cause of 172/176 running lean?

[musiccitysho]

I'm at wits end trying to resolve this 172/176 system running lean condition.
What besides changing O2s, replacing the ect,tps,cleaning the maf, discontinued use of a K&N, checking fuel pressure, checking manually for vaccuum leaks using propane, water or carb cleaner, and visually inspecting every coupler or connection could possibly be causing this.
Im getting the CE light after about 10 minutes of driving most likely because thats how long its taking the O2s to get heated. I get bad mileage, although I dont seem to have any drivability or idle issues so I think I can rule out fuel injectors.
I have searched every post using every keyword I can think of but nothing has led me to a solution.
Has anyone in the "lean club" had any luck? or any one with any ideas?

 

[wood_e]

Has anyone in the "lean club" had any luck? or any one with any ideas?

I'm thinking the silicone intake hoses will cure my problem...

 

[AutoSHO]

When my fuel pressure was low due to a bad FPR, I was having Oxygen Sensor codes come up occasionally, along with getting poor fuel economy.

 

[musiccitysho]

What do I look for in a bad FPR. In a search I saw something that said to pull the hose and if theres fuel in it then its bad, if thats right then mine is ok. Most of the posts mentioned hard starts or idle problems as symptons.
After replacing the ect and cleaning the maf ...again, (with a half of can of elect. cleaner) it took much longer before I got a light.
Im starting to wonder if the oil they use on the K&N is repelling the cleaners, so even though Ive stopped using it and cleaned the maf several times maybe there is still residue thats impairing its readings? After all I didnt start getting the lean codes until I installed the filter. Kind of makes sense.

 

[RJ-92]

Im starting to wonder if the oil they use on the K&N is repelling the cleaners, so even though Ive stopped using it and cleaned the maf several times maybe there is still residue thats impairing its readings? After all I didnt start getting the lean codes until I installed the filter. Kind of makes sense.

Bingo. Don't use a K&N. The oil can coat the hit wire on the MAF and cause a lean condition.

Pull the MAF, clean it with brake cleaner, give it a shot of compressed air to make sure the brake cleaner is dissolved. Then instal a paper filter. This should solve your problem.

 

[Porkchop]

Im dealing with that now ... In reality the only reason for a running lean code is unmetered air entering the intake. Have you physically tightened all the intake bolts including the runner couplers?

 

[AutoSHO]

Im dealing with that now ... In reality the only reason for a running lean code is unmetered air entering the intake.

... or low fuel pressure.

To test the FPR you need to get a Fuel Pressure Tester.

 

[Porkchop]

Advance auto has them for ~ $30 so does napa

btw..been there done that

 

[wood_e]

I've measured my fuel pressure before and it checked out. I'll let you know if the silicone hoses help... if i ever get them.

If you search under my name and lean you'll find a large thread with my expirences, and steps to diagnose the problem...

 

[musiccitysho]

RJ- I pulled the K&N out and went with a paper filter a while ago (months) after posting and reading about all the lean conditions and fouled MAF's caused by them. Not too mention that this started shortly after I put the K&N in and hasnt cleared it up since.
I have cleaned the MAF at least a dozen times since. I guess I'll try the carb cleaner, Ive used electric contact cleaner in place of it because of the warnings about the harsh chemicals in it, but it would probably dissolve oil better and costs alot less.
Porkchop- I have inspected and tightened every coupling, hose, and gasket that can be seen, then once more for peace of mind.
I'll go for the carb cleaner and see if that gets the job done.

Wood-e PM sent

Thanks all

 

[RJ-92]

Sounds like your O2s might be shot. I believe I got a similar code when mine went out.

 

[musiccitysho]

I would suspect the O2s but they were both replaced less than 20,000 miles ago and they both read the same lean condition... one after the other....When I clear the codes and drive the car until heated the light illuminates for a minute then goes out for a sec. then back on with the second code, I could see one O2 being defective and dying prematurely but not both and surely not both at the same exact time as happened when this began, these codes were never present individually.
I think youre right on about the K&N because I was CE light free until shortly after I put it in, about a year ago. Im gonna go and unload a whole can of carb cleaner on the MAF if necessary and see if thats it.

 

[rangerj]

Have you checked the throttle body gasket? How about the snorkle tube that runs from the air filter box to the throttle body. A crack or split in the snorkle tube can cause a lean condition. Look at the connection hoses on the intake plenum/intake manifold connection for cracks or splits. rangerj

 

[musiccitysho]

Yes Ive visually inspected them thoroughly, followed up by running propane around all the edges of the couplers, IAC/TB gaskets, and the snorkel with no spikes or dips in idle or revs.
Today I sprayed the heck out of the maf and the 55cm port with a whole can of carb cleaner and between that and the new ECT that I put in yesterday it seems to have greatly decreased the frequency of the codes, I went for a 40 minute drive with no light, I thought I had it beat. Previously it would consistently come on as soon as I reached normal operating temp. Unfortunately I just went for a 10 minute trip to the store and the CE light triggered again... Bummer. Its still a mystery to me.

 

[musiccitysho]

Just a passing thought...
Anyone know if carbon buildup on an O2 would cause it to read lean, and if so can they be cleaned?
Im thinking that the dirty maf and bad ECT may have initiated the lean condition then while the EEC compansated and caused it to run rich that the O2s may have become fouled and cant read the exhaust gases correctly.

 

[musiccitysho]

Well it turns out that the new ECT and using the carb cleaner instead of the electrical contact cleaner on the MAF did the trick!
Hurrah! Finally, no more lean codes and back to the mileage that I knew and loved. I took it for 100 mile "spirited" run, hoping to get the O2's good and hot enough to burn off any residual carbon buildup on them. Sure enough its been code free since, the mileage picked up and acceleration became more responsive, man its been missed.
Big Thanks to everyone, and I hope that this helps some of the others in the lean club. I'm going for a drive!