bronc3buster842001
1/2 ton status
Only codes are for the auto tranny and egr. Egr dont make a difference. tried both ways. Data from first post is running down the hiway.
CK5
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96 k1500 falls on its face(Fixed)
- Thread starter bronc3buster842001
- Start date
Was 55 psi fuel pressure under load?
Can you get oxygen sensor voltage readings when going down the road?
Sorry for the milliion questions, just a hard problem to solve via internet.
Can you get oxygen sensor voltage readings when going down the road?
Sorry for the milliion questions, just a hard problem to solve via internet.
bronc3buster842001
1/2 ton status
Fuel pressure was checked with key on, engine off. Will have to borrow the scanner again and find someone to drive so I can watch the data.
I just dont see how fuel pressure would make it run rich.
I just dont see how fuel pressure would make it run rich.
That's the thing I don't think it is. There is no way a scanner can acurately say the A/F is 12:1; the stock narrow band sensors don't read accurate below 14:1. The computer might be commanding 12:1, but anything can mess up the actual A/F. Your symptoms say lean, so that is what I want to confirm/rule out before you spend any more time or money, especially as often as I see weak fuel pumps. The vortec CPI is very sensitive to fuel pressure, they usuallly won't run when the fuel pressure gets below 58 psi.
If you have a fuel pressure gauge reconnect it and go for a drive. It should go from 55 psi at idle to at least 58-60 under WOT and not drop at all, again they will not run below 58 psi WOT.
If you have a fuel pressure gauge reconnect it and go for a drive. It should go from 55 psi at idle to at least 58-60 under WOT and not drop at all, again they will not run below 58 psi WOT.
bronc3buster842001
1/2 ton status
Will try that. Just have to find a way to to mount a gauge so i can see it while driving.
dave w
1/2 ton status
If I was to guess, I'd say the PCM was incorrectly commanded to Power Enrichment (PE) mode? I don't have the program file for the vehicle posted, but I posted a screen shot showing the RPM graph for PE mode for an Express Van L31 Vortec. Most PE modes are set for 12.5% AFR.
dave w
dave w
bronc3buster842001
1/2 ton status
So how does one fix this. Ive changed the ecm out and the same thing.
dave w
1/2 ton status
I need to study the PCM program of the vehicle to understand what "sets" PE mode. Some PE modes are RPM, some PE modes are TPS % and yet other PE modes use CTS, TPS, and RPM.
I don't think the computer is the problem, but I think the PCM is getting an input from something (sensor maybe) to run PE Mode.
The data log is a clue, the RPM's, TPS, and CTS are close to PE Mode set points?
dave w
I don't think the computer is the problem, but I think the PCM is getting an input from something (sensor maybe) to run PE Mode.
The data log is a clue, the RPM's, TPS, and CTS are close to PE Mode set points?
dave w
bronc3buster842001
1/2 ton status
So will I be hurting anything by still driving it. This is my only vehicle.
Will borrow the scanner again and try to get some more data.
Will borrow the scanner again and try to get some more data.
dave w
1/2 ton status
I don't have a good answer if it will hurt anything or not. More data log information will help.
dave w
bronc3buster842001
1/2 ton status
prob. be a few days before I can get the scanner again, as I have to borrow one. But I will post back when I have some new info.
bronc3buster842001
1/2 ton status
Ok I double checked the fuel pressure. It had 50 with the key on, engine off. went up to about 55 when i reved it up and then slowly fell back to 50. Looks like Ill start by changing the fuel pump. Prob needs one as the truck has almost 200k on it. Next step will be the upgrade for the injectors.
bronc3buster842001
1/2 ton status
Also double checked my codes and got 2 for both 02 sensors reading low voltage.
bronc3buster842001
1/2 ton status
Ok got the scanner last night to get more data. Had a few things to do today. Well now the truck decides it wants to run like it should. So I got the scanner and pulled some more data. Will get it posted later this evening.
Thunder
3/4 ton status
When is the last time you changed the fuel filter? O2 sensor showing low voltage means its running lean. IMO fuel delivery problem. Clogged Filter, weak pump, crack/hole in the fuel line somewhere.
still should check the rubber lines in the tank at the pump and pickup tube for cracks. seen it a few times, twice in this type of truck. 2-3 hours could save a lot of hassle n cash. what have you got to loose at this point.
bronc3buster842001
1/2 ton status
I changed the filter a few months ago. Will pull the bed 1 day and check the pump.
You should see what the fuel pressure is under load. Romp on it while going down the road and see what happens
bronc3buster842001
1/2 ton status
Was going to go to town earlier, and truck ran like ****. Then the check engine light started to flash. Any clue as to what that means.
dave w
1/2 ton status
I would like to help. It's not easy to help over a keyboard.
The way I know how to help, with a vehicle that is not in my shop is with data logs. The data logs I get the most useful information from are from WinALDL or DataMaster TTS. Data logs show several minutes of recorded sensor input going to the computer. Data logs help figure out what sensor has failed. Data logs might help figure out if maybe the EGR is stuck open, or maybe the fuel pump pressure is low.
Data logs do not help figure out engine problems, like a vacuum leak, bent or broken push rod, worn down camshaft lobe, or any other mechanical problem. Data logs are useful tools for an engine in good mechanical condition.The pics below are screen shots from DataMaster TTS data logs. WinALDL is not as nice as DataMaster, but similar. When a technician can't be with the vehicle to help troubleshoot, a data log is really the only option to help over a keyboard.
dave w
