is it possible RTT doesn't work on certain ECMs?

[TTVert]

I have a 2000 C5 that i was trying to do some RTT on today. I ensured Real time mode was set to VE but no changes I make effect anything. I ensured I was running off the RAM table. I went to 0 in the idle VE cells as a sanity check as well as surrounding in case it was averaging them and it did nothing. Ditto up into the 80s. AFR just stayed where it was. I had attempted this w/ the MAF failed and without. Fuel trims disabled as well as with it forced into open loop and without. Looking for any input you guys may have as I'm a bit stumped here. Everything I have seen about this indicates I've done what I need to do to run RTT.

Thanks much guys

Dave

[murfie]

Did you try adjusting your secondary table. When you fail MAF it reverts to that. RTT adjust the primary table.

[TTVert]

Rtt pulls the primary ve table for rtt from what I gather and I cannot change that. Does that mean I cannot rtt without being in closed loop with maf skewing results? I think I did also try to rtt after bringing the maf back online thought.

[Jon S.]

Rtt pulls the primary ve table for rtt from what I gather and I cannot change that. Does that mean I cannot rtt without being in closed loop with maf skewing results? I think I did also try to rtt after bringing the maf back online thought.

No - that is not what he meant.

The 1999 and 2000 P01 PCM operating systems used 2 VE Tables - a primary and a secondary (or backup). The PCM will default to the secondary (or backup) VE Table if certain DTCs are present - like those required to fail the MAF - when attempting to tune the VE.

The 2001 and 2002 P01 PCM operating systems were updated to use a single VE Table - these are your best option, if you wish to use all of the RTT functions.

If you need to retain your 2000 model year OS - then straight up tuning using a Wide Band Oxygen Sensor is your best option - as the VE portion of the RTT option does not integrate with the early P01 PCMs.

[TTVert]

No - that is not what he meant.

The 1999 and 2000 P01 PCM operating systems used 2 VE Tables - a primary and a secondary (or backup). The PCM will default to the secondary (or backup) VE Table if certain DTCs are present - like those required to fail the MAF - when attempting to tune the VE.

The 2001 and 2002 P01 PCM operating systems were updated to use a single VE Table - these are your best option, if you wish to use all of the RTT functions.

If you need to retain your 2000 model year OS - then straight up tuning using a Wide Band Oxygen Sensor is your best option - as the VE portion of the RTT option does not integrate with the early P01 PCMs.

I understand what he meant and I know it falls back to secondary VE when MAF fails. However when you do RTT it pulls a VE table. That VE table has the values of my primary VE table so I have to assume that is the table it is modifying during RTT. So it appears with my 2000 PCM I cannot do RTT of VE when the MAF is failed.. Not a deal breaker, just wanted to make sure I wasn't doing something wrong. I may play around w/ RTT VE w/ MAF enabled just to see if it actually does mess w/ fueling. I still planned to log VE against commanded AFR vs. actual and go from there. I've had this same tune in the car for 10+ years and I think the fuel blends these days and an intake tract mod are ticking her off lately. I don't race anymore but i've noticed it leaning out more than I'd like. Fixed that w/ MAF tables mods but I think i want to go through it again and fine tune the MAF frequency a bit more as well go through VE table again.

Dave

[Jon S.]

OK - it sounds like you have more experience tuning than your initial posts appeared to indicate.

If you were using a different software platform, my suggestion would be to update to 2002 OS 12212156, while retaining the vehicle's 2000 model year VIN - but this is a challenge with HP Tuners - as it creates a VIN / OS mismatch.

I did this with my own 1999 GM vehicle back in the day - and I typically recommend this approach to others.

[Bill@HPTuners]

why not post your .hpt file you are working with, too many variables

[TTVert]

OK - it sounds like you have more experience tuning than your initial posts appeared to indicate.

If you were using a different software platform, my suggestion would be to update to 2002 OS 12212156, while retaining the vehicle's 2000 model year VIN - but this is a challenge with HP Tuners - as it creates a VIN / OS mismatch.

