We had the y-pipe off while swapping the tranny and found this:

http://members.aol.com/blownf1/driver_cyl3.jpg
http://members.aol.com/blownf1/passenger_cyl4.jpg

The inside of the collector tube on the second cylinder from the front on each side of the motor looks brand new, while the other 3 look "normal". If you take your finger and wipe inside, the black sooty ones leave a finger mark and your fingers comes out black as I would expect. The other one seems as though nothing has ever passed down it....your finger comes out clean. The white coating almost looks like ceramic overspray from the coating process.

We pulled the plugs on 3, 4, and 6 (for reference) and they look a bit white with a hint of light brown, but don't look abnormal. The motor has a couple thousand miles on it, seems to run great, idles fine, and put down over 500rwhp/tq recently. I was expecting a bit more, but the trans was slipping so we're solving that issue this week. I'm planning to pick up an IR temp gauge so we can compare the temp at each header tube...any other suggestions?

I'm very confident in the RR adjustment, and it's not loosing any coolant, or anything else weird. Could this be the result of running rich? Fuel washing the tube? Why only the 2 though?

Any ideas? TIA!!!

 

Clogged or bad injector causing that cylinder to run lean?

Dan

 

Definitely wouldn't be the result of running too rich, it would have sooty material in it like the others. It's running lean in that cylinder for some reason, or that cylinder just isn't running at all. I don't know why you would want to compare tube temps, you should be able to know which cylinders aren't firing by following the tubes. I would check your spark at those cylinders, and check your injectors at those cylinders as well.

 

Either running lean or not running at all.

 

Ok, we're planning to do some basic checks this week...but I've got too much stuff off it right now to run it. Any ideas why it would be the second cylinder back on either side? Just coincidence? The plugs from those cylinders look fine...so I have to believe thier running, or were at one time at least.

I figured it'd be helpful to check the tube temps since some people tune by EGT. As far as running rich, I wondered if raw fuel could be cleaning out the tube if the cylinder wasn't firing?

 

If it's injector related ..... I think it's a big time coincidence that you have two injectors bad, that there's one on each bank and they both happen to be the second injector back! That's a huge coincidence to me.

If it were opti related ..... wouldn't you notice a serious mis? have you done any logging to check for misfiring? Didin't you say that the plugs pulled from those cylinders looked good?

I definitely agree that something abnormal is going on there but whatever it is has to originate from something that is going to have some knid of symetrical impact. I guess thata does bring one back to the opti but I can't see how.

How about the PCM? Could there be something in the message to the injectors? Could those injectors have been programmed to open too long or something? I don't know much about programming but maybe they are match up in the tables because they are the same cylinder on opposite banks or something?

 

I'm planning to check the injectors are being pulsed tonight, then we'll probably pull the rail to see if it's firing each one. If anything, the car seems to be running a bit rich at idle and low speed cruising since the tune, but runs like a raped ape. <shrug>

 

We checked spark, air, fuel, injector harness, etc...even fired up the individual cylinders with open headers....it's DEFINITELY igniting the mixture in there! Everything seems to check out comparably to the cylinder next to it. I'm gonna call SLP tomorrow just to see if they've ever heard of something like this. At this point, we'll likely button it back up, slap the new tranny in and see how it runs.

 

honestly i'd say its in the design of the exhaust. each cylinder will send a negative and positive pulse. what is happening i think is that on your exhaust stroke that would normally push out that part of the collector another cylinder is actually sending a pulse back up sort of negating flow out of that part of the collector. in plainer terms as that cylinder that would normally fire down that chamber of the collector, another cylinder is actually passing a pressure wave back up that chamber. what happens is the flow simply gets diverted to another chamber on the collcet. it simple seeps out one of the other three holes.

you typically see this a lot more on 2 stroke motors rare on 4 strokes.
pipe lengths, diameters, and radius's of the bend all play a roll, the frequency of the wave...all kinds of technical ****. changing cylinder heads or modding them diff pistons, chamber volumes all will alter the flow. whereas your exhaust might not do this on a stock motor it does on yours.

honestly, its not a big issue. dont be too concerned with it.

do you sorta get what i'm saying, i tried to explain it the best i can. i'm not guaranteeing this is whats doing it, but its my best guess.

also i pm'd you with a question. hit me back if you can.

 

holy **** i just realized this thread is from over a year ago. ever figure out what it was