Ok, so I have EGR issues as some may have seen. I dismounted the EGR valve from my 5.7L TBI and noticed there was a block-off plate there. I cleaned the insane amount of carbon there was in the EGR and ports and put the EGR back in. I thought the EGR was gone but cleaning it brought it back to life.

However, something feels weird now. Idle is steady, WOT seems ok but very low throttle application makes the engine sputter, which it wasn't doing when the EGR was blocked.

What real problem would someone have tried to fix by blocking off the EGR?

I was thinking maybe something stupid like retarded timing (no EGR makes a normal engine ping). Or something even stupider like trying to always keep the ECM running in open loop to avoid sensor problems.

What do you guys think?

I did check for vacuum leaks by spraying insane amounts of water everywhere theres a vacuum hose and/or connection.

Instead of spraying insane amounts of water, you might want to try spraying small amounts of carb cleaner around the vacuum hoses and vauum sources. Changes in idle speed will indicate a leak.

I don't believe spraying water will work.

5.7 TBI what year what vehicle is this in.Putting this info in your signature would help greatley when you need a good answer so members do not have to go look in your profile just a fyi

I would assume this is a caddilac brougham or a fleetwood

1991 Cadillac Brougham d'Élégance. However, I have the dealer repair book, except for the fact everything always resumes to : Use special tool J-XXXXX to check, it'* pretty helpful. It says my problem could come from a partially always open EGR... I HOPE the last owner didn't block the ports for such a ridiculous reason...

car needs a complete tune-up anyways, it'* just the moneyz that aren't there to do it all at once!

Id have to go out to my truck and look at the egr valve but im sure this test will apply to it (Same engine in my truck..Kinda lol) it used to be a 5.7 lol

https://www.gmforum.com/trouble-shooting-test-procedures-141/egr-solenoid-test-296250/

Thanks! I'll try that out, but my problem feels more like a vacuum leak than a faulty solenoid. The more I think about it, the more I think the valve might be partially always open.

And I think it'* pretty much the same thing as your truck : it'* a 5.7L TBI w/ 4L60 tranny and even a trailer connector with a brake compensator and everything. It'* mostly a truck :p

Haha well mine lived its life up till 190k miles as a stock LO5 5.7 tbi..but at 190k miles it was pulled bored and stroked out to a 383 stroker..But anyways if you suspect bad vaccum lines try spraying them with carb cleaner and see if idle changes look for any cracks seperations or anything out of the ordinary.personally i would test that egr valve still

Well it was running "fine" before I removed the block-off plate ; I was just getting a code 32 everytime I would cruise for some time and it was running rough. Now it runs too smoothly and nearly dies at low throttle XD I'll just change the valve to begin, once that'* out of question I'll see.

At least, I have a better idea of what to check. And with the price of gas, I won't mind eventually getting more than 23L/100km

Anyways, for now it won't run until it'* fixed, I don't really like thinking about the effort and strain I'm putting on this poor engine.

Well before you start throwing money at it test the valve you have now and if its good then we need to look elsewhere