v3n0m

I have an 01 ws6 m6. Has headers, ory ( no cats), and slp lm1. Have no idea if the car has had a tune before but im guessing not. 3 days ago on the way home from work i shot up to about 80mph in fourth and while i was on the gas i felt a miss. I didnt really think much of it and thought it may have been because she was low on fuel. Next day i took the car a couple blocks away and got gas. On the way from there to work was bucking really bad under accel and i heard some popping/ backfires. As i was pulling into work the ses light was flashing. Got to looking under the hood and found one of the plug wires was barely on the plug and couldnt get it to stay on, wife brought me a set of plugs and wires and i only replaced that one there in hopes that would fix the issue and get me home where i could finish the job, but oh no. On the way home it was buckng as bad as ever and i heard some popping coming from the pass side header collector which i thought was odd because the bad plug wire was on the drivers side. Im in the process of finishing up the plugs and wires now...the back 2 on the pass side are giving me a fit lol. Has anyone else had similar problems? What did u find? Once the plugs and wires are done ill be taking it to autozone for them to scan it and post some codes up here. This is my dd and now im having to bum a ride from the wife....reallyyyyyyy stressing me out, dont have much money to throw at this thing atm. Any help would be greatly appreciated. Thanks guys.

LS6427

iTrader: (2)

Well, flashing SES means "multiple cylinders misfiring". So maybe a few wires are loose and not snapped on tight.

Other than that, failing 02 sensor(s) cause misfires. So does bad gas or low fuel pressure issues. A failing Crank Shaft Position sensor can too. But also a failing Cam Shaft Position sensor, because it dictates when the fuel injectors fire fuel into the cylinders.

Gt the codes read and see if you have something other than "multiple misfires".

While you're doing the plug wires...make sure all the spark plugs are tight.....

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v3n0m

Ill put up what codes its throwing tomorrow as soon as I finish installing the new plugs and wires. That is IF it makes it to the store and back. With any luck the new plugs and wires will fix it, but if not itll be one stressful ride. The car just does not want to go. It will crank right up and idle fine, but with any acceleration it jerks like crazy. They have an Innova 3020 obd2 code reader at advanced for like 30 bucks. Think this would do the job? Really dont want to drive the car if its still doing this, feels like its going to die at any moment.

LS6427

iTrader: (2)

Advance Auto reads codes for free.....don't buy a scanner.

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Alex L.

iTrader: (16)

The back passenger plug is easy to remove if you Jack up the side of the car and get it from the bottom. Remove the coil packs to do the rest.

Marc 85Z28

iTrader: (8)

No it doesn't. It means he has a catalyst damaging misfire.

Not with long tube headers. With LTs everything is easiest from up top. Driver's side is very easy. Passenger side only requires removal of the ignition coils. It's a 40 minute job.

Bacon

Marc is right - flashing SES doesnt always mean multiple misfires.

Without the code, we can't help you. Best case scenario, it shows a misfire isolated to a single cylinder. If this happens, swap parts (plugs, wires, injectors, coils, etc) to other cylinders. Clear code and drive again. When the SES light comes back, check which cylinder it moved to. If it didnt move, its more likely valve issues.

If its multiple misfires, it's likely a sensor that serves all cylinders (aka crank position, O2, etc), or fuel pressure.

Get that code and report back

v3n0m

Got the plugs and wires changed out. Was easiest for me to pull the coil packs off and use a shallow well 3/4 on the plug socket for back plug. By the time i had it finished up it was about time for me to leave for work. Drove it around the block and its back running with no issues, other than ses of course. I decided to drive it on in to work ( about 12 miles) and had no issues. Still plan on finding out whar codes were thrown and getting a tune. Ill post the codes as soon as i get them...thanks A LOT for the help guys.

v3n0m

Got the codes...it was throwing po300 and po133, they told me it meant multiple missfire and 02 sensor. I suppose i have the missfire issue resolved. Im thinking the only way i can fix the sensor issue is with a tune? Like I said, running longtubes and ory (no cats).

Marc 85Z28

iTrader: (8)

P0300 is a random misfire, not necessarily a multiple misfire. It means the PCM is reading intermittent misfires on several cylinders, but not often enough on a single cylinder to trigger a cylinder related misfire. This DTC is commonly set on LS engines due to poor ignition wire to spark plug continuity.

The P0133 is a slow response DTC for the driver's side upstream oxygen sensor. A tune will not fix this. A new oxygen sensor will. This is common on cars with long tube headers.

v3n0m

Thanks for clearing that up man. So if i get the new sensor, no more ses light? Or will it just pop up again with time?

LS6427

iTrader: (2)

For all practical purposes......flashing SES means......"multiple cylinders misfiring"....... We've all been here before about a million times with flashing SES lights. From there.....you need to simply look at what causes multiple misfires....and you'll quickly find the issue.

Failing or failed 02 sensors cause it all the time. Thats why I mentioned it above......You probably found the problem. Bad 02 sensors cause terribly rich conditions, causing misfires in ALL cylinders. Commonly referred to as.....multiple misfires. LOL

Hope you got it.....

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Marc 85Z28

iTrader: (8)

No, it doesn't.

It means you have a catalyst damaging misfire. A single cylinder misfire can cause the MIL to flash. I just finished replacing all the lifters in a 08 Envoy due to a single collapsed DOD lifter here at work. Customer's concern was running rough and flashing MIL. It was misfiring on a single cylinder only.

Hope you got it...

LS6427

iTrader: (2)

If you give people textbook quotes from maintenance and repair manuals all you will do is lead them in the WRONG direction......when almost always it's a simple fix. 99% of the time when an SES light flashes its REALLY because there are multiple misfires......and diagnosing for that is what needs to be done first. Not tearing into the ****** lifters.

We go easiest to hardest here....don't steer people in the wrong direction and cause them to spend money when the simple things need to be looked at first. And twisting in a new 02 sensors is the direction I sent him......not this catalyst bullshit.

Easy simple **** first.......period.

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Marc 85Z28

iTrader: (8)

You're the one leading people in the wrong direction here. It's subtle differences like this that lead to misdiagnosis. Per OBD-II REQUIREMENTS the MIL must flash to indicate a catalyst damaging misfire. This can be a single cylinder or multiple cylinders. I does NOT have to be a multiple misfire. A multiple misfire MIGHT trigger a DTC, and it MIGHT cause the MIL flash. A catalyst damaging misfire will ALWAYS trigger a DTC, and will ALWAYS cause the MIL to flash.

Furthermore, an oxygen sensor with a slow response failure WILL NOT cause a misfire.

Lastly, I used the Envoy as an example, not as a fix for his issue. And if it helps any, on that Envoy, some other uninformed hack (like you) already replaced the simple things like plugs, wires, coils, and even the intake gaskets lol

You'll have to clear the DTCs. Either disconnect the battery/PCM/PCM power fuse for several minutes, or use a scanner. The DTC will not return until the sensor is contaminated again.