can someone please look at my datalog
02-12-2014, 09:11 PM
#1
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can someone please look at my datalog
http://www.mediafire.com/download/wm...l/02-12-14.uni
it's a 96 trans am a4 in a 88 s10. it has been converted to 94 obd1 with no emissions and has a cold air intake. stock engine with s10 swap headers and true dual exhaust no cats. runs rich i changed the oil 3 days ago i smelled a lot of gas in the oil. my fuel pressure is low about 30lbs at idle. need help. thank you
it's a 96 trans am a4 in a 88 s10. it has been converted to 94 obd1 with no emissions and has a cold air intake. stock engine with s10 swap headers and true dual exhaust no cats. runs rich i changed the oil 3 days ago i smelled a lot of gas in the oil. my fuel pressure is low about 30lbs at idle. need help. thank you
02-13-2014, 07:39 AM
#2
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Re: can someone please look at my datalog
I am certainly no expert on this and I'm sure Fred or Bob will be along soon with good info. But it looks to me like the fuel trims are maxed out low at about 108 with the PCM trying to cut back on the excessive fuel. Has this PCM been "tuned" lately? It could just be a bad tune using too high an injector pulse width? Again, no expert here, just guessing. Let's see what the experts say...
Last edited by GaryDoug; 02-13-2014 at 10:39 AM.
02-13-2014, 09:15 AM
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Re: can someone please look at my datalog
I saw this yesterday, but had to download a new copy of DataMaster.
You indicate 30psi fuel pressure at idle. It that with or without the vacuum compensation line connected to the fuel pressure regulator? Is there any evidence of wet fuel in the vacuum line?
You indicate 30psi fuel pressure at idle. It that with or without the vacuum compensation line connected to the fuel pressure regulator? Is there any evidence of wet fuel in the vacuum line?
02-13-2014, 09:27 AM
#4
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Re: can someone please look at my datalog
What are your mods, specifically is your CAI MAS from an F-Body LT1, also confirming TB stock and no injector changes or tuning done ? I see two things that jump out.
1- your MAS air flow at record 5682 is 8.77 AFGS in idle at 550 RPM, that's about 30+ % higher than a stock setup (mine ran at 6.63 AFGS /600 RPM) result is your injector BPW (pulse width) 3.36 Ms is also 30+% higher. So the PCM is adding 30% to much fuel. My guess is the MAS is reading high. You can try w/key off disconnecting MAS, start it up and ignore the SES indicator, engine will be running in SD mode, let it get into closed loop and see what the ST and LT BLM's look like. AFGS will be 0 in SD mode but the injector BPW should drop to near 2.5 Ms at a 650 RPM idle. If they don't drop it's not MAS.Hook it back up and let us know results..
2- Not as critical... your IAC is at 0 in record 5682, looks like PCM is holding idle OK using timing, but it's pointing to either a small vac leak or the TB blades are opened a crack to much. TB voltage TPS is good at 0.59 so you don't have a lot of wiggle room to close the blades. Could try closing them to 0.50 volts and see what IAC does at idle..
1- your MAS air flow at record 5682 is 8.77 AFGS in idle at 550 RPM, that's about 30+ % higher than a stock setup (mine ran at 6.63 AFGS /600 RPM) result is your injector BPW (pulse width) 3.36 Ms is also 30+% higher. So the PCM is adding 30% to much fuel. My guess is the MAS is reading high. You can try w/key off disconnecting MAS, start it up and ignore the SES indicator, engine will be running in SD mode, let it get into closed loop and see what the ST and LT BLM's look like. AFGS will be 0 in SD mode but the injector BPW should drop to near 2.5 Ms at a 650 RPM idle. If they don't drop it's not MAS.Hook it back up and let us know results..
2- Not as critical... your IAC is at 0 in record 5682, looks like PCM is holding idle OK using timing, but it's pointing to either a small vac leak or the TB blades are opened a crack to much. TB voltage TPS is good at 0.59 so you don't have a lot of wiggle room to close the blades. Could try closing them to 0.50 volts and see what IAC does at idle..
Last edited by bobdec; 02-13-2014 at 09:30 AM.
02-13-2014, 09:48 AM
#5
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Re: can someone please look at my datalog
Gary already covered it... the PCM is pulling out massive amounts of fuel. Almost everything else appears normal. There are places where the LTFT's are pulling out the maximum they can (15.6%), and the STFT's are pulling out even more, making the total fuel cut about 40%. Definitely something wrong with the injectors or the tune.
Some questions:
Is there any evidence that the injectors are not the correct 24#/HR GM Multec units?
Did the PCM come with the engine, or is it from another vehicle, where it might have been tuned for larger injectors?
Since you have non-stock exhaust, where are the O2 sensors mounted? Seems odd that before it goes into closed loop, the right O2 sensor is pretty much stable at 910mV. The left sensor starts at 450mV (cold reading) and eventually catches up. Are you using 4-wire heated sensors? I don't see any codes for the heater circuits, so it appears you are.
