thatsupnow

hey there guys whats happenin? IM coming from the 305 engine that was in there just finished building a 355 with 10.5:1 comp ratio, Holley stealth ram, 26# accel injectors(stock fuel pressure), trickflow heads, and GM perf cam 208*/221* @ .050 .474/.510 I/E, Base timing I believe is 8*, Ive replaced all the sensors, the fuel pump is new BBK performance pump 255L and finally I got a custom chip burned from pcm for less(A buddy recommended them he said his was spot on). My question is why oh why does this thing throw a code 44-lean exhaust? no other codes just 44. could the stock fuel pressure not be good enough? maybe the injectors are too small? Bump them up to 30# maybe? Or the chip isnt calibrated perfectly? Ive checked for vacuum leaks, checked all the voltages on the sensors everything I can possibly think of on my own and with doing a total internet search. Any help would great thank you for your time in helping me out with this situation.

vetteoz

iTrader: (13)

Including the O2 sensor ?

If it is reading wrong then you would get the lean code because voltage is not what the ECM
expects to see;
and the ECM can't tell the difference between actual lean exhaust , a faulty sensor , or bad wiring to the sensor ; only that it is getting the wrong feedback

Code 44
This code will be set whenever the ecm perceives a lean exhaust condition.
The condition to set the code is met when ECM sees a low O2 output voltage (less than 0.2V)
around a minute in closed loop.
The main causes for this is a grounded O2 sensor, low fuel pressure, restricted injectors, contaminated fuel, exhaust leaks or bad air switching valve.


Only thing to do is buy the ALDL cable
http://www.aldlcable.com/
and datalog the engine to see what it is actually doing.
If the tune is off then you could send the log to PCMforless so they can correct the tune

thatsupnow

yea man Ive replaced the O2 sensor too, umm i just remembered that there was about 3/8 tank of gas in there from last summer but I siphoned as much as i could and put some fresh 94 in the tank but no fuel system cleaner so maybe could be some crap in there, when you take a datalog will it have info on how to tell how the engine is running? thanks for the link too im gonna get one of these cables

kenbob

i just had this happen and it was a vacuum leak find any excess air goin into your intake

thatsupnow

I wonder if I maybe tried out one of them 3 wire heated o2 sensors like the bosch 13077? And if that doesnt work Ive got a buddy who has an ALDL cable that Ill just take a datalog of the motor.

305sbc

iTrader: (3)

Exhaust headers?
Are you running the AIR system?

It is possible you have an exhaust leak at the cylinder head.
It is also possible that you have a vacuum leak.

Are you datalogging this?

thatsupnow

yea Ive got shorty flowtech headers with 3" y pipe and 3" flowmaster cat back Ive tightened everything up on the exhaust, cat is gone the o2 sensor is located right on the drivers side collector, all the AIR stuff is gone too. The only place I can think of where there could be a vacuum leak is right where the top part of the stealth ram intake bolts up with the base Ill get some gasket sealer and see if that fixes anything otherwise Ill just go grab the ALDL cable from my buddy and see exactly what the hell is going on. This is starting to get really annoying!

305sbc

iTrader: (3)

The heated O2 sensor is something to try. Many engines with headers & no CAT end up needing them to avoid the codes.

Damon

Beg borrow or steal a scan tool. Gotta see it the way the ECM sees it when you're dealing with custom stuff.

One of the first things you're going to want to look at are the "block learn modifiers". That's the fuel trim it's using to modify the pre-programmed fuel maps, based on O2 sensor input. There are quite a few block learn "cells" depending on RPM and load. If they're all maxed out at 160 when you enter closed loop (when the ECM is paying attention to the O2 sensor inputs) you are lean. A reading of 128 is the middle of the range and I believe 108 or thereabouts is the bottom of the range. The number refers to how much fuel is being added or subtracted from the what the base fuel maps are calling for. If the block learn is at 128 it's injecting exactly the amount of fuel that the fuel maps are saying to. As the number goes higher it's injecting MORE than the maps call for (trying to compensate for a lean condition). Lower and it's less (compensating for a rich condition).

I've run into that code before on occasion. Sometimes it's a bad sensor or wiring, sometimes it's telling the truth. Of note was one occasion where everything was maxed or nearly maxed at 160. Turns out the injectors we installed were not the 30# units the programming thought it was running- they were only 24# injectors in reality. Installing the proper sized injectors brought the block learn numbers back down to sanity very quickly.

thatsupnow

yea I finally figured it out after putting in a heated O2 sensor and using my trusty new aldl cable I could see exactly what the deal was and turns out it was a bad fuel pressure regulator. I guess the non adjustable holley regulators for the stealth ram are just crap, but I put a new adjustable regulator bumped pressure up to around 50 no more code 44!! Now its just time to work on the fine tuning of this chip