Acceleration on the Highway, advice sought.

[paul2005TB]

I have 7.7k miles on my TB and ever since the first day I drove it with 6 miles on it, it has what I think is a weird anamoly in its response to throttle.

For instance, on the highway going 55mph, if I punch the throttle the engine immediately drops down to 2nd gear ( approximately 4k RPMs ) and then after about 3(eternal) seconds it seems, extra fuel (finally) feeds into the cylinders and power arrives... Now I had initially thought this was part of the break in period and the computer telling the engine not to overdue it with so few miles, but now as I near 8k miles I am wondering.

I can imagine the engine dropping down one gear and responding within a second with plenty of power, BUT Im getting an incredible jump in RPMs with no corresponding jump in power... it just rolls there whinning and me waiting...

Is this normal?.. how would you describe your response on the highway at say 55mph to a punch at the throttle?

On the bright side I do get over 20mpgs on the highway (55mph) so I suspect that the engine is in fine condition.

[big ed]

one answer = get a tune. :yes:

[TBlazin7]

From what I have read, it could be because the TB is not on a drive by wire system so response may be delayed a bit.

[hatchet669]

part of it is the Fuel Enrichment Module... i think that is what its called... it is programmed to save fuel and use little if the RPMS are under 5000 rpms i think... but after that point it dumps alot of fuel... another part is what tblazin said and that this aint a fly by wire... its electric control so there is a slight delay... and yes get a tune it will help all around

[MTPockets]

..For instance, on the highway going 55mph, if I punch the throttle the engine immediately drops down to 2nd gear ( approximately 4k RPMs ) and then after about 3(eternal) seconds it seems, extra fuel (finally) feeds into the cylinders and power arrives...

You'll want to keep the OD/lockup to 2nd gear kickdowns to a minimum.:crazy: Those are pretty rough on a 4L60E. As far as the boost of power around 4-5KRPM's, yeah, that's software. The software g-roo's know more about this, but AFAIK, there is a power enrichment mode that kicks in at higher RPM's during specific throttle positions.

Joel

[paul2005TB]

Greatly appreciate the counsel, it sounds like you are saying that your I6 TBs would give a very similar response to this scenario. If that is the case then this is perfectly normal and maybe the I6 does not have the power that I thought it would. Still not sure why 3rd gear with the 3.73 gearing wouldnt produce more than enough pep for these scenarios.

[ghoster]

Mine shifts the same way yours does. I never liked that hard slam down to second, and it seemed like overkill in alot of situations. My tune helped it alot. Generally I prefer to pull it down manually, just shift it down one gear with less throttle on it. I wait for the shift, then slowly lean on the throttle til I get what I need.

[MTPockets]

Yeah, the 4 to 2 slam-down happens every time at speeds around 45-60mph. I hate it. Above ~60 it will pop down to 3rd which is much less aggrevating. That's pretty common OEM programming for all slush-o-matics.:worried: I try to keep mine shifted in 3rd all the time unless I'm on the hyway, then I slide it into OD.

Joel

[paul2005TB]

you guys dont know how grateful I am for your help, insight and advice. It is alot better knowing that other TBs are the same. I guess I need to read up on getting a custom tune.