RPMs hanging post Magnum XL install

Just had a Magnum XL installed. When I press the clutch the RPMs will hang for a couple seconds before dropping; mostly 1st and 2nd gear.

I did a crank relearn and it did not change anything.

I am getting a code for the output speed sensor circuit as I did not install an Abbot box. The 2015 uses the wheel ABS sensor for speed and my speedometer works fine.

Think it's related? What else might it be?

Thanks!

It's the speed sensor I believe.

Found another similar thread on svt, but didn't see a resolution posted.

http://www.

svtperformance

.com/forums/showthread.php?1088016-Swap-MT82-out-installed-Tremec-magnum-XL-2-97-cruise-control-doesnt-work-in-6th-gear

isedawishy said:

Just had a Magnum XL installed. When I press the clutch the RPMs will hang for a couple seconds before dropping; mostly 1st and 2nd gear.

I did a crank relearn and it did not change anything.

I am getting a code for the output speed sensor circuit as I did not install an Abbot box. The 2015 uses the wheel ABS sensor for speed and my speedometer works fine.

Think it's related? What else might it be?

Thanks!

Click to expand...

You will need the Abbott box and a retune to adjust for the new gear ratios. I ran into the same issues after being told by BBR to leave the OSS disconnected. Nothing short of a terrible experience dealing with them. Bought the Abbott box from JPC and Lund retuned it and that did the trick.

That's pretty frustrating since everyone and their mother say we don't need one :(

Did you also try to have Lund retune without the Abbot?

Yeah I was pissed! The speedo works without it sure, but the car doesn't run like it's supposed to. Lund did not try to retune it without the box. He said it was absolutely necessary to have the OSS signal, and I didn't know of another way aside from using the box. Here is the original email and the response.

"Hello,

I just swapped the MT-82 in my 2015 GT to a Tremec T56 Magnum XL and am experiencing some driveability issues. Specifically, on the 1-2 and 2-3 upshifts, the throttle seems to hang open and the RPM's rise a few hundred instead of dropping. Blow by racing informed me that the output speed sensor on the transmission is not necessary since the speedo is based off of the wheel speed sensors, so I currently have that sensor disconnected. The only other difference I can think of between the two transmissions that might cause something strange like this is the gear ratios. Are there parameters in the tune for my individual transmission gear ratios that need to be adjusted to accommodate this swap? Also, is there anything that needs to be done in the tune to allow the cruise control to function properly?"

Lund: "Frank,

Unfortunately Blow By Racing is incorrect. The OSS must be connected for the PCM to know what gear it is in and to control the cruise control properly. There is also tq by gewr logic and without OSS that logic is confused. So you will need to get the correct signal to the PCM for the OSS and at that point we can adjust the gear ratios for the trans.

Thanks,

Jon L Sr.

Jon Lund | Owner and Calibrator"

Hm, I wonder what they mean by correct signal? Correct as in it's reading or correct as in it must be calibrated. Maybe they can calibrate as long as it's reading.

It looks like the OEM 3 wire is simply externally powered and the Tremec 2 wire is internally powered. I assume if the Tremec is wired into the OEM harness it would read but the pulse count per mile with the OEM sensor would be different.

Ah well, I'll keep reading. Worse case on Monday I'll order the Abbott box.

I appreciate the information you've shared. I wish these shops would update their write ups and be more open. Yes, technically the speedo does work, but the car drives like shit. ><

Tremec is a badass trans i had one in my last car jpc installed it never had a single issue with it and the cc worked in 5th and 6th...

What clutch did you go with?

The 11-14 for sure required an Abbott box, as the speedometer fed from the speed sensor.

I'm using Mcleod RXT with the setup.

I spoke to someone I found on Instagram and he said he installed a MSD-8509, magnetic signal stabilizer.

https://www.msdperformance.com/products/distributors/distributor_accessories/parts/8509

I went ahead and ordered it as it's much cheaper than an Abbott. I get it Tuesday and will report back! Hopefully Lund can send me an updated tune ahead of time so I can test it right after.

I'll wire it as such,

Black - ground
Red - ignition power
Violet & Green - Tremec speed sensor
Yellow - middle wire on OEM speed sensor plug

I hope that does the trick ,good luck!

Msd-8509 is a no go gents. It recognizes the signal now as my check engine is off, but RPMs are still hanging. I assume it's due to the signal simply being converted, but not to specific values which the car requires.

Guess an Abbott box is in the future. On a good note, at least the wiring is all done.

Any pictures of these connections? :cheers:

isedawishy said:

The 11-14 for sure required an Abbott box, as the speedometer fed from the speed sensor.

I'm using Mcleod RXT with the setup.

I spoke to someone I found on Instagram and he said he installed a MSD-8509, magnetic signal stabilizer.

https://www.msdperformance.com/products/distributors/distributor_accessories/parts/8509

I went ahead and ordered it as it's much cheaper than an Abbott. I get it Tuesday and will report back! Hopefully Lund can send me an updated tune ahead of time so I can test it right after.

I'll wire it as such,

Black - ground
Red - ignition power
Violet & Green - Tremec speed sensor
Yellow - middle wire on OEM speed sensor plug

Click to expand...

isedawishy said:

Msd-8509 is a no go gents. It recognizes the signal now as my check engine is off, but RPMs are still hanging. I assume it's due to the signal simply being converted, but not to specific values which the car requires.

Guess an Abbott box is in the future. On a good note, at least the wiring is all done.

Click to expand...

Did you have Lund update your tune? The Abbott box in itself won't fix it either until the tune is updated. You might be okay with the msd if he can update the scaling in the tune

Yes, I had Lund refresh the tune. He's asking for a data log to see if the output is properly reading. I'll have to get him one when I get off work.

I too have the Abbot box installed on my Lund tuned Magnum trans car and have some RPM hanging. Not a real problem so I have not had it retuned yet; good to know that Lund is working on the issue.