Engine woes or fueling issues?
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Joined: Jun 2021
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From: Shlumpt, TX
Engine woes or fueling issues? The other day I went to turn on my truck and it gave me a loooong crank. Let off the key and cranked it and it fired right up. Extremely choppy and low RPM. Walked away for a second and it starts revving up on its own and then steadies out. I get in it and try to drive and it is sputtering, puttering and not moving forward just about. Parked it and saw white smoke coming out of the tail pipe, not a lot but just a little wisp of it. I am assuming that was unburnt fuel as it does not really smell like oil.
No codes, no oil leaks, oil pressure is good, not overheating, coolant looks good, oil is beautiful.
Check fuel pressure and my fuel pressure when priming the pump was low, 50 PSI and it would drop slightly to about 47 or so. Figured since that isn't in GM spec maybe the pump is going bad and it just quit on me. I did check the regulator and it seems to be working properly, no gas coming out of it and when you unplug the vacuum line, pressure shoots up.
So I replaced the pump. Pressure is now at 55 key on engine off, drops down to 50 near immediatly which I have read is normal(?) it did not do a 5 psi drop with the old pump though so I am thinking this is in spec and correct since now that it is over 50 the regulator is telling it to bleed off a little since it is not cranking. Fuel pressure when running is about 48-50.
So here is what I have right now:
Here are the checks I have done after the fuel pump replacement:
I am at a loss at this point. Tomorrow I will spend time trying to get my AFR gauge to work properly. I think I am going to switch the fuse tap that it is on and put it somewhere else. It won't turn on every single time and when I connect the laptop it kicks the channel off of HPTuners. I will try my old way of actually installing it though and see if that works. I may be able to borrow a scan tool.
Any ideas? MAF is kind of what I am thinking next, perhaps get a log and see what the MAF voltage is? IDK pls help me
No codes, no oil leaks, oil pressure is good, not overheating, coolant looks good, oil is beautiful.
Check fuel pressure and my fuel pressure when priming the pump was low, 50 PSI and it would drop slightly to about 47 or so. Figured since that isn't in GM spec maybe the pump is going bad and it just quit on me. I did check the regulator and it seems to be working properly, no gas coming out of it and when you unplug the vacuum line, pressure shoots up.
So I replaced the pump. Pressure is now at 55 key on engine off, drops down to 50 near immediatly which I have read is normal(?) it did not do a 5 psi drop with the old pump though so I am thinking this is in spec and correct since now that it is over 50 the regulator is telling it to bleed off a little since it is not cranking. Fuel pressure when running is about 48-50.
So here is what I have right now:
- Truck still will not crank over the first turn of the key. It will the second time though.
- Truck seems to be running rich, I can smell it and there is white smoke coming out of the exhaust
- No codes
- There is more smoke than the other day
Here are the checks I have done after the fuel pump replacement:
- The fuel pressure regulator seems to be working. When I unplug it no gas comes out and the pressure on my gauge goes up. I do not believe it to be the regulator unless someone else has a different test
- I pulled apart my intake and air box and it seems to be clean. Filter is clean and the air box unobstructed.
I am at a loss at this point. Tomorrow I will spend time trying to get my AFR gauge to work properly. I think I am going to switch the fuse tap that it is on and put it somewhere else. It won't turn on every single time and when I connect the laptop it kicks the channel off of HPTuners. I will try my old way of actually installing it though and see if that works. I may be able to borrow a scan tool.
Any ideas? MAF is kind of what I am thinking next, perhaps get a log and see what the MAF voltage is? IDK pls help me
Thread Starter
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Joined: Jun 2021
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From: Shlumpt, TX
Nice and wet. Personally they smell somewhat like a mix of oil and gas. I don't know, my nose I guess may not be calibrated.
This kind of leads me back to thinking pressure regulator again. Also I had the pressure gauge hooked up for about an hour and it only dropped down to about 40 PSI in that time.
Thread Starter
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From: Shlumpt, TX
Bueller.... Bueller...?
Okay attached here you will find a video of my smoky exhaust and a log of it starting up and idling. Whenever you see the throttle increasing that is the truck doing that on it's own and not me. I don't touch anything during this time except my phone to record the video I took.
MAF looks okay to me for being at idle. I can try a pressure regulator but I am unsure if that would fix it. Still have to go to the parts store at some point so I can pick up and try a regulator.
This is the only log I am taking tonight, the truck revs a little too high for my neighbors. Wish the Impala wasn't taking my shop space right now.
Sorry for my retarded video, just trying to give as much information as possible.
