JeffHarbert
JeffHarbert HalfDork
8/15/17 2:21 p.m.

I have a couple thousand miles under my belt with the P71 now, which has 121k miles. I noticed from day one that the drive-by-wire throttle is difficult to modulate with any finesse. Give it a little gas, not much happens. A little more, same thing. A little more and it takes off. It's even worse in reverse, and today the engine started surging slightly with the transmission in reverse with no throttle input at all.

This is really only a thing at low speeds like taking off at a green light or backing into a parking space. Anything above 15mph is fine. Tranny shifts firmly at full throttle with no slippage and kicks down when I want it to. There is a slight delay when turning the overdrive off with the button.

Dunno if it's related, but I can't get above 19mpg. It's rated at 15/23, but I've been able to get 1-3mpg better than EPA in everything I've owned, at least with all-highway tanks. Not this thing though.

No evidence of gremlin droppings under the hood. Dr. Google hasn't been any help, so I thought I'd ask the hive. Any ideas what could be causing this?

edizzle89
edizzle89 Dork
8/15/17 2:48 p.m.

the first thing I'd do is clean the throttle body out really well. I have seen several drive-by-wire cars develop really weird issues that completely went away with a simple cleaning. something about DBW makes them sensitive to being dirty. Plus its cheap and easy to do

floatingdoc
floatingdoc New Reader
8/15/17 7:43 p.m.
edizzle89 wrote: the first thing I'd do is clean the throttle body out really well. I have seen several drive-by-wire cars develop really weird issues that completely went away with a simple cleaning. something about DBW makes them sensitive to being dirty. Plus its cheap and easy to do

How's that done?

GameboyRMH
GameboyRMH MegaDork
8/15/17 7:57 p.m.
edizzle89 wrote: something about DBW makes them sensitive to being dirty.

Probably the fact that the throttle servo is much less forceful than the driver's right foot an can be held up by levels of stickiness that would go unnoticed with a cable throttle.

JeffHarbert
JeffHarbert HalfDork
9/10/17 5:38 p.m.

I wanted to follow up with this and add a post for future reference.

Today, thanks to the advice of a helpful YouTube video on recalibrating the drive-by-wire throttle, I disconnected the negative battery cable, touched it to the positive terminal to clear the ECU, reconnected the battery, then started the car and let it idle until it was warmed up. I took it for a drive afterwards and it's definitely improved, especially in reverse. Long as we got the goods, I call this a win.

I took off the intake tube to look at the throttle body. Looked clean enough to perform surgery. The town of Glen Alpine, NC maintained this thing pretty well. Either that or they cleaned it trying to fix this same problem.

Link to video goodness

Oh, and I finally broke 20mpg. Got 21.4 two tanks ago, possibly related to running a can of BG44K in that tank.

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