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Old 04-01-2010, 02:32 AM   #1
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Default Really Strange Problem with Tune

So today I used Tunerstudio and it's VE Analyze system to smooth out my VE tables. On the ride home from work it seemed to work really well and I was almost dead on with my targets in all ranges.

So I disconnected the laptop and went for another drive and all was still well.

Then I parked my car for about 4 hours but when I took it out again everything was really rich. My idle, which was around 14.9 when I did my first drive was now between 11.9 and 13.6 which was causing erratic idle. Cruising at 10 psi vacuum was now at 13.7 when it was at 14.7 and under boost I was going into the high 11's when before it was right at 12.5.

The only variable I can think of that changed was the outside temperature was much cooler.

Any ideas why this would suddenly change after the car had been sitting?

I don't just think it's tunerstudio either. When I was using megatune and megalogviewer I would get a really good tune only to find it went rich or lean after I let the car sit overnight.
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Old 04-01-2010, 09:43 AM   #2
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were you still in warmup mode (ie, coolant temps under 160*F)
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Old 04-01-2010, 10:10 AM   #3
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If this is a 1.6 car, make sure your IAT sensor is hooked up. I had a wire walk out of mine once and the sensor read 55* or something so each time the weather changed, so did the AFR.

Where is your o2 sensor? If its getting too close, it will read incorrectly when it gets hot.
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Old 04-01-2010, 10:20 AM   #4
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Quote:
Originally Posted by Braineack View Post
were you still in warmup mode (ie, coolant temps under 160*F)
I second this... Also can you post a log??
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Old 04-01-2010, 11:29 AM   #5
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It's a 1.8 and unless it's somehow getting "stuck" in warmup mode that shouldn't be it as I probably drove for 30-40 minutes. The O2 is pretty far down the pipe and has always read correct (I had it installed for a few weeks with the car still stock).

I will check the wires on the IAT just in case but when I check the intake temp in megatune it seems to be changing appropriately. I'll also try to get a log posted in a few when I get out of class.
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Old 04-01-2010, 12:27 PM   #6
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The second time you drove it, were you running VEA live? If not, it's possible the tuning you did on the previous drive didn't get saved into the controller. Even with "update controller" checked in VEA live I still have to click send or burn, or else it will revert to what the VE table was prior to tuning when I power off the MS. The easy way to tell if your updated table got saved, without staring at the actual numbers in the VE table, is to shut off the car and with TS still running, key the ignition on again to power up MS. If a difference report pops up, your tuned table wasn't saved to the controller.
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Old 04-01-2010, 12:40 PM   #7
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Thanks Scott but I'm sure I sent it to the computer as I clicked both send and burn. The second time I drove it (after using the analyzer) the car was fine, exactly how it ran while the analyzer was running. The problem didn't arize until the next drive when everything got very rich.

Ok, so here are two logs. The first log (test1) is from the car as it was when I posted this last night. Notice how everything is very rich. I waited to start this log until the car had reached 160 degrees and EGO correction was on but it didn't seem to be doing much. I also kept an eye on the digital temp gauge which seemed to be working perfectly as well.

Then I spent about 15 minutes with VE Analyze and everything was back to normal. So I burned those values and did another quick log which is Test2.

I also kept an eye on my IAT reading but it seemed to be spot on the entire drive.

However I don't think I will know anything until I give the car a few hours to cool down and see if it gets rich again.
Attached Files
File Type: xls test1.xls (517.3 KB, 45 views)
File Type: xls test2.xls (658.5 KB, 39 views)
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Old 04-01-2010, 03:03 PM   #8
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Sorry for the double post but I just went for a long drive with VE Analyze running and it seemed to be tuning everything right. So when I got to a place where I could stop for a minute I burned the new values to the controller and my idle went straight up! I turned the analyzer back on and after a minute or two it evened back out.

This may not even be related but, in theory, when I burn those values to the controller it shouldn't have done much of anything since the program was updating the values on the fly, correct?
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Old 04-01-2010, 03:14 PM   #9
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blip the throttle after you hit burn so things can re-stabilize. it shouldn't change anything, its just locking in the changes. also, don't autotune idle cells.
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Old 04-01-2010, 03:15 PM   #10
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Ok, I was trying to use autotune to adjust idle as well, dumb move on my part I guess!
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