Truck uses Throttle Follower P/N Tables when In Gear

[ferocity02]

Started messing with throttle follower yesterday. My PCM thinks it's in 1st gear all the time (according to GM.GEAR) with the 4L60E to T56 swap, even with the T56 segment swap from an f-body. Maybe it's because my clutch switch is not hooked into the PCM.

Anyways, I zeroed out the throttle follower decay rate and decay delay in P/N (B4319 B4320). When I rev the engine the RPM's will hang at around 1300 RPM indefinitely when I'm parked. I did not try it when moving. So I put these tables back to stock and now it's back to normal. This tells me that the PCM is using the P/N throttle follower tables even though it claims to be in gear.

Other P/N tables in the tune, like idle speed and idle airflow, are also zeroed out but it's correctly using the In Gear tables anyways.

Anyone know what's going on here?

Thanks! :cool:

[ferocity02]

Just spent some time in my log to see what the throttle follower was doing, and indeed it is using the P/N decay and delay tables even when moving and in 1st gear according to the GM.GEAR PID.

But why isn't using the P/N tables anywhere else? Other P/N tables in the tune that are zeroed out are the idle speed, idle airflow, and throttle cracker.

[joecar]

GM.GEAR is used by the AT, I don't believe it is used/updated for MT.

MT determines gear by gear ratio (try logging GM.BOXRATIO).

Both AT and MT use the P/N tables... for MT P/N means clutch is disengaged (detected via CPP switch).

IDK why it's not using the other P/N tables (is your trans segment for AT or MT...?)

[ferocity02]

If the PCM is supposed to use the P/N idle speed table but it is zeroed out, will it perhaps default to the In Gear table instead?

The trans segment is for a manual, I used an f-body manual segment and 12212156 OS.

I will try logging GM.BOXRATIO

[ferocity02]

I logged GM.BOXRATIO and it never left 0.0.

Using the P/N throttle follower tables is not a problem, in fact I just spend a couple hours working on them. But it's concerning why it's using these P/N tables and no others...

[joecar]

Looking back thru my logs looks like BOXRATIO and GEAR only work for AT.

MT has no gear indicator at all.

P/N works for both AT and MT as noted above.


Do you have the CPP installed...?

[ferocity02]

Looking back thru my logs looks like BOXRATIO and GEAR only work for AT.

MT has no gear indicator at all.

P/N works for both AT and MT as noted above.


Do you have the CPP installed...?

I do have a clutch switch but it's not hooked to the PCM. It's only job is for allowing starting and to cut cruise control.

If the P/N tables also work for a manual, why do the stock '02 Camaro and Corvette manual tunes have the P/N idle speed and idle desired airflow zeroed out?

[joecar]

Good question, I don't know yet.

[ScarabEpic22]

Im going to sound like a broken record here ferocity02, but why cant you just wire the CPP switch into the PCM? Im pretty sure most of the issues you're having are directly related to it not being connected to the PCM, sounds like you're getting frustrated so IMHO it'd be a LOT easier to just wire it up like GM had it and copy the values from a manual 4.8L tune to start with. You keep spending tons of time fighting it, why not make it easier on yourself?

[ferocity02]

Im going to sound like a broken record here ferocity02, but why cant you just wire the CPP switch into the PCM? Im pretty sure most of the issues you're having are directly related to it not being connected to the PCM, sounds like you're getting frustrated so IMHO it'd be a LOT easier to just wire it up like GM had it and copy the values from a manual 4.8L tune to start with. You keep spending tons of time fighting it, why not make it easier on yourself?

Because it works well enough for me without the clutch switch hooked to the PCM, no need to add complexity to the tune either.

The question here is if a manual tune does use P/N tables when the clutch is depressed or when it's in neutral, why are the idle P/N tables zeroed out in stock manual tunes? And why does it use the P/N throttle follower tables but no other P/N tables? My truck is clearly using the In Gear tables for some things, and the P/N tables for others. At this time, and without further understanding, I don't see how adding the clutch switch will help this.

I also don't understand how the PCM knows when the trans is in neutral, other than the clutch being depressed, or if VSS is 0 and RPM is > 0.

[ScarabEpic22]

Because it works well enough for me without the clutch switch hooked to the PCM, no need to add complexity to the tune either.

The question here is if a manual tune does use P/N tables when the clutch is depressed or when it's in neutral, why are the idle P/N tables zeroed out in stock manual tunes? And why does it use the P/N throttle follower tables but no other P/N tables? My truck is clearly using the In Gear tables for some things, and the P/N tables for others. At this time, and without further understanding, I don't see how adding the clutch switch will help this.

I also don't understand how the PCM knows when the trans is in neutral, other than the clutch being depressed, or if VSS is 0 and RPM is > 0.

What I was trying to say is you are adding complexity to the tune by not wiring it up like GM did. You are spending loads of time troubleshooting issues that simply wouldnt exist if you connected the CPP to the PCM. It is great that it is working without it hooked in, but I think you're running in circles trying to figure out a way around a simple issue that is easily remedied. To me, the easiest way to find a solution would be to run the wires to the PCM from the CPP and any other sensor that a factory manual truck would have so it is exactly like GM would have wired it. Then start with all of GM's stock settings for a 4.8L manual (only one I know that came with a manual) and start tweaking from there.

I do not know exactly how the PCM determines gear with a manual trans, I think Joe posted about it a week or two ago. I believe it is a combo of RPM and VSS, but dont quote me on that.

