6.0 LS running poorly

grcthird · Jul 28, 2015

Check the fuel pressure while it is running under load. May have to get a second hose to get the gauge to where you can see it while driving. Just because it makes good pressure at idle doesn't mean it is at highr rpm. Would also explain a lean code.

Got any lizards in the fuel cell?

ridgetopauto · Jul 29, 2015

Fuel pressure good through all power ranges never drops. Fuel pressure regulator doing it's job. Did an injector bleed down on each injector and they were all dead nuts. The off idle problem is it just hesitates you can hear the throttle open and suck air. On allot of these swaps I can't read missfires until I do a cam crank variation learn then I can usually read them fine, I can't on his for some reason. Could be the knock sensors, but it would have to be pulling a **** load of timing out for it to run like it does we can check that next. I put mine in the side of my block. I also like my **** running better than Wizzo's.

Sawzall · Jul 29, 2015

I drove my buggy with the scanner connected. The timing dropped to 15 degrees retarded or after zero at the exact time it fell on it's face. It seemed to control the timing normally unless it was placed under a load. The previous time it was my TPS sensor. You could see the sensor drop out with the scan tool also.

wizzo · Jul 29, 2015

ridgetopauto said:
I also like my **** running better than Wizzo's.

Hateful!!!! hahaha Seriously though..........

redneckengineered · Jul 30, 2015

wizzo said:
Hateful!!!! hahaha Seriously though..........

I didn't know Josh knew how to use a computer let alone compose such a detailed post.

tc1 · Aug 8, 2015

Mine has done something similar on a couple rides my ignition relay was fried. Went to a lager one no trouble yet. I was dropping voltage to the coils no misfires on scanner but felt like it was missing all the time.

robpate · Aug 9, 2015

I was having similar issues with my 408LS. Off idle it would sputter and fall on its face but would eventually open up and definite power loss at all rpms. Only code it would throw was Random Misfire. Changed coil packs, changed map, crankshaft and camshaft position sensors, new plugs and wires still no change. Fuel pump was good at 65 psi and checked filter. Finally came down to the fuel injectors. Took them out and clean them with B-12 fuel system spray cleaner and they were completely filthy. All kinds of black trash came out of them. Finally just decided on new injectors and that was my problem all along. Runs perfect now. Just saying.

knaffie · Aug 10, 2015

This place did a great job for me when I was trying to chase down an issue. I bought rebuilt injectors from them then sent mine in as cores so I didn't have to wait for shipping both ways and labor to rebuild.

http://www.fuelinjectorconnection.com/

croes · Aug 11, 2015

Who tuned it? Sounds like there is something in the tune that needs corrected if you can't see misfires, I would definitely get that corrected. My 5.3 had random misfires when I first ran it, turned out it was the injectors.

Did you change plug wires too? Make sure they aren't shorting out on anything. If there is something up with the injectors and its running lean that could cause it to run hotter.

What are the ST and LT fuel trims reading?

wizzo · Aug 11, 2015

croes said:
Who tuned it? Sounds like there is something in the tune that needs corrected if you can't see misfires, I would definitely get that corrected. My 5.3 had random misfires when I first ran it, turned out it was the injectors.

Did you change plug wires too? Make sure they aren't shorting out on anything. If there is something up with the injectors and its running lean that could cause it to run hotter.

What are the ST and LT fuel trims reading?

Dyno tuned by Dynoproven.com Jonathan and Cassie do mainly diesel tuning but have done a fair amount of LS as well. It's been close to 4 years since they tuned it.