Is the MAF sensor a stock GM part? AFGS seems high at 650RPM idle.
You indicate no emissions.... does this include deleting the EVAP system?
I wouldn't continue to drive it under these conditions, where you smell fuel in the oil. You are going to destroy the piston rings, and possibly all the bearings.
Some questions:
Is there any evidence that the injectors are not the correct 24#/HR GM Multec units?
Did the PCM come with the engine, or is it from another vehicle, where it might have been tuned for larger injectors?
Since you have non-stock exhaust, where are the O2 sensors mounted? Seems odd that before it goes into closed loop, the right O2 sensor is pretty much stable at 910mV. The left sensor starts at 450mV (cold reading) and eventually catches up. Are you using 4-wire heated sensors? I don't see any codes for the heater circuits, so it appears you are.
Is the MAF sensor a stock GM part? AFGS seems high at 650RPM idle.
You indicate no emissions.... does this include deleting the EVAP system?
I wouldn't continue to drive it under these conditions, where you smell fuel in the oil. You are going to destroy the piston rings, and possibly all the bearings.
02-13-2014, 10:44 AM
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02-13-2014, 04:14 PM
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Re: can someone please look at my datalog
yes I have 30lbs fuel pressure with vacuum line connected. I have no fuel in vacuum line. i have no mods stock tb and mass air flow. i have a impala intake elbow with the filter about 12 in in front of the maf. I disconnected the maf and drive it again here is the datalog. I would thank everyone for their time I
appreciate the help.
http://www.mediafire.com/download/cr...lt/2-13-14.uni
appreciate the help.
http://www.mediafire.com/download/cr...lt/2-13-14.uni
02-13-2014, 06:12 PM
#10
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Re: can someone please look at my datalog
The engine is from a 96 trans am the pcm is a 95, 16188051 bmfn. i found 2 numbers on the injectors 01d056b and 3239. the sticker is off the maf. i flashed the pcm to 94 with lt1 edit i got the stock tune from them.
02-14-2014, 09:36 AM
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Re: can someone please look at my datalog
Totally different results without the MAF sensor. LTFT's are now positive, adding fuel. In Cell 16 they are 131/128 by the end of the log. Cell 7 is 133/132.
You either have the wrong MAF sensor, or it is defective. Next you have to figure out why your fuel pressure is low. When you go into power enrichment mode (PE), the O2 readings look a bit low compared to typical stock tune, running mid 800's. Not all that bad, but may account for the knock/knock retard you are getting.
At idle, remove the vacuum compensation line from the fuel pressure regulator. Hold you finger over the end of the line to prevent a vacuum link. Fuel pressure should be 43.5psi. GM specifications accept anything in the range of 41 - 47psi.
Reattach the vacuum line. Fuel pressure should drop proportional to intake manifold vacuum. For a stock cam, the fuel pressure will typically drop about 8psi from the "no vacuum" reading.
Tape the gauge to the outside of the windshield. Take it out on the highway, full throttle, at least 5,000 RPM. Fuel pressure should not drop below 40psi.
You indicate you "got the stock tune from them." Who is "them"?
You either have the wrong MAF sensor, or it is defective. Next you have to figure out why your fuel pressure is low. When you go into power enrichment mode (PE), the O2 readings look a bit low compared to typical stock tune, running mid 800's. Not all that bad, but may account for the knock/knock retard you are getting.
At idle, remove the vacuum compensation line from the fuel pressure regulator. Hold you finger over the end of the line to prevent a vacuum link. Fuel pressure should be 43.5psi. GM specifications accept anything in the range of 41 - 47psi.
Reattach the vacuum line. Fuel pressure should drop proportional to intake manifold vacuum. For a stock cam, the fuel pressure will typically drop about 8psi from the "no vacuum" reading.
Tape the gauge to the outside of the windshield. Take it out on the highway, full throttle, at least 5,000 RPM. Fuel pressure should not drop below 40psi.
You indicate you "got the stock tune from them." Who is "them"?
05-26-2014, 11:02 PM
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Re: can someone please look at my datalog
I.m sorry it took me so long to respond back. Busy working. One day i read lt1howto.com the article about pcm tuning for dummies. One part of the article talks about the constant 12v for the pcm and ignition 12v i thought about it and decided to check. My lt1 was already in my s10 when i bought it with a stand alone harness. i went threw the harness and found the orange power wire for the pcm was connected to a ignition 12v source causing the pcm to relearn every start up. It runs better not running rich and shifting good. Thanks for all the help you guys are great.
05-27-2014, 11:41 AM
#15
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Re: can someone please look at my datalog
Do you still have large negative LTFT's? Your solution explains why the LTFT's reset to 128 on each startup, and it was hard to start. But it doesn't explain why the LTFT's were so far off to begin with.