Hitting Rev limiter

[OLS108]

Ok guys i have had my 3.73 diff gears in for a couple of months and have had the speedo changed at Power Torque, but at WOT i hit the rev limiter in 2nd everytime at the Track and it plain pisses me off i have a best of 13.90@102.4mph so i have two questions.
My car is a stock tune VX I Berlina Auto with genie extactors twin 2 and a half inch system, MCAI and the 3.7 diff gears
my misses is taking the car to Power Torque tomorrow if she can get it in.
1.what can be done and how much is it going to cost?.

2. how much time do you guys think it has cost me over the 1/4?, hitting the limiter then having to take my foot off the go pedal and apply it again slowly.

[Doug]

Common for A4's moving to 3.7 diff gears to hit the rev limiter in 2nd. Can be resolved by making PCM changes to the transmission shift points. (And I guess rev limit if you wanted to go that way.)

Power Torque could definitely fix it - but I don't know how much it would cost.

I know people with their own tuning software who took a few attempts to get the shift points right to stop hitting the rev limiter. This related to inexperience, and the difficulty in testing WOT 2-3 shifts on the street. ;)

[OLS108]

cheers any idea what i should up the rev limiter too ? this is a family car that willbe doing a bit of drag racing, say 1 meet every month or two

[seldo]

Why don't you ask Powertorque..? I think you will find they will tickle it for you probably for free, or a carton ...;)

[OLS108]

Why don't you ask Powertorque..? I think you will find they will tickle it for you probably for free, or a carton ...;)
yeah but i might not get a chance to speak to them personaly as my misses
( the homer simpson of cars ) has to take the car in for me. and i gotta work
anyone know the Pirce of a dyno run ? might get an idea of what sort of power the old girl is making.!

[Delco]

Ok guys i have had my 3.73 diff gears in for a couple of months and have had the speedo changed at Power Torque, but at WOT i hit the rev limiter in 2nd everytime at the Track and it plain pisses me off i have a best of 13.90@102.4mph so i have two questions.
My car is a stock tune VX I Berlina Auto with genie extactors twin 2 and a half inch system, MCAI and the 3.7 diff gears
my misses is taking the car to Power Torque tomorrow if she can get it in.
1.what can be done and how much is it going to cost?.

2. how much time do you guys think it has cost me over the 1/4?, hitting the limiter then having to take my foot off the go pedal and apply it again slowly.


Did you have the speedo changed or the tune changed to suit the diff gears.

If you only had the speedo setup then go and get the shift points sorted out and grab a tune while you are at it.

Are you using the same tyres at the track as on the road - can make a difference if the shift is close to the limiter , doesnt make much of a tyre size change to get it to bang onto the limiter.

[Doug]

Best to speak with a professional on raising the rev limiter, and on what they might recommend you do to ensure this doesn't have adverse effects. I don't think this is the solution you should be looking at though.

As I understand it, the problem relates to how transmission shifts occur. The PCM requests the shift, and then there is a variable delay before the transmission actually does it. During this time the rev's increase.

An example, with totally made up figures...

Car hits 5800 revs at WOT, PCM requests shift.
Revs keep increasing..
Transmission actually ends up shifting at 6100 revs.

Change diff gears to 3.7's. Means revs increase quicker...

Car hits 5800 revs at WOT, PCM requests shift.
Revs keep increasing
Car hits rev limiter at 6200rpm as the transmission hasn't shifted yet

So the solution is to lower the point at which the shift is requested, so that it actually happens under the rev limiter. So to end the made up example…

Car hits 5600 revs at WOT, PCM requests shift.
Revs keep increasing
Transmission actually ends up shifting at 6100 revs.

[OLS108]

yeah trust me guys id Love to get a tune but at the moment $1200 is WAY out of my reach, as its Moving time and we all know how expsenive it can be.
i hope it wont cost too much or i wont be able to get it done for a while, anyway will find out tomorrow.
PS any idea what sort of numbers to expect on the dyno ?

[XLR8 V8]

yeah but i might not get a chance to speak to them personaly as my misses
( the homer simpson of cars ) has to take the car in for me. and i gotta work
anyone know the Pirce of a dyno run ? might get an idea of what sort of power the old girl is making.!


