zain

I ask because there are times where I swear my PES G2 A4 is being held up by the tip.

Figure the torque converter has some pressure level beyond which it allows the driven side to slip. This level being throttle and "load" derived. And if the engine gives it more than it wants, rather than allow the driven side to break away and engine RPMs climb away - it asks for a timing retard, or otherwise backs the engine off.

Does this make any sense?

Because for certain gear ranges and RPM ranges, my PES A4 quattro tip and my stock Passat 4motion 2.8 seem to have exactly the same RPM climb rate for WOT.

Makes me think about possible adjustments to the torque converter/tranny. Or swapping in S4 components.

Am I off in the weeds?

TIA

Zain

ihavenoaudi

i don't think the tranny would send a timing retard to the ecu(although it might be able to since the whole car is computer controled.)

Paul H. (near Annapolis, MD)

The Bosch ECU does have a routine by which it will reduce power output to a specific target upon sensing a signal from the transmission. The target is programmed into the ECU (not the TCU). How it goes about meeting this target it beyond me, but I would be surprised if it is only using timing retard.

This would explain why the torque you are feeling while this is going on is the same in both cars (same target). In fact, as far as I know the Tip sends this signal every time it shifts.

As for the driven side breaking away, it will do this without asking for a power reduction if you really get on it in 5th gear (in Tip mode so it can't downshift). Mine does, and I have only a chipped 1.8T. (The 1.8T uses the same ZF 5HP19 Tiptronic unit as the 2.8 but with different programming). It pulls nicely until about 3K RPM and then the RPMs shoot up to about 4500 with no corresponding increase in acceleration.

Paul

zain

is described in my shop manual as "only on shifts." Presumably just there to avoid spinning the engine on shifts. Do you suppose it's happening at other times? Because if it does, then yeah, that's what I'm feeling.

I don't feel the engine RPM getting ahead of the transmission - like something slipping. Not even in 5th as you report. So if I'm not imagining the problem, I guess I should look for that signal from the TCU-to-ECU with my VAG.

The thing about engine mods that include injector changes (like my supercharger) is that the computed torque values are wrong. So, if you interrogate my ECU/TCU the "actual torque" values for a given RPM WOT are similar to stock - because it's using RPM and ijector pulse width to figure torque from a look-up table. But with the bigger injectors actual fuel delivery is higher for a given pulse width. So in theory the tranny should just maintain all its shift points and behaviors, just see more torque, even if it fails to compute that it's there.