Bug in Boost control temp comp table

soxfan143 · Post by **soxfan143** » Wed Dec 08, 2010 4:39 pm

Hondata, I found a bug in the boost control logic. Once the temp seems to go below 32 degrees IAT the boost control goes haywire. It is adding 5% duty across the board under 32 degrees IAT. And the temp comp values in the temp comp table are not doing anything. No matter what value I enter it doesn't effect the boost. Here is a cal and log showing this. In the log at 20,01 is where the boost control is active and the IAT is under 32 degrees in 3rd gear and the boost duty is 5% higher than the lookup table. Then I shift into 4th and the IAT just get's to 32 degrees but the IAT is still 5% higher. Then once the temp seems to just get above 32 degrees the boost duty goes back to the actual value in the lookup table. This is driving me insane hitting boost cut randomly.

mucter · Post by **mucter** » Wed Dec 08, 2010 4:54 pm

Mike didn't mention he's running the private beta version of 1.1.6.7. His customers that are running the normal 1.1.6.7 aren't having the sub-freezing issue he's experiencing.

And to add to this, here's my experience on the 1.1.6.7-private build.

The ambient temps were in the mid teens week before last, and my IAT was right at 32 degrees (as measured from right before the throttle body). My car was going from 0% duty to 100% duty on the BC with no variance in between.

This didn't work out well.... LOL. My car shot up to 23.5 psi and then hit boost cut and then bounced up to 25.6 psi!!! It's a miracle my engine didn't explode as my injectors didn't have what it took to fuel that much boost and I leaned the F out.

Anyways, here is the log showing this as well as my cal. Since the weather has warmed back up here, I've had no further issues with the boost control.

It seems as if it's an issue with temps at or below 0 degrees C? Maybe something is wrong with the internal logic for negative temps?

Post by **Hondata** » Wed Dec 08, 2010 5:26 pm

I've emailed Mike. I'm looking at it and it is something to do with the IAT being below about 35 degrees. You should set a boost cut.

soxfan143 · Post by **soxfan143** » Wed Dec 08, 2010 5:30 pm

Hondata wrote:I've emailed Mike. I'm looking at it and it is something to do with the IAT being below about 35 degrees. You should set a boost cut.

Boost cut is set, Thanks Derek.

mucter · Post by **mucter** » Thu Dec 09, 2010 12:11 am

Hondata wrote:I've emailed Mike. I'm looking at it and it is something to do with the IAT being below about 35 degrees. You should set a boost cut.

My boost cut was at 21 because I like a bit of headroom over my target boost of 18-19 psi, doesn't do much good with the wastegate actuator seeing zero air. The turbo spooled up so fast reacting to it before it happened wasn't really an option.

At any rate, I'm glad you're looking into it. I'm just heading into the cold season up here in Oregon so it'd be nice to not have to worry about this. I thought my solenoid was failing on me when it happened, it'd be nice to find that it's just a bug.

ajpturbopittsburgh · Post by **ajpturbopittsburgh** » Fri Dec 10, 2010 11:18 am

Hey you guys are talkiing about a private build or something. I am using 1.1.6.7 is mine ok or does it have this bug too?

I haven't had my car out lately so I don't know...It'd be nice to know because if it does have the bug I just won't take it out til it's fixed in a new version.

So you mean if the IAT's are lower than 32 degrees F then the boost duty cycle will go to 100! Oh lord....THank god for boost cut because I'd probably be making 1000 hp and I would blow the top off for sure lol

soxfan143 · Post by **soxfan143** » Fri Dec 10, 2010 12:04 pm

It's in all versions of FPM. The bug has been fixed for next release. And yes, any IAT under 32 degrees and the boost control goes haywire. It will vary on how much boost will increase. Mine only jumped up 5-6% but it was enough to wreak havoc.

ajpturbopittsburgh · Post by **ajpturbopittsburgh** » Fri Dec 10, 2010 4:45 pm

5 or 6 percent duty cycle? Well that would make me hit boost cut in 3rd gear and up....I guess becuase I have the frequency at 50 hertz. The difference between 30 duty cycle and 35 would be 10 psi and 15 psi respectively. I run race gas above 12 psi.

So could I just set all duty cycle to 0 to avoid the problem? Or will it still spike because of the bug?

Hondata any chance you could get the fixed version out before you guys leave the office for the weekend? It's about 20 degrees in pittsburgh right now with no warm temps in sight.

Post by **Hondata** » Sat Dec 11, 2010 10:49 am

When the IAT is below freezing it will read the correction from the highest index. Just make the highest temperature value 0 or negative and you will be ok.

ajpturbopittsburgh · Post by **ajpturbopittsburgh** » Sat Dec 11, 2010 12:03 pm

Not sure I follow you but my highest index for intake air temp is 248 and the corresponding duty cycle compensation is -10.

Is that good?

mucter · Post by **mucter** » Sat Dec 11, 2010 3:23 pm

Hondata wrote:When the IAT is below freezing it will read the correction from the highest index. Just make the highest temperature value 0 or negative and you will be ok.

The weird thing about that, my highest index was set to -40 duty because if the IAT somehow managed to get that hot, I have it pull a ton of duty so the car won't boost much. Yet when it was below freezing, my duty went to 100%... weird. If you fixed the bug though, guess it doesn't matter.