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Hey guys,
I am fighting with an odd throttle oscillation issue on this 2019 D1X car I am tuning. Setup is as follows:
D1X Stage 2 Blower - 4.75" pulley - about 11-12psi at 7500
FIC 1000cc injectors
DW400
Right around .8-.9 airload around 35-40% throttle the car will cut in and out. I CANNOT figure out why this keeps happening, any help is appreciated.
Kris
I can't open the tune but the log looks like an IMRC issue. Jumping between MP 0 and 14 and corresponding IMRC sensor fluctuation.
Whoops, sorry about that, try it now.
The IMRCs are adjusted to open at .35 airload and close at .30. Since the throttle closure is occuring and dropping load below that threshold, they are closing. IMRC function is retained for cruising and idle. Car idles perfectly and get 25+mpg cruising even with the blower.
Kris
you're 100% sure on the torque and torque inverse tables being correct?Quote:
Originally Posted by kris5597
No need to scale the MAF for 11psi unless your maf located on IC
I'm 100% the math is right to get the torque values I got, I am not 100% that the resulting number is correct. I noticed the commanded torque drops below the actual torque right before the issues start to occur. But I've been down this road before on correcting the torque tables before on this issue and it did not resolve the problem. Is it the same issue causing the problem, that I am unsure of as well, but it detoured me from going down that avenue as of yet.Quote:
Originally Posted by aaronson
Kris
Hi Kris, apparently we are right down the road from each other.
I went through the logic flow and the torque request does equate to the correct load of about 0.85. The load is translated into the correct airflow of about 11 lb/min. The throttle opens to the predicted angle to achieve 11 lb/min. At this point, I would expect it to fine-tune the throttle angle to keep it at 11 lb/min, but the control loop appears to "blow up". The PI control parameters appear to all be stock, so unfortunately I can't tell why it's doing this. However, I did notice something very peculiar, and that is that the Manifold Vacuum (ETC Model) value goes to 0.200 inHg during the oscillation, which is a very deep vacuum and obviously erroneous. I can't tell how it calculates this, but I'm certain it's wrong and likely the inputs to the model are wrong. I'm betting that this is where the problem lies, but I looked all through the cal data and don't see where the inputs to this Manifold Vacuum ETC Model (as opposed to SD model) are.
Have you checked the bypass valve? I think I would try removing the vacuum line and see what effect that has. I could see the airflow not responding as the TB model predicts if the bypass valve is changing the upstream pressure.
I'll try and disconnect the line and see if it's the culprit, if it is in fact the culprit, tuning around it, I'm not sure how to do.
Kris
Hmmm, If you remove vacuum line to bypass and no change then that could be an issue. Bypass is faulty. Trying to catch up to this thread...hows your throttle body data? Stock? Torque model?
Stock throttle body data/ stock throttle body and Intake manifold setupQuote:
Originally Posted by rryanfla
Torque model was based around a 2019 Whipple base map.
Kris
Kris are you using measure speed density tables or Whipple speed density? Also torque model for Whipple and Procharger are going to be quite different down low.