Is my Throttle Position Sensor shot?

Justen · 11-09-2009, 06:19 PM

I've been tryin to set the timing on my new rebuild, but i couldnt seem to get the idle low enough or stable enough to set it correctly. So i put the BACV back on thinking it would help. But the idle still sucked. And it backfires and floods like crazy on startup.

I made the TPS check light, and tested it. I can turn the set screw so that only one light comes on (like its supposed to) but its very sensitive, and even a tap on the throttle cable can screw up the adjustment and make the second light come on. Then i test the tps with a multimeter, but i'm not getting any continuity from prong A to B, and something like 850 k'ohms on E to D. I assume that the sensor is completely shot...

...I just find it wierd that this one could be bad, because the car used to idle fine before the rebuild. Have they been known to go bad or short out that easily, even if theyre just sitting on a shelf?

rx4ur7 · 11-13-2009, 03:15 PM

Trust your DVM. Afraid you need a new TPS. I had one that failed the tap with a screw driver test. Would run fine until it hit a pot hole or rail road tracks. Also failed when I tapped on it or played with the wiring harness.

Justen · 11-15-2009, 08:37 PM

Well i guess i'm off to find a new sensor. Thanks for the input.

rx4ur7 · 11-20-2009, 04:03 PM

Autozone has them, cheaper than Mazda but still pricey.

11-09-2009, 06:19 PM	#1
Justen In Too Deep Join Date: Jun 2009 Location: Clifton, NJ iTrader: (3) Posts: 112 Rep Power: 16	Is my Throttle Position Sensor shot? I've been tryin to set the timing on my new rebuild, but i couldnt seem to get the idle low enough or stable enough to set it correctly. So i put the BACV back on thinking it would help. But the idle still sucked. And it backfires and floods like crazy on startup. I made the TPS check light, and tested it. I can turn the set screw so that only one light comes on (like its supposed to) but its very sensitive, and even a tap on the throttle cable can screw up the adjustment and make the second light come on. Then i test the tps with a multimeter, but i'm not getting any continuity from prong A to B, and something like 850 k'ohms on E to D. I assume that the sensor is completely shot... ...I just find it wierd that this one could be bad, because the car used to idle fine before the rebuild. Have they been known to go bad or short out that easily, even if theyre just sitting on a shelf? __________________ 1990 TII, fresh rebuild Atkins rebuild kit, RA apex seals Med. Streetport, TB mod, rebuilt turbo, ported wastegate, GodSpeed FMIC RacingBeat Turbo-back straight exhaust, Bonez test pipe, emissions/nest removed hks intake, Walbro, Profec B spec-2

11-15-2009, 08:37 PM	#3
Justen In Too Deep Join Date: Jun 2009 Location: Clifton, NJ iTrader: (3) Posts: 112 Rep Power: 16	Well i guess i'm off to find a new sensor. Thanks for the input. __________________ 1990 TII, fresh rebuild Atkins rebuild kit, RA apex seals Med. Streetport, TB mod, rebuilt turbo, ported wastegate, GodSpeed FMIC RacingBeat Turbo-back straight exhaust, Bonez test pipe, emissions/nest removed hks intake, Walbro, Profec B spec-2

11-13-2009, 03:15 PM	#2
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson iTrader: (0) Posts: 231 Rep Power: 17	Trust your DVM. Afraid you need a new TPS. I had one that failed the tap with a screw driver test. Would run fine until it hit a pot hole or rail road tracks. Also failed when I tapped on it or played with the wiring harness.

11-20-2009, 04:03 PM	#4
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson iTrader: (0) Posts: 231 Rep Power: 17	Autozone has them, cheaper than Mazda but still pricey.