A friend has an '89 Townace with a 2.0l petrol injected engine. Occasionally it is hard to start and when running it sometimes starts running as if on three cylinders. Backing off the throttle or increasing would get it spinning smoothly again. The other day it refused to start at all. After reading a little about it and talking to people who knew more than me, I had a look. I found that if I disconnected the plug on the Throttle Position Sensor, I could start it. If I put it back on it became hard to start, but this seemed to be regardless of the throttle position. When it was warmned up, it would start fine with or without the TPS cable connected. Am I barking up the right tree? Are there any other things that I might need to look at? Thanks.
- (#5914) Brent, 23 Oct 02

dunno. can you pull any trouble codes out of the system?
generally, you short te1 and e1 in the diagnostic socket, turn the ign on, and look for blink codes on the efi warning light.
does the tps have the iat (intake air temp) sensor built into it, perhaps?

hth

- (#5915) david millere, 23 Oct 02

Thanks David for yuor response. Forgive my lack of knowledge, but I can't seem to find the diagnostic socket. I've looked under the dash, heater, radio etc. I can find the fuse box etc. Is there an easy way to identify the diagnostic socket?

The TPS doesn't seem to have the air intake temp sensor built in. There is one in the air intake pipe about 30cm before throttle valve.

I managed to test the TPS. The socket has four connectors. The resistance between pin 1 (bottom) and 3 (third up) varies smoothly from approx 1.3k to 5k which seems to OK. I've since found out that there should be an idle contact closing between pin 1 and 2 when the throttle is closed. This isn't happening, so will try to adjust the TPS to correct this.

I checked the temperature sensors in the water too. The main one varies from 2k at cold to 0.47k when hot which is apparently acceptable. The other sensor seems to go from 30ohms at cold and switches to 52ohms when hot. Is this a cold start type sensor?

Thanks for your help.
- (#5939) Brent, 27 Oct 02

All sounds plausible, Brent, the resistances check with those in my book (for the US model...) And yes the 30-52 ohm sensor is the cold start injector's time switch.
The check connector should be beside the airfilter, from any info I have. It may not be the standard large rectangular jobbie that toyota normally use, rather a two pin round socket dangling down the back of the aircleaner. Wires might be gray and brown.

David
- (#5940) david miller, 28 Oct 02