Remember_54

Hello Guys need you HELP

Hummer H2 2003

Engine:
LQ4 Generation III,364 CID (6.0L) General Motors Vortec

Magna Supercharger with 3.2" pulley on it which were installed before engine rebuild and worked fine.

in rebuild we bore and hone to 102.630mm
install a lot of good new HD parts like, coated pistons,rods, valves, springs for valves,high volume oil pump & water pump.

also installed new:
Manley timing set LS 3-bolt with captive Torrington thrust bearing and 9 keyway sprocket:
We set timing chain to A2 position which will advance my intake centrline 2 degrees. The camshaft has 115 degree intake centerline and 115 degree lobe separation.
Here is a link to my cam card.

Comp cams LS camshaft XR265HR 212/218 degree @ 0.050" 0.558"/0.563"lift

actually we did everything fine engine working good, compression in all celndr also good, but there was something wrong with ignition and ECU, I bought Autocal from blackbearperformance, so my ECU is tuned right

After a lot of logs and tunes we still have this errors:
PO300 Missfire multipal engine missfires
PO342 camshaft position sensor circuit low voltage
PO343 camshaft position sensor circuit high voltage

we also had PO106 but that was repaired from blackbear guys thru Autocal

Spark plug are brand new wires new, i checked all wires everywhere everything looking fine.we checked again all lines even the processor which is connected to this wire diagram - nothing

I think maybe it is problem with this new camshaft or timing chain and it course wrong distribution?

Another thoughts we have very bad fuel here and after rebuild we bought piston with -15cc., so new compression maybe is ok with better quality fuel, not our quality, because when driving i can here PING after 2000rpm


Guys i really need you help, I just do not know what to do, 2 years of rebuild now, which is still not finished, we do not have any good shop or specialist guys here, that why all this was done by myself and general engine re builder, nobody rebuild such kind of engine here, the one which they can rebuild is 1980-90 ladas (russian car, with out any ECU) so they never seen that kind of problems, I`m located 3000miles away from Turkey, our country name is Azerbaijan, so guys really need your suggestions, hope will able to resolve this.
because now car drives like 200hp Hummer where i was think about 500hp-550hp, before rebuild it was much better maybe all this because of camshaft and which i changed?

TIM Z

iTrader: (12)

When you installed the engine you could have possibly damaged the Cam sensor wiring. Its easy to do , I know haha.

Misfires can be caused also from cracked spark plugs. May want to try another new set.

Is the misfire count in your tuning raised for your cam?

Remember_54

i changed sensor with new one, after engine installed, i will check wiring one more time, i installed two new sets, no result, still showing PO300.

In tuning loq, it is showing some missfire, but sometime it is showing zero counts.

thanks for you help. will try to check wiring again

budhayes3

iTrader: (19)

Often when installing an aftermarket camshaft, the PCM will interpret the new camshaft's running characteristics as misfires when there actually is none, since aftermarket camshafts will have more overlap than stock and also cause different crankshaft speeds which the PCM may think is a misfire. Make sure that the PCM is tuned accordingly for the cam and that the misfire counter is softened up to compensate so that you're not chasing a ghost.

As for the cam sensor codes, first thing that I'd do would be to take Tim's advice and check the wiring and connector to the cam sensor and make sure that nothing's damaged, and/or none of the terminals are spread out in the connector. The cam sensor gets it's signal from an eccentric ground in to the rear of the camshaft...any possibility that it got damaged during the cam install, or that it's a newer style camshaft for a GenIV that doesn't have the cam sensor lobe?

TIM Z

iTrader: (12)

No prob bud, wanna see ya get it figured out so you can enjoy it.

Can your software be configured to detect which cylinder is misfiring?

Maybe someone else will chime in and have a good tip for ya.

EDIT, i see Billy posted at the same time, he has some good advice there to double check.

Billy rocks!

Remember_54

good POST!!!

sensor lobe is this type, and actually i do not think that it is damaged, anyway we changed it again if something is can happen it is only wiring which we also checked but

Remember_54

thanks, really good help guys, after year of rebuilding and trying to sort everything Im back to the really bad results, before rebuild car was not bad, but pistons rings was down, so i decide to rebuild it with all this nice stuff, but now it really bad, i think because ECU can not get used to new parts, like camshaft and timing chain, we also think that missfire happens in passenger side but we checked today all spark plugs and nothing.

i really tired with all this i will be even happy to pay for tickets, hotel and donate for guy who will repair all this. ((((( dreaming to drive my hummer with more than 200 hp

budhayes3

iTrader: (19)

Thanks for the kind words Tim...you're quite rockin' yourself!

good POST!!!

Since you know that the cam and cam sensor are good, all that's left is the wiring and PCM. Check the integrity of the wiring from the PCM to the sensor with a multi-meter, and hopefully you'll find an open, short, or excessive resistance. If that all checks out, somethings amiss in the computer

Good luck man, keep us updated on how you make out!

Remember_54

guys need you help again,


we checked all wires and sensor itself, nothing, we checked even processor where sensor connected, so everything is right and working fine, no any issues, what i think is to change timing chain and camshaft back to factory, i think this camshaft is making wrong distribution and it is showing missfire, what you thinks guys?

Remember_54

guys onother issue when we was rebuilding engien, guys from shop did not plug right plus and minus, our alternator was damaged that time, and we change alternator, but there we had some issues with wiring it was also not right, then we sort everything, so im thinking maybe something wrong with ECU that time?