Trans OSS signal starts dropping after 5500Rpm - TCCoA Forums
 
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post #1 of 6 (permalink) Old 05-09-2012, 05:40 PM Thread Starter
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Trans OSS signal starts dropping after 5500Rpm

Problem I'm having and it PISSING ME OFF.

If I'm at WOT and go past 104MPH the car like all of a sudden drops out of gear. I data logged it and I noticed that the MPH would go up and the corrected MPH would start counting down once past 102MPH. When the corrected MPH would get to about 57MPH it would command 2nd gear and there's where the problem starts. I started data logging the OSS and that's when I noticed the drop in shaft speed after about 5500RPM. I already replaced the OSS and went over the tune with a fine tooth comb. What am I missing?

Anybody else have or had this problem before?

Specs are 94 T-Bird, PI swaped heads and intake 4R70w Trans out of a MarkVIII 3.73 gears and a A5W0 ECM. I can send my bin and data log to any ody that wants to take a look.

I've come into this world with nothing and still manage to have some of it left.

ASE Master Technician and Advanced Level Specialist.
It's not what I know, It's knowing what I don't know.

1994 Thunderbird, 4.6 V8, PI heads, SVO Blower, 8# pulley, 2.5 duel exhaust, 4R70W, MarkVIII converter, Mark VIII differential, Trac-Loc, 3.73 gears, H&R 1.5 lowering springs, bilstien rear shocks and SC front struts.
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post #2 of 6 (permalink) Old 05-09-2012, 08:37 PM
50 years of Mercury Cougar 1967/2017
 
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Good luck. I had the same issue. At 105 the trans. tried to downshift to second gear.
It would not go into 2nd and just freewheeled.
Went with a seperate transmission controller.

Quickest N/A Modular MN12.
1995 XR7-11.77 @ 113.29 (3537 lbs.)
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post #3 of 6 (permalink) Old 05-09-2012, 09:11 PM Thread Starter
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Quote:
Originally Posted by r429460 View Post
Good luck. I had the same issue. At 105 the trans. tried to downshift to second gear.
It would not go into 2nd and just freewheeled.
Went with a seperate transmission controller.
well, I guess its good that I'm not alone.

does the seperate trans controller ignore the OSS?

I've come into this world with nothing and still manage to have some of it left.

ASE Master Technician and Advanced Level Specialist.
It's not what I know, It's knowing what I don't know.

1994 Thunderbird, 4.6 V8, PI heads, SVO Blower, 8# pulley, 2.5 duel exhaust, 4R70W, MarkVIII converter, Mark VIII differential, Trac-Loc, 3.73 gears, H&R 1.5 lowering springs, bilstien rear shocks and SC front struts.
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post #4 of 6 (permalink) Old 05-10-2012, 09:49 AM
50 years of Mercury Cougar 1967/2017
 
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I did not install the unit.
I think it does by pass the OSS.
FYI, they had the trans. out of the car torn down, put on a trans. dyno, changed the cars computer, (this worked for 1/2 hour of test drives).
They changed MLPS, OSS and trans. fluid.
Ohm checked all transmission sensors, within spec.
I had the car retuned with no change in the problem.
I think there are more with this issue, but they are not posting.

Quickest N/A Modular MN12.
1995 XR7-11.77 @ 113.29 (3537 lbs.)
01/31/18 PBIR
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post #5 of 6 (permalink) Old 05-10-2012, 10:06 AM
50 years of Mercury Cougar 1967/2017
 
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My issues started right after i had the TFS heads installed.
This increased the engines operating range.
Ask anything else, This is all I remember right now.

Quickest N/A Modular MN12.
1995 XR7-11.77 @ 113.29 (3537 lbs.)
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post #6 of 6 (permalink) Old 05-10-2012, 11:38 AM Thread Starter
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Problem solved!!!

sailorbob sent me an updated strategy with PID MNOSSPER and the description is
"MNOSSPER - The minimum time that must elapse between the rising edges of the Output Shaft Speed Sensor signal in order for the signal to be considered valid. Calculate using this formula:

ticks = (3 * cpu clock frequency in Hz) / (max shaft speed in rpm * no. of OSS pulses per rev)"

any way it had a value of 365 and I changed it to 265. After that I could run it up to 8000Rpm without a problem.
I hope this helps anybody else that has this problem.

I've come into this world with nothing and still manage to have some of it left.

ASE Master Technician and Advanced Level Specialist.
It's not what I know, It's knowing what I don't know.

1994 Thunderbird, 4.6 V8, PI heads, SVO Blower, 8# pulley, 2.5 duel exhaust, 4R70W, MarkVIII converter, Mark VIII differential, Trac-Loc, 3.73 gears, H&R 1.5 lowering springs, bilstien rear shocks and SC front struts.
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