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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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Can you pull the BLM's by individual cell? Do you smell fuel in the exhaust at idle? By "step on the gas" do you mean high engine load at part throttle, wide open throttle, or both?
 

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Discussion Starter · #3 ·
I am not able to see them at a different cells, my computer only shows one spot that has the blm number. it is at part throttle that the numbers go up. At idle it is in the low 120's. I do not smell gas in the exhaust but it is a strong Exhaust smell. spark plugs show it as running lean lean not rich but again 10mpg?
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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There is no field labeled "CELL"? You may have the BLM in one block, and the cell in another. The fact that the BLM changes based on throttle position would appear to indicate there is a matrix of cells defined by the RPM on one axis and engine load in some form on the other.

I'm assuming that the ECM may be a bit more primitive than the 4th Gens that I am familiar with. But I thought GM had a fairly similar approach through the years. Are you using DIACOM? Haven't seen that in years.

To actually run rich, it could be either a faulty O2 sensor or a "false" lean condition. The false lean can be caused by misfires and exhaust leaks before the O2 sensor. The false lean causes the BLM to rise above 128 and add fuel the engine doesn't really need.
 
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Ramblin' Wreck
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The 87 5.7L pcm seems to provide the BLOCK LEARN MULTIPLIER CELL along with the BLM. If you are using Diacom, I see on the product web site that a sample display of a 91 Chevy 5.7L shows the cell number just after the BLM.

http://www.rinda.com/acro/dcmstd.pdf
 

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Discussion Starter · #6 ·
I use a snap on scanner and am not sure on where to get the other reading on it.

The 02 has been replaced 3 times and is now a heated 3 wire sensor to make sure the Headers are not making it cool down to quick. ALL 8 plugs have been removed and they look as if it is running lean. So then where is the gas going? I am lost and dont know what to do next. I have started a forum on third gen that has some more info on the car and pictures of the plugs. take a look and see what your thoughts may be. thanks again for any help.

http://www.thirdgen.org/forums/tpi/727673-350-tpi-new-engine.html

Niko
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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You said "computer" leading me to believe you were running software.

Have you checked the fuel pressure? Have you looked for leaks? Have you checked the fuel pressure regulator for leaks? All those conditions could consume fuel, cause it to run lean, and cause the BLM's to elevate under heavy load. You have to check the fuel pressure for bleed down after the prime, which will identify leaks. Test is on the road under heavy load (5000 RPM/WOT) to see if the system is capable of holding the pressure up where it belongs.

Have you checked the oil for fuel dilution?

Have you accurately checked the mileage, over several tank fills, dividing miles driven by gallons pumped?
 

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Discussion Starter · #8 ·
Yes , of course. I fill the car up and count miles to gallons as I know that is a problem. it averages 10-11mpg.
 

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As you questioned me about the engine. The injectors were all replaced with remanufactured parts and the fuel pressure regulator was also replaced. Fuel pressure is holding for roughly 30 minutes after the key is removed and and the injectors are not leaking. They were replaced after this problem was found just to knock them off the list. The regulator was never leaking and fuel pressure is holding at 44lbs.

http://www.thirdgen.org/forums/tpi/727673-350-tpi-new-engine.html
 

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Would have been good to know all the info you gave the guys on 3rd Gen. Wouldn't have needed to ask you all the questions.

Without going back and standing on my head and squinting to look at the fuzzy scanner screen photos, what is the coolant temp on the scanner with the engine fully warmed up?
 

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...out of curiosity. Tried running a tank of E0 through it? Can't see ethanol killing your mileage that badly, but, on my LT1, I went from 18-24cty to 15-18. Just a thought.
 

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Discussion Starter · #13 ·
No I fill it up with 93 octane. THe car is all stock other than exhaust and only has 1500 miles on the engine. Never thought that i would have this kind of problem that no one can figure out.
 

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"FT CELL" is the long term fuel trim (LTFT, or BLM) cell. When the FT CELL changes, the BLOCK LEARN will change to the learned value stored in that cell.
 

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Discussion Starter · #16 ·
"FT CELL" is the long term fuel trim (LTFT, or BLM) cell. When the FT CELL changes, the BLOCK LEARN will change to the learned value stored in that cell.
Well , are there any thoughts as to what my problem may be from this video"?
 

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Too blurry, the numbers are too far separated from the labels. Is there any way the scanner can dump a .csv file of the records? If there is I would be glad to review the data log, using Excel and a technique I've improved over a period of 15 years. You have to look at maybe a 1/2-dozen interrelated parameters ar the same time. Not feasible with a fuzzy, real time video, with numbers spread all over the screen.
 

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Discussion Starter · #18 ·
Too blurry, the numbers are too far separated from the labels. Is there any way the scanner can dump a .csv file of the records? If there is I would be glad to review the data log, using Excel and a technique I've improved over a period of 15 years. You have to look at maybe a 1/2-dozen interrelated parameters ar the same time. Not feasible with a fuzzy, real time video, with numbers spread all over the screen.
do you have the snap on program for the diagnostc machines? I dont know any other way to change the type of video
 

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After reading through the other thread, I see you got pretty much the same responses I gave you. And multiple requests for a data log file. Appears to me that "ASE doc" gave you excellent guidance and told you how to capture the data using your Snap On Solus Edge. I don't know anything about operating that device. Did you review the operating manual for it to see how to produce a log file? It may be as simple as downloading software from the Snap On website.

If you insist on making videos, at least try to get the camera in focus so the numbers can be easily read. I can see maybe 30% of the numbers clear enough to make them out, but then every time I look for a number I need next, it's too blurry to read.

I don't think the info they gave you on the EGR was too meaningful. When the EGR opens the flow into the cylinder is exhaust gas, not "air". If it's flowing exhaust, it displaces air and reduces the air flow through the MAF. MAF, if accurate, tells the ECM there is less air flow, ECM reduces fuel flow to match. Let's say there's a leak in the EGR system, and the engine is pulling in air through the leak. MAF reading drops, fuel is reduced, engine runs lean, BLM's increase based on O2 sensor reading. But... EGR is typically not send at idle, or above 3,500 RPM, or at wide open throttle. It is only used at part throttle, steady state cruise conditions as you pointed out.

What caught my eye in the screen shots is the diverted valve for the AIR system. The 4th Gens don't have that. AIR flows only into the exhaust manifolds, never into the cat. And the 4th Gen AIR pump is electric, so it can run for a couple minutes on start to heat up the cat, and then shuts off. Your diverted valve allows the AIR to flow into the exhaust manifolds for startup, then switches the AIR flow to the cat for closed loop. What if you have the connections reversed, and you are flowing air into the exhaust manifolds. O2 is going to read lean and BLM's are going to elevate. Faster the engine turns the faster the belt driven pump turns and the more air gets dumped into into the exhaust. Could explain rising BLM'S at WOT. Wouldn't explain runnin lean.
 
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