One last shot... Breaking up!

WyoSyclone

WyoSyclone

Active member
Re: One last shot... Breaking up!

BoostedSUV said:
I just tried running the truck with the O2 disconected to make sure I wasn't getting a false signal to ECM. I don't get any CEL after 10 mins, truck stays in 'Open Loop' and the O2 mV stay around 457. When I bring the RPMs up the truck still breaks up but the O2 mV don't move so I don't appear to be getting a false O2 signal so it would appear that the O2 circuit is functioning.....
Click to expand...

So, doesn't this point towards a mechanical problem outside the realm of the ECM/monitored parameters? That could be: AFPR, fuel pump, restricted return line, vacuum problem. We know it's going lean... what can cause that? Too little fuel, or too much air. I'll take a look tomorrow at that other DM uni you sent me Matt.. there has to be a clue there somewhere!
 
WyoSyclone

WyoSyclone

Active member
Re: One last shot... Breaking up!

cloneman315 said:
what is the wbo2 do when it breaks up?can you datlog the wbo2?
Click to expand...

I've got those logs Brian.... it shows gradually going lean into the area where it starts breaking up, then it kind of hooks North and goes a bit leaner a bit faster. I'm going to look at the vac readings again tomorrow to see if there is some correlation.... what a mystery this one is!

edit... if you look at the screen capture in my post #272, you can see what the AFR's are doing.... this was logged with the PLX
 
T

turboj91

New member
Re: One last shot... Breaking up!

BoostedSUV said:
The weird part is seems to be doing it at 2100 and 2700 now instead of 1900 and 2500. So weird!


How about the 1100 rpm stumble. Did that move up in the range along with the other two trouble spots?

Funny how a larger injector just moved your problem up the rpm range. hmmmmmm????
Click to expand...
 
BoostedSUV

BoostedSUV

Active member
Re: One last shot... Breaking up!

WyoSyclone said:
So, doesn't this point towards a mechanical problem outside the realm of the ECM/monitored parameters? That could be: AFPR, fuel pump, restricted return line, vacuum problem. We know it's going lean... what can cause that? Too little fuel, or too much air. I'll take a look tomorrow at that other DM uni you sent me Matt.. there has to be a clue there somewhere!
Click to expand...

Well Aside from changing the fuel lines and filter (which is about a year or so old), everything has been gone through. Pump was changed 3 weeks ago, as well as the sending unit, blew the lines out with compressed air, AFPR was taken apart and inspected, cleaned out the fuel rail, swaped injectors etc... you've read everything you get the idea. Unless I've got a bent line from back of the rail down, I didn't see anything when I followed the fuel lines from the tank forward. Another thing is FP looks perfect, i can watch it in the truck. Goes down with vac, and up with boost...

Truthfully I think it's an ignition miss-fire somewhere/some how. Upper intake gasket is brand new, as well as TB gasket. Lowers look good from what i can see looking down ports, all the Vac lines are a new kit from the GP and I tested them with a vac tester. Truck idles at 850-900 so there's no sign of leak.


Another thing I tried tonight while the truck was breaking up is I manually sprayed the the meth injection to add fuel and the truck continued to break up but the WB showed rich... read 11.5....
 
BoostedSUV

BoostedSUV

Active member
Re: One last shot... Breaking up!

cloneman315 said:
truck doesnt have a msd with a two step does it?
Click to expand...

no but that's sort of the symptom I get. not quite as extreme of a 2-step though,but it feels as though i hit limiter if i bring the RPM's up slowly. I also just put the MSD box in last week. Prior i was just using MSD coil and Dist..
 
WyoSyclone

WyoSyclone

Active member
Re: One last shot... Breaking up!

BoostedSUV said:
Well Aside from changing the fuel lines and filter (which is about a year or so old), everything has been gone through. Pump was changed 3 weeks ago, as well as the sending unit, blew the lines out with compressed air, AFPR was taken apart and inspected, cleaned out the fuel rail, swaped injectors etc... you've read everything you get the idea. Unless I've got a bent line from back of the rail down, I didn't see anything when I followed the fuel lines from the tank forward. Another thing is FP looks perfect, i can watch it in the truck. Goes down with vac, and up with boost...

Truthfully I think it's an ignition miss-fire somewhere/some how. Upper intake gasket is brand new, as well as TB gasket. Lowers look good from what i can see looking down ports, all the Vac lines are a new kit from the GP and I tested them with a vac tester. Truck idles at 850-900 so there's no sign of leak.


Another thing I tried tonight while the truck was breaking up is I manually sprayed the the meth injection to add fuel and the truck continued to break up but the WB showed rich... read 11.5....
Click to expand...

Ah, good move on the spraying.... sounding more and more like an ignition issue.

edit... if the ignition module fails, doesn't that stop pulsing the injectors, thus making it go lean?? Wouldn't it show rich otherwise (loss of spark, continuation of fuel)??
 
cloneman315

cloneman315

Active member
Re: One last shot... Breaking up!

try going to a dark parking lot, garage etc,turn off all the lights watch the fan,start the truck move wires around etc look for arc,s laugh but it works!
 
BoostedSUV

BoostedSUV

Active member
Re: One last shot... Breaking up!

I had plugs gapped at .025, I pulled them out and put new ones in gapped at .028. It does kind of feel like my truck used to feel at 15psi when i had .035 gap and was getting spark blow out. Kind of hard to believe that's my issue at a low RPM especially with an MSD ignition.
 
BoostedSUV

BoostedSUV

Active member
Re: One last shot... Breaking up!

cloneman315 said:
try going to a dark parking lot, garage etc,turn off all the lights watch the fan,start the truck move wires around etc look for arc,s laugh but it works!
Click to expand...

Just pulled out the old MSD wires and threw a brand new set of taylor wires on the truck along with a new cap and rotor...
 
TYTILIDIE

TYTILIDIE

METH HEAD
Re: One last shot... Breaking up!

This is terrible. I feel bad for you man. So you said you DID try the stock chip right? If so, looks like you are taking wires apart, not sure what else it could be. Maybe you can borrow a harness to see? It still would be odd to me that a wiring issue would give you trouble at certain RPM's. Make 100% you rule out the tune if you haven't already.
 
cloneman315

cloneman315

Active member
Re: One last shot... Breaking up!

try them around 18 to 20 cant hurt,thats were i run mine,but again i know its low rpm but you need to try it all.try the dark under hood check first!!
 
BoostedSUV

BoostedSUV

Active member
Re: One last shot... Breaking up!

cloneman315 said:
try them around 18 to 20 cant hurt,thats were i run mine,but again i know its low rpm but you need to try it all.try the dark under hood check first!!
Click to expand...

I will tighten the gap on my NGK TR7IX to .022 and put them back in the truck. I did spray all the wires with water and didn't get anything going on. I will do the dark test and see what happens tho
 
BoostedSUV

BoostedSUV

Active member
Re: One last shot... Breaking up!

TYTILIDIE said:
This is terrible. I feel bad for you man. So you said you DID try the stock chip right? If so, looks like you are taking wires apart, not sure what else it could be. Maybe you can borrow a harness to see? It still would be odd to me that a wiring issue would give you trouble at certain RPM's. Make 100% you rule out the tune if you haven't already.
Click to expand...

Dude it's killing me and it's $350 for a new engine bay harness, or $200 used. I did try running the truck on the stock chip and got the same results, only worse of course bec of the 3 bar map and bigger injectors. I also tried burning a few .bin files and tried different tunes.

I'm missing something stupid and I know it! We're all going sleep better when we come up with it! :lol:
 
You must log in or register to reply here.
Top