EGR need replacing??
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Cross-Country
Joined: Sep 2006
Posts: 53
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EGR need replacing??
My 96 F150 (5.8) has a miss. I have replaced plugs wires rotor button etc. still got it. I put vacuum on the egr and it died which is normal I think. I then with engine off pulled vacuum on the EGR and it leaked down. I then ran the truck with the EGR vacuum disconnected. It ran smooth as silk like this. Do I need EGR valve replaced?? No codes!!!
Freshman User
Joined: Mar 2021
Posts: 25
Likes: 2
Are you saying you drove the truck with the EGR disconnected, or that you just let it idle & rev up in the driveway with it disconected? I know on other cars I tested EGRs on, they all held the vacuum for a very long time when applied with engine off.
Either way, what is your base timing set at? Did you pull the SPOUT when you set it?
Did you clean the igntion coil mounting location? And the TFI module mounting location? Corrosion/crap in these 2 areas cause misses in the 4.9
How are your grounds looking? There are quite a few located all over & many issues (from misses to radios not working) can be fixed by cleaning & retightening all the grounds.
Do you have an aftermarket distributor? The reluctor/stutter wheel (it controls spark timing on each cylinder & is located under the rotor) inside the aftermarket distributors are crap & they are never machined to the exact tolerances. The dimensions of the teeth should be: .398 to .400 for the large teeth & .258 to .262 for the small tooth.
Either way, what is your base timing set at? Did you pull the SPOUT when you set it?
Did you clean the igntion coil mounting location? And the TFI module mounting location? Corrosion/crap in these 2 areas cause misses in the 4.9
How are your grounds looking? There are quite a few located all over & many issues (from misses to radios not working) can be fixed by cleaning & retightening all the grounds.
Do you have an aftermarket distributor? The reluctor/stutter wheel (it controls spark timing on each cylinder & is located under the rotor) inside the aftermarket distributors are crap & they are never machined to the exact tolerances. The dimensions of the teeth should be: .398 to .400 for the large teeth & .258 to .262 for the small tooth.
Thread Starter
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Cross-Country
Joined: Sep 2006
Posts: 53
Likes: 0
I disconnected it and drove it and it ran fine.
I tested the vacuum with the engine off. It didn't hold at all.
It is a 5.8L
I have checked my grounds.
I checked the timing without the PIP and it was fine. I don't remember the numbers, I have that info in the truck and I am not with it right now.
It has an after market distributor and I haven't checked it yet.
Thanks
I tested the vacuum with the engine off. It didn't hold at all.
It is a 5.8L
I have checked my grounds.
I checked the timing without the PIP and it was fine. I don't remember the numbers, I have that info in the truck and I am not with it right now.
It has an after market distributor and I haven't checked it yet.
Thanks
Fleet Owner
Joined: Oct 2005
Posts: 20,780
Likes: 1,746
From: Kentucky
The EGR valve should hold vacuum as previously noted. I would suggest to replace it. When the EGR valve is commanded open the EVR solenoid is modulated open via the computer. You effectively are introducing a small vacuum leak when the EGR is commanded on. The computer is increasing the duty cycle of the EVR to compensate.That's why you are most likely not getting any EGR flow error codes.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Is there vacuum on the EGR line at the valve at idle? There should not be but if there is the EVR(vacuum regulator) next to the coil could faulty or there could be a problem with the electrical side.
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