Okay attached here you will find a video of my smoky exhaust and a log of it starting up and idling. Whenever you see the throttle increasing that is the truck doing that on it's own and not me. I don't touch anything during this time except my phone to record the video I took.
MAF looks okay to me for being at idle. I can try a pressure regulator but I am unsure if that would fix it. Still have to go to the parts store at some point so I can pick up and try a regulator.
This is the only log I am taking tonight, the truck revs a little too high for my neighbors. Wish the Impala wasn't taking my shop space right now.
Sorry for my retarded video, just trying to give as much information as possible.
Thread Starter
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From: Shlumpt, TX
TPS voltage or throttle percentage? Voltage is .55. Throttle Percentage (SAE) shows like .4%. I don't know what the SAE means, not really sure what this is.
Stuck throttle body?
Stuck throttle body?
Thread Starter
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From: Shlumpt, TX
Spending some time thinking today perhaps a dangerous game,
The last thing I did before the truck quit running was fill the tank back up. I had a little over a quarter tank iirc. What are the chances I just got some dog **** water or alcohol polluted gas? I mean thinking about it that may explain the long crank and the smoke coming out of the tail pipe? I am not sure but I need the truck back to running at some point lol I was thinking about trying out some stabilizer or buying one of those gasoline alcohol content vials to just check. Maybe if there is one with water level? I don't know.
Tomorrow I was thinking about driving it the 30 miles or whatever until it decides to throw a code out at me.
Edit: Small update, bought an smoke machine. Going to smoke the intake and if there are any leaks.
The last thing I did before the truck quit running was fill the tank back up. I had a little over a quarter tank iirc. What are the chances I just got some dog **** water or alcohol polluted gas? I mean thinking about it that may explain the long crank and the smoke coming out of the tail pipe? I am not sure but I need the truck back to running at some point lol I was thinking about trying out some stabilizer or buying one of those gasoline alcohol content vials to just check. Maybe if there is one with water level? I don't know.
Tomorrow I was thinking about driving it the 30 miles or whatever until it decides to throw a code out at me.
Edit: Small update, bought an smoke machine. Going to smoke the intake and if there are any leaks.
Last edited by shakenfake; Sep 5, 2022 at 08:50 PM.
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Verdad Gallardo Thread Starter
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Joined: Jun 2021
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From: Shlumpt, TX
In my log I took a map reading but I think I took the sensor voltage so it’s incorrect. Might take another one
What is KOEO?
Engine runs at idle after you let it warm up a couple minutes. It will surge and almost stall until finally coming to life and then idles. It stinks and smokes.
What is KOEO?
Engine runs at idle after you let it warm up a couple minutes. It will surge and almost stall until finally coming to life and then idles. It stinks and smokes.
Thread Starter
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Joined: Jun 2021
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From: Shlumpt, TX
Ah so you are looking for MAP readings at KOEO and engine running at idle correct?
Whenever I tried to select MAP as a channel on HPTuners I was unable to, only got that voltage one. I can try again with my scan tool.
Whenever I tried to select MAP as a channel on HPTuners I was unable to, only got that voltage one. I can try again with my scan tool.
Thread Starter
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From: Shlumpt, TX
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From: Woodstock, GA
Try doing a "repoll for supported parameters" in the VCM scanner app. See if it loads your channel.
Thread Starter
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From: Shlumpt, TX
For fun here is one with the MAF unplugged. Still had a hard start, took two cranks, and some smoke coming out but not a lot. About 3 minutes and 30 seconds into the file, 7:33:50, I plug the MAF back in and you can see the change, I don't really think it is the MAF based on this information. Truck changed idle slightly but nothing drastic and no more smoke than with the MAF unplugged. If someone sees something I do not please let me know but I think it is safe to cross out the MAF in this scenario. Still dumping fuel like a mother though.
EDIT VERY IMPORTANT: Actually something I noticed that it did not do was dip down in idle and stall and surge like it was doing. I forgot this when I was typing, does that mean it is in fact the MAF sensor? Still seems to be dumping fuel but why won't the truck start first crank? Unsure.
Thoughts peanut gallery? I'm back to thinking maybe I need to just drive real rich until it decides it wants to give me a code lol
EDIT VERY IMPORTANT: Actually something I noticed that it did not do was dip down in idle and stall and surge like it was doing. I forgot this when I was typing, does that mean it is in fact the MAF sensor? Still seems to be dumping fuel but why won't the truck start first crank? Unsure.
Thoughts peanut gallery? I'm back to thinking maybe I need to just drive real rich until it decides it wants to give me a code lol
Last edited by shakenfake; Sep 7, 2022 at 07:58 PM.
