I built a twin turbo setup for an 8.1L Kodiak RV... Every time we drive it the computer see's boost and throws the MAP/MAF CEL and goes into limp mode. I'm assuming I need to recalibrate these for boost so my question is do I have to purchase an enhancement to make this work or can I readjust the maps that I already have access to. Are there any tips for adjusting these maps?
go to engine diagnositcs in the tuner and raise the p1514 table
So wait, it's a 502BBC RV, with twin turbos? Can I have a picture?
Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.
PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.
Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
618/618 motor
906/862 spray
Caterpillar 50 Forklift- Duramax swap
I got this issue solved I think (didn't trip the DTC yesterday). Plus I did the 2 bar MAP enhancement. So far so good. But the computer keeps closing the throttle even though we are maintaining it at the pedal and it's causing big driveablilty issues.
For the pics send me an email address and I'll send you a few
PM sent!
Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.
PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.
Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
618/618 motor
906/862 spray
Caterpillar 50 Forklift- Duramax swap
I thought all 8.1's ran a gen 3 pcm. Either way, if it's closing the throttle on you, that's torque management...play with / disable it.
Okay so here's the latest... It's not closing the throttle. The airflow is so much greater (even before boost) that the computer just needs tuning, at least I'm pretty sure.
So here's the picture: 50mph, about 2500RPM, 30% throttle
before the turbo's the timing was around 30 degrees, MAF about 8, MAP around 180 (my gauge is messed up), duty cycle around 15% and it ran smooth.
now with the turbo's the timing is around 15 MAF is at 18, MAP is 340, and duty cycle is around 28%
when this happens the computer starts spazzing out... The duty cycle, timing, and MAF/MAP signals are all over the place. Do I need to adjust the VE tables or do I need to make changes to the MAF curve? I've never tuned a MAF so this is new to me.
It would be more useful if you post the log and tune so we can look at it.
Your description doesnt make sense....what units are those? Any MAP reading greater than 100(kpa) says its in boost, which doesnt make sense for a non-turbo vehicle.
what's the easiest way to post them?Originally Posted by Atomic
that's why I said my gauge is messed up. It is boosted but on my gauge your not in boost until you're above 360KPA
Basically I took a drive while it was stock and datalogged it. Then I replicated that same driving condition after installing the turbo's and datalogged it. The problem condition shows up at 50mph, 30% throttle, and 2500 RPM.
MAF is lb/min, MAP KPA
click on "post reply" then below the box you type in click on add attachments at attach the log files and click upload
the highway file was stock and the flutter is with the turbo's. I was comparing the 1:52 range from the highway file to the :30 range on the flutter file
Man you have a lot of going on you need to work on....first off, what does your MAP read with the engine off? You are getting a lot of knock. You are also never going into PE, and are therefor running leaner than you should as your O2s keep switching around stoich.
Post the .HPT file that's in there now so we can help.
Well I haven't even begun tuning... I thought I had an issue beyond what tuning could fix. The MAP reads around 80KPA with the engine off I think. Bill is trying to help me fix that. I'm not worried about WOT or PE yet because it can't even handle cruising at 5 in/Hg.
Here's the file
OK...your VE table is a complete disaster, your boost enrichment table is set to 1.00, so it's ignored...that means you're using PE only, on an engine with a turbo...I'd much prefer to use BE than PE on a turbo setup, since depending on gear, and throttle condition, boost can vary by RPM...you've also got the enrichment rate set low, bring that up to 1.0.
Also, this is a gen 3 PCM/operating system. Re-post this in the gen 3 section, you'll get more help. Gen 4 engines use different computers.
Last edited by MikeOD; 03-15-2012 at 06:12 PM.
How can you tell if it's in PE? Atomic says I'm not going into it (which is what I thought) and MikeOD's saying I did. Also where is the boost enrichment table??? I can't find it
He said its the only one you're using, not that you are going into it. It's based on throttle position and rpm in the fuel, power enrich tab. BE is in the same tab.
It will either use BE or PE, whichever commands more fuel...PE in your tune always commands more fuel.
I'd use PE to command normal NA engine AFR, then use BE to command what additional fuel you want as you add boost on a slope from the normal PE AFR to the max boost AFR.
Reply With Quote