Possibly a bad maf

[ohioboxster]

Originally Posted by Norminhouston

Go to an AutoZone store. They will scan for free.

Really? Wow thats awsome I didnt know that!

[ohioboxster]

Yeah the cel just came on the other day thats why I dont think its the supercharger. Its a new problem.
So I just got back from Autozone and my car had ten codes as follows,

p0300, p0306, p0304, p0305, p1121, p0150,p1313, p1314,p1317,p1117

Well, cylinders 4,5,6 mis-fired, 02 sensor bank 2 sensor 1 (pre cat) and a maf code. Im thinking I must have screwed something up on 3 cylinders when I changed the plugs, all the codes seem to be related to three cylinders. I hope 4,5,6 are on the drivers side or Im going to have to pull the SC unit out if the issue is with the coils. I cant think of what in the world I could have done, unless its just the 02 sensors. This is one of those times when I dont want to just start replacing parts. Any thoughts?

[MNBoxster]

Originally Posted by ohioboxster

Yeah the cel just came on the other day thats why I dont think its the supercharger. Its a new problem.

Hi,

I think it's the MAF, but possibly exacerbated by the increased flow from the supercharger.

I wouldn't be surprised to see a shortened lifespan on supercharger installations because they're the Hot Film type and a little less rugged than the Hot Wire type, it'll be interesting to see. Good Luck!...

Happy Motoring!... Jim'99

[Gary Gaukler]

Originally Posted by ohioboxster

Yeah the cel just came on the other day thats why I dont think its the supercharger. Its a new problem.
So I just got back from Autozone and my car had ten codes as follows,

p0300, p0306, p0304, p0305, p1121, p0150,p1313, p1314,p1317,p1117

Well, cylinders 4,5,6 mis-fired, 02 sensor bank 2 sensor 1 (pre cat) and a maf code. Im thinking I must have screwed something up on 3 cylinders when I changed the plugs, all the codes seem to be related to three cylinders. I hope 4,5,6 are on the drivers side or Im going to have to pull the SC unit out if the issue is with the coils. I cant think of what in the world I could have done, unless its just the 02 sensors. This is one of those times when I dont want to just start replacing parts. Any thoughts?

Your codes are interesting. I looked them up in the Bentley manual. According to the manual, p1313-1317 do not exist for the 5.2.2 DME in your car, but they refer to cylinder 1,2,5 misfires with DME 7.2. That would mean you misfire on almost all cylinders, not just one bank... P1121 is the TPS, not a MAF code.

My thoughts: I don't see very much here that would point to a MAF fault. Also I don't think it is likely that you screwed up the coils / plugs. However, all codes can be related to fueling issues. You may be running severely rich / lean. Have you had the car on the dyno after the sc install to verify your A/F ratios?

Gary

[Gary Gaukler]

One other thought: You said it stumbles at idle for a while, and then it goes away. That could be another indicator that your fueling is off. The first couple of seconds at idle the car is in open loop: the o2 sensors won't correct the A/F ratio until they have warmed up. Hence you are running off some standard fuel maps. Once the car is idleing in closed loop, the o2 sensors correct the mixture.

[MNBoxster]

Hi,

I mentioned this in another thread, but start by reading your plugs. This is a diagnostic which has all but been forgotten on this day of OBDII cars where people rely more on scanners, but is still a very valid way of discovering what's going on directly inside the cylinder.

As mentioned, the codes you're getting will often not point to a particular problem. A fueling issue or bad MAF will manifest themselves in conditions which other sensors detect or cannot account for and so those codes are thrown instead.

Aside from fuel and air issues, I think there's a distinct possibility of a vacuum leak somewhere as well.

But, as I said, read the plugs. Whitish-gray indicates a lean A/F mix, Tobacco Brown is a proper stoichiometric mix and Black would indicate a rich mix. Go from there. Hope this helps...

Happy Motoring!... Jim'99

[ohioboxster]

Originally Posted by MNBoxster

Hi,

I mentioned this in another thread, but start by reading your plugs. This is a diagnostic which has all but been forgotten on this day of OBDII cars where people rely more on scanners, but is still a very valid way of discovering what's going on directly inside the cylinder.

As mentioned, the codes you're getting will often not point to a particular problem. A fueling issue or bad MAF will manifest themselves in conditions which other sensors detect or cannot account for and so those codes are thrown instead.

Aside from fuel and air issues, I think there's a distinct possibility of a vacuum leak somewhere as well.

But, as I said, read the plugs. Whitish-gray indicates a lean A/F mix, Tobacco Brown is a proper stoichiometric mix and Black would indicate a rich mix. Go from there. Hope this helps...

Happy Motoring!... Jim'99

Well here it is can you see it good enough?

[MNBoxster]

Originally Posted by ohioboxster

Well here it is can you see it good enough?

Hi,

Not the clearest pic, but the plugs look OK. This leads me to think vacuum leak, because whether it was fuel or MAF, either would affect A/F Mix, which by your plugs is good...

Happy Motoring!... Jim'99

[ohioboxster]

Originally Posted by Gary Gaukler

One other thought: You said it stumbles at idle for a while, and then it goes away. That could be another indicator that your fueling is off. The first couple of seconds at idle the car is in open loop: the o2 sensors won't correct the A/F ratio until they have warmed up. Hence you are running off some standard fuel maps. Once the car is idleing in closed loop, the o2 sensors correct the mixture.

Gary,
That makes sense, would the maf have anything to do with fuel on start up when its in open loop? The interesting thing is the fact that after I reset the cel from the ecu the car ran fine. I let it sit for a few hours before I went to work and normally it would stumble on start up. Well, it didnt stumble at all but on the way to work the cel light came on. In the morning it stumbled a little. Its weird its getting progressively worse unless I reset the ECU. This kind of makes me think a sensor, not sure.