Most consistent tune
Most consistent tune Would it be more consistent (et wise) to run a sd tune at the track? Or would it be better to set the car up open loop ? I am looking to have a race only tune that yields the most consistency. Any other recommendations to get the car the most consistent.
Open or closed loop has nothing to do with the maf sensor.
Closed loop uses the o2 sensor to adjust fueling, open loop does not.
Now my preference.....remember this is just my opinion and others my disagree
If your looking for consistency, nothing beats an open loop speed density set up. When I get a ve table nailed down (and I mean nailed down) I don't like o2 sensors ******* with it. o2 sensor integrity can also change depending on many variables which can drive you mad when trying to get everything to repeat from pass to pass. I also, don't want a maf deciding what my motor is ingesting. I know what it is ingesting and I have found great consistency in the ecu only relying on the IAT and MAP sensors to calculate fueling.
Others will argue, but talk to bracket racers that use efi....the less sensors you have trying to compensate the tune the more consistent it will be.
I have a feeling that most of the tuners that would disagree with this are not considering that you are talking about a track only tuneup.
Closed loop uses the o2 sensor to adjust fueling, open loop does not.
Now my preference.....remember this is just my opinion and others my disagree
If your looking for consistency, nothing beats an open loop speed density set up. When I get a ve table nailed down (and I mean nailed down) I don't like o2 sensors ******* with it. o2 sensor integrity can also change depending on many variables which can drive you mad when trying to get everything to repeat from pass to pass. I also, don't want a maf deciding what my motor is ingesting. I know what it is ingesting and I have found great consistency in the ecu only relying on the IAT and MAP sensors to calculate fueling.
Others will argue, but talk to bracket racers that use efi....the less sensors you have trying to compensate the tune the more consistent it will be.
I have a feeling that most of the tuners that would disagree with this are not considering that you are talking about a track only tuneup.
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OL SD is fine just make sure it cant make too much of an adjustment to your fuel table.... this way if you have a O2 that goes bad you dont get a totally botched run. +/- 10% is quite a bit of a leash.... +/-5% is more ideal.
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Factory PCMs can be set to make no corrections at WOT.
My FAST XFI does not support a MAF. I run it in open loop. Closed loop would be fine in high gear. In low gear it winds up too fast. My tables are in 500 RPM increments. In lower gears, and the VE table not right, it chased it's tail trying to make corrections in closed loop. I.E: lean at 7000, the correction showed up at 7500, which may not have needed a correction. Then pulling that fuel back out at 8000, etc.
As it is the logger shows 12.75-1 to 12.88-1 all the way up. That is where it runs quickest. Makes more power on the dyno at 13.2-1, but we don't race dynos, do we? :-)
If it was closed loop in high gear, it would be fine.
My VE table's other parameter is MAP KPA, in 3 KPA increments.
Once I get to run it at various BARO conditions, and get that row dialed in, it repeats very well when I see those conditions again.
I log every run and seldom have to touch the tuning until I change the engine around.
GM uses MAF sensors on their multi million dollar 24 Hrs of Datona cars,I so the negative comments about MAFs are misguided. People just don't know.
Factory PCMs can be set to make no corrections at WOT.
My FAST XFI does not support a MAF. I run it in open loop. Closed loop would be fine in high gear. In low gear it winds up too fast. My tables are in 500 RPM increments. In lower gears, and the VE table not right, it chased it's tail trying to make corrections in closed loop. I.E: lean at 7000, the correction showed up at 7500, which may not have needed a correction. Then pulling that fuel back out at 8000, etc.
As it is the logger shows 12.75-1 to 12.88-1 all the way up. That is where it runs quickest. Makes more power on the dyno at 13.2-1, but we don't race dynos, do we? :-)
If it was closed loop in high gear, it would be fine.
My VE table's other parameter is MAP KPA, in 3 KPA increments.
Once I get to run it at various BARO conditions, and get that row dialed in, it repeats very well when I see those conditions again.
I log every run and seldom have to touch the tuning until I change the engine around.
