Rev limit?

scupking · Jun 6, 2007

I was going thru my 93 custom tune on my Xcal2 and my neutral rev limit and drive rev limit was set to 6,500 RPM. I moved both down to 6,000RPM but I'm thinking of moving it down to 5,800 RPM. Will moving it down force the car to shift at 5,800? I have an auto.

goshia · Jun 6, 2007

Yes it will, how would it go above 5800 if that is waht you told the computer to hold the limiter too.

scupking · Jun 6, 2007

goshia said:
Yes it will, how would it go above 5800 if that is waht you told the computer to hold the limiter too.

That’s what I figured. I just didn't want it to sit there bouncing off the limit. I will lower it to 5,800 RPM.

Don 95Vert · Jun 6, 2007

The rev limiter has nothing to do with shifts - if the shift normally takes place at 6000 and you lower the rev limiter to 5800, you'll bang the limiter on the shifts...

scupking · Jun 6, 2007

Don 95Vert said:
The rev limiter has nothing to do with shifts - if the shift normally takes place at 6000 and you lower the rev limiter to 5800, you'll bang the limiter on the shifts...

That’s what I don't want. I just want to lower my WOT shift points to 5,800. For some reason when going WOT from 3-4 my engine seems to slip and revs up but I think it has something to do with my shift points. I have lowered my shift point pressure; 1-2 by 10 didn’t touch 2-3 and lowered my 3-4 by 5. Lowering 3-4 seemed to help some but I still get the strange rev change.

CobraRed_96_GT · Jun 6, 2007

scupking said:
That’s what I don't want. I just want to lower my WOT shift points to 5,800. For some reason when going WOT from 3-4 my engine seems to slip and revs up but I think it has something to do with my shift points. I have lowered my shift point pressure; 1-2 by 10 didn’t touch 2-3 and lowered my 3-4 by 5. Lowering 3-4 seemed to help some but I still get the strange rev change.

thats the o/d band engaging in a vertical clutch action sort of method then switching into o/d. No way to avoid that beautiful piece of ford engeneering - i've completely rebuilt my 4R70W with performance in mind and even though my 1-2 are in <.20 seconds the 3-4 takes a bit with some "revving-up" in between cuz u cant alter the accumulator spring and piston like on 1-2 and 2-3 on 3-4 cuz it doesnt even have one, lol - it's overdrive. Oh well, o/d isn't used for performance anyways it for saving gas. When being liberal with the gas you should have o/d off anyways.

spederman · Jun 6, 2007

I dont have an auto but have the xcal 2. I thought i remembered reading that the xcal 2 can set shift points for auto's. Isnt one of the menu's on the tuner for shift points?

MaxedGT · Jun 7, 2007

scupking said:
That’s what I don't want. I just want to lower my WOT shift points to 5,800. For some reason when going WOT from 3-4 my engine seems to slip and revs up but I think it has something to do with my shift points. I have lowered my shift point pressure; 1-2 by 10 didn’t touch 2-3 and lowered my 3-4 by 5. Lowering 3-4 seemed to help some but I still get the strange rev change.

How fast are you going to be able to shift 3-4 at wot! 120 mph? If you don't want slippage on the shifts, you increase shift pressure. I doubt the tranny is even designed to withstand multiple 3-4 shifts at wot. The last thing you want is to hit the rev limiter on shifts and that's what will happen if you lower rev limiter too low.

scupking · Jun 7, 2007

MaxedGT said:
How fast are you going to be able to shift 3-4 at wot! 120 mph? If you don't want slippage on the shifts, you increase shift pressure. I doubt the tranny is even designed to withstand multiple 3-4 shifts at wot. The last thing you want is to hit the rev limiter on shifts and that's what will happen if you lower rev limiter too low.

I alwasy keep OD off unless on the highway and even then I don't turn it on when gettnig up to highways speed (80mph). The strange rev happens when going from, lets say 50 then going WOT. So then I guess it would be 2-3 and not 3-4?

scupking · Jun 7, 2007

So is it true that it’s better to have hard shift pressures? To me it would seem that a hard shift would put more stress on the transmission?

scupking · Jun 7, 2007

Ok I’ve been doing some more testing. The strange rev happens between 2-3 shift and from 4,000 to 5,000 RPM. Could it be a timing thing, Air fuel ratio or something else? It doesn't happen in that RPM range from 1-2.

2002BLGT · Jun 8, 2007

scupking said:
Ok I’ve been doing some more testing. The strange rev happens between 2-3 shift and from 4,000 to 5,000 RPM. Could it be a timing thing, Air fuel ratio or something else? It doesn't happen in that RPM range from 1-2.

so is it happening at WOT or part throttle , if you are at WOT shouldnt it be shifting closer to 6000 rpms ....or is it happening as the RPMS fall back to 4-5K when it shifts?

Lookin4Stang · Jun 8, 2007

scupking said:
So is it true that it’s better to have hard shift pressures? To me it would seem that a hard shift would put more stress on the transmission?

To my understanding, quicker shifts = less heat but hard/violent shifts are no good either. I had a shift kit on my older car and the general consensus was to make the shifts quick and precise but never hard. Increasing line pressure to firm up the shifts is usually safe as long as it is done sparingly.

scupking · Jun 8, 2007

2002BLGT said:
so is it happening at WOT or part throttle , if you are at WOT shouldnt it be shifting closer to 6000 rpms ....or is it happening as the RPMS fall back to 4-5K when it shifts?

It happens as the RPMS are going up on WOT, before the shift. It actualy happened today between 5-6k RPM. So it seems to very some. But it is only on the 2-3 shift.

2002BLGT · Jun 8, 2007

scupking said:
It happens as the RPMS are going up on WOT, before the shift. It actualy happened today between 5-6k RPM. So it seems to very some. But it is only on the 2-3 shift.

are the RPMS jumping up or stalling for a second or what , can you describe the problem a little more ?

scupking · Jun 8, 2007

2002BLGT said:
are the RPMS jumping up or stalling for a second or what , can you describe the problem a little more ?

Jumping up. The engine just changes to a different tone and almost sounds like it’s over revving, even though its not. It's hard to explain, I will try to get a video of this.

MaxedGT · Jun 9, 2007

Could it be you're running out of power at high revs? If so change your fuel filter to start with.

scupking · Jun 9, 2007

MaxedGT said:
Could it be you're running out of power at high revs? If so change your fuel filter to start with.

I was actually just thinking about doing that. I also should probably get new spark plugs. I have 55,000 Miles on her; the fuel filter and plugs are still original.

MaxedGT · Jun 9, 2007

Good plan.

scupking · Jun 10, 2007

What are good plugs to get?

Rev limit?

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