Acceleration Problem - any thoughts?

[N40GL]

Since you folks are all gathered around Carlisle with nothing much to do, maybe you can help someone out here in the land of $8.00 gas.

I took the Marauder in for tires, rear shocks, a battery and lubrication of the aftermarket suspension Zerk fittings. Got it back and started to drive home. Put my foot down and it roared off as usual. But, I lifted and put my foot down again and it bogged. Couldn't get more than 1,500 revs, with my foot to the floor (and it decreased from there until I rolled to a stop). After stopping, put my foot down and it roared off again, only to repeat the previous problem. Almost like the throttle cable got bound up, but then why did it get "unbound?" Just coasting isn't much of a change in circumstances.

It's back in the shop for them to check it out. While I wait, I'd be interested in what you experts all think. While I wait for the car, I'll continue to ponder $7.89 Premium and $7.99 diesel (diesel is taxed higher in the Golden State, and yes we are looking for a way to move outta here).

[1Marauder]

Check CIA, and make sure all secure no air leaks. Sounds like maybe fuel pump, clogged filter?

[Prospect62]

I have no idea if this is a legitimate diagnosis or if it relates to your issue BUT...

I changed my battery after the car sat in the garage all winter and for the first day or so of driving it this summer, it stumbled off the line under throttle a bit. After a while, it cleared up on its own. My thought at the time was with the old battery being discharged for awhile and then unhooked while I changed it that maybe the PCM had to relearn or recalibrate the throttle position or some such nonsense.

Definitely could be a cable issue in your case, though.

[blazen71]

Blew off an intercooler boot

[N40GL]

Here's the interim answer, to be verified when I pick the car up this afternoon (assuming its fixed). The tires that went on are exactly the same size as the ones that came off (not BFG's, but Firestone, albeit a different series since the Firehawk Indy500 Wide Oval's aren't made any more). Not the factory size (which is 235/50R18 and 245/55R18 BFG g-Force T/A KDWS) but the same size as Kenny Brown put on (255/45R18 and 255/50R18 - Pirelli P-Zero Rosso).

This time around, the car is throwing ABS codes and traction control codes (according to the tire store - I didn't think to check it). Totally odd, in my head, since the new tires should be no different than the old tires. But the symptoms are right for ABS/Traction Control getting 'confused' (historically, we know Steve Babcock told us that uniform winter tire sizes all the way around will also cause the ABS/Traction Control sensors to get confused - these are the same symptoms).

So I authorized them to change to Cooper Zeon RS3-G1 tires (in the factory-spec sizes). If it somehow is the tire, then this should correct the problem, but I AM perplexed as to why it occurred in the first place. Weight of the tire, maybe?

Contact patch size on the factory-spec tires is 27.25" Front/28.61" Rear and the Firestones is 27.04" / 28.04" (formula: Sidewall Height * 2 plus Diameter, which I know ignores the weight of the car but allows for uniform comparison). So this should be well within the tolerance for the ABS/Traction Control sensors.

Stay tuned for the next episode (and soon you'll know (Paul Harvey's voice) "The rest of the story!"). Puzzling...

[N40GL]

(duplication of previous post)

[SilverPhoenix]

If possible, I would check the first set of tires they installed to ensure they were, in fact, 255/45 & 255/50, if after the Coopers are installed the issue disappears...

FWIW, I'm on my 3rd set of Cooper Zeon RS3s and really like them.

[Mr. Man]

Did they put the Firestone tires on correctly? Maybe they put them on backwards.

[Joe Walsh]

Did they put the Firestone tires on correctly? Maybe they put them on backwards.

Yep....might've been the problem.
The labor pool is very shallow and tire stores have to hire 'Techs' that know nothing, and check nothing.
They just mount the tires, try to balance them correctly (even though modern Hunter machines do EVERYTHING for the Techs) and throw them on the car.

BTW: California gas/fuel prices are INSANE!!
But, Nancy Pelosi and her drunk husband can afford high priced everything.

[Joe Walsh]

I KNEW my slow a$$ computer would double post!

POS!

[N40GL]

And, now for the rest of the story...

The Coopers fixed it. The Firestones, exact same size, and exact same install caused the problem. Lord knows they were installed in the correct stagger - I checked them often enough. But now everything works. Weird.

Thanks for all the suggestions.

[Prospect62]

That's the strangest explanation for an engine "stumble" that I've ever heard.

[RubberCtyRauder]

That's the strangest explanation for an engine "stumble" that I've ever heard.

If you don't maintain a 3-6% tire diameter difference front to rear on cars with traction control, it will activate and engine will stumble or lose power while trying to accelerate