system too lean
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system too lean
I have a 1998 F150 recently under heavy acceleration the engine pings really bad. Once then CEL came on the codes were P0171 B1, P0174 B2, P0175 B2
all of these are system too lean. Where should I look first? EGR ,PCV,Fuel filter,
all the above?
all of these are system too lean. Where should I look first? EGR ,PCV,Fuel filter,
all the above?
Cargo Master
Joined: Dec 2004
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From: NE Texas
I would check all those things but the first thing I would do would be to check the fuel pressure. If it hasn't had a fuel filter really recently, just put one on. Even if it has been changed recently, a bad tank of gas or two can plug it up.
You could have some plugged EGR passages but that is easy to test by warming up the engine and then disconnect the source to the EGR valve and apply vacuum with an alternate source to the EGR valve while engine is idling. If applying the vacuum kills the engine, then the passages are most likely clear enough that the EGR is not the problem.
Also don't overlook the possibility of a vacuum leak, especially if the truck idles rough.
I doubt the PCV would be causing this but check it.
Good luck and keep us posted,
Doc
You could have some plugged EGR passages but that is easy to test by warming up the engine and then disconnect the source to the EGR valve and apply vacuum with an alternate source to the EGR valve while engine is idling. If applying the vacuum kills the engine, then the passages are most likely clear enough that the EGR is not the problem.
Also don't overlook the possibility of a vacuum leak, especially if the truck idles rough.
I doubt the PCV would be causing this but check it.
Good luck and keep us posted,
Doc
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Joined: Sep 2005
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I had same codes on my 98 4.6,, cleaned the MAF and problems cleared up!!!
Also check the small rubber el (90) on the pcv valve,, on the drivers side, mine had a cut in the bend.
Also check the small rubber el (90) on the pcv valve,, on the drivers side, mine had a cut in the bend.
Last edited by swright_47; Feb 13, 2006 at 03:47 PM.
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I changed the fuel filter, and unplugged the vacuum line to the EGR, with the engine warmed up, and replaced it with a different source of vacuum the engine slowed but did not die. Engine idles smoothly, has no misses at all only pings when the throttle is pressed down beyond half way.
Cargo Master
Joined: Dec 2004
Posts: 2,232
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From: NE Texas
You need to check the fuel pressure and not just at idle. With the guage connected rev it up real good and see if the pressure falls off any at all. If it does the problem is in the fuel system. Maybe the pump but could be a plugged line or anything that is preventing the fuel from flowing adequately.
Good luck,
Doc
Good luck,
Doc
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Joined: Mar 2004
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From: Suisun City
I have the EXACT same problem on my 1998 F-250 Light Duty. My mechanic had me run a product called "44K" I believe which helped for a while than problem came back. I tried running a "mid" grade gasoline which helped somewhat. When I run "supreme" in it the engine stops pinging. If you find out what the problem was/is please post for me.
Thanks,
Jason
Thanks,
Jason
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did you clean the maf, that will cause it to run lean, with the codes, its more than likely dirty maf, cracked, or leaking pcv or hose, fuel pump or restricted fuel pressure.
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From: St Louis
Actually, with these codes, the engine is NOT running lean, it is running RICH.
The LEAN codes of P0171 and P0174 mean that the O2 sensor is reporting that the exhaust is lean, the computer has maxed out fuel enrichment, and the exhaust is still too lean according to the O2 sensors.
This happens when there is unmeasured air entering the intake (vaccum leak) or when the MAF is mis-reporting the air entering the intake (clean the MAF).
Steve
The LEAN codes of P0171 and P0174 mean that the O2 sensor is reporting that the exhaust is lean, the computer has maxed out fuel enrichment, and the exhaust is still too lean according to the O2 sensors.
This happens when there is unmeasured air entering the intake (vaccum leak) or when the MAF is mis-reporting the air entering the intake (clean the MAF).