There's a cool invention going around .... relatively inexpensive .... and would work wonders to help fix your problem ..... it's called A PHONE!! :lol: :lol:

Ring them up and ask 1. How much to fix your shift points, and 2. How much for a dyno run. :D


Simple as that. :)

[OLS108]

There's a cool invention going around .... relatively inexpensive .... and would work wonders to help fix your problem ..... it's called A PHONE!! :lol: :lol:

Ring them up and ask 1. How much to fix your shift points, and 2. How much for a dyno run. :D


Simple as that. :)
a PHONE ??? are you joking they are way to New and fang dangled for me to consider does this power torque have Morse code ? :lol: :lol:
yeah good idea mate i would have called today but i have been flat out and will be like that tmorrow

Cheers again guys

[Mongy]

Get Mark to revise your shift points. At WOT the computer relies on reaching a programmed RPM and a programmed speed. By lowering the diff ratio your are reaching the programmed rpm criteria but not the speed, so the gearbox will not shift when it needs to. It is a common problem when you put a lower ratio diff in. Some PCM's for some reason also do not react to the input even when it is changed. If yours is one of the few that do this you may have to fractionally raise your rev limit (within reason) to compensate. Have no fear, Mark knows how to rectify your problem.

[XLR8 V8]

a PHONE ??? are you joking they are way to New and fang dangled for me to consider does this power torque have Morse code ? :lol: :lol:
yeah good idea mate i would have called today but i have been flat out and will be like that tmorrow

Cheers again guys

Sorry mate, I forgot for a second that you're one of those bogan blokes who drive V8 Holdens :driving:

[OLS108]

Sorry mate, I forgot for a second that you're one of those bogan blokes who drive V8 Holdens :driving:
yeah thats the second time ive been called a bogan today lol :lol:
i dont think it has anything to do with my truckie singlet and pack of winnie blues and me rubber thongs( joking i dont smoke ) :D

Thanks again guys i will report back tomorrow to let you know how i got on !
PS anyone got Any idea how much time i would be losing by hitting the limiter ?

[VX8255]

Get Mark to revise your shift points. At WOT the computer relies on reaching a programmed RPM and a programmed speed. By lowering the diff ratio your are reaching the programmed rpm criteria but not the speed, so the gearbox will not shift when it needs to. It is a common problem when you put a lower ratio diff in. Some PCM's for some reason also do not react to the input even when it is changed. If yours is one of the few that do this you may have to fractionally raise your rev limit (within reason) to compensate. Have no fear, Mark knows how to rectify your problem.

My car had one of these pcm's in it, and in the end would'nt respond to a 20mph change in the 2-3 shift point, we had been chasing the problem for quite a while, changed the pcm, does exactly what we wan't now, 1st 6500rpm, 2nd 6500rpm, limiter set on 6800rpm has'nt hit the limiter once lately. :D

[VT_SS_II]

My car had one of these pcm's in it, and in the end would'nt respond to a 20mph change in the 2-3 shift point, we had been chasing the problem for quite a while, changed the pcm, does exactly what we wan't now, 1st 6500rpm, 2nd 6500rpm, limiter set on 6800rpm has'nt hit the limiter once lately. :D

Interesting.

When I got my MAF-Less tune done last year I also had to have a new PCM put in as it had been slightly edited before by Sam's Performance and had been locked. (Mark at Powertorque suspected it was done in the early days of LS1 tuning and before LS1 Edit software).

Anyway, a month or so after the tune was done I came across the problem of it hitting the rev limiter at the 2-3 change while at the drags. (standard 3.08 diff gears) It didn't do this before the tune so I just put it down to just a oversight when the shift points where done.
I havn't worried about getting it looked at yet as I thought I'd just leave it until I go back after I get 3.73's put in.

I'll keep in mind these comments about the PCM when it comes time for the re-tune.

[untamd]

You also maybe have to be careful when hitting the limiter if you have the standard auto, i have had a few changed before in my old car, when it was hitting the limiter it burnt out the bands in the auto, apparantly they are not so good in these boxes.






Veasna

[XLR8 V8]

Interesting.

When I got my MAF-Less tune done last year I also had to have a new PCM put in as it had been slightly edited before by Sam's Performance and had been locked. (Mark at Powertorque suspected it was done in the early days of LS1 tuning and before LS1 Edit software).

