rob777 Posted March 12, 2015 Report Share Posted March 12, 2015 So I'm boosting the other day and all of a sudden my truck starts running terrible. Exhaust sounds fluttery when accelerating. Thu thu thu. Flashing engine light. I scan it p0300?. I figure maybe I killed a plug. I run the live scan on my diablo to see all the cylinders. It is misfiring on 4,5,6. I throw some fresh plugs wires. No dice still missing. I put on spare maf. No different. I run it to the muffler shop they check the cats fo blockage. They test good with a back pressure gage I notice cyl 6 has way more counts 232. Cyl 5 - 44. Cyl 4 - 66. I verify fuel pressure. 55 at idle. I thing 6 has the most count so maybe it's triggering the others. I swap coils. No difference. I throw in some injector clean just for goofs. I swap injectors. No difference. I do a compression check. Cyl 4 and 6 are only 130 if I do a 3 second crank. The others about 150. So those two next to each other I think maybe a head gasket between the combustion chambers. I don't own a leak down tester and I don't trust too many people touching the ss.. I have a good friend that's pretty damn good with motors and I have been really sick and don't have too much energy to do it myself. So I have him yank the heads to replace the gaskets. The gaskets look good and no apparent damage to anything visible. I have him take the heads to the machine shop to get tested. The machine shop guy says I have two burnt valves and some weak springs. 1 warped valve marginally.. He goes thru them replaces the springs and valves laps them in. My buddy re-installs everything. Starts her up she is purring nice while warming up for twenty minutes or so while topping off the antifreeze and so on. Takes her around the block and all of a sudden flashing light running terrible. Get it back to the house. Re-check all connectors. Everything looks good. Running terrible!?. Do a live monitor on the scanner. Both fuel trims are ar -10. It is running pig rich. My buddy my brother and I have checked everything. Idles rough and missing like crazy. I am running out of ideas. What to do next? Any ideas would be greatly appreciated thanks Quote Link to comment Share on other sites More sharing options...
MID12sSSS Posted March 12, 2015 Report Share Posted March 12, 2015 (edited) Hmm... Fuel trims are off... Burnt valves... Running pig rich... I assume fuel fouled plugs.. All on the same bank... I'd throw a oxygen sensor at it. The sensor may be crap, thinking you're lean, so it's over fueling to compensate. You could swap the front sensors left to right and see if the misfires follow to the other bank? Or just throw a known good one in and see how she runs. I don't care for "shotgunning" parts at a truck hoping to fix the problem.. But without running the proper diagnostics myself, that's all I can suggest. And I think you might get lucky. If the "Bank 2 sensor 1" O2 sensor fixes the issue, then I'd go through and put fresh plugs in it. Cuz like I said, I'm sure they're fouled out. Edited March 12, 2015 by MID12sSSS (see edit history) Quote Link to comment Share on other sites More sharing options...
rob777 Posted March 12, 2015 Author Report Share Posted March 12, 2015 Unfortunately both banks are rich. Had new 02 sensors a few months ago Quote Link to comment Share on other sites More sharing options...
Aldofashow Posted March 12, 2015 Report Share Posted March 12, 2015 Sounds like you need a good tuner to hook up and see what's going on I wouldn't keep throughing parts at it Quote Link to comment Share on other sites More sharing options...
MID12sSSS Posted March 13, 2015 Report Share Posted March 13, 2015 (edited) .... Edited March 13, 2015 by MID12sSSS (see edit history) Quote Link to comment Share on other sites More sharing options...
MID12sSSS Posted March 13, 2015 Report Share Posted March 13, 2015 Unfortunately both banks are rich. Had new 02 sensors a few months ago Hmm... Quote Link to comment Share on other sites More sharing options...
rob777 Posted March 13, 2015 Author Report Share Posted March 13, 2015 I found a guy that specializes in Los engines. I'm going there tomorrow have him run his checks. Tonight I'm trying to do a comp check just to verify compression after the valve job and new gaskets. Thanks for any info anyone can think of. It's awfull hard seeing my baby run this way! Quote Link to comment Share on other sites More sharing options...
MID12sSSS Posted March 13, 2015 Report Share Posted March 13, 2015 How does it idle? Maybe vacuum leak? Unmetered air could cause it to run lean, and it could be dumping fuel to compensate? Quote Link to comment Share on other sites More sharing options...
MID12sSSS Posted March 13, 2015 Report Share Posted March 13, 2015 My DD ran like shit when I bought it. Got it for cheap and limped it home to fix it up. Had multiple misfire, fuel trims way off, and idled like crap. Took a brake clean can and sprayed around intake, throttle body, etc. When I sprayed near throttle body it'd stumble really bad. Replaced the gasket, and reset KAM. Fuel trims were much better and it idles awesome now. Just an idea. I'll keep brainstorming. Haha Quote Link to comment Share on other sites More sharing options...
rob777 Posted March 13, 2015 Author Report Share Posted March 13, 2015 I replaced intake and exhaust gaskets with the head gaskets. Tried spraying carb cleaner all around to double check. Could not find a leak. My friends ls specialist buddy is hopefully coming over tommorow to check it out. It's is idling really rough and low rpm about 500. Barely will rev up. Quote Link to comment Share on other sites More sharing options...
rob777 Posted March 13, 2015 Author Report Share Posted March 13, 2015 The battery was disconnected for a few days while working on it I wonder could the tuning lose its programming? Quote Link to comment Share on other sites More sharing options...
rob777 Posted March 16, 2015 Author Report Share Posted March 16, 2015 Update. It seems the 30 minute drive to my friends even babying it clogged the cats. Especially the pass side. Remove and straight piped it. Runs like a beast again. However it used to have a really nice sound with the STS turbo. Now, without the cats sounds raspy and sort of obnoxious At least the misfires are gone. Quote Link to comment Share on other sites More sharing options...
Downeast Johnny Posted March 16, 2015 Report Share Posted March 16, 2015 Update. It seems the 30 minute drive to my friends even babying it clogged the cats. Especially the pass side. Remove and straight piped it. Runs like a beast again. However it used to have a really nice sound with the STS turbo. Now, without the cats sounds raspy and sort of obnoxious At least the misfires are gone. Sounds like your making progress. The raspy sound is a common complaint once the cats are removed / gutted. Quote Link to comment Share on other sites More sharing options...
MID12sSSS Posted March 16, 2015 Report Share Posted March 16, 2015 You didn't have a P0420 code? I figured you'd have a catalyst efficiency code w/ clogged cats... But atleast you figured it out! Quote Link to comment Share on other sites More sharing options...
Aldofashow Posted March 16, 2015 Report Share Posted March 16, 2015 If you get sick of the rasp you could always get some high flow cats or resonators to help get rid of the rasp Quote Link to comment Share on other sites More sharing options...
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