Chevy Tahoe, Cold-Start Rattle in Exhaust

Re: Chevy Tahoe, Cold-Start Rattle in Exhaust

PostBy: freetown fred On: Tue. Dec. 11, 2012 2:57 pm

:wtf: That's just plain old fashioned irritating ain't it? :(
freetown fred
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Re: Chevy Tahoe, Cold-Start Rattle in Exhaust

PostBy: EarthWindandFire On: Fri. Dec. 21, 2012 1:57 pm

I am researching for a car/truck/suv to replace my Dodge Ram and found this note attached to the Toyota Land Cruiser.

The 2UZ-FE (the only engine available in North America) has log-style exhaust manifolds that were prone to crack and create a "ticking" sound during a cold start. The crack is usually the size of a human hair and would subside shortly after the engine is started as the manifold heats up and closes the gap. There were enough complaints to create a TSB (Technical Service Bulletin) but because it was not considered a safety issue, no recall was issued.
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Re: Chevy Tahoe, Cold-Start Rattle in Exhaust

PostBy: wilder11354 On: Fri. Dec. 21, 2012 11:13 pm

I'm thinking its fuel firing in manifolds. Reason....electronic injection richens fuel for eng coolant temp, air temp, especially in colder temps. For a few seconds it runs on this set parameters, but once O2 sensors read gas, and readjust mixture, fuel leans out. and afterfire stops popping in exhaust. Now how to test this theroy? take to a friend that has a good scanner with readouts, check to see what temp sensors are reading before startup to actual ambient air temp, then start engine and listen to rattle and watch to see what reading changes when rattle disappears, sensor temps, O2 fluctuations.But if either of the temp sensors are way off from actual ambient temp, I would suspect its a bad sensor and change it, regardless of rattle noise But I would suspect an out of range temp sensor, and O2 sensors adjust mixture back(leaner) to stop cat contamination.
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