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post #1 of (permalink) Old 06-27-2001, 05:55 PM
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\'90 Chevy 350 cold start

Hi, All- New user.
I have a '90 chevy 1500 with a 350. On a cold start, the engine runs rough with the RPM's rising and falling from about 200 to about 1600 with a rythmic vroom, vroom, vroom.
The problem gets worse as the outside temperature gets lower, and is almost non existent at 80F. However, if I try to drive too soon, even on a hot start, the engine bucks and hesitates. both problems last about 30 secs.- longer in cold weather. No codes are being set......Any ideas?

'91 Chevy 4X4 Sport-33x12.5-K&N-Headers/custom-Clarion w/2 12's--2 Honda 4X4's
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post #2 of (permalink) Old 06-27-2001, 06:00 PM
 
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Re: \'90 Chevy 350 cold start

Welcome aboard ! [img]/wwwthreads_images/icons/smile.gif[/img]

It kinda sounds like a sensor[img]/wwwthreads_images/icons/crazy.gif[/img]
But before switching any of those out, I would start with the basics, and by basics I mean a basic tuneup.
cap, rotor, plugs, maybe plugwires (if you don't know how old they are, then they need replaced).
If it still acts up then it is a sensor. And at least you will have a fresh tune up and know of a few things its not![img]/wwwthreads_images/icons/laugh.gif[/img]

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post #3 of (permalink) Old 06-27-2001, 06:09 PM
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Re: \'90 Chevy 350 cold start

I drive a 92 1500 and it does the same thing. does urs die sometimes if u put it in gear

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post #4 of (permalink) Old 06-27-2001, 06:15 PM
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Re: \'90 Chevy 350 cold start

Yes, mine does it all the time, despite a recent tune up, has done for about a year, and will sometimes stall even before I put it in gear!

'91 Chevy 4X4 Sport-33x12.5-K&N-Headers/custom-Clarion w/2 12's--2 Honda 4X4's
post #5 of (permalink) Old 06-27-2001, 06:18 PM
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Re: \'90 Chevy 350 cold start

check your prom code if may need to be updated. I know in a 90 gm 5.7L with a code of aujj,axwd,and auah all had to be upgraded to a different chips because of idle roughness, spark detonation when cold, and idle fluctuation. you might have a superseeded prom installed.

good luck

DJ

post #6 of (permalink) Old 06-27-2001, 06:38 PM
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Re: \'90 Chevy 350 cold start

Thanks for the suggestion, Can I just replace the chip with an aftermarket (superchip, etc.) maybe?

'91 Chevy 4X4 Sport-33x12.5-K&N-Headers/custom-Clarion w/2 12's--2 Honda 4X4's
post #7 of (permalink) Old 06-27-2001, 09:23 PM
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Re: \'90 Chevy 350 cold start

well, my 89 350 started doing the same thing a few months ago - it would stall when i started it up, so i had to keep my foot on the gas till it warmed up. now i live in florida so there really isnt any COLD starts, but it would still do it in the mornings. i replaced the o2 sensor ($20) and that fixed the problem

Mike ~
* Earnhardt Forever *

89 Chevy K1500 - 350TBI/700R4/NP241 - 3" lift - 33's - other goodies, but not enough! [img]/wwwthreads_images/icons/tongue.gif[/img]
post #8 of (permalink) Old 06-28-2001, 12:35 PM
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Re: \'90 Chevy 350 cold start

yeah your chip can be replaced with a aftermarket chip but first get the 4 letter code off of it and check to see if there is a newer factory chip available that cures the problems your describing. If you get the code and post it i(and others on here) can check for you if you like. Reason on this is that if you put a aftermarket chip in (superchips, jet,etc.) and it is setup for the old code it wont have the revisions in it. But if you order a chip with the newer code ..... For your year truck you can probably get one for 35-45 bucks at the dealer or i can give you a name of a guy at JET who would sell it to you for around 85 plus shipping. But no sense changing it if thats not the problem.

DJ(dude)

post #9 of (permalink) Old 06-29-2001, 01:14 PM
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Re: \'90 Chevy 350 cold start

I had the same problem, changed the TPS sensor and the O2 sensor, then it went away.

Steve M
1990 Chevy K1500 Silverado
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post #10 of (permalink) Old 06-30-2001, 07:54 AM
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Re: \'90 Chevy 350 cold start

Kind of sounds like a coolent tempature sensor to me. The coolent tempature sensor tells the computor how to "choke the engine." They are realitivly inexpensive, they are locaated to the top of the intake manifold near the water neck outlet. It is probally a brass based plug with a 2-wire clip in it. I know I guy who works for UPS he said that is one of the first things they replace on thier 4.3L vans (same part # as a 5.7L or 350). When I had my 6 cylinder mine went bad and never sent a trouble code.

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