I did this with my own 1999 GM vehicle back in the day - and I typically recommend this approach to others.

Yeah I know a bit more than I lead on, i was just in hurry putting in the pertinent details (Or so I thought). At this point I'm very happy w/ the setup and I don't really care much if I have a secondary VE table that in turn doesn't allow RTT when the MAF is failed, just wanted to know if something had changed in HPtuners. I did re-enable MAF and did some RTT testing so it does work when the primary VE is being referenced which makes sense now. I have been using it since their first release but stopped playing w/ the car many years ago so i wasn't sure if something had changed. Especially after watching videos and seeing how people are doing VE tuning these days. MUCH easier today than it was 10+ years ago that's for sure. I'm shooting for ~2% afr error, what do you guys typically shoot for while doing speed density tuning? May be overkill since i'm going to run a MAF in closed loop which will correct non PE fueling in all but the worst tunes anyway lol.

Bill@HPTuners thanks for the suggestion but what would my tune tell you? I just wanted to know if I can do RTT on an ECU w/ a secondary VE table where i put it in SD failing MAF and force open loop. Obviously the ECM is referencing the secondary VE in this case but RTT seems to pull and only edit the primary correct? No way to have RTT reference the secondary VE table?
Dave

[Bill@HPTuners]

well it would tell us if you are using the MAF RTT or SD RTT custom operating system for starters...

[Bill@HPTuners]

Its even stickied

[TTVert]

Its even stickied

Thanks, I did not think this applied in this situation since i was merely asking about a function of the software. I'm happy to answer any questions pertaining to this butI hope you understand but for liability reasons I do not want my tune out in the internet world. See my OS below.

9381344 -> 1281005
1 Bar MAF - Enhanced (RTT)

[murfie]

Do you still have your non enhanced time file? You will need to create a 1 bar SD enhanced file from the OS tab in it, to remove the MAF and RTT the primary VE table. If that option is in the OS tab, some don't have it.

[5FDP]

I agree, the 1 bar speed density enhanced OS is way better for this.

[TTVert]

Do you still have your non enhanced time file? You will need to create a 1 bar SD enhanced file from the OS tab in it, to remove the MAF and RTT the primary VE table. If that option is in the OS tab, some don't have it.

I have my stock tune, i don't even know when I would have switched to enhanced. I can always just look at the comparison log and copy/paste if it comes down to it.
Ago5FDP, can you elaborate why you think it's better? I have been trying to find literature on the difference and I'm not able to. The online help file search doesn't seem to like me usually though.

Dave

[5FDP]

The speed density OS removes the stupid secondary VE table. Makes tuning faster/easier.

[TTVert]

does it do anything else? Can I still use my MAF w/ this setup?

[5FDP]

It also lets you retain the factory style high/low octane table function even if you did remove the MAF sensor and went speed density only.


Yes, the MAF will still work as normal with a speed density OS.

[TTVert]

So when doing sd tuning I would not have to fall back to the low octane table? Is there something documenting all of the difference so I know what I'm getting into before I do it? Is there a help file aside from the online one? I did see the following but i'm not sure what this all means exactly (Particularly "speed density mode only" and "new VE multiplier.." and if it even applies to my 00 ECM. I'd also like to know if the dual spark table just means it handles the advance tables like it would if there was a MAF present?

1bar Speed Density Enhanced (GenIII V8)

This enhancement contains the following features:

Speed Density mode only
Dual (High and Low Octane) Spark table support
new VE Multiplier vs. TPS vs. RPM table, with non-linear TPS resolution and RPM resolution
Secondary VE table not used (if applicable)

[Bill@HPTuners]

Yes, the MAF will still work as normal with a speed density OS.

Not exactly true, maf is coded out in all the SD operating systems where a secondary VE table was present if memory serves me.

[5FDP]

I've run the MAF on a speed density OS before and a 2 bar OS. Same with the E38 2 bar OS's.

I still have to fail the MAF in a speed density OS for it to want to fail immediately and not take two/three tries to start. Makes me wonder that if it's coded out why is that step still needed.