egr
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Mountain Pass
Joined: Dec 2007
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egr
I have a 91 f150, 300 six, 125,000 miles. I had bucking and jerking when I bought it 3 months ago. I did the egr block off, engine ran fine. The other day, I installed a egr restrictor to turn the cel off. I put a 5/32 hole in the restrictor plate. Now it bucks and jerks while the engine is cold.WHen it is warm it runs great. The cel is off though. Is 5/32 hole letting too much exhaust gas in? Before it bucked and jerked cold or hot. Now its bucking and jerking when it's cold. Any ideas? I also replaced the throttle body gasket while I was under there. It cured my hesitation off idle.
More Turbo
Joined: Feb 2004
Posts: 704
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I'm not familiar with the 1991 system but there should be a TVS (Thermal Vacuum Switch) or some other method to keep the EGR from functioning when the engine is cold. It sounds like that's not working correctly.
Lou Manglass
Lou Manglass
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Mountain Pass
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You are probably right. It just started throwing codes. Its shows 327 and 328, which have to do with the operation of the egr and evp. I should just put the block off plate back and not worry with it anymore. The CEL doesn't bother me that bad. I'd rather it be on and run right than to be off and buck and jerk.
Postmaster
Joined: Dec 2006
Posts: 3,603
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From: Spokane, WA
All the systems including the EGR must be working properly. Re-engineering any part of the system like blocking or removing EGR function does not cure anything and may actually cause more problems.
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Mountain Pass
Joined: Dec 2007
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Really need help guys. I've explained what I've done in previous posts to this thread. Well I disconnected this egr all together and capped off green hose. I'm still getting the bucking and jerking now but the cel is 172 (always lean) and 332 (egr flow) which is from the egr being disconnected. I know 172 is an 02 sensor. Does it need replacing or is what I've done with the egr causing this lean condition. Is the egr valve stuck open allowing too much egr gases in even though teh vacuum line is disnconnected?
Postmaster
Joined: Mar 2002
Posts: 3,545
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From: Coal Region
if it is doing it when cold, then it is on open loop. after it is warm the o2 sensor will switch to closed loop. when in open loop the PCM doesnt read the o2 sensor and dumps an extra amount of fuel into the engine.
IIRC, the EGR flows all the time except at WOT.
i have my EGR blocked off and capped (headers) and i have a constant CEL. my advice, go back to stock and see how it runs. if it is still acting up then retuen it back to the blocks off state. 5/32" isnt to much.
IIRC, the EGR flows all the time except at WOT.
i have my EGR blocked off and capped (headers) and i have a constant CEL. my advice, go back to stock and see how it runs. if it is still acting up then retuen it back to the blocks off state. 5/32" isnt to much.
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Mountain Pass
Joined: Dec 2007
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I took your advice optikal . I went back to stock egr. No restrictor, no block off, everything hooked up. While I was taking the restrictor out I noticed that I had only put one egr gasket in between the plate and the intake and egr valve. I bought two and thought I remembered putting one on both sides of the plate. It must have fallen out when I was trying to get the bolts started because I found it between the valve cover and where the vacuum solenoids are. I was probably getting a vacuum leak of some sort there since the gasket was not in place. Anyway, the stumble at part throttle is back, which I figured. I'll probably go back to the total block off again soon, or try the res. plate with both gaskets this time. THanks
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Mountain Pass
Joined: Dec 2007
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I unhooked green egr line to stop the bucking only to have it start running rough again with the 172 code. I replaced the oxygen sensor and fixed that. Now it runs like a champ. Thanks for your help.
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