[ferocity02]

What I was trying to say is you are adding complexity to the tune by not wiring it up like GM did. You are spending loads of time troubleshooting issues that simply wouldnt exist if you connected the CPP to the PCM. It is great that it is working without it hooked in, but I think you're running in circles trying to figure out a way around a simple issue that is easily remedied. To me, the easiest way to find a solution would be to run the wires to the PCM from the CPP and any other sensor that a factory manual truck would have so it is exactly like GM would have wired it. Then start with all of GM's stock settings for a 4.8L manual (only one I know that came with a manual) and start tweaking from there.

I do not know exactly how the PCM determines gear with a manual trans, I think Joe posted about it a week or two ago. I believe it is a combo of RPM and VSS, but dont quote me on that.

By complexity I mean having to adjust both P/N and In Gear tables rather than just one or the other. I have yet to find an LS1B tune for a manual 4.8L. Do you have one?

[ScarabEpic22]

I havent, one of my buddies has one but he lives 5 hours away from me and I didnt have my V2 when I saw him last.

If someone has a VIN for a manual 4.8L, I can bench flash my LS1B PCM with it the next time I use Tis2Web then read it out for everyone.

[ferocity02]

I take back what I said earlier... it is hit and miss whether or not the truck is actually using the throttle cracker table. I kept adding air but it seemed like nothing was happening, so I made the entire table 12 g/s to see if it really was working, and it was, but it seemed to only add the air when I am first starting off from a stop, then it would decay out as I continued to drive for 5-10 seconds. Very strange... I even made the P/N and In Gear cracker tables the same and it did the same thing.

How can I figure out if throttle cracker/follower are active? I've been logging GM.IAC "Idle Air Control Position" to see the steps and then GM.IACDES_B "Desired IAC Air Flow". Can someone explain exactly what IACDES_B is? I was thinking it's the sum of idle, cracker, and follower airflow. But at idle it displays about 0.4 g/s less than my desired idle airflow.

I logged GM.TSTATE00 "Transmission State 00" and a bunch of other transmission stuff, and it said that my clutch is depressed all the time, except when I turn the engine off then it says released. None of the other trans PIDs were informative, but it does recognize that it's an "M6".

[darcy]

How can I figure out if throttle cracker/follower are active?

Try logging GM.IAC_TC_DMA and GM.IAC_TF_DMA for Cracker and Follower.

[ferocity02]

Try logging GM.IAC_TC_DMA and GM.IAC_TF_DMA for Cracker and Follower.

They aren't available for my PCM :(

[joecar]

You might be able to change OS to one that supports the _DMA pids.

[slows10]

I havent, one of my buddies has one but he lives 5 hours away from me and I didnt have my V2 when I saw him last.

If someone has a VIN for a manual 4.8L, I can bench flash my LS1B PCM with it the next time I use Tis2Web then read it out for everyone.

Does your buddy have a dbc or dbw 4.8 manual tune? I assume the op is looking for a dbc 4.8 manual tune?

[slows10]

OP, minitryker posted a 4.8 manual tun exactly 4 weeks ago in this forum. Not very hard to find if you know where to look. Also contrary to forum belief that a 4.8 was not the only truck to come with a manual. There were quite a few 6.0 lq4 with a manual trans over many year models.

[ferocity02]

Something is definitely funky... A log I made shows throttle cracker airflow being added suddenly at random times and then quickly decayed out. Sometimes it is added in odd double-spikes which start right when I hit 18 mph, and it adds 6 g/s which is correct (see frame 1024). Then then sometimes it will add it when I hit 3 mph which is the correct TC activate speed, here too it also adds the correct amount (see frame 690).

Perhaps it's calculating something in the background so when it hits 18 mph it suddenly thinks it's in gear. Clutch switch or not, this isn't right.

I might go back to the auto tune since I didn't have any issues with that.

[ScarabEpic22]

Does your buddy have a dbc or dbw 4.8 manual tune? I assume the op is looking for a dbc 4.8 manual tune?

Its a 00 or 01, so DBC Im betting.

[ferocity02]

Well I switched back to an auto tune and it seems much happier. It's using all of the In Gear tables now rather than just some of them. I am using f-body manual throttle cracker and follower settings, they need some slight tweaking but overall they work great.

[macca_779]

I can confirm that my factory manual 99 ls1 using os5 also uses the throttle follower P/N decay rate table. Everything else uses in gear tables

So your situation is not unique. FWIW Aussie ls1 cars don't use the clutch switch for the PCM either.

[ferocity02]

I can confirm that my factory manual 99 ls1 using os5 also uses the throttle follower P/N decay rate table. Everything else uses in gear tables

So your situation is not unique. FWIW Aussie ls1 cars don't use the clutch switch for the PCM either.

Interesting! What about throttle cracker? That's the one I was having the most issue getting to work consistently.

[macca_779]

Interesting! What about throttle cracker? That's the one I was having the most issue getting to work consistently.

In gear tables are used for cracker

[ferocity02]

Do you know if the PCM thinks the clutch is depressed or released? For my LS1B PCM there were some transmission state pids that would give the info on the clutch, forgot which one though. Mine thought the clutch was depressed the whole time.

[macca_779]

Do you know if the PCM thinks the clutch is depressed or released? For my LS1B PCM there were some transmission state pids that would give the info on the clutch, forgot which one though. Mine thought the clutch was depressed the whole time.

No idea as I've never bothered to log it

[ELake20]

On my 03 I never had any issues with using the A4 tune with DTCs disabled. I bumped my idle to act as a stall saver for acceleration at traffic lights and that was about it. Suffers from some small drivability issues, slight surge on accel but wbo readings were acceptable.