Misfires and coils, a RIP Tuning experience
As some of you may know RIP Tuning is new to the board. A little over a month ago I picked up an 08 335 hardtop vert for the shop. After playing with it for a month with different tunes and downpipes, catbacks and intercoolers, I was scheduled to get it on the dyno on Monday (yesterday). Unforunately, Sunday night the car threw a SES light, was shaking and did not want to rev cleanly after a session of agressive driving. Checked the codes via the Access Port and sure enough misfire on 1 and 2. I used the AP to check the AFR's, Fuel Pressure on LPFP and HPFP and everything turned out good. So I figured tune up time, lets get some coils and plugs. I have a very good supplier for these but they were unable to get me the coils til Tuesday so I orderd 4 from him and got 2 from my local dealer for cylinders 1 and 2.
After receiving the 2 new coils and installing them with new plugs, to my dismay, the problem was still there. No improvement what so ever. As you can imagine I was scratching my head. I checked the AFR's on bank one with the AP and it was showing 20.1 AFR's, but all the numbers for the fuel pumps looked good. I thought great time to buy 2 new injectors. Before I did so I thought lets look and see what the plugs tell me. So after pulling the plugs they were starting to turn black with soot and I could tell there was either way too much fuel or my coils were not firing properly, but they were brand new coils! Remember I had 20.1 AFR's, which did not add up to what I was seeing on the plugs. I had a similar experience earlier on in my tuning days and learned that way too rich of a condition can show a false lean with the wideband. That is what was happening here. The computer was also dumping more fuel because the wideband was showing so lean, and it was compounding the problem.
I backed off working with the car on Monday and waited til my other 4 coils came in. When I recieved my new coils they were a different part number and also a differnent design. They did not have the soft rubbery coating on them. They were hard plastic and a tighter fit when installing. I called my supplier to double check that I had the correct part and he stated that these are the replacement coils for the other part number that he had ordered for me. So after installing the new coils the problems were solved and have not shown back up. The car is running better than it ever has since I have owned it.
My suggestion is for you to get the new part for the coils as it has made a huge difference in how my car has driven.
Below are the part numbers for your reference.
Old part number
12 13 7 594 937
Replacement part number
12 13 1 712 219
Also I cannot explain how helpful the Cobb AP is when you are trying to trouble shoot this car. If you ever plan on working on this car yourself the AP is worth its weight in gold on how much time it will save you being able to see the live data.
I have attached a picture below so you can see my plugs and the boxes the coils came in. Sorry I did not take pictures of the coils when installing them