Please help with blow by issue - Third Generation F-Body Message Boards

transtang78 · 08-23-2009, 09:53 PM

i have a 90 rs with 5.7 from a 94 van tbi now the problem when i start the car the egr valve pulses up and down and the car runs likecrap if it even stays running, so i disconnected the egr solenoid and the car rus great but it builds crankcase pressure. egr seems to hold pressure with a vacumm pump, i replace ecm the other day but i think the problem is the egr solenoid after i replaced it and started the car it took time to idle but when it did i had a lot of crankcase presure enough to push oil out the dipstick tube. anyone have any ideas

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Fast355 · 08-23-2009, 11:14 PM

Quote:

Originally Posted by transtang78

i have a 90 rs with 5.7 from a 94 van tbi now the problem when i start the car the egr valve pulses up and down and the car runs likecrap if it even stays running, so i disconnected the egr solenoid and the car rus great but it builds crankcase pressure. egr seems to hold pressure with a vacumm pump, i replace ecm the other day but i think the problem is the egr solenoid after i replaced it and started the car it took time to idle but when it did i had a lot of crankcase presure enough to push oil out the dipstick tube. anyone have any ideas

Welcome to the board neighbor.

I doubt a blowby problem is causing the EGR problem.. However it could be a bad or incorrect EGR valve or even a plugged catalytic converter. A catalytic converter that is stopping up would make the most sense as it would cause excessive blowby past the rings as well.

On a side note what other components were used for the swap? Does it have the 350 injectors, 350 knock sensor, and 350 ECM?

transtang78 · 08-23-2009, 11:23 PM

thank you neighbor, the cat is new only 2 mths old, if the egr valve isnt opening properly wouldnt that cause excess gases to build up. i dont understand why the egr valve surges up and down.

Fast355 · 08-23-2009, 11:26 PM

Quote:

Originally Posted by transtang78

thank you neighbor, the cat is new only 2 mths old, if the egr valve isnt opening properly wouldnt that cause excess gases to build up. i dont understand why the egr valve surges up and down.

I honestly haven't messed with the stock EGR valves from the F-bodies much, but I know on the Trucks/Vans the valve is designed to pulsate as it regulates the flow of EGR into the intake. GM made about 3 different types of EGR valves depending on the application and I know a 1994 Van uses a different control method than the F-car did. What this amounts to is you need to run the OEM 305 F-car EGR valve if you are using the stock ECM.

transtang78 · 08-23-2009, 11:40 PM

i will try that