solareclpse2000

ok guys im sorry this is gona be a long post and i dont type great so please bear with me. first off i have a 2000 z28 LQ4 6.0 short block, LS1 241 heads bee hive springs, intake, bosch stock injectors, ect. i have a high duration comp cam but not sure of the specs real lopy ( good lopy not bad) a previous owner did all this work to it. and msd coils and wires. long tube headers and a few other things im likely forgetting. the PCM has been shop tuned in the past for a custom tune which i have no clue what they did. i was just told by the owner who did the build it was done to accomadate the larger displacement.

the problem
all was fine i had an engine light on since i had the car for a bad o2 sensor and never got to replaceing it. in the middle of driving on the highway all of a sudden this misfire started. it misses at idle and up to about 2200 RPM, it misses beyond that too its just nearly impossible to feel. so i get to working on it. check codes. 3 seperate o2 codes come up for the 2 o2 sensors ( the down stream 2 are removed and codes deleted out of PCM so no light for those) so i figure ill run a full tune up. first checked fuel pressure, running about 59 psi steady idle and under throttle ( i figured this was how they increased the fuel for the 6.0 ) took the coil spark tester to it and all coils sparked good. ( 40mm gap jumped it fine) so i got spark plugs, oil chage, fuel and air filters and 2 new o2 sensors. replaced all that ( i omited the wires cuz my MSD wires looked and fired fine ) got all this done and still no change. i did notice on the number 6 cyl old spark plug it was black and dry, like too rich carbon fouling, and cyl 2 was a little dark with mild deposits, all other plugs looked good.so it was time to break out the auto enginuity ( laptop based OBD II port diagnostic tool commonly used on ford diesel f series )

diagnostics results
i got some weird stuff from this while monitoring the o2 sensor voltages and trims. im getting that the passenger side bank is really really rich ( 160 miles to a tank of gas rich) its even noticable that the pass side engine compartment is remarkably hotter than the driver side just by leaning under the hood. my headers are running all stupid kind of hot on that side, but not the drivers. pass side o2 sensors is reading in the 0.8 -0.9 v range. while the driver side is 0.01 - 0.09 so i figured must be an injector stuck open. so i took cyl 6 and 2 injectors and swaped them to the driver side bank. figured with the spark plugs showing overfueling those should be the culprits. so swapped the injectors over and still had the same thing, pass bank is overfueling. so i figured maybe coils and wires. swapped the coil racks and all wires and still pass bank showed way rich when it should have moved to the driver side if any of those parts were bad. but from start to finish it stayed the same

summary
so with all the testing nothing i could do woulkd change the over fuel scenario in the pass side bank. i am now at a complete loss of what is going on. i pulled the valve cover to check for broken springs or anything and found none. all springs looked good but number 8 cylinder exhaust valve was halfway open. my impression has always been with hydraulic cams the valves should all close when oil pressure is removed. is this correct? could this be the issue? if so that valve could be bent and sticking open but im not sure. monday ill likely pull the valve cover again and manualy turn the engine to check it out dont know why i didnt while i was in there. there is no smoking no oil loss and no oil contamination either. ill post up still frames of the testing i did, some bar graphs and line graphs for the o2 sensors and the pics of the old plugs if i can figure the picture thing out. please help guys this thing is running like pure crap and its my families only vehicle right now so i cant afford to have it down for long. thanks in advance.

solareclpse2000

these are the real time graphs my laptop was reading on the o2 sensors. all were recorded at idle

solareclpse2000

pics of plugs, had to resize the pics, the number 2 cyl plug looks wet like oil fouling but its just the pic it wasnt glossy or oily it was kinda light minor ash deposits but the browning would tell me more over fuel. what do yall think?

am i doing an accurate diagnostics here or am i missing stuff? i really cant think of anything else to do besides compressions tests and IR thermometer each header bank but i have neither fo those tools yet. i have a deisel compression tester which would work but i dont have the spark plug thread adapter for it and glow plug adapters are way too small or too big

solareclpse2000

o and another detail i forgot. these graphs were taken before i swapped the injectors and coils to the other side. from the start when i was getting the rich fuel numbers for the pass bank and was trying to determine if it was an injector i recorded these. this is what happened when i unplugged an injector. inj number 6 and then inj number 2. i pulled inj 4 as well just didnt save the graph. any inj i pull gives the same results. and this is pulling a single inj at a time. i didnt test more than one at a time cuz it didnt make much sense to me if the engine was gonna be stumbling anyways. i figured it would have corrupted my results

solareclpse2000

number 6 cyl inj was pulled about 30 seconds and then when i pulled the other one you can see it was around the 45 second mark.

solareclpse2000

over 100 views and noone has any advice on this? can someone please give me a forum or someone i can reach out to who can answer this?

68Hybrid

I've been battling a similar issue for about a year.
LQ4, dart heads, t-speed 228R cam, long tubes.

Mine seems to be fine at full throttle (a recent trip to the strip confirmed so). But part throttle, especially from 100 degrees up to just shy of operating temp, it regularly drops to what feels like 4 or 6 cylinders. Once at operating temp, I can tell it is just not running right. People who drive behind me say it smells like its running super rich. If i put my foot to the floor, problem goes away. I don't have the necessary tools to look at trims myself so i finally took it to my tuner.
He said: O2 sensors can fail and not throw a code. My drivers side O2 shows a constant voltage, while the other shows a constantly changing voltage. This is a sign of a dead O2 (constant voltage), but because the computer can still complete the circuit with the O2, it hasn't thrown a code. He told me to replace my O2s, (rock auto has the best prices I've seen) and replace my plugs since i've been driving for so long with nasty fuel trims. Once that is done, he suspects the problem will go away.

I hope this helps-- good luck!

solareclpse2000

yea i already went that route and while the new o2 sensors and plugs did make it slightly better its still there. nearly unbearable. but at WOT the miss is still there it just feels like its gone. like there is enough fuel pumping through the cylinders that it overcomes the feeling of the miss, but its still overfueling, if that makes sense, kinda hard to explain

solareclpse2000

can anyone at least confirm or deny if all the valves should close when the engine is off on a hydraulic cam? im a little worried that one of my exhaust valves were half open when all the others were closed

solareclpse2000

ok guys i had a new development tonight. a new code popped up while i was driving tonight which i have never seen before. and the code is on the driver bank code p1134 im posting the still frame of the code. anyone know what causes this?

solareclpse2000

bump.