I have it set to start logging when connected. What sensors should I tell it to log.
I can't see the image due to an issue with PayPal it seems. I sent a question in to see what is going on with that since it was deducted from my account.
CK5
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No acceleration to pass (LY6)
- Thread starter jdot2004
- Start date
I have it set to start logging when connected. What sensors should I tell it to log.
I can't see the image due to an issue with PayPal it seems. I sent a question in to see what is going on with that since it was deducted from my account.
Look at MAF, MAP (might be called boost or vacuum), LTFT, STFT, throttle position and pedal position. For logging be sure to include vehicle speed and RPM. You might find you're missing vehicle speed or its incorrect, as this can cause a lot of deiveability issues. I think there are cam sensors as well as crank sensors and strange issues can arise if the cam signal is gone or programmed wrong.
Did the engine, trans and PCM all come from the same donor? You might be missing some vehicle signals that have to be programmed out. But scanning the stuff already mentioned should make it clear if you have a bum sensor, low fuel flow or something basic.
Did the engine, trans and PCM all come from the same donor? You might be missing some vehicle signals that have to be programmed out. But scanning the stuff already mentioned should make it clear if you have a bum sensor, low fuel flow or something basic.
Due to issues along the way, the engine (08 2500hd), trans (4l70e from monster) and CPUs (both from psi conversion) are not from the same donor. When I spoke with psi they said it shouldn't be from the different trans.
Gonna take a ride now and see if I can log anything.
Now that my account is sorted out I can see the dash image you posted. I set up my dash with those items and added a couple to log. I have sent myself 3 data logs, from idle and gave it a little throttle to make sure it was working. where can I get information on what kind of numbers I should be looking at?
For fuel trims, you want close to zero. Anything more than 10 is worth looking into. O2 readings should constantly bounce between 0-1V. Throttle should go something like 18 to 86. Apply common sense, as MAF and MAP should change according to changing throttle. Anything stuck at zero is a bad signal (or not available to the tool).
I've had a chance to look it over and, while I do not have the best idea of what I am looking at, I think I am understanding a little...maybe! I cleared all my existing logs and I am going to take it for a ride again.
Here's what I have seen so far:
Long term fuel trim bank 1 ranges from -1.56 to -12.5. For the most part it levels out around a -6 and keep even with bank 2.
Short term fuel trim bank 1 ranges from -3.9 to a +5.4
Long term fuel trim bank 2 ranges from -.78 to -10.15
O2 stayed between 0 and 1
Throttle stayed between 18 and 86
As rpm goes up Intake manifold pressure comes down and MAF goes up. Intake manifold pressure at idle is 4.6 and maf at 60.5. at 1500rpm 3.48 and 118.23.
@Blue85 You say apply common sense but this is like calculus all over again for me. It seems legit that as RPM goes up the manifold pressure should come down since the throttle is opening and the MAF should go up since air is being drawn past more rapidly. Is this right?
Other then a couple of spikes in fuel trim it stayed with in a 10. they just happened to be negative numbers. does this matter?
Here's what I have seen so far:
Long term fuel trim bank 1 ranges from -1.56 to -12.5. For the most part it levels out around a -6 and keep even with bank 2.
Short term fuel trim bank 1 ranges from -3.9 to a +5.4
Long term fuel trim bank 2 ranges from -.78 to -10.15
O2 stayed between 0 and 1
Throttle stayed between 18 and 86
As rpm goes up Intake manifold pressure comes down and MAF goes up. Intake manifold pressure at idle is 4.6 and maf at 60.5. at 1500rpm 3.48 and 118.23.
@Blue85 You say apply common sense but this is like calculus all over again for me. It seems legit that as RPM goes up the manifold pressure should come down since the throttle is opening and the MAF should go up since air is being drawn past more rapidly. Is this right?
Other then a couple of spikes in fuel trim it stayed with in a 10. they just happened to be negative numbers. does this matter?
A negative fuel trim means that the ECM has been reducing fuel needed (from the baseline table) for the O2 sensor to read stoich under that operating condition. A positive trim is the opposite. STFT is what the ECU is doing right now to get the O2 reading where it should be. LTFT is adjusted as the lean or rich condition is going on for a long time. In a sense, the ECU is self-tuning.
The O2 should always be jumping up and down rapidly under normal conditions. When the engine is started cold they won't respond at first.
If you have a fuel delivery problem it will show up as positive trims as RPM/load increase. If you can tape a fuel pressure gauge to the windshield while driving, this question can be answered.
The O2 should always be jumping up and down rapidly under normal conditions. When the engine is started cold they won't respond at first.
If you have a fuel delivery problem it will show up as positive trims as RPM/load increase. If you can tape a fuel pressure gauge to the windshield while driving, this question can be answered.
Is the Fuel pressure provided by the obd reader not a good measure of fuel pressure?
Honestly I'm not aware of the sensor, as none of my vehicles are very new. If it's there and varying a little around a reasonable pressure, that's probably OK. I'm used to people posting pressures they measured in the driveway, which is best case scenario. Real issues show up at WOT and high RPM.
the last trip I took did not show any fuel pressure on the graph so I will try taping a gauge to the windshield this week. What should I be watching for it to do? I have only tried in my driveway and it stayed at about 58-60 and didn't change when I gave it gas.
Fuel pressure will not fluctuate with engine speed. You just need to see that the needle is steady within the spec range of 55-62psi. Revving in the driveway isn't quite the same as the load of the truck moving down the road.
If you do have a fuel delivery issue what you would see is a drop of pressure under load while driving. As pressure drops below 55psi the engine would be running worse, stumbling or missing. Also you'd have fuel trims and o2 sensor values trending lean because the engine isn't getting the fuel it's trying to maintain. If it was low enough for a long enough of time it would also set codes for the o2 sensors and fuel trim. I'd still run it with the fuel pressure gauge on to rule that out but you'd have the data from the o2's and fuel trim values.
I do have the data from my last couple trips if anyone is willing to review them for me. Right now I'm just trying to color coordinate the spreadsheet based on throttle position to see what the fuel trims and O2 do at a higher throttle. Based off info previously given to me in this thread, something isn't right but I don't know what, based off the data, or where to start to correct it.
Also, I am still not getting any codes. So, I want to think that would mean my sensors are good, coils and injectors are good and that the fuel pump would be the only other thing it could be but don't want to waste the money if I'm wrong...
Did you take a ride watching fuel pressure gauge while driving? Still curious what the pressure is doing when it falls on it's face.
I still have not rented the Gage to check the pressure I'm driving. But I was going over the engine and see moisture near the one fuel injector so I decided to pull them out. So far I have pulled the injectors out of the 3 and 5 cylinder and they've both had this Gunk inside. Any idea what it is?
I put in a new fuel pump, cleaned and tested the injectors for leaks and it seems to get up and go now. Fuel pressure maintained at 58psi. It's gonna take some getting used to for the rear ratio and louder exhaust.
The crap in the injectors is from lack of a fuel filter. One of Gm's brighter ideas. The crud doesn't seem to bother them much, our service trucks at work usually get 250-300k before needing injectors, and that's using crappy fuel.
I would put a filter somewhere. Using a screen only at the pickup scares me.
