BoostedSUV
Active member
Please refer to this updated/condensed thread: http://www.syty.net/forums/showthread.php?p=762788#post762788
Thanks guys!!!
Thanks guys!!!
Last edited:
One last shot... Breaking up!
- Thread starter BoostedSUV
- Start date
BoostedSUV
Active member
Re: One last shot... Breaking up!
Another thing I forgot to mention... the truck will not do this in OPEN LOOP it only starts doing it in CLOSED LOOP and the warmer the engine temps get the worse it breaks up.
This truck used to have this issue years back where it would go LEAN and break up before I began tuning it with Nolan. We were able to "tune it out" where it would stop breaking up at these very same RPM's and now it's back doing it again and the same spots.
Another thing I forgot to mention... the truck will not do this in OPEN LOOP it only starts doing it in CLOSED LOOP and the warmer the engine temps get the worse it breaks up.
This truck used to have this issue years back where it would go LEAN and break up before I began tuning it with Nolan. We were able to "tune it out" where it would stop breaking up at these very same RPM's and now it's back doing it again and the same spots.
BoostedSUV
Active member
Re: One last shot... Breaking up!
If someone can tell me where to host DM files I will put them up for the GURUs to look at...
If someone can tell me where to host DM files I will put them up for the GURUs to look at...
turbodig
Active member
Re: One last shot... Breaking up!
Ignition system isn't causing a lean-out... fuel system is. This is verified by both your stock o2 and wideband.
There are only so many fuel system parts- Fuel pump, injectors, FPR. Voltage to these, and the control system. Assuming you're watching FP on the gauge at the time this happens, that'd rule out fuel delivery.
Pull the o2 sensor connector- what does it do? Pull the o2 wire to the ECM, what does it do?
Your symptoms are consistent with a dead/dying fuel pump, but if you have pressure that doesn't droop, that's not the case. Wiring would be the top suspect from there.
Ignition system isn't causing a lean-out... fuel system is. This is verified by both your stock o2 and wideband.
There are only so many fuel system parts- Fuel pump, injectors, FPR. Voltage to these, and the control system. Assuming you're watching FP on the gauge at the time this happens, that'd rule out fuel delivery.
Pull the o2 sensor connector- what does it do? Pull the o2 wire to the ECM, what does it do?
Your symptoms are consistent with a dead/dying fuel pump, but if you have pressure that doesn't droop, that's not the case. Wiring would be the top suspect from there.
Windedv6
Ty n 10s
Re: One last shot... Breaking up!
Check the wire that the air/fuel gauge was spiced into. They are usually spliced into the wire that signals the computer from the o2 sensor. It's been along time (10 years) since I had a stock computer, but if I recall correctly it was an orange wire. I had seen where people just used a cheap scotch lock to splice into it for the air/fuel gauge. Scotch locks can cut the wire and when you remove them it can cause a cut wire inside the insulation jacket and you don't know it.
John
Check the wire that the air/fuel gauge was spiced into. They are usually spliced into the wire that signals the computer from the o2 sensor. It's been along time (10 years) since I had a stock computer, but if I recall correctly it was an orange wire. I had seen where people just used a cheap scotch lock to splice into it for the air/fuel gauge. Scotch locks can cut the wire and when you remove them it can cause a cut wire inside the insulation jacket and you don't know it.
John
Try Me
New member
Re: One last shot... Breaking up!
Dont assume on plugs, replace them all. Ive had spark plugs "go bad" before like flipping a switch. Usually causes a misfire and would make the mixture rich not lean but its easier than parting out the truck.
Fuel Filter? Fuel Pump?
Find a shop to clean and flow-check the injectors?
A Broken valve spring could even cause that. It may not even show under a compression test, but once you get some rpm up a valve could be hanging open slightly.
You said the map sensor and tps are reading normal?
Engine to firewall and Engine to frame grounds good and clean?
Just throwing ideas out there.
Dont assume on plugs, replace them all. Ive had spark plugs "go bad" before like flipping a switch. Usually causes a misfire and would make the mixture rich not lean but its easier than parting out the truck.
Fuel Filter? Fuel Pump?
Find a shop to clean and flow-check the injectors?
A Broken valve spring could even cause that. It may not even show under a compression test, but once you get some rpm up a valve could be hanging open slightly.
You said the map sensor and tps are reading normal?
Engine to firewall and Engine to frame grounds good and clean?
Just throwing ideas out there.
autoaddictions
Active member
Re: One last shot... Breaking up!
Do you have any thing hooked up to the tpms sensor. Meth ect. I had the same problem at the hooters meet 2 years ago. truck ran like shit no power couldnt rev engine cleanly. turned out to be a bad razor alky kit. I cut the tpms wire free and it ran perfect.
Do you have any thing hooked up to the tpms sensor. Meth ect. I had the same problem at the hooters meet 2 years ago. truck ran like shit no power couldnt rev engine cleanly. turned out to be a bad razor alky kit. I cut the tpms wire free and it ran perfect.
BoostedSUV
Active member
Re: One last shot... Breaking up!
Dig, Nolan suggested an Ignition missfire causing a lean symptom or false lean reading. I agree with you, since the wideband is a stand alone unit and shows lean as well it's not a false reasing.
FP does rise with boost and fall with vacuum as normal. I watched the gauge at all rpm levels and it does not drop at all, it is consistant with boost/vacuum. So I agree it's not fuel delivery..
I will try unplugging the O2 sensor and see what happens as well as checking the purple signal wire that used for the A/F guage I took out. It appeared to be good but I will look closer.
Dig, Nolan suggested an Ignition missfire causing a lean symptom or false lean reading. I agree with you, since the wideband is a stand alone unit and shows lean as well it's not a false reasing.
