PN F75E-9C915-AA function
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Elder User
Joined: Aug 2001
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From: South Texas
PN F75E-9C915-AA function
Application 99 F150 4.62WD automatic
I think this part to be the source of a hesitation/miss problem I have been chasing for the last 30K miles (lean condition).
Main Symptom is a miss hesitation at 1/2 throttle load 40-50 mph range.
Blocked off the main vacuum line to this at the intake and hesitation/missfire apears to be gone.
Web search of the part calls it a Diverter valve and shows it to be part of EGR system.
On this truck, it appears to be part of the canister purge system. Any thoughts?
thanks
Dialtone
I think this part to be the source of a hesitation/miss problem I have been chasing for the last 30K miles (lean condition).
Main Symptom is a miss hesitation at 1/2 throttle load 40-50 mph range.
Blocked off the main vacuum line to this at the intake and hesitation/missfire apears to be gone.
Web search of the part calls it a Diverter valve and shows it to be part of EGR system.
On this truck, it appears to be part of the canister purge system. Any thoughts?
thanks
Dialtone
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Yep! It's a bad coil giving you the problem not the EGR system.
The normal operation of the EGR is part of what causes a bad coil to stumble.
That's what is making you think it is the direct cause of the stumble.
Search for threads about this, there are quite a few.
I brought this to the internet about a year ago because most don't know what the real cause is.
The issue generally dosn't set a code so is hard to ID the coil that is the cause without a dealer stress test or replacing all 8 with good ones and hope for the best.
The coils are subject to so many heating and cooling cycles over time that the windings develope shorted turns that result in lowered output and failure to fire the plugs under those light load very lean conditions.
The reason the wire developes shorted turns is the wire is only coated with a varnish that get worn thru turn to turn from expansion and contraction.
Good luck.
The normal operation of the EGR is part of what causes a bad coil to stumble.
That's what is making you think it is the direct cause of the stumble.
Search for threads about this, there are quite a few.
I brought this to the internet about a year ago because most don't know what the real cause is.
The issue generally dosn't set a code so is hard to ID the coil that is the cause without a dealer stress test or replacing all 8 with good ones and hope for the best.
The coils are subject to so many heating and cooling cycles over time that the windings develope shorted turns that result in lowered output and failure to fire the plugs under those light load very lean conditions.
The reason the wire developes shorted turns is the wire is only coated with a varnish that get worn thru turn to turn from expansion and contraction.
Good luck.
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Elder User
Joined: Aug 2001
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From: South Texas
Well, I hate to bust your bubble, but I changed BOTH coil packs with new ones today and it DID NOT fix the problem (but seemed to help somewhat). This led me to start blocking off intake vacuum ports in an attempt to find the culprit.
Even with this one blocked (after changing out coil packs), I still have a little stumble at times but it is much much less than before. It was getting so bad that I could barely go up a freeway on ramp behind some slowpokes without getting jerked all over the place.
I will give you your due that coils helped, but there is still something else going on.
I really find it strange that an engine that idles this smooth, has power to burn when romped down on, and gets 20 MPG on the highway, cannot negotiate a simple on ramp at 40-50 mph.
I guess tomorrow I will do the plugs/wires again. I ran across an article stating that 99 used 2 different plugs in the factory setup (AWSF32PG and AWSF32P), but replacements with AWSF32PP for both banks would work. I do not recall what plugs (motorcraft) I put in last time, but will make an effort to get the EXACT plugs this time.
Even with this one blocked (after changing out coil packs), I still have a little stumble at times but it is much much less than before. It was getting so bad that I could barely go up a freeway on ramp behind some slowpokes without getting jerked all over the place.
I will give you your due that coils helped, but there is still something else going on.
I really find it strange that an engine that idles this smooth, has power to burn when romped down on, and gets 20 MPG on the highway, cannot negotiate a simple on ramp at 40-50 mph.
I guess tomorrow I will do the plugs/wires again. I ran across an article stating that 99 used 2 different plugs in the factory setup (AWSF32PG and AWSF32P), but replacements with AWSF32PP for both banks would work. I do not recall what plugs (motorcraft) I put in last time, but will make an effort to get the EXACT plugs this time.
New User
Joined: Feb 2008
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Im having the same EXACT problems. In fact, if I didnt know better I'd think you were discribing my truck.
Ive changed plug wires, new plugs, new O2 sensor, ran Sea Foam through it (tank and crankcase only).
Please let me know if you find the issue. I hate taking the truck to the dealer-they like to rip your head off when they can.
Ive changed plug wires, new plugs, new O2 sensor, ran Sea Foam through it (tank and crankcase only).
Please let me know if you find the issue. I hate taking the truck to the dealer-they like to rip your head off when they can.
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Elder User
Joined: Aug 2001
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From: South Texas
It's fixed....For now anyway.
3 problems found.
1. Split vacuum cap on the upper barb of the PCV valve. Could not see it, but heard it while standing near that side with engine running.
2. Coil packs
3. Spark plugs (Replaced Autolite AP764 with APP 764)
Before replacing the plugs, I went on a 100 mile trip for work and had 1 or 2 incidents of the chugging. After replacing the plugs, 20 mile drive trying to get it to happen with no incidents.
So in conclusion, unless you have a vaccuum leak like I did, go for the coils and plugs. Make sure the plugs are double platinum's
3 problems found.
1. Split vacuum cap on the upper barb of the PCV valve. Could not see it, but heard it while standing near that side with engine running.
2. Coil packs
3. Spark plugs (Replaced Autolite AP764 with APP 764)
Before replacing the plugs, I went on a 100 mile trip for work and had 1 or 2 incidents of the chugging. After replacing the plugs, 20 mile drive trying to get it to happen with no incidents.
So in conclusion, unless you have a vaccuum leak like I did, go for the coils and plugs. Make sure the plugs are double platinum's
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Dialtone
1997 - 2003 F150
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Aug 11, 2010 07:17 AM
