cchvyd28

iTrader: (2)

Hello, as you can see from the tittle of my post I am getting SeS codes for Lean on Bank 1 and 2 and was looking for some helpful ideas. I have already replaced the upstream O2 sensors, fuel filter, fuel pump, and the fuel pressure regulator. As well as cleaned the Mass air sensor, TPS, and throttle body.

The mods done to the car are listed in my sig, and all were done to the car by the previous owners son, and the dad (who sold the car) didn't really know all what was done, so I am just going off of what i can see. The intake air temperature sensor was also relocated to the bottom of the ram air box like it is on the ram air trans am's. And it has an aftermarket Granetelli Mass airflow sensor. I bought the car in november of 2013 and the SeS light came on shortly after that.

Also maybe on a related note, maybe not i am not sure, once in a great while the Rpm's will hang at about 2200 even at a stop. If i blip the throttle a few times it will go back to idling at right around 800. But hooked up to a scanner i watched the throttle blade position and it always closes to 0%.

I have been reading around quite a bit, and have found a lot of people saying a vacuum leak is likely. I looked around and sprayed brake clean around the intake and some other spots and did not notice the engine change any in how it was running.

The guy that has been helping me work on the car is running out of ideas, so i figured i would take a shot and see if anyone here had any ideas. The only thing my buddy suggested was getting the engine smoked to see if there was a hidden or hard to find vacuum leak somewhere.

Thanks in advance for any help or ideas any of you may be able to offer.

Ed Wright

iTrader: (1)

Put the stock, untouched MAF back on it. Should fix it. Put the one on it now on EBay where it belongs. :-)

cchvyd28

iTrader: (2)

Not doubting you or anything, that very well could be the issue. But when we had the scanner hooked up, at idle, the MAF was reading 4 grams/sec. Which is in spec according to Mitchell. It says spec is 4-7 grams/sec. I dont remember what it was reading under various rpms because my buddy was reading the scanner and i was working the throttle.

3 pedal SS

iTrader: (1)

Check your intake elbow for cracks. Also,make sure it is on the TB all the way.

FSTFBDY

iTrader: (1)

triple check for vacuum leaks again.

ThoR294

iTrader: (6)

too leans means the engine is seeing too much air coming in, or there is not enough fuel. it differentiates between the MAF and the O2s. Check for vacuum leaks... check for gunked up fuel injectors... and honestly try to get a stock MAF and see what happens. I hear nothing but bad things about aftermarket MAFs

cchvyd28

iTrader: (2)

Sorry i am new to fuel injected vehicles and the terminology. but i assume you mean the tube going from the air box to the throttle body?

As far as the vacuum leaks i will check again, and will probably still get the engine smoke tested to be sure. and i may hit up some junk yards tomorrow and see if i can find a MaF just to try out.

thanks for the quick responses guys.

ThoR294

iTrader: (6)

Correct, that is the intake elbow

Ed Wright

iTrader: (1)

Mitchel is full of ****. A V8 engine of 350", at idle typically pulls 8 grams per second. 4 grams? That will damn sure be lean. Typical for aftermarket (junk) MAFs. Crapatelli MAFs typically also have a higher failure rate than factory units.
There is zero hp there. If, on a dyno, you baseline it with a stock tuning & MAF, then with a butchered MAF, it will usually show a small gain due to the fact the factory tuning is very rich @ WOT. Under reporting air flow will lean it. Makes it look good. The gain comes from leaning it, not less restriction like too many want to think. Drive it 30 miles or so you have high long term fuel trims. The PCM then adds the same percent of fuel at WOT to try to protect the engine. Any gain is then gone. I have proven this to guys multiple times. You can end up richer @ WOT than before which equals an actual small power loss! The factory MAF flows all the air a stock, or mild, engine can use.
Guys used to put adjustable regulators on to lean them on the dyno by turning fuel pressure down. Same effect on long term fuel trims as with butchered MAFs.
Tuning is the only way to lean one with no long term learning issues.
Getting rid of that damn thing will most likely fix your car. It absolutely will not run faster with that thing on it.
Good luck.

Chopstix

iTrader: (1)

^^ what he said ...my car had a granetelli on it when I bought it...switched back to the OE MAF and the car ran better

pr_lt1

Ok, no matter if the engine is heavily modified for example, 355, 383 or 396, mild or heavily CNC ported heads, small medium or big cam or/with power adder. The air fuel ratio usually favors stock maf vs aftermarket maf?

Ed Wright

iTrader: (1)

I have not seen an aftermarket MAF that was not junk. Porting (actually butchering) people always remove the vane in the center, even "de-screening" causes more turbulence. Ditto aftermarket MAF ends. As my black car progressed I played with that stuff a lot. Well past 400 rwhp I could make the same power with the stock unit. About 425 or so it started to like the 85mm MAF from a 5.3L/6.0L 2000s Chevy truck. (About $85.00 my cost at the Chevy dealer, plus an adapter pigtail). At 450 rwhp it was worth almost 10 rwhp. Creen still in it. That is an egg-crate style air straightener, not a "screen" to keep bugs out. SLP told me they flow tested those at nearly 1000 CFM. Anybody that knows much about this knows that is more than 98% of you guy's LT1s are capable of pumping. Saying "I don't want that restriction on my intact tract" is just comical. If it flows more air, it is not a restriction, regardless of what your eyes are telling you. Ditto mono-blade TBs. LOL
At the end of my running the 383", it was making 532 rwhp through 4.30 gears and a 4400 non-lock converter. I A-B-A tested the untouched 85mm truck MAF against Speed Density. Made average 6 rwhp more in SD mode. Had shown zero increase below 500 rwhp. At the Hallsville Texas track I A-B-A (MAF-SD-MAF) tested Speed Density. No change in ET, not quite 1/2 MPH. Everybody knows MAF systems correct for weather changes better, so how many need SD mode? Or, "OL/SD"? LOL

cchvyd28

iTrader: (2)

Just wanted to update on my issues. I went to the junkyard on sunday and pulled a stock MaF sensor off of a mid 90's pick up (checked advanced auto's website, part numbers were the same). installed it, cleared the code, and drove the car about 75 miles since then with no codes coming back or pending. New MaF is reading about 7.75 grams/sec. So thank you for your suggestions.

As for my other issue of the revs hanging up, that i noticed is still happening. I notice it tends to happen after i slow down or come to a stop after going WoT. thinking it may be a sticking or binding throttle cable.

Anyways just wanted to let you guys know it seems to be fixed, and thank you guys for the help and quick replies.