Engine pinging at extreme rate. Sensor -30 degrees

[Kev]

My car has been pinging bad (hard to drive at any speed and not to hear the pinging). Had one of those data scan tools pluged into it and took it for a drive and it picks up the pinging even when I cant hear it.

Anyway, to the point. The data reader is picking up that a temperature sesnor is reading as if its -30 degrees ??? The temp guage works correctly as warms up etc and once warm, so there must be another sensor somewhere. I dont think its the one in the bottom of the radiator, have been told this is re the transmission so it wont go into overdrive when cold.

Hopefully one of you may be able to help me and tell me where the suspect sensor is.

Thanks heaps, Kevin

 

[Jake Breyck]

im not sure about the 1uz but most toyota motors have 3 temp sencors. so the guage could be file but the ecu seesm somthing completely diffrent. as for what one to change/check on a 1uz, um ill let someone else chime in.

 

[rms]

The 1uz has 2 temp sensors, one green, one brown.
Almost under the coil on the drivers side front. Don't know which is the gauge, but try unplugging them one at a time.

 

[cribbj]

Erol, here's what our USDM UZ's have for coolant sensors

1. The small sensor with gray housing is for the dash mounted coolant temperature gauge

2. The big one with green housing is the CLT sensor for the EMS

3. The big one with gray housing, I think, is a bimetallic type thermostatic switch for the cold start injector

 

[rms]

Thanks John,
The ones I have seen here, mainly Japanese imports, don't have provision for the grey switch. Could be specific to the North American market ?

 

[cribbj]

Erol, do your front water bridges even have that mounting boss for the thermostatic switch? I've got a plug in mine, but if I could find a bridge without it, it would look cleaner.

Kev, sorry for the drift.

 

[Kev]

I appreciate the help, I just wasn't looking hard enough and it helps to pull a few things off. My car is a Celsior (import to Oz) and mine has all three of the sensors you mentioned cribbj. Now for some more work and testing.

Thanks heaps, Kevin

 

[Peewee]

Every Toyota I've seen has a single wire for the dash guage (same position as the small grey one in that pic, but without the plastic grey sheath).
A 2 wire green sensor for the ecu.
And a 2 wire brown sensor for the CSI. (same position as the large grey one in your pic, but with a brown sheath.


Kev, is it the airtemp sensor thats reading -30 or the engine temp sensor?
Air temp sensor is in the AFM.
Normally if they read -30 then they are open circuit, and the ecu ignores the reading and reverts to a standard map.
That said though, the CEL would definitely be on if the circuit went OC.

Give it a check though, and compare the resistance of the sensor to this.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/FI/FI_113.gif

 

[Peewee]

The ones I have seen here, mainly Japanese imports, don't have provision for the grey switch. Could be specific to the North American market ?

Erol, its possible you have only seen 95-97 1UZ's, as all 89-94's will have the CSI switch. The 95-97 dropped the CSI and went to standard cold start enrichment.

 

[rms]

I don't know what year the engines have been Peewee, luck of the draw I guess.
My '90 Celsior probably has the CSI switch, but I have not had reason to pull the plastic covers yet (fingers crossed).

 

[White ls400]

Is that picture of the front coolant bridge...
Is it hidden by a cover...
Anyone got any idea how much aud these sensors would be worth

 

[cribbj]

I bought the (2) water temp sensors from a Toyota, not a Lexus, dealer @ 25% off list for around $60 USD.

The cold injector start switch is the expensive one. By itself it's around $110 USD.

I don't know what the Lexus dealers would charge for these, but it seems many Lexus prices are 2 x Toyota, for essentially the same part.