Ported MAF Causing Problems?
Thread Starter
Le Mans Master
Joined: Dec 2003
Posts: 5,867
Likes: 17
From: Phoenix Arizona
Ported MAF Causing Problems?
Has anyone here experienced intermittent "lean condition" codes because of ported MAF housings/no screen, etc?
I've got a TPIS ported MAF housing & removed screen and crossbars in my MAF, and am getting a P0172 code that sets the second it goes into closed loop. I can clear the code and it doesn't come back until next drive.
I've read that modifying the MAF can cause this. True?
I've got a TPIS ported MAF housing & removed screen and crossbars in my MAF, and am getting a P0172 code that sets the second it goes into closed loop. I can clear the code and it doesn't come back until next drive.
I've read that modifying the MAF can cause this. True?
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Are both ends of the MAF without screens?
The screens act as difuser to allow the air to flow evenly over the heated elements. Some have removed them with no problems...but the screens are there for a reason.
The screens act as difuser to allow the air to flow evenly over the heated elements. Some have removed them with no problems...but the screens are there for a reason.
Thread Starter
Le Mans Master
Joined: Dec 2003
Posts: 5,867
Likes: 17
From: Phoenix Arizona
I added the ported housing and per TPIS instructions removed the "extra" crossbar material. These codes weren't immediate, and are intermittent, so I didn't associate them with this mod right away.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
The extra "less" restrictive diameter of the housing may be allowing an uneven flow reading...if the housing was all you changed.
Might be worth a shot:
If you have an extra bit of "widow" screen (plastic) from a home improvement store you could stretch it across the face of the MAF (on the incoming air side) and let the air filter housing/clamp hold it in place to see if the codes subside while the screen is in place. This should create a more even flow across the MAF element....just make sure it doesn't get sucked in.
I'm not sure how the plastic screen would hold up over extend heat/time so your on your own with that aspect.
Might be worth a shot:
If you have an extra bit of "widow" screen (plastic) from a home improvement store you could stretch it across the face of the MAF (on the incoming air side) and let the air filter housing/clamp hold it in place to see if the codes subside while the screen is in place. This should create a more even flow across the MAF element....just make sure it doesn't get sucked in.
I'm not sure how the plastic screen would hold up over extend heat/time so your on your own with that aspect.
Last edited by engle1147; Feb 27, 2010 at 11:42 AM. Reason: CYA added
Intermediate
Joined: Jan 2010
Posts: 45
Likes: 1
By "extra" crossbar material you mean the heat sink fins, right? Your lean condition is caused because the heated wires "see" only a small percent of the air flow going through the housing. Once you gut the housing the percentage of total air flow the wires "see" is less. Putting the trash screens back on will probably have no effect.
When I gutted my MAF I also ported the heads , bigger camshaft and increased the fuel pressure and had no problems with codes being set.
If you have an adjustable fuel pressure regulator you could try increasing the fuel pressure. A tune will correct the problem. You could also try replacing the fins with a small lump of epoxy to change the percentage of air the crosshairs see. I would try the fuel pressure regulator first and a tune second. I hate the thought of a piece of epoxy coming loose and entering the engine or damaging the cross hairs.
When I gutted my MAF I also ported the heads , bigger camshaft and increased the fuel pressure and had no problems with codes being set.
If you have an adjustable fuel pressure regulator you could try increasing the fuel pressure. A tune will correct the problem. You could also try replacing the fins with a small lump of epoxy to change the percentage of air the crosshairs see. I would try the fuel pressure regulator first and a tune second. I hate the thought of a piece of epoxy coming loose and entering the engine or damaging the cross hairs.
Thread Starter
Le Mans Master
Joined: Dec 2003
Posts: 5,867
Likes: 17
From: Phoenix Arizona
The engine is a 383. Around the same time I did the ported MAF housing I also switched out the shortie headers for longtubes, and installed 3" high flow cats, and 3" B&B exhaust - I have a feeling this may be contributing to the lean codes, though I was told the changes shouldn't require retuning.
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Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
You should really retune it.
If something, a little piece of debris hits that filament it will make that MAF useless and cause it to go lean. Happened to my 78 (descreened). THere were teeny pieces of leaves in there, guessing at some point the filament got tagged. Car would go intermittently lean, drove me NUTS trying to find the problem. Eventually it blew the head gasket.
If something, a little piece of debris hits that filament it will make that MAF useless and cause it to go lean. Happened to my 78 (descreened). THere were teeny pieces of leaves in there, guessing at some point the filament got tagged. Car would go intermittently lean, drove me NUTS trying to find the problem. Eventually it blew the head gasket.
Advanced
Joined: Nov 2009
Posts: 56
Likes: 0
From: Louisville Ky
Here's my two cents.I did this mod awhile back and my 86 L98. It is working fine so far. I did ported the plenum and add an adjustable fuel pressurer regulator and true dual exhaust and vortex breather. I'm hoping I don't start get codes.
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
well, you are obd2 and i am obd1, but I've never had a problem with mine at all. But i have heard, like others have said, that if the air doesnt hit the element right it will cause problems.
