Headers glowing just a little, is this normal?
- Thread starter JH96GT
- Start date
Yep... your final run (red lines) look damned near perfect. I can't imagine your heads glowing with an AFR of 12.
Keep in mind however, that your dyno shows power runs!
Who knows what the AFR is while you're sitting there at idle. It might need a little tweaking. He might have even forgotten to look at idle AFR....
I mean... I don't imagine that you had the hood open and were sitting on the front bumper doing 100+ MPH when you saw the heads glowing.
Keep in mind however, that your dyno shows power runs!
Who knows what the AFR is while you're sitting there at idle. It might need a little tweaking. He might have even forgotten to look at idle AFR....
I mean... I don't imagine that you had the hood open and were sitting on the front bumper doing 100+ MPH when you saw the heads glowing.
Yep... your final run (red lines) look damned near perfect. I can't imagine your heads glowing with an AFR of 12.
Keep in mind however, that your dyno shows power runs!
Who knows what the AFR is while you're sitting there at idle. It might need a little tweaking. He might have even forgotten to look at idle AFR....
I mean... I don't imagine that you had the hood open and were sitting on the front bumper doing 100+ MPH when you saw the heads glowing.
Nope, it was in garage and I was reving it up to about 3k and holding to heat it up. W/ My MAC's and O/R H, my neighbors love me....
Thanks for the help. But if I decide to do the 100 mph trick, I need a volunteer for riding on the hood. I'll even take off the hood for some hand holds.....
Lemonade
Founding Member
cobradvm
New Member
I have a question for you - how did the tuner get your AF to go from 14 to 12? As Daggar alluded to earlier, if he simply bumped the fuel pressure, he has done you no favors. Unless you have a chip. Tweecer, PMS or some other engine management system, the only way he can make your AF drop like that is to bump the FP.
When you do a dyno run at WOT, the car goes into open loop (OL). The computer disregards any input from the O2 sensors since it doesn't car about fuel economy, and reads from its WOT tables. The dyno operator reads the AF as being lean - on your case 14 - way lean - he should have aborted that run and never let you get close to 6000 rpm with an AF of 14. Anyways, he sees your lean, and bumps your FP at the AFPR. Now you immediately repeat the run, and Walla! AF is now 12 - everything is great. Well perhaps not - the car has not run in closed loop where it is reading the O2 sensors. Once you drove the car off the dyno, you are no longer at WOT, and the car is now in closed loop and the computer adjusts the AF based on the readings from the O2 sensors which now read rich - surprise, surprise - the computer wants an AF of 14.7 for complete combustion so it shortens your injector pulses. This is all fine and dandy except it puts these adjustments into the WOT tables as well - now after driving around for a while (a few hours) if you do a WOT, your AF is back to 14! Also as Daggar points out, there is a limit to what the computer can adjust things to (10-20%). Once past that, it can't make any further adjustments so it will stay rich across the board.
Anyway, hope that makes some sense - I suspect you are simply lean and the eec4 has compensated for the tuner bumping the FP. I have been through this with my own car - I had it dynoed 3 times with the FP getting bumped each time - you may need some other tuning device as mentioned above to get the tune right in the car. I ended up getting an AF gauge and a PMS to get my car tuned right.
When you do a dyno run at WOT, the car goes into open loop (OL). The computer disregards any input from the O2 sensors since it doesn't car about fuel economy, and reads from its WOT tables. The dyno operator reads the AF as being lean - on your case 14 - way lean - he should have aborted that run and never let you get close to 6000 rpm with an AF of 14. Anyways, he sees your lean, and bumps your FP at the AFPR. Now you immediately repeat the run, and Walla! AF is now 12 - everything is great. Well perhaps not - the car has not run in closed loop where it is reading the O2 sensors. Once you drove the car off the dyno, you are no longer at WOT, and the car is now in closed loop and the computer adjusts the AF based on the readings from the O2 sensors which now read rich - surprise, surprise - the computer wants an AF of 14.7 for complete combustion so it shortens your injector pulses. This is all fine and dandy except it puts these adjustments into the WOT tables as well - now after driving around for a while (a few hours) if you do a WOT, your AF is back to 14! Also as Daggar points out, there is a limit to what the computer can adjust things to (10-20%). Once past that, it can't make any further adjustments so it will stay rich across the board.
Anyway, hope that makes some sense - I suspect you are simply lean and the eec4 has compensated for the tuner bumping the FP. I have been through this with my own car - I had it dynoed 3 times with the FP getting bumped each time - you may need some other tuning device as mentioned above to get the tune right in the car. I ended up getting an AF gauge and a PMS to get my car tuned right.
I can't imagine that any tuner worth his salt would just bump fuel pressure and call it quits although you do make a good point.
I'd just assumed that this car was chip tuned but didn't actually ask the question. To me, reference to a "tuner" means chip tuned.
That said, the difference between the 14 and the 12 AFR run would have been the result of modifying the fuel tables to get the AFR where it's supposed to be. My suspicion is that little or no attention was paid to idle and part power portions of the tune (neglecting this area seems fairly common. Folks tend to dial in the xfer function, and breakpoints and let the EEC do the rest).
I'd just assumed that this car was chip tuned but didn't actually ask the question. To me, reference to a "tuner" means chip tuned.
That said, the difference between the 14 and the 12 AFR run would have been the result of modifying the fuel tables to get the AFR where it's supposed to be. My suspicion is that little or no attention was paid to idle and part power portions of the tune (neglecting this area seems fairly common. Folks tend to dial in the xfer function, and breakpoints and let the EEC do the rest).
cobradvm
New Member
I don't quite understand. What are you wanting to know? How it was tuned originally?
I haven't had a another tune since posting.
I hate to upset the apple cart hear but headers don't glow from a lean mixture. The only reasons they will glow is from either an overly rich mixture and or retarded timing. A lean mixture will raise combustion chamber temps and cook spark plugs but a rich mixture/retarded timining will ignite the unburned fuel in the exhaust system and cause the headers to glow. Sounds like your tuner might have found you some extra WOT power but screwed-up your tune at idle and part throttle.
87_stang
Member
As for your volunteer... Try Ryan218 in the talk forums. Just tell him that, that's the way EVERYONE does it. He'll believe you!
cobradvm
New Member
You had posted a dyno graph that should two runs - one with an AF of 14 - presumably that was the first run and one with an AF of 12 - what did the tuner do to the car to get the AF to drop?
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