Vacuum issues
05-23-2018, 11:02 PM
#1
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Vacuum issues
Alright guys bare with me for a second... So long story short I failed smog for high NO at the 25mph level.. the truck is a 1990 f150 with the 5.0. I had the exhaust replaced headers back with all compliant smog parts. The smog mech told me he thought it was my EGR. Took that apart and sure enough it was stuck. Freed the EGR and still nothing. Checked for vacuum in the line leading to the egr. Nothing. Replaced the EGR vacuum solenoid.. nothing... Checked the lines to the vacuum canister and between the egr and the solenoid. No obstruction. Obviously there's the most likely candidate being a leak somewhere however I just wanted to check in and make sure there's not something I'm missing checking prior to pulling all the lines and hoses to replace them.. any suggestions... I'm reading voltage to the solenoid 12v. Issues with the truck are a high, low (almost stalling) combination of idle for a couple minutes prior to warming up and being just fine. From what I hear the truck has a lot more potential than what it's showing me.. 0-60 in a lot so to speak.. So possibly a loss of power in the mix as well. Due to the EGR not operating due to no vacuum. Please help haha
05-23-2018, 11:15 PM
#2
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What do you mean by "nothing"? No change in the NOx level? No EGR flow? No movement of the EGR? No change in the EVP?
This diagram & its caption explain the EGR system:
(phone app link)
It would also help us help you to see everything about the truck in your signature:
(phone app link)
This diagram & its caption explain the EGR system:
(phone app link)
It would also help us help you to see everything about the truck in your signature:
(phone app link)
05-25-2018, 11:32 AM
#4
Trace it back....
Vacuum at EGR valve?
Yes: Is it enough to operate the valve? If it is then the valve is either still sticking or your problem is elsewhere. Maybe the EGR sensor is part of the problem?
No: Is the vacuum line broken, clogged, kinked?
Is there vacuum at the relay outlet?
Is there vacuum at the relay inlet?
Is the relay supply vacuum line broken, clogged, kinked?
etc.
Vacuum at EGR valve?
Yes: Is it enough to operate the valve? If it is then the valve is either still sticking or your problem is elsewhere. Maybe the EGR sensor is part of the problem?
No: Is the vacuum line broken, clogged, kinked?
Is there vacuum at the relay outlet?
Is there vacuum at the relay inlet?
Is the relay supply vacuum line broken, clogged, kinked?
etc.