Viper

iTrader: (6)

What did you do to resolve this in the last 30 days?

I'm in the same boat, very strange stuff ( O2 readings, P1136 etc ).

I'm almost ready to dump another $150 into O2's but I'm hesitating , looking for ideas.

All the issues are on the driver side.

Jake99SS

Speed, Inc. found this to be a header leak in the collector. They ordered a new header and it should be coming in shortly. They put in a new O2 sensor for me to get the car running but the car has started running crappy again. Checked for broken springs last night but found nothing so the PCM must realize it's got a bad exhaust leak again.

I'm getting a P0171 lean code now. Hopefully the header will be in soon.

Viper

iTrader: (6)

OK, time to figure out if I have a header leak or not. Thanks man.

Randy WS6

iTrader: (69)

I am having the exact same problem down to a "T" sounds like you are driving my car. This did not start till i put the long tubs on.and I don't have any header leaks ether, I've looked and replaced every thing i could think of with no help I even have a MAFT and it don't change it ether off or on blowing my mind and bill fold .there hast to be a fix some were.

VT2 EXEC LS1

TTT

I'm having a silimar probem as well Posted my problem under a different thread but haven't had much response.

I have a 346 LS1 with a GM GrandAm cam, Speed density tune running in open loop mode (O2's are installed but PCM doesn't reference them). Sounds like the car is popping and backfiring in the exhaust when it misses. Starts missing badly between MAP 78 - 95 between 1100 - 3000rpm. Clears up over 3000rpm and starts to pull like a freight train to the limiter at 7200rpm.

To date I've replaced:
Plugs
Plug wires
Ignition coil packs
Fuel injectors
Cam and Crank angle sensors
PCM

Are per the firing order 1-8-7-2-6-5-4-3 :

Cylinder:
1 - Plug fouled
8 - Plug fouled
7 - Plug clean
2 - Plug clean
6 - Plug fouled
5 - Plug fouled
4 - Plug clean
3 - Plug clean

This problem only started to occur after I changed my headers and exhaust from 1-5/8 headers (4-1) and twin 2.5" system to 1-7/8 long tube headers and twin 3".

Anyone know WTF is going on? I've checked all the earths on the PCM harness and body, checked continuity of the PCM wiring harness (no faults), alternator voltage is 14.7v with the car running. PCM shows no error codes.

Randy WS6 - did your missfiring occur only after the long tubes on? Does it clear up at WOT as the revs increase?

Randy WS6

iTrader: (69)

yes, it did not start loading up till I put the long tubs on ,I ordered the DEI.Exhaust Wrap Kit from Summit today, it comes with 2 - 2"-50' rolls and stainless steel tie wraps and heat paint to paint what you don't cover. and I ordered new 02 buns to weld up closer to the joinning primarys to see if that will help!!!!!!!!!!!!!!!!!

JoeDirt

I am having this problem also , 02 on the drivers side is flat and al the drivers side plugs are black !! Pass side plugs are fine. Drivers side LTFT are +25 , pass bank is +3

slyws6

anyone ever find the problem? I am having the exact same problem currently with my new 6.0L and turbo setup.

-Sly

Tiger2o69

iTrader: (16)

Well looks like everyone is having this problems, same here. My cars acts like it wants to die at idle but feels ok at wot but i know its now because i dynoed the other day and it was like 300 which is really low for what i think.

JoeDirt

Well . . .I beleive I had a massive vacuum leak on my drivers side header bank at the very back causing my LTFT's to go +25. In reality because the leak was after combustion chamber in my header flange the car was really runing PIG RICH on the drivers side bank as evident from the smell and black suity pipes. I cranked everything down but didnt reset the battery and ran it till the LTFT's came down on there own . . . about 70 - 100 miles. Not long after they returned to normal the drivers side bank pegged +25 again and this time the car was sputtering and missfiring which it didnt do the first time. I pulled my drivers side o2's and they were so black you could barely see the slats.

Anyways I clened em and swithched banks and LTFT's are back to +5 on the drivers and +7 on the pass which was +3 with the good o2 so well see how it goes.

VT2 EXEC LS1

Well the solution to the missfiring I experienced was caused by the 1-7/8 primary pipes. Basically, with the Grand Am cam I'm running, there wasn't enough exhaust gas velocity to encourage scavanging in the cylinders - hence it would only clear up as the engine speed increased over 2800rpm - stabilising at 3500rpm. Changed the headers to a 1-3/4 size primary and all has been running well for almost 8 weeks now.