Put the Cobra on a loading dyno last week and ran into some problems with tuning
1st pull the car had a miss anything above 4000rpm and the motor was visibly stumbling
Holding speed around 3k it had a slight misfire every 10 sec. “light pop”
1st thing we tried was to change the plugs
I was running tr7ix and my tuner didn’t like that so we changed them out for some tr6's
That cleared it up some but the misfire was still there.
He tried clearing it up with tuning and nothing seemed to help. He even had SCT on the phone and they also made some changes to the tune remotely and none of that helped.
We moved the coils around and no real noticeable change doing that either.
One thing he noticed was the voltage to the ECM was dropping around 12.6 volts at WOT. So we put a charger on it while we ran it and that did not change anything.
At the end of the day he tried another tune from a Whipple car and the car ran smooth and did not stumble once. After looking at the afr it was running a little lean. 12.1 Or so, he made one change to the tune and hit 11.4 afr and the motor started to miss and stumble again.
At this point he thinks it’s one of the coils causing the problem.
I have two dyno sheets and it’s very clear in the log when it drops power.
I also did a WOT run in 2nd gear on the street and have a livelink log file of that. WOT is at the end of the log.
It really does seem the coil(s) could be the cause but I keep thinking about the low voltage at WOT. I’m also seeing this on the street in my logs. A cold start shows 14.4 volts at idle. Once it’s warmed up and driven it’s around 13.8 at idle.
I called a local ford dealer and they said there is a computer that can test the coils. Wds 2000? Know anything about this? Do you think it might show a weak coil?
I’ve ohm’ed the coils out and all of them are in range and none show a large difference.
the only noticable diffrence was leaning the car out but it was still down on power just smoother
both runs are with 8 degrees of timing
RapidShare: Easy Filehosting - 2nd gear WOT run @ end
if the downloads get maxed out let me know and i will unload it again
Thanks
1st pull the car had a miss anything above 4000rpm and the motor was visibly stumbling
Holding speed around 3k it had a slight misfire every 10 sec. “light pop”
1st thing we tried was to change the plugs
I was running tr7ix and my tuner didn’t like that so we changed them out for some tr6's
That cleared it up some but the misfire was still there.
He tried clearing it up with tuning and nothing seemed to help. He even had SCT on the phone and they also made some changes to the tune remotely and none of that helped.
We moved the coils around and no real noticeable change doing that either.
One thing he noticed was the voltage to the ECM was dropping around 12.6 volts at WOT. So we put a charger on it while we ran it and that did not change anything.
At the end of the day he tried another tune from a Whipple car and the car ran smooth and did not stumble once. After looking at the afr it was running a little lean. 12.1 Or so, he made one change to the tune and hit 11.4 afr and the motor started to miss and stumble again.
At this point he thinks it’s one of the coils causing the problem.
I have two dyno sheets and it’s very clear in the log when it drops power.
I also did a WOT run in 2nd gear on the street and have a livelink log file of that. WOT is at the end of the log.
It really does seem the coil(s) could be the cause but I keep thinking about the low voltage at WOT. I’m also seeing this on the street in my logs. A cold start shows 14.4 volts at idle. Once it’s warmed up and driven it’s around 13.8 at idle.
I called a local ford dealer and they said there is a computer that can test the coils. Wds 2000? Know anything about this? Do you think it might show a weak coil?
I’ve ohm’ed the coils out and all of them are in range and none show a large difference.
the only noticable diffrence was leaning the car out but it was still down on power just smoother
both runs are with 8 degrees of timing
RapidShare: Easy Filehosting - 2nd gear WOT run @ end
if the downloads get maxed out let me know and i will unload it again
Thanks
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