Hesitating shifts

[Andrew_99GTP]

Ever since I went turbo my trans does not like to shift. Under light throttle it isn't as noticeable and med you can just notice it. But at WOT it is really bad. I will get to the point where the car should shift and it will just hold the rpm for a sec or two and then shift. When it does this at WOT it slams into the grear pretty hard. 1st gear to 2nd gear is the worst. I thought maybe it was in the TM so I pretty much shut TM off and it still does it. Maybe I missed something. Also I am out flowing my maf, whether or not that matters? Anyone have any ideas?

[Trannyman95]

Ever since I went turbo my trans does not like to shift. Under light throttle it isn't as noticeable and med you can just notice it. But at WOT it is really bad. I will get to the point where the car should shift and it will just hold the rpm for a sec or two and then shift. When it does this at WOT it slams into the grear pretty hard. 1st gear to 2nd gear is the worst. I thought maybe it was in the TM so I pretty much shut TM off and it still does it. Maybe I missed something. Also I am out flowing my maf, whether or not that matters? Anyone have any ideas?

You need a tune and trans set up for the power levels unquestionably! If your trans is stock then it is going to hate you with a turbo. Is anything done to your trans at all? A maxed out maf table is much better than one that isnt reading high enough as low maf signal will definately cause delayed shifts. You are going to have to lower your shift speeds and up your shift pressure tables quite a bit. I have no idea what you have for pcm settings now but you will definately need to do some tuning with the trans parameters.

[Andrew_99GTP]

I guess I could have given you some more info right away .

It is still a 100% stock trans, the shift pressure and shift time are the same as a zzp 1.0. Can you raise the shift pressure above 96psi through the pcm? If not how soon in the step table do you have the pressure at 96psi, I am using a dhp for tuning btw.

[Trannyman95]

I dont know if DHP offers this since I use HPT, but there is a Force Motor Current table, or two tables depending on the pcm. This is the desired pressure control solenoid amperafe vs commanded pressure table number. 0 being low pressure and this means higher amps, 1 is max, and 96 or 100 is the high end of the pressure table, and 0 amps is max line pressure but you generally cant turn this all the way to 0 or it will throw a code. Also I dont know what you can and cannot watch with the scanner, but you need to go out and drive the car at WOT when this is happening and watch "Commanded PCS Amps" If it is around .2 then it is too high and not generating enough pressure for what your trans is requiring. A shift kit set on medium to high setting would probably help you out greatly since your trans is stock and soon to be a pile of black dust under the car! If you can view commanded amps then you know what the pcm is wanting for amps and you can look up on the amperage table in the tuner where that number is at and make adjustments, which a lower number will produce higher line pressure. Get all of that? lol

[Andrew_99GTP]

My dhp doesn't have any of that. I have been thinking of getting an HPT. Is it worth the extra money?

I went back and looked at my tune again and found that none of my perf shift pressures were changed? I copied a zzp 1.0 pcm file? So I up'd all of my pressures and it feels better but I still can't really tell because I can't do a WOT shift because I out flow my maf. I need to get my afc installed.

On a side note the tranny feels a bit loose durning the shifts I am hoping it lasts the summer.

[Trannyman95]

Why do you want to install an AFC if you have a tuner? You can adjust your entire maf table with the tuner and is going to do the exact same thing as an AFC and is one less thing to plug in and fail. Even though you currently are maxing out the maf why not go WOT? you can work on plenty of things in the tune go help that out, or just go to a larger throttle body or maf sensor to give yourself more head room. If you used a ZZP file and it was for an 01 or newer car then likely the perf shift tables are still stock since 01 and up never had the performance shift button and I dont think they modify those tables but it should certainly be changed on an 00 and earlier pcm.

[TDCRacing]

The AFC to my knowledge provides external MAF recalibration throughout the MAF's entire flow range. It's kind of hard to explain but i belive the afc only works within the maf's range.Not beyond that. So i dont see how you can add or subtract hertz to the actual maf its self. Even if you could the maf sensor is only going to read what it was ment to read. wich is everything below 11,500. If im not seeing something just let me know. im not too too firmiliar with afc's for the fact i have never used one before

[Reptile]

Yup yup. It's extremely simple to scale the MAF with a PT. That's the way I tune now so that I dont jack up the PE or the AE tables too much. Either way it all goes back to the grams/sec in the PT MAF tables.

[Andrew_99GTP]

Yup yup. It's extremely simple to scale the MAF with a PT. That's the way I tune now so that I dont jack up the PE or the AE tables too much. Either way it all goes back to the grams/sec in the PT MAF tables.

Please explain because I am obviously missing something here?

[Reptile]

If you go into the MAF table with your powertuner, you can see how it has the volume listed in grams/sec. To fatten up the fuel, you can add or subtract a % of fuel within the frequency range that is either too lean or too rich. Key to this is do not make a big jump in your adjustments. Highlight the boxes you want to change, then custom fill. If you are going to add 1% then you need to type in 101 and click percent. Same with pulling fuel, except you enter 99 and click percent.

Basically you're telling the comp that there is more/less air coming into the throttle body at that given frequency. You won't see much change visibly in the table, because you might be going from 2.86 g/sec to 2.89, but it does make a huge difference in the tune.

I personally think it's a decent way to tune on the fly, especially at the track...and you don't need to reset your fuel trims for this. This is just the way I do it on my car, and a couple people that I tweak for.

