When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
After using my icarsoft a few times, I decided to check out some of the data it is capable of providing. Not surprisingly, I found that the intake flap is broken @ 223K miles. While looking at some of the transmission parameters, I noticed that the torque converter never showed as locking. Typical data shown while rolling down the highway at 75 mph:
The transmission doesn't have any error codes, shifts fine, doesn't shudder and doesn't feel like it is slipping. I thought transmissions were pretty aggressive at locking up the TQ for fuel economy, but I never saw the screen indicate lockup under a variety of driving conditions. It always read "slipping" and showed converter slip speed usually < 100 rpms while underway. Is that normal? Does the icarsoft not provide accurate data?
Check it out for real. Oncce you're above 45mph, give or take (I think it's lower for the diesel, slightly higher for the gas), the TC should be locking up. You can tell based on throttle input vs RPM. You should notice that the a slight increase increase in throttle input doesn't cause an immediate jump in RPM. Meaning, if it's locked up, you can slightly increase throttle while the RPM doesn't immediately "jump" up a bit. Instead, if the TQ isn't locked up, the RPM will jump up as soon as the throttle is increased. Otherwise, it won't "jump" and will, instead, just increase steadily as speed increases. Dont need no computer to check that!
RPM and speed seem to go up linearly at 45-50 with part throttle, so it appears to be at least mostly locking up. No indication of any problems, just thought it was curious.
I didn't save it, but I found a MB document somewhere for the 722.6 with a graph of TQ behavior, and it only fully locks up at high rpm/light throttle. Under other conditions, it was partially or fully unlocked. Not sure if the 722.9 is programmed in a similar fashion.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
