Odd Problem

shard

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#1
I have a somewhat odd problem, if anybody has encountered similar I would appreciate a few pointers:

With cruise control switch ON cruise NOT SET.
Apply throttle and the car drops into limp mode NO MIL
Drop into 2nd apply throttle car responds as it should, can then shift to D and car will drive as normal.
Run diagnostic:
1st occasion - TPS, O2 Sensor and Speed Sensor 2
2nd occasion - TPS
3rd occasion - TPS and O2 Sensor.
I have checked these items, according to TSRM all are in spec This does not happen everytime i drive only once a fortnight or so.
As Cruise does not directly connect to TPS/O2 or Speed Sensor I have not a clue what's happening here.
Thanks in advance

1990 Supra 7M-GTE Auto
 

3p141592654

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#2
when you say limp mode, what do you refer to? The transmission or the engine?

The common input to all these systems is speed, and I have seen problems when the speedo cable is not spinning smoothly. You will see the speedo needle fluctuate and systems dependent on the speed sisgnal like cruise, ECU, and ECT will sometimes quit.
 

shard

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#3
Engine drops into limp mode, virtually zero acceleration. I will check the cable, though I greased the top end about 8 months ago (clocks out for bulb replacement).
I wasn't aware that the gearbox had a limp mode.
thanks for the reply 3p
 

3p141592654

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#4
A bad speedo input would not cause the engine to lose power. Only an issue with the AFM or ignition would do that. So i' m a little confused with your symptoms.

If the speedo needle is smooth and not wobbly then the cable is good.
 

shard

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#5
This is an odd one, thats why I asked on the forum. It's harder to lock down because it only happens occasionally. I have checked most components that could be involved and have applied silicon contact grease to plugs and connectors, replaced a slightly dodgy earth wire on the coil pack. Intermittent faults are a major pain in the arse!
Speedo is smooth not wobbly. I'm starting to think it could be speed sensor 2 beginning to fall over.