Quick question...

I've noticed when driving my '08 TL-S (AT) that if I let off the throttle when I know it is in top gear, a few seconds later I can feel a sort of "surge." It almost feels like it is upshifting (the RPM's do go down slightly) but I know it's not shifting because I've tapped the gear selector over into ManuMatic while accelerating lightly, it says it's in 5th on the display, I tap it back over into full auto and ease off the pedal - then I can feel the slight shift thing. I've also counted shifts and I know I can feel more "steps" than 5! Now my curiosity is bugging the piss out of me!

At first I was thinking it was the torque converter locking up, but it would have done that way before getting into the overdrive gears (4th & 5th) right?

My next thought was whether or not the J35A3 engine has cylinder deactivation. I've scoured the net but I can't find anything very technical on the J35A3 engines. Just the basic VTEC and ULEV stuff.

The '08 Accord has a very similar engine (at least it puts out the same 286 hp) and it *does* have cylinder deactivation modes (4 cyl & 3 cyl). Anyone have any good technical/engineering docs on the J35A3 other than a service manual? More like a technical writeup of it's particular VTEC strategy, cylinder deactivation, etc - that kind of stuff.

Thanks guys... My geek side has got to understand these things!

 

gradelogic

 

Quick response!

Yeah, I know about GradeLogic but that holds it in a lower gear on decel down a hill or accel up a hill. It's already in top gear when I feel this "surge" or "step" and I know it's not a transmission shift (by looking at the gear indicator). Also it's doing this on flat road so there's no Grade to Logic!

Maybe I should try this in ManuMatic and then I'll KNOW 100% that it is not a gear shift. Plus, being in SportShift mode would deactivate GradeLogic. I'm 99% sure already though, it's too slight and the RPM's don't fall enough for it to be a shift.

Hmmmm....

 

grade logic is NOT DEACTIVATED during SS, I try to upshift on the bridges during my commute to save on gas and it will override me for the upshift. When you let off the gas, the surge is the gear disengaging, such as if you are coasting, that will reduce the engine braking felt therefore, the surge.

 

There is cylinder deavtivation in the 3G TL - any of 'em. I'd bet my '07 TL-S on it.


However, with this "feature" in the new Accord, there's a good chance (IMHO) it'll show up in the 4G next year.

 

Did you mean to say that there is *no* cylinder deactivation in the 3G's and that there's a good chance it will show up in the '09 4G?

Just trying to follow you...

 

maybe its the torque converter?

 

Yep. Sorry.

I'd bet my TL-S that there is NO cylinder deactivation in any 3G engine.


(you should've taken the bet, then pointed that out - lol )

 

i know what hes talking about... its a noticeable feeling..

say you are driving in mild traffic stop and go, and your going about 30mph or so, you take your foot of the gas. and a split second later the car kind of jerks a and seems to be engine braking and slowing down. or if you are on the parkway doing around 60ish and you take your foot of the gas, you feel a surging/jerking.. i think it has something to do with the drive-by-wire system.....

by the way, the TL-S is NOT J35A3 (i think thats the honda oddysey or ridgeline) its a J35A8....the accord is also J35 block, but it may not be the same. the accord is 268hp, not 286hp.. also, it has I-VTEC, which is a much more noticeable vtec system.. its the same as the RSX..

btw..my friend got the 08 Accord V6 coupe.. and it boogies... my tl-s is still quicker, but his car is pretty damn close... i should ask him to drive his car to see if it does it too.

 

temple of vtec dyno'ed one and it put out almost 268 to the hubs...

 

Damn! Yep, you're right. I could have ended up with another TL in the driveway

Ahhhh, thanks for the correction. Yea, I see now the Accord is 268hp - must be my dyslexia acting up. It was the hp ratings that were making me think they were similar engines but now I see that I was waaaay off!

 

well, the i-vtec in the accord block will surely make up for its HP loss when compared to the J35a8 block... now.. if we weigh the accord and tl, if the accord comes in 100lbs or more LESS than the TL, they should run pretty closely


csmeance.. not to doubt your readings or findings... but if thats true, then honda has created the first 0% power loss drivetrain in the industry !!! i find it hard to believe that these results were accurate... no car ever puts down what it claims..... @ the hub should be closer to actual BHP, but there should still be some kind of loss, especially in a 5AT transmission.

 

There is deactivation in the Honda. For Acura, there is none!

 

I think you answered your own question. It is Torque converter lockup.

 

not to doubt your thinking, but, who said it had zero loss? The accord's engine is underated by Honda so it won't knock on the TL-S sales and so it will compete evenly with competitors. If you do read the Temple Of vtec article (vtec.net), you can see that they were surprised to at the results.

 

im curious to see that article too.... do you have a link?

it would make sense to under-rate the engine for a sales perspective, but i would like to see some dyno graphs and charts...

 

just being humorous here but my quick answer would be : AT

lol.

 

The iVTEC system in the K-series is not the same as that on the J-series. The K iVTEC (RSX/Civic/TSX) = VTC (cam phasing) + VTEC. The J iVTEC (AV6/Odyssey) = VCM + VTEC (or IMA + VTEC for the AV6H).

 

http://vtec.net/articles/view-article?article_id=719873

 

is it possible our engines are under rated too?