[Andrew_99GTP]

If you go into the MAF table with your powertuner, you can see how it has the volume listed in grams/sec. To fatten up the fuel, you can add or subtract a % of fuel within the frequency range that is either too lean or too rich. Key to this is do not make a big jump in your adjustments. Highlight the boxes you want to change, then custom fill. If you are going to add 1% then you need to type in 101 and click percent. Same with pulling fuel, except you enter 99 and click percent.

Basically you're telling the comp that there is more/less air coming into the throttle body at that given frequency. You won't see much change visibly in the table, because you might be going from 2.86 g/sec to 2.89, but it does make a huge difference in the tune.

I personally think it's a decent way to tune on the fly, especially at the track...and you don't need to reset your fuel trims for this. This is just the way I do it on my car, and a couple people that I tweak for.

Ok I knew all of that, but that isn't my problem.

This is how I understand it. Air passes over the maf sensor and creates a hz reading (more air a higher hz reading). The pcm takes the hz reading looks up the maf table. Say you are getting 5000hz, the pcm goes to the maf table looks at the 5000hz cell and then whatever number is next to it is how much air is coming in and the pcm makes its adjustments accordingly.

I am not using the AFC as a tuning method, I just need something to scale the hz readings so I don't ever go above 11500hz (which I am going above right now). I won't be using the afc to adjust my fuel trims or anything like that. Moreless I am tricking my pcm into thinking I have a bigger maf.

[TDCRacing]

So what happens when you do max out the maf? where does it get it's fueling info from? or does it go off of the last hz reading before it goes beyond that 11500 threshold? or does it do off of the 11500 hz cell? Resorts to VE table? just curiouse. The way i see it is that the maf has a max output frequency of 11500hz. And theres nothing that can add additional hz to the maf or trick the pcm into doing it. I mean a sensor can only read what it can readright, not more not less? now i would understand if it was tricking the pcm to read different data than it was actually reading but still in the sensors range. maybe i just dont understand how the afc works though. I understand it to wok by adding or subtracting a percentage of fueling to the maf's frequency range (under 100% would be less fuel and over 100% would be more) but not above or below what the maf is allowed to read.

[Andrew_99GTP]

So what happens when you do max out the maf? where does it get it's fueling info from? or does it go off of the last hz reading before it goes beyond that 11500 threshold? or does it do off of the 11500 hz cell? Resorts to VE table? just curiouse. The way i see it is that the maf has a max output frequency of 11500hz. And theres nothing that can add additional hz to the maf or trick the pcm into doing it. I mean a sensor can only read what it can readright, not more not less? now i would understand if it was tricking the pcm to read different data than it was actually reading but still in the sensors range. maybe i just dont understand how the afc works though. I understand it to wok by adding or subtracting a percentage of fueling to the maf's frequency range (under 100% would be less fuel and over 100% would be more) but not above or below what the maf is allowed to read.

It isn't that the sensor won't read over 11500hz it is the pcm table doesn't go over 11500hz and you can't change that. So if you scale the maf sensor reading then you can keep the hz reading under 11500 so you stay in the table. When you run a bigger maf sensor you still can't go over 11500hz, but with a bigger maf your hz reading will go down because of the larger bore. So if I were to scale my maf by 50% and I was getting a hz reading of 5000hz it would be the same as 10000hz on an unscaled maf. Are you following? So my grams/sec on the scaled maf at 5000hz would be the same as the grams/sec at 10000hz on an unscaled maf. Make sense? I just used 50% as an example because it was easy, I won't scale my maf by that much.

[Andrew_99GTP]

So what happens when you do max out the maf?

The pcm uses the 11500hz grams/sec cell for fueling causing the car to go very lean.

On a side note the sensor will read above and beyond 11500hz because when I out flow it I have seen 11550 on the pt. The table is the limiting factor.

[Trannyman95]

I know what you are saying, yes the pcm table stops at 11500 but that doesnt mean you need an AFC to tune the car, again they dont even sell them anymore because it is not needed to tune the car and you dont need the maf table only to rely on WOT fueling. How high does the sensor actually read??? Good question, but as I mentioned a few times before keep in mind that you have to rescale your entire MAF table to compensate for this if you make the input value lower with the AFC. ALL of your fuel trims will be wrong except in PE mode where it doesnt use them, but once you lower your maf input then the car will run excesively lean since you will have to lower the signal a bit, and then you have to go into other tables to add fuel anyways so why waste time with an AFC? You have a tuner and again the maf table is not the only thing to use for WOT fueling. Buick GNs max out the maf often when only at half throttle or not anywhere near peak boost and rpms but is not a problem because proper tuning corrects this. Once the maf input is at the max of what the pcm can read then the maf value will continue to climb but the pcm only uses the last highest point on the table. If you want to use the AFC to help your problem that is fine and you will have a lot of work making fuel trims and WOT fueling correct again, I am just trying to make you realize that it is not necessary and that the vendors dont use them anymore because it can all be done in the tuner.

[Reptile]

OK, I see what you're saying. I don't think there is a way to keep it from going over a certain Htz range. It's one of those work with what you're given type of things.

If you want to trick it into thinking you have a bigger MAF...you'll most likely have to enter in a bigger maf table. But you're possibly still going to have to worry about the frequency range.