I haven't had time to work on it b/c of work but I took all the panels off last night and I'm going through wiring and visual things currently. Gonna do some simple tests and checks before I dig in.

croes · Aug 11, 2015

Just an FYI, I think these are a great investment. I run a Dashdaq in my buggy that lets me realtime monitor the engine and read/clear codes if necessary. But I also have one of these for all of our other vehicles, I use the DashCommand app.

http://www.amazon.com/ieGeek%C2%AE-Bluetooth-Interface-Diagnostic-Smartphone/dp/B011UF3USM/ref=sr_1_14?ie=UTF8&qid=1439314969&sr=8-14&keywords=obd2+bluetooth

1TONZR2 · Aug 11, 2015

Chris, what kind of pickups do you have in your fuel cell? Type of fuel line? Damn ethanol in the fuel will eat away at certain types of rubber. Could have a line collapsing because of that or the guts of the fuel line is trying come apart.

wizzo · Aug 12, 2015

1TONZR2 said:
Chris, what kind of pickups do you have in your fuel cell? Type of fuel line? Damn ethanol in the fuel will eat away at certain types of rubber. Could have a line collapsing because of that or the guts of the fuel line is trying come apart.

4 of the Walbro pickups in the cell, braided fuel line from Jegs http://www.jegs.com/p/JEGS-Performance-Products/JEGS-Pro-Flo-350-Series-Nylon-Braided-Hose/761335/10002/-1 I'll

croes said:
Just an FYI, I think these are a great investment. I run a Dashdaq in my buggy that lets me realtime monitor the engine and read/clear codes if necessary. But I also have one of these for all of our other vehicles, I use the DashCommand app.

http://www.amazon.com/ieGeek%C2%AE-Bluetooth-Interface-Diagnostic-Smartphone/dp/B011UF3USM/ref=sr_1_14?ie=UTF8&qid=1439314969&sr=8-14&keywords=obd2+bluetooth

I've got some sort of deal like that, I hook it up and then can access it from my fancy phone! Pretty cool really.

wizzo · Aug 12, 2015

Worked on this thing again last night.

Sprayed starting fluid underneath intake and around throttle body, no change.
Tested current knock sensors and put one on the side of the block with extended harness, no change.
Injector leak down test again, all with in 3 lbs. Drop to 47-50 on gauge. If there was trash in one, you would think it would show itself.
Fuel pressure checked again, when loaded, FP increases and then comes down once off load.
02's checked again, no change.
Checked grounds, un hooked harness from computer and tested with power probe.
Swapped all coil packs on bank 1, no change.
Swapped pedal module, no change.
Replaced crank pos. sensor, no change.
I was gonna swap the fuel pump b/c I have a spare but I forgot it at home.

I'm getting a different computer to try today at lunch and see what happens. After that I'll tear into the fuel system but with the fuel pressure and leak down tests seeming to be good, I wouldn't think it would be fuel system related but at this point :fish:

Another thing was, while we were working on it, the throttle pedal became unresponsive. We swapped the control module and it started working. Swapped back to original and still worked. Only other time I've had that happen was during an ECORS race, we got some water in the intake and I had to shut of the disconnect for the computer to reset and then back in action. Then Jessica Huffman's Diddy put a Milo's sweat tea jug over the filter and we finished the race.

grcthird · Aug 13, 2015

Look at the individual cylinder misfires while running using the scan tool. Swap coils with any one that is misfiring and see if the misfire moves.

wizzo · Aug 14, 2015

grcthird said:
Look at the individual cylinder misfires while running using the scan tool. Swap coils with any one that is misfiring and see if the misfire moves.

Not showing misfires on scan tool.

I tried the other computer and no luck. Swapped fuel pumps, no change. I'm going to AOP this weekend to watch the show and :drinkers:

If you see a guy thumb'n rides it'll be me more than likely!!!!

wizzo · Aug 14, 2015

Pulled the fuel rails and injectors. No significant debris in the rails or injectors. I drained the rails into a container and nothing noticeable came out. I'm soaking the injectors in sea foam now and going to "pressure" clean them both ways after they soak.

extremetownie · Aug 14, 2015

Chris it looks like you have tried everything else. Have you tried a compression test? Maybe it is actually something mechanical that only shows up warm ( or cold ) what ever the case may be. If all else fails ,i will give you $350.00 for that peice of junk 6.0.