GM uses MAF sensors on their multi million dollar 24 Hrs of Datona cars,I so the negative comments about MAFs are misguided. People just don't know.
Last edited by Ed Wright; Nov 6, 2013 at 07:45 PM.
Please don't post information that you don't know about. It screws people up. OLSD means the o2 sensors are ignored, therefore no correction could ever be made.
We have tuned tons of cars that bracket race, many of which have wons their respective classes numerous times. There is more to consistency than just OL vs CL. If you're just comparing OL vs CL then OL would be more consistent IF your tune is dialed in. This is running stock pcm still not aftermarket setups.
If it's a race car with open headers and a factory computer you certainly don't want it in closed loop!
When using the FAST XFI or be Holley in closed loop you need to set the min TPS for closed loop to 95% to 100%, usually the min RPM to 6000 or 6500.
When using the FAST XFI or be Holley in closed loop you need to set the min TPS for closed loop to 95% to 100%, usually the min RPM to 6000 or 6500.
I only got a few shakedown runs about a month ago. I let off after the 1/8 mile the first couple of runs. Car seem to run fine. The last couple of runs were 1/4 mile, about the 1,000' mark the car acted like it was bouncing off the rev limiter. It did not do this in
1st and 2nd gear, only 3rd gear. Rev limiter was set at 7200 then change it to 7500, still bounced. I didn't notice what rpm it was at when it started to act this way, could it be pulling fuel in 3rd gear only. Th400 RMVB. Car ran 131 mph cutting out.
Sorry to hi jack OP.
1st and 2nd gear, only 3rd gear. Rev limiter was set at 7200 then change it to 7500, still bounced. I didn't notice what rpm it was at when it started to act this way, could it be pulling fuel in 3rd gear only. Th400 RMVB. Car ran 131 mph cutting out.
Sorry to hi jack OP.
Last edited by RENE'S RAGE; Nov 10, 2013 at 09:01 AM.
Why would you not be watching the tach when you thought it was bouncing off the rev limiter? Be aware, the factory tach is a joke. They move too slow to be useful anywhere but high gear, and then read high.
Get yourself an Autometer play back tach. Even log with a good scan tool. RPM would be correct, except that the data stream update rate is too slow. You only see "data frames", or several data snap shots, with a scanner so data between data frames is lost. You likely won't see the actual WOT shift RPM. But, you will be able to watch injector pulse width to KNOW it is pulling fuel like you think it is. If the injector pulse does not narrow, but the O2 mvs drops you evidently have a fuel supply issue, or a misfire which makes the O2 mvs fall off.
Seat of the pants guessing is a waste of your time and things like valve spring life.
If you don't already have one, I would buy the tach.
Get yourself an Autometer play back tach. Even log with a good scan tool. RPM would be correct, except that the data stream update rate is too slow. You only see "data frames", or several data snap shots, with a scanner so data between data frames is lost. You likely won't see the actual WOT shift RPM. But, you will be able to watch injector pulse width to KNOW it is pulling fuel like you think it is. If the injector pulse does not narrow, but the O2 mvs drops you evidently have a fuel supply issue, or a misfire which makes the O2 mvs fall off.
Seat of the pants guessing is a waste of your time and things like valve spring life.
If you don't already have one, I would buy the tach.
Yes, the passes were seat of the pants. My factory tach only goes to 7,000. First time out in 5 years for me.
First time for new motor and trans. Dyno tune only.
Next year will log runs and track tune. Will get a tack also.
My question is why did it bounce off the rev limiter in 3rd gear and not
In 1st and 2nd gear?
First time for new motor and trans. Dyno tune only.
Next year will log runs and track tune. Will get a tack also.
My question is why did it bounce off the rev limiter in 3rd gear and not
In 1st and 2nd gear?
Last edited by RENE'S RAGE; Nov 10, 2013 at 03:43 PM.
i have holley EFI on my BBNOS combo that would run circles around any **** that you have.... so please dont be a dick to me.
Sounds like your BBNOS combo with Holley EFI is fast.