Engine Braking
- Thread starter Dzchey21
- Start date
there is no way to say turn it on or off... that wasnt written in to the ECM like the 15+ trucks.... im trying to build it so its almsot not noticable in the lower RPM range but stil holds the truck back at highr RPM.... its proving to be a challange since there is no real EX brake tables to work with other than the TQ tables but adjusting them on their own does almost nothing....
SO what I did was just take the desired boost tables and the VGT tables and set them to 10 psi and about 85 percent to start in the 0 torque column and I have it working pretty well, after 1400 rpm it tapers off in boost so like you said during normal non-tow/haul function it works like normal. Just wondering how everyone else was doing it.
i think that is about the only real way to make it work.... how have you found it working? does it spike to desieed pressure and then turn off... like almost surge or does it hit 10PSI and maintain it???? im fighting the spike and surge problem ( it bounces in boost pressure once it hits 10 it turns off and then once its below 10 it will turb back on ) with the ones ive tried to build.... even with different vane configurations still same problems....
The only way I was able to get it close was to match the correct VGT duty cycles. So at 2500 RPM 10 PSI desired is only like 65% duty cycle, but at 1800 RPM desired is 92%, that's the only way to keep it from surging.
Have either of you ever experienced a p1247 (low boost) after extended exhaust braking with a heavy load in tow with a tune or these experimental tunes? I can't seem to figure out if it's from the hard climb or the exhaust braking on the back side of these grades. But it occurs shortly after both events. These were the GH off tunes. It's almost like the VGT is stuck open until the engine is stopped and the code is cleared. No other codes are present. If you give it too much throttle it would smoke like crazy with the boost maxed out at 16psi. I've since return to stock exhaust and put the H&S on-tunes for the time being until I can run in this configuration. I suspect it a combination of the tuning and lack of back pressure. The turbo functions fine otherwise.
Haven't got that far yet. I'm thinking however that commanding 10 psi in some spots isn't going to cut it because it can't achieve that and I will eventually get a code. So I plan to refine it more. Part of the problem is testing under no really load makes it slow down so fast it's hard to keep track of vane position and boost pressure so I need to set up some data logs