Anyway, a month or so after the tune was done I came across the problem of it hitting the rev limiter at the 2-3 change while at the drags. (standard 3.08 diff gears) It didn't do this before the tune so I just put it down to just a oversight when the shift points where done.
I havn't worried about getting it looked at yet as I thought I'd just leave it until I go back after I get 3.73's put in.

I'll keep in mind these comments about the PCM when it comes time for the re-tune.


Could also be that your converter has started slipping a little.

[Holden Nut]

Speaking of hitting the rev limiter. My car still with the original 3.08's, hit the rev limiter every run last time I went to the drags...wtf is making this happen?

[OLS108]

OK i picked up one of those "phones" Today and rang Paul at PT and i asked him what the Go was, he said its not uncomon for an auto to do this after diff gear change, and because i already paid for the them to change the speedo he will get mark to fix it up for me for free!!! :D ( top Blokes ) anyway while she is in there i will get a dyno sheet to see what sort of numbers she is pulling.

[seldo]

OK i picked up one of those "phones" Today and rang Paul at PT and i asked him what the Go was, he said its not uncomon for an auto to do this after diff gear change, and because i already paid for the them to change the speedo he will get mark to fix it up for me for free!!! :D ( top Blokes ) anyway while she is in there i will get a dyno sheet to see what sort of numbers she is pulling.
Well I'll be durned....! How about that! It wasn't that hard was it..? I guess we can say you failed rocket-science exams...?...;)

[Doug]

Seem to get a lot of good reports about PT - with a response like that, little wonder. :)

[Tonner]

My car had one of these pcm's in it, and in the end would'nt respond to a 20mph change in the 2-3 shift point, we had been chasing the problem for quite a while, changed the pcm, does exactly what we wan't now, 1st 6500rpm, 2nd 6500rpm, limiter set on 6800rpm has'nt hit the limiter once lately. :D
Was That after an Edit?

[BLACK 346]

a PHONE ??? are you joking they are way to New and fang dangled for me to consider does this power torque have Morse code ? :lol: :lol:
yeah good idea mate i would have called today but i have been flat out and will be like that tmorrow

Cheers again guys

da da dit/da da da
da/dit dit dit dit/dit/da dit da da
da dit dit/da da da/da dit/da
dit dit dit/dit da/dit dit dit da/dit
da da/da da da/dit da dit/dit dit dit/dit
da dit da dit/da da da/da dit dit/dit

If you can't read that use the phone :)

[seldo]

Seem to get a lot of good reports about PT - with a response like that, little wonder. :)
Yeah, and apart from being legends as tuners and general go-faster gear, they are also just a bunch of really good no-BS guys... I mean, I hate to say it...But I told you so...(don't you hate smart arshes...!) Apart from all that, I still reckon a carton of something...(gold ...;)) is a nice way to say thanks..
It seems that they are currently re-doing a couple of biiiiiiigg stroker engines that someone else charged $70k...:shock: to build... (true, that's the story... $70k...!) and they even had the pistons in back-to-front so the fly-cuts were arse-about...:shock: After fixing the first, the bloke was so stoked that his mate brought his sister-car in to be fixed as well....

[OLS108]

da da dit/da da da
da/dit dit dit dit/dit/da dit da da
da dit dit/da da da/da dit/da
dit dit dit/dit da/dit dit dit da/dit
da da/da da da/dit da dit/dit dit dit/dit
da dit da dit/da da da/da dit dit/dit

If you can't read that use the phone :)
:lol: :lol: :lol: thats funny but i dont think i liked what you said about my mum :mad: :lol: :lol:

[seldo]

da da dit/da da da
da/dit dit dit dit/dit/da dit da da
da dit dit/da da da/da dit/da
dit dit dit/dit da/dit dit dit da/dit
da da/da da da/dit da dit/dit dit dit/dit
da dit da dit/da da da/da dit dit/dit

If you can't read that use the phone :)
That's a bit like drum music....
mw mw mmm, mw mw mmm
(bum titty, bum titty, bum bum bum. bum titty, bum titty, bum bum bum.) ;)

[Tonner]

Thats good work Gene :lol:

[VX8255]

Was That after an Edit?

That was after about 50 edits!!!

[Tonner]

I wonder if there is a batch number or ? for these suspect PCM's and how they go with the more recent tuning equipment

[VX8255]

I wonder if there is a batch number or ? for these suspect PCM's and how they go with the more recent tuning equipment

I don't know, because after I changed the pcm, we began using hp tuner for editing.