My LCD screen project, boost, WBO2, Knock, etc

[NickS VR4]

Awesome, look forward to this.

Sent from my Nexus 7 using Tapatalk 2

[james92tsi]

Sweet!

If the blue board version doesn't work, I am capable of soldering my own ugly hacked-together version with some guidance on pinout & components required.

[TurboSinceBirth]

Antero, I'm still having some issues so bear with me since this is new to me.

I updated to v2.26 without any issues. The problems I'm having with evoscan are not related to the firmware at all. I only datalogged rpm, coolant temp, air temp, knock, AFR, and boost this time. My sampling rate is much better except that now the numbers get all weird after 2800-3k rpms with the exception of boost and AFR. RPMs go to zero, coolant temp rises from 176 to almost 100+ higher from one cell to the next, I've noticed the LCD BC will flash at me "overheating" when my car is fine, air temp is supposed to be fixed at 89.6 for the ARC-2 but when it does these other things air temp starts decreasing so I have values ranging from 60s, single digits, 20s, etc. I also have sporadic knock counts of 160, 203, 255, and 186 when I know for a fact that I'm knock free.

Is this something related to the calibration or maybe like an ecu ground? I don't quite know but I've been having these problems for multiple months and am only now seeing some of the quirks once I start datalogging.

[BlackStealth]

TurboSinceBirth: The LCDBC is receiving corrupt serial data from the ECU, that is why the values are crazy. If during datalogging it goes even worse, this indicates noise is being transmitted on the OBD port when it should be all silent at that particular moment. The 8Mhz version LCDBC can't handle two simultaneous serial inputs without corrupting the data, so it relies on the fact the OBD port is quiet at appropriate times.

Boost and WB02 data values are not transmitted from the OBD port, that is why those particular values are correct. Again, this points to noise on the OBD port.

Going to a 16Mhz version LCDBC would make some improvements (for datalogging), but not fix the noise you're receiving on the OBD port. I'd still suggest looking at the grounding locations for your ECU as the cause of your noise.

On my 1993 RT/TT, my ECU (MFI Circuit) uses grounding locations 2, 6 and 10. On my car I've scraped the paint off of grounding location #2 so it gets a clean electrical contact.

[BlackStealth]

TurboSinceBirth: I'll build an OBD noise filter for you. I'll work on it this afternoon.

[TurboSinceBirth]

I will check the ECU grounds later on this week Antero. I had been meaning to do that since reading about it earlier in this thread but after not having as many issues with disconnects I guess it got put on the backburner. That definitely makes sense what you explained though. I knew about a few of those grounding locations but hadn't dug out the manual just yet. I'll definitely check them out though. I'm anxious to get it fixed. Thanks for the help.

[BlackStealth]

Here are three OBD filter designs.

Design 1: Uses 220 picoFarad capacitor between pins 4 and 5. ** WORKS **

Design 2: Uses 10 Kilo ohm resistor and 100 picoFarad capacitor. ** DOES NOT WORK **

Design 3: Uses 33 microHenry inductor and 82 picoFard capacitor. ** WORKS **

If you build it as a small serial adapter that fits in between the MUT cable and the LCDBC the only other important wire required is DB9 pin9 uninterrupted (it provides 12volts).

[TurboSinceBirth]

Has anyone had problems overboosting at the track? Or at least the boost settings not being the same for the street vs the track? I had it set at 19 psi last night but was going over that. I turned down the duty cycle to 9% or thereabouts and it was hitting 20.6 psi. I may have developed some boost leaks. I couldn't get a clean pass in though because it was running lean due to hitting too much boost.

[BlackStealth]

I don't know what "PSI End=xx.x" is set to, but if it's set to a large number and by lowering the duty cycle number it is certainly possible that turbo spoolup assistance is never turned off.

[TurboSinceBirth]

On the street I had the psi end turned up to 17 psi and it worked fine, but was a different story. I turned it down to about 14 psi and lowered the duty cycle to below 10. That was my last pass which netted me 20.6 peak boost. I may have to check the duty cycle offset numbers also. I just though it was weird how much it changed going from the street to the track and was one of the reasons I couldn't get a clean pass. Maybe it could have been under more load somehow. I wasn't able to mess with it anymore due to a coolant leak. I was also running about 20-30 degrees warmer in the staging lanes than on the street which was irritating. Probably a combination of my fans not working or mostly inadequate ducting between the radiator and FMIC, and the FMIC and bumper.

Do you have any other ideas for gear based boost Antero? I can set it for 4th gear since I'll never see a higher gear at the track and WOT in 5th or 6th isn't practical plus I don't have a desire to go that fast.