is less than 176 degrees the computer is in open loop, cold start mode. In this mode it adds "choke" enrichment fuel for cold start and idle.

A third possibility is a more old fashion event where the exhaust cross over under the intake manifold has carboned up and closed off so no engine heat is available to force fuel evaporation and warm the TBI around the throttles to prevent ice formation.

Bogie
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