wire to change on the 01 ho for top speed?

[MHindman]

I read before about cutting some wire and hooking it up to a switch to make it go faster... please fill me in... Mike

 

[Vaughn MacKenzie]

How about tricking the ECM?

I think it is the white/orange wire going to your PCM, pin #27. The downside is your speedo & odo stop working.



Here is a better idea for the Electronic Wizards of TDR:



Wire #43 (orange & white) going to the ECM is the Vehicle Speed Sensor signal. I think it is fed from the PCM and at this point will not affect your instrument gauges. All someone has to basically do is see what sort of signal is there, probably a pulsed signal that changes frequency, and make a box to splice inline that will hold the frequency from allowing the ECM to see anything higher than what 110 mph represents (I think it begins defueling at 112).

I don't know what the ECM would then "think" if the RPM continues to rise while the vehicle speed remains steady, but, the ECM is probably too stupid to realize that the two signals do not compute (clutch slippers don't set off codes)



Vaughn

 

[Vaughn MacKenzie]

Oops, meant to post this ECM plug pinout :

 

[MHindman]

so it will still run the same, up untill 112? i wont lose any power or anything. I really done want to mess with this, unless i have to. I really dont need to go over 112 anyway, i just want to get there as fast as i can Thanks for the help

Mike Hindman

 

[Diesel Freak]

Just did a little number crunching.



At 2700 RPM with a 6spd, 265x75R16 tires and 3. 55 gears you are traveling at 98 mph.



After 2700 rpm the engine starts to defuel (stock) this is a function of rpm and not vehicle speed. The reason the truck does not pull as hard above 2700 rpm (98 mph) is because the engines power is dropping off.



3500 rpm is a calculated 127 mph



Adding injectors is the best way to get more RPM... . they compensate a little for the defueling by the ECM above 2700 RPM.



These trucks do not have a top speed governor... . just an RPM limit on the engine.

 

[JerryWallace]

speed limiter

There has to be a speed limiter on some of the Rams. The reason I say this is the last time my truck was on a dyno, I was able to pull 5th gear runs all the way to red line. I thought I would try a 6th gear run but I was only able to get to 2500rpm and about 88mph for my speed. At 2500 the truck de-fueled as if someone turned the key off. I'm not sure if there is a pattern to the Rams that have this speed limiter as far as where they're made or how they're equipped. Oh well, it's kind of disappointing to know that I have one of them. Maybe it's due to it being a Mexico made truck instead of U. S.

-Jerry

 

[Diesel Freak]

That is odd. I have an early 2001 ETH and it runs all the way up!



Think of it this way.

Let's say it takes 40 HP to run at 50 MPH on a flat road.

Then it takes 160 HP to run at 100 MPH.

To run at 127MPH it would take 258 HP... . interesting isn't it.



Now lets look at the HP of a stock ETH as it passes 2700RPM. It dropps like a rock while aerodynamic drag, and parasitic driveline losses are increasing exponentially. That is why it can not accelerate worth a crap past about 105mph

 

[Diesel Freak]

This should clear it up

 

[Diesel Freak]

Shoot, the resolution sucks.



The X axis is speed in MPH from 100 to 130 in 3MPH increments.



The Y axis is HP from 150 to 275 in 25HP increments.



The red graph is required power.



The green graph is available power.



Looks like the top speed for a stock ETH should be about 117MPH

 

[mmeyn]

Have a 2001 HO 6spd and been up to 125 and then got out of it felt like it was getting loose I guess because it has coil springs up front. never felt her defuel just whistled right along, watch the exhaust temp though

 

[Vaughn MacKenzie]

Cliff, there was a thread last year talking about this, it does seem there is a speed-related governor on some of the trucks at least. There were a couple posts saying 112mph it starts to defuel but who knows if that is true or not. I can say for sure with my truck, especially since adding the DD2s, I can definitely feel it cutting back right after I pass 110. I've been up to 118 both when my truck was stock and now with the DD2s. It acts like that is as fast as the ECM will let it go, even though I am a good 200rpm below redline.



As far as HP above 2700rpm, on the dyno at Diesel Thunder in Spokane, my HP didn't take a serious dive until after 3300rpm.



Vaughn

 

[Diesel Freak]

Originally posted by Vaughn MacKenzie



As far as HP above 2700rpm, on the dyno at Diesel Thunder in Spokane, my HP didn't take a serious dive until after 3300rpm.



Vaughn

gotta love those DDII's

 

[Todd T]

your right about fooling the ECM, but..... when you cut this wire it kils a govenor circuit that also keeps the engine from stalling on take offs. what i found, is with the wire cut, the speed limiter IS disabled. but the truck then if you dump the clutch in first gear would die.



Micheal, I have been in contact with Mark at TSTabout this. I have also heard someone has a box you can put on to fix it at the pump. although I'm not sure if that box is for this or just to allow it to rev over 3200RPM's.



I simply put a switch mounted in the cab that i turn off when i need to go fast and back on for normal driving.



it is the white wire with an orange trace. it can be found at the connector above the valve cover.



have fun.

 

[Vaughn MacKenzie]

Todd, I think I'll try your idea, but instead splice in a switch to Wire 43 going to the ECM in hopes it will not affect the speedo.



Vaughn

 

[Todd T]

vaughn, cutting the wire where i said to does not kill you speedo,



it is a feed out of the PCM to the ECM. the ECM as stated before compares the VSS to fuel flow and then defuels at a specified rate/speed ratio.



I cut mine and extended both sides into the cab and mounted a switch inside the roof of the ashtray. works great



I plan to work on a circuit that is either boost driven or voltage driven off that lead, that will do this automatically. the problem is it is a sine wave on that wire.