FP does rise with boost and fall with vacuum as normal. I watched the gauge at all rpm levels and it does not drop at all, it is consistant with boost/vacuum. So I agree it's not fuel delivery..
I will try unplugging the O2 sensor and see what happens as well as checking the purple signal wire that used for the A/F guage I took out. It appeared to be good but I will look closer.
BoostedSUV
Active member
Re: One last shot... Breaking up!
Filter is newer, pump is a walbro and Fuel Pressure looks good throughout the rpm range. I also went over all the grounds under the hood for a previous issue and I did not find anything loose or broken. It's possible I could have missed one but they all looked good.
Filter is newer, pump is a walbro and Fuel Pressure looks good throughout the rpm range. I also went over all the grounds under the hood for a previous issue and I did not find anything loose or broken. It's possible I could have missed one but they all looked good.
BoostedSUV
Active member
Re: One last shot... Breaking up!
I do have a meth kit but it's a simple SMC kit that just reads boost off of a vacuum line to trigger it. I don't have anything hooked up to any sensors at this time, only had an A/F gauge hooked to o2 signal wire and that is no longer there... It's something stupid and I'm missing it. I've been chasing it for weeks now and can't drive the truck so it's getting frustrating.
I do have a meth kit but it's a simple SMC kit that just reads boost off of a vacuum line to trigger it. I don't have anything hooked up to any sensors at this time, only had an A/F gauge hooked to o2 signal wire and that is no longer there... It's something stupid and I'm missing it. I've been chasing it for weeks now and can't drive the truck so it's getting frustrating.
BoostedSUV
Active member
Re: One last shot... Breaking up!
I going try running it with out the O2 tonight as you and Dig have suggested and see what that does. I know it's something stupid but I've run out of ideas so this is what I need... A little more advice from the experts. Oh and Dave, there's no MSD box in the truck yet but I have one become an issue in my racecar and we chased everything around before realizing it was a $700 ign box gone bad! My truck just has MSD plug an play dist, coil, and wires...
I going try running it with out the O2 tonight as you and Dig have suggested and see what that does. I know it's something stupid but I've run out of ideas so this is what I need... A little more advice from the experts. Oh and Dave, there's no MSD box in the truck yet but I have one become an issue in my racecar and we chased everything around before realizing it was a $700 ign box gone bad! My truck just has MSD plug an play dist, coil, and wires...
![Quickstop [UK]](/forums/data/avatars/m/5/5165.jpg?1570199786){kind=avatar}
Quickstop [UK]
Combating adversyty.
Re: One last shot... Breaking up!
you're not running it with your ALDL jumpered and by starting it in ALDL mode you did something to the ECM?
you're not running it with your ALDL jumpered and by starting it in ALDL mode you did something to the ECM?
BoostedSUV
Active member
Re: One last shot... Breaking up!
I
I don't have anything jumpered on the ALDL, just have the ALDL cable plugged into my laptop. I suspected I may have somehow did something to theECM so I went to GM and bought a Reman one I have the same issue. The truck doesn't seem to idle as well with the new ECM but other than that it made no change by putting a new one in.
I
Re: One last shot... Breaking up!
Could you have disturbed some "crap" in the fuel lines when changing/attaching the FP sending unit?!? Perhaps something got into one of the injectors and clogged it up?!?! Just a thought.
Good ground and power to the pump? While I don't think it's the case, I have seen harmonics/vibrations play a role in the power to the fuel pump before. A certain RPM generates a certain vibration that messes with an already loose connection. Can you phyiscally "shake" the harness while it's running and see if you can recreate the condition. That's usually worked for me as a decent test for intermittent wiring shorts.
Could you have disturbed some "crap" in the fuel lines when changing/attaching the FP sending unit?!? Perhaps something got into one of the injectors and clogged it up?!?! Just a thought.
Good ground and power to the pump? While I don't think it's the case, I have seen harmonics/vibrations play a role in the power to the fuel pump before. A certain RPM generates a certain vibration that messes with an already loose connection. Can you phyiscally "shake" the harness while it's running and see if you can recreate the condition. That's usually worked for me as a decent test for intermittent wiring shorts.
BoostedSUV
Active member
Re: One last shot... Breaking up!
I litteraly just removed my mech. FP gauge and screwed in the sender for the elec gauge. I didn't really move much to disturb anything on the rail but anything is possible at this point. I also just put in a racetronix wire kit about 6 mos ago so I'm not thinking voltage to the pump or ground to the pump itself is an issue. Maybe an issue to injectors or elsewhere in the fuel system but I wouldn't suspect the pump.
I litteraly just removed my mech. FP gauge and screwed in the sender for the elec gauge. I didn't really move much to disturb anything on the rail but anything is possible at this point. I also just put in a racetronix wire kit about 6 mos ago so I'm not thinking voltage to the pump or ground to the pump itself is an issue. Maybe an issue to injectors or elsewhere in the fuel system but I wouldn't suspect the pump.
WyoSyclone
Active member
Re: One last shot... Breaking up!
This might be a stupid question, but is there any way the sender for the electric FP gauge could be protruding into the fuel rail/line and restricting fuel flow??
I just looked at my Autometer sender and it couldn't do that, but I thought I'd ask anyway.
This might be a stupid question, but is there any way the sender for the electric FP gauge could be protruding into the fuel rail/line and restricting fuel flow??
I just looked at my Autometer sender and it couldn't do that, but I thought I'd ask anyway.
BoostedSUV
Active member
Re: One last shot... Breaking up!
no, I have an EGR block off plate the EGR function has been disabled in the .bin file I'm running