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EGR test


adallak

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This is an LT1 engine. The other day I was testing EGR passages by depressing the diaphragm of the EGR valve with fingers at idle. Despite the engine was warmed up, it died when barely pressed on the diaphragm.  I know it indicates that the EGR passages are clean, but it would take much more movement of the diaphragm to make my 4.9 l engine die. It could be an indication that the passages on the 4.9 were in worse shape than the ones on this LT1, but anyway I was surprised. It just means this engine is so much more sensitive to EGR flow.

The saddest thing in life is wasted talent

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I would guess that the EGR tubes on the 4.9 were restricted with crud to the point of almost being plugged.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I cleaned the tubes inside of the TB on 4.9 regularly, but who knows what was going on elsewhere. I still think the LT1 should not have died because of little pressure on the diaphragm. The Fleetwood is very sluggish now and then. The fuel economy dropped to 10 MPG around the town. It improves by itself, that's what puzzles me and makes me check every possible cause all the time. I know all the usual suggestions - sensors, exhaust leaks, dirty injectors, etc. but you do not do anything , just wake up one morning and the power is back.  

The saddest thing in life is wasted talent

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There was a TSB for an updated egr valve and a PCM reflash back in the day. Any vacuum leaks? The ignition coil tower is ok, no corrosion?

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5 hours ago, barczy01 said:

There was a TSB for an updated egr valve and a PCM reflash back in the day. Any vacuum leaks? The ignition coil tower is ok, no corrosion?

I am aware of the TSB, never heard of PCM reflash, though. It's been my impression that retuned Corvette's LT1 for use in Fleetwoods was not really well-tuned. The engine is super sensitive to vacuum leaks, EGR, exhaust leaks and a million of other things.  Chasing all possibilities on a 22 years-old car is not easy nor it is fun. :)

 

Most of its life the car was in Florida, I did not drive it much during New England harsh winters either, so it is in a good shape rust-wise. The engine bay is clean, no corrosion. The coil is good as well. If I start to replace every part, which "might be not good enough", I better get a newer car.  

The saddest thing in life is wasted talent

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He's talking about a PCM software update. It is a reflash. I doubt you would be able to do the reflash anyway, the programming is like finding hens teeth.

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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1 minute ago, winterset said:

Where on earth are you going to find a car newer than 22 years?  Good luck

Obviously, I did not mean another Fleetwood. :)

The saddest thing in life is wasted talent

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