[QUOTE=shakenfake;20455637] Still had a hard start, took two cranks [/QUOTE]
My .02 until others reply...
Two cranks sometimes indicates bad cam sensor, as the computer tries its backup strategy of guessing which half of the 720 its in on second try. But that doesn't explain the rich fuel and the rest, unless the missing cam signal is an indicator that the PCM is missing a ground or something that's causing other inputs/outputs problems.
Your MAF at KOEO sounds correct to me.
You mentioned accidentally filling with E85, I believe you'd have a lean condition not a rich one if my thinking is right. E85 requires 30% more compared to pump.
Are you running Closed Loop mode? I can't look at your log from this machine but you probably should be checking to see if your trims are high or not, or even working. See if your O2 sensors are switching up and down, and if not find out why your PCM doens't have control over the fuel. I think -25% LTFT should have thrown a code.
If you get any hint at all that this might be a stuck open injector, you probably shouldn't run it to avoid hydrolock. Your balance test shows that's not it though.
My .02 until others reply...
Two cranks sometimes indicates bad cam sensor, as the computer tries its backup strategy of guessing which half of the 720 its in on second try. But that doesn't explain the rich fuel and the rest, unless the missing cam signal is an indicator that the PCM is missing a ground or something that's causing other inputs/outputs problems.
Your MAF at KOEO sounds correct to me.
You mentioned accidentally filling with E85, I believe you'd have a lean condition not a rich one if my thinking is right. E85 requires 30% more compared to pump.
Are you running Closed Loop mode? I can't look at your log from this machine but you probably should be checking to see if your trims are high or not, or even working. See if your O2 sensors are switching up and down, and if not find out why your PCM doens't have control over the fuel. I think -25% LTFT should have thrown a code.
If you get any hint at all that this might be a stuck open injector, you probably shouldn't run it to avoid hydrolock. Your balance test shows that's not it though.
Last edited by mk3cn4; Sep 8, 2022 at 03:14 PM.
Thread Starter
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From: Shlumpt, TX
You are the third person to mention the cam sensor lol
I did not accidentally fill with E85. I'm running 93 octane. I said that I thought I might have some bad gas because this all started right after I put a fresh tank in it.
LTFT seems to be stuck on 0 forever but I've never even seen LTFT move when this truck was stock.
I am passed the injectors unless they all suck. They all tested the same on my injector balance test I did.
My plan tonight is to pull the IAC out and see if it is gummed up or otherwise stuck. I meant to do that over the weekend and did not.
I did not accidentally fill with E85. I'm running 93 octane. I said that I thought I might have some bad gas because this all started right after I put a fresh tank in it.
LTFT seems to be stuck on 0 forever but I've never even seen LTFT move when this truck was stock.
I am passed the injectors unless they all suck. They all tested the same on my injector balance test I did.
My plan tonight is to pull the IAC out and see if it is gummed up or otherwise stuck. I meant to do that over the weekend and did not.
All that black smoke and wet plugs I agree wayy too much fuel. My take on having too much fuel: You've already demonstrated the injectors aren't stuck open and your MAF and MAP are reporting the right amount of air, so this fuel should be controllable by the computer either way if in CL mode or by a properly tuned VE table if OL mode. Idle Air Controller I guess could cause air problems, but to this degree? Maybe check O2 sensors and see if they are pegged high, if so your trims should be pulling it down. Without seeing the tune it's hard to tell if CL is enabled at idle, with a cam may not be... or even if your Misfire checking is disabled etc. Check your tune and make sure your tuner didn't disable all the CEL reporting. Can't imagine not getting any codes in this situation unless it was a stripped down flat racing type of tune, but those usually are SD and don't use MAF.
Edit: is this just an idling problem or does it go away when you drive? You mentioned "I get in it and try to drive and it is sputtering, puttering and not moving forward just about" so I am assuming happening all the time. If so probably not your IAC.
Last edited by mk3cn4; Sep 8, 2022 at 04:31 PM.
Thread Starter
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From: Shlumpt, TX
I did not tune it I used mailordertuner from Casey. I seem to be running in open loop and then going into closed loop like normal. Tune is attached. I have been running this specific tune for almost a year now and have been running the base tune for about 2. I would be very surprised if it was my tune.
O2 sensors seem to be going up and down like normal. CELs seem to be only turned off what is normal for a truck that lost weight and was swapped.
O2 sensors seem to be going up and down like normal. CELs seem to be only turned off what is normal for a truck that lost weight and was swapped.
