Missing on top end, help?

[Dr. Matt]

Ok, 2004 L, built motor stage 2 cams stage 3 heads, ported Eaton, all the bolt ons including pumps/ injectors, TR6's, stock coils. Fuel Pressure is good (58#s), AFR is good (One tune is 11.4-8, other is 12.0-2) does it on DD tune as well as race tune, both by JJ & making 16-17#'s of boost.

I put in new plugs and filter this spring before first time at the track and it ran great, best of 12.04. Next time at the track it started missing so I went home, put in a new fuel filter and even though plugs were less than a month old I replaced them and miss went away. Old plugs looked perfect (TR6's gapped at .034). So I went to the track again and ran great, got a 12.03. The miss came back next time I went to the track with only about 500 miles on this set of plugs and less than 100 miles since the previous trip to the track where I ran great. The truck only misses above 80 MPH WOT in 3rd gear.

Went to see a buddy who works at dealership and he did their "back door scan" after I got it to miss and nothing showed up. Took him for a ride with the Ford scanning tool and his laptop hooked up and it missed but no problems showed on his live reading or the scan. We both thought it must be a weak coil so he gave me his "test" coil to try swapping from cyl to cyl. He said no way was it 2 bad ones because it didn't shake bad enough to be two cylinders missing. Went through swapping the good coil to all 8 holes and no change. OHM checked all my coils while I had them out and all are fine. Decided to tighten plug gap to .030, all looked good again so I regapped and put them back in. Still misses but finally got a DTC P0511. Can't find info about that code.

Help/suggestions?

Matt

 

[Derek@Amazon]

sounds like spark blow out... try gapping the plugs down to .028-.032 and see if it goes away.

 

[boomr]

Ok, 2004 L, built motor stage 2 cams stage 3 heads, ported Eaton, all the bolt ons including pumps/ injectors, TR6's, stock coils. Fuel Pressure is good (58#s), AFR is good (One tune is 11.4-8, other is 12.0-2) does it on DD tune as well as race tune, both by JJ & making 16-17#'s of boost.

I put in new plugs and filter this spring before first time at the track and it ran great, best of 12.04. Next time at the track it started missing so I went home, put in a new fuel filter and even though plugs were less than a month old I replaced them and miss went away. Old plugs looked perfect (TR6's gapped at .034). So I went to the track again and ran great, got a 12.03. The miss came back next time I went to the track with only about 500 miles on this set of plugs and less than 100 miles since the previous trip to the track where I ran great. The truck only misses above 80 MPH WOT in 3rd gear.

Went to see a buddy who works at dealership and he did their "back door scan" after I got it to miss and nothing showed up. Took him for a ride with the Ford scanning tool and his laptop hooked up and it missed but no problems showed on his live reading or the scan. We both thought it must be a weak coil so he gave me his "test" coil to try swapping from cyl to cyl. He said no way was it 2 bad ones because it didn't shake bad enough to be two cylinders missing. Went through swapping the good coil to all 8 holes and no change. OHM checked all my coils while I had them out and all are fine. Decided to tighten plug gap to .030, all looked good again so I regapped and put them back in. Still misses but finally got a DTC P0511. Can't find info about that code.

Help/suggestions?

Matt

P0511 Idle Air Control Circuit Malfunction
Detailed Description
This DTC is set when the PCM detects an electrical load failure on the IAC output circuit.

Possible causes :-
IAC circuit open.
VPWR to IAC solenoid open.
IAC circuit shorted to PWR.
Damaged IAC valve.
PCM damaged.
IAC circuit short to GND.


Diagnostic Aids
The IAC solenoid resistance is 6 to 13 ohms. Monitor the IAC PID duty cycle and/or voltage.

 

[Dr. Matt]

Thanks for the info. DTC must not be related to miss at top end then. Truck normally idles perfect but it did stumble and die after I pulled off the highway and stopped after a WOT pull to about 110 testing coil #8. It has never done that in the past and idles great since so maybe I'll clean my IAC valve When I do my next plug change.

Matt

 

[FordFanStan]

When you are ready to make the upgrade Matt, I suggest getting the Weapon X coils with iridium plugs. I have seen all types of weird feedback issues with stock coils so even if you're swapping it may not eliminate all your issues. I seen on the other forum you said you had BR7's you were going to try, to let you know, those are not iridium, only the NGK IXs , Denso ITs, and Weapon X plugs are iridium that will suit our application. Kepp me informed buddy, FFS

 

[Dr. Matt]

Stan,

The 7's I Have are the IX's so hopefully they work. I'll let you know. Hoping I don't have to buy coils to get into the 11's.

 

[Dr. Matt]

Well I put in the NGK BR7Ix's that came in my built motor from Dante. I origonally swapped them out for TR6's because the idle and driveability were really bad with the first tune I got (not JJ's tune). Now the truck idles better with these plugs at .028" gap than it ever did with the TR6's. I made two back to back pulls on my DD tune up to 130 and don't feel any miss at all. I guess I'll see how it does for the next two weeks and see if I can get my Heaton fed DMP motored WMS tuned full weight truck to run an 11 on the 27th.

I have a brand new set of TR6's in the garage too and I'll definately be taking them to the track, just in case. It took me 45 minutes to swap out the plugs even though they were already gapped and I already had the tools out. I bet without the EGR I could do it in 40.

Thanks for all the suggestions & help guys!
Matt

 

[FordFanStan]

:thumbsup: Glad I could help. We supplied you those plugs for a reason oke: But seriously with your boost and power level I think you should stick with an iridium and in that heat range. Keep me updated bud and I will try to get you a sig soon. FFS

 

[Dr. Matt]

Thanks again Stan. I take it you got the pics. I'll let you know how it does on the 27th.

Matt