Erratic throttle response when cold

[Goran]

Originally Posted by HPsauce

Any suggestions how to do that? I've tried in Tip mode and the symptoms were still there as noted a couple of posts previously.

I meant, if we assume both my S8ts were healthy engine wise, and I swapped from the Auto version to the Manual, and the hesitation/scalded cat disappeared, the Auto transmission must? have been causing the effect.
I know its a crude deduction, considering so many factors between the two cars. I just cant shake the thought that because there is a TCU module and software in the Auto ECU to reduce engine power for the benefit of the transmission, its bound to be trouble. As far as I know the manual version has no such interference (different software, no TCU), so the engine will respond directly (with proviso that its electronic) to pedal input, and doesn't care if you burn the hell out of the clutch. I know I have already done so on a couple of occasions

You cant remove the TCU and ECU software for TCU interference and still drive the car, so its not testable on a Auto version. I assume in the Auto TCU interference is always available even in Tip mode, to protect the transmission. Maybe if Mike does his manual conversion he will be in a unique position to test what happens when you swap transmission types (and remove TCU) without changing the engine.

[HPsauce]

I like your thinking Goran. It certainly feels to me (as a computer guy) more like a control electronics issue than anything else.
The puzzle is mainly what conditions trigger it, it's not consistent enough yet to start pointing the finger in any specific direction, though significant turns at lower speeds seem to be implicated.

[Delboy]

I know from my D3 that the gearbox ecu asks for a gear change and there is sometimes a hesitation in the gear change compared to whats displayed on the dis.

The 3000 rpm but little acceleration can only be gearbox related with either a clutch pack slipping or the torque converter slipping with the gearbox being in to high a ratio.

I'm unfamiliar with D2's so not sure if the box behaves the same as the d3 but in the d3 in sport mode the tcu locks the torque converter up earlier to allow for a more direct drive allowing for better acceleration.

Have you got sport mode on the D2?

[HPsauce]

Originally Posted by Delboy

Have you got sport mode on the D2?

Yes, and I've also been told it locks up in Tip mode, but I get the same problem there.

It doesn't really feel like anything is slipping, just lack of power from the engine and reluctance to change gear (up). When I "blipped" the throttle in Tip mode it didn't change revs or gear but suddenly felt urgent and responsive.

[HPsauce]

I don't know if Jesse (Fast Show ) ever had a whole week of HP sauce, but....
Today I 'ave mostly been driving........... an S8!

I'm not saying it's fixed, only time will tell for sure, but it's consistent and responsive, getting a "decent move on" with only a gentle right foot. Without any need to use Sport mode, but if you do it really does get going.

This makes me think that what I referred to previously as the occasional "scalded cat" mode was in fact just "normal S8" and that my right foot had learned to be heavy from being used to it being pretty sluggish most of the time unless I floored it.

Certainly feeling more positive today.

[David's8]

Good news and I hope - for your sake - that what is possibly the longest running thread on a single problem will come to an end.

[HPsauce]

I hadn't realised how long it was! I wonder if the previous owner (and the trader I got it from) knew it had this weird problem and hoped it wouldn't show up too much.

Anyway, it's also starting better, so now I just have to wait and see how it behaves.

[Sir WIll]

Interesting stuff my D3 does have similar problems so I may change the Fuel Pressure Regulator and have a look.

Anyone have the part number for a 2003 D3 4.2v8?

[HPsauce]

It will almost certainly be the same, but put your car details in on the ECP web site to confirm.

The Bosch one I got was ECP part number 440440090 which according to them applies up to 05/2006.

Note that I now have a spare briefly-used aftermarket one (noted earlier in the thread, cost me £34) that I just don't know for sure is good or bad.
Happy to pass it on at a big discount (P&P plus beer money I guess) if anyone wants it for testing.

[HPsauce]

Originally Posted by HPsauce

wait and see how it behaves.

Still feeling good.
Picked SWMBO up just now from the station (3 miles away) and on the way back decided to try Sport mode. She was not best pleased.