Steve
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What is the best method for cleaning the MAF? How delicate is it I would hate to ruin it if it is not already bad. I have checked for vacuum leaks @ the manifold, I have changed the aif,and fuel filter. I have checked the fuel pressure,and the fuel pressure regulater, all of those tests have shown to be ok.
I have not cleaned the MAF but that will be the very next thing I do, and I will keep everyone posted on the out come. Thank you to everyone for all your advise.
I have not cleaned the MAF but that will be the very next thing I do, and I will keep everyone posted on the out come. Thank you to everyone for all your advise.
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From: Suisun City
I thought I would update with my "pinging" findings
I recently did my 100K service with my local mechanic. I took him several articles that I had printed out from this thread talking about the "pinging" problem these trucks have and what people have done to trouble shoot them.
The morning I took my truck in he had a friend there that had been a Ford mechanic for 26 years so I started asking him about my truck and it's common problems. He recommended to my mechanic to pull the throttle body and make sure the egr ports were clear. My mechanic charged me an extra $135 to do this. He said the ports were clear with no carbon build up.
To make a long story semi shorter even after doing the full blown 100K service my truck still "pings". I didn't notice if for about a month or so because I still had a full tank of supreme gas and my truck doesn't ping when I run supreme. As soon as I got about half way through my tank of regular I noticed the pinging was back. Needless to say I just filled back up with supreme today.
I have done everything possible to stop the pinging and it still persists so I guess I'm stuck paying the extra .20 to .30 cents a gallon to run supreme but I guess it's better than paying 5K for a new engine.
If someone finds a silver bullet that fixes this problem I hope you share it with the rest of us.
Thanks,
Jason
The morning I took my truck in he had a friend there that had been a Ford mechanic for 26 years so I started asking him about my truck and it's common problems. He recommended to my mechanic to pull the throttle body and make sure the egr ports were clear. My mechanic charged me an extra $135 to do this. He said the ports were clear with no carbon build up.
To make a long story semi shorter even after doing the full blown 100K service my truck still "pings". I didn't notice if for about a month or so because I still had a full tank of supreme gas and my truck doesn't ping when I run supreme. As soon as I got about half way through my tank of regular I noticed the pinging was back. Needless to say I just filled back up with supreme today.
I have done everything possible to stop the pinging and it still persists so I guess I'm stuck paying the extra .20 to .30 cents a gallon to run supreme but I guess it's better than paying 5K for a new engine.
If someone finds a silver bullet that fixes this problem I hope you share it with the rest of us.
Thanks,
Jason
Hotshot
Joined: Jan 2004
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From: St Louis
Clogged EGR ports won't cause pinging, they will cause insufficient EGR flow problems.
OTOH, if there is EGR flow when there shouldn't be, you will definitely get pinging or spark knock. Typical causes of this symptom are leaky EVR solenoids or EGR valves with a pintle that does not seat properly and seal off the flow.
I clean the MAF by gently spraying the sensor filaments with either a contact cleaner or brake cleaner. The brake cleaner is cheap, readily available, and leaves no residue.
Steve
OTOH, if there is EGR flow when there shouldn't be, you will definitely get pinging or spark knock. Typical causes of this symptom are leaky EVR solenoids or EGR valves with a pintle that does not seat properly and seal off the flow.
I clean the MAF by gently spraying the sensor filaments with either a contact cleaner or brake cleaner. The brake cleaner is cheap, readily available, and leaves no residue.
Steve
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Today I bought a can of contact cleaner and sprayed the little things in the MAF. Amazingly enough what once were kind of a brown color sparkeled shiny silver. I reassembled the air cleaner and went for a test drive and the pinging stopped completely. Thanks to everyone for all your help, especially projectSHO89 for your sugggestion on cleaning the MAF. I can now sleep better at night. The true test of this comes soon when I drag my boat to the lake. Maybe this trip my truck won't get so P/O at me.
