1990 Other Chevrolet Models Chev 454 idles high and blows bl

Tiny
DUSTYBOTTLES
  • MEMBER
  • 1990 CHEVROLET
  • V8
  • 2WD
  • AUTOMATIC
  • 80,000 MILES
I have a chev 454 with TDI in a motorhome. It started missing and sputtering and seemed to be flooding out, blowing black smoke. I removed the catalytic converter and put a straight pipe in its place thinking it might be stopped up. I put Lucas engine treatment through it. I did a tune up, dist cap, rotor, plugs and wires, the replaced the 2 fuel injectors, the iac, fuel filters. Now when I start it cold it idles high and the idle fluxuates from 24-3500 rpm, vacuum at the intake manifold is 20" and fairly steady. It puts off a little blue smoke. Then when I let it warm up and shut it down and restart, I have to put the accelarator to the floor to start it and it sputters and blows black smoke and won't stay running. I let it set overnight and it starts good again with the same high idle, a little missing. Every other start has the same result. I still have the catalytic converter out and plan to replace it with a new one when I get the engine running right. Thanks so much for your help, this is driving me crazy.
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Thursday, January 28th, 2010 AT 3:54 PM

3 Replies

Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Hi
Use ohm meter check resistence on Coolant temp sensor. On intake near thermostat.
20 deg-13,500 ohms
70 deg.-3400 ohms
160 deg.- 450 ohms
If sensor has high resistence or open will cause engine to run rich
Let me know
Thanks for donate
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Thursday, January 28th, 2010 AT 4:26 PM
Tiny
DUSTYBOTTLES
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Thank you for your prompt reply to my question (within minutes), I only wish I had contacted you about $250.00 ago! It might have been a simple answer to you but it was rocket science to me and my "mechanic" friends. I changed the sensor and my problem was gone, a $12.00 cure. Again thanks a million, it won't be the last you hear from me!
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Thursday, January 28th, 2010 AT 7:03 PM
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Great glad to have helped and Please return again
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Thursday, January 28th, 2010 AT 8:47 PM

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