I've got a 1988 T.B.I. maro and it is hard to start and it will die if I don't give it 1500 rpms for about 1 1/2 minutes. I think it has a lot to do with the cold weather because it was fine in the summer. Any helpful tips would be appreciated.


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1988 305 TBI camaro. Flowmaster exhaust, K&N air filter, complete IROC-Z makeover (strips, ground effects, interior...etc), kenwood c.d. player.

 

Z28,

Time to clean the throttle body and IAC, and make sure the CTS and IAT sensors are working.

Low air and coolant temperatures are supposed to cause the ECM to enrich the mixture to compensate for cold starts. If one or both of the sensors aren't reporting the correct data to the ECM, the fuel map will be too lean for cold starts.

The IAC also needs to be operational to work with the enriched fuel curve and admit the correct idle air. The fact that you have to hold the throttle open to make it run is a sign that the IAC is not working properly or the IAC air passages are resttricted with dirt and buildup.

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Later,
Vader
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"I cannot take this any more... Saying everything I've said before..."
Adobe Acrobat Reader 4.0

 

Mine does the Same thing, But thats Cause I have No Choke

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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Livin' the Stereotype

 

Z28 / Bort,

Oh, yeah. Another point is that "cold" is relative. Last week it got above freezing here for the first time since early December. We were considering a picnic/beach party, but couldn't shovel a big enough area at the lake shore.

The "cold start" tables come into effect when the CTS sensor is below 104° (40°C) and the IAT/MAT sensor is within 10° of the CTS. The IAC is stepped at a higher rate (multiplier) when the CTS is below 90° (32°C). Because of this, the IAC is supposed to open more at "cold" engine temperatures. A week or so ago, at -15°F, my TBI was idling at 1,600 all by itself for almost a minute before it started stepping to a lower idle speed. Your engine should be doing something similar, but to a lesser extent.

There are a lot of other engine and control parameters that depend on the CTS reading, and I'm guessing that the air is just cool enough in 'Bama to chill the sensor right to the edge of that critical point.

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Later,
Vader
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"I cannot take this any more... Saying everything I've said before..."
Adobe Acrobat Reader 4.0

 

Thank you. I figured it had something to do with sensors. Forgive my ignorance, but what exactly does IAT and CTS stand for. And how much do you think it would cost to replace/fix them. Thank you.

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1988 305 TBI camaro. Flowmaster exhaust, K&N air filter, complete IROC-Z makeover (stripes, ground effects, interior...etc), kenwood c.d. player.