Coolant temp sensor differences between the years...

[CPT Furious]

Hey folks,

Here is my situation. I swapped my old motor out for a JDM one a few years back and I have been looking at some of my sensors and it seems like some of them are different from my original setup. Since the harness that came with the motor was in better shape than mine, I went ahead and used some of it's connectors as well.

The problem was that some of those said connectors didn't match up to the USDM sensors. Without much hesitation, I went ahead and swapped out some of those sensors, too. Now, the wire colors match (ECU is brown/green, CSI switch is black/green) and the resistances seem correct according to the TSRM, but the first start of the day still takes about three tries before it's successful but all the starts after that are fine.

I have also checked the CSI itself per the TSRM and it injects fuel just fine. Nice mist and everything. There are no codes. Any thoughts on if the sensors resistances are different for different years or if they work in different ways...? :1zhelp:

Also, I have an HKS VPC, Apexi S-AFCII, HKS 550cc injectors, J-tube eliminated, 12 volt mod, Walbro in the tank.

 

[malloynx]

hey lane, all i know is that the JDM and USDM coolant sensors are different. when i had my old JDM, i had to use my USDM coolant sensors

 

[shaeff]

i just popped my JDM motor in, (when i first got it) and just swapped the connectors. i've never had a problem to date...

-shaeff

 

[Disco Stu]

I know the sensor from my USDM 87 n/a did not fit in the new 89 harness that I got. The way they work should be the same no matter how you swap it though.

 

[IJ.]

I know the sensor from my USDM 87 n/a did not fit in the new 89 harness that I got. The way they work should be the same no matter how you swap it though.

Yo

 

[Disco Stu]

Or just forget the sensor and go for real power with a JDM 1J yo. That's what the real racers do dude! *makes bov sounds with mouth* PSSSSShhh Powered By Toyota, yeah!

 

[IJ.]

<cracking up here>

 

[CPT Furious]

Okay, so here is a thought. If I think I am getting too much gas on initial startup and the CSI time switch increases resistance with temperature (or at least it looks that way) could I simply unplug the connector so it sees infinite resistance and won't tell the CSI to inject fuel, or do I have the theory of operation messed up?

 

[IJ.]

Lane: I'd expect that the throw a code and maybe put the ECU into limp mode.

 

[mrnickleye]

If you dont want the cold start injector to come on, just unplug the connector to the injector. It won't set a code. Warm climates like So. Cal, S. Texas, S Fla. won't even notice its missing.

 

[CPT Furious]

I'll try that tomorrow and see if it helps at all with the starting issue.

 

[Satan]

Bringing this up from the past, 'cause I need a little help...

I have a BRAND NEW 89+ engine harness and it won't fit any of the sensors which are on the ~87 engine I have now, or the JDM engine which I've just replaced. Are all the USDM T-Stat housing sensors the same, 87-92? Or, are there also some differences in pre-89 and 89+?

 

[IHI-RHC7]

You should just give me that harness, it will never work on your car.

 

[Satan]

Ain't giving this bad boy up.... VERY nice.:naughty:

Going into my 1990 MKIII, using an earlier 7M engine, from a 5-speed... what's new, just Frankensteining like usual...:evil2:

 

[CPT Furious]

Okay, finally looked at this some more. I went ahead and plugged my old CSI time switch in, cut the "JDM" connector out and spliced the wires to my old time switch using the TSRM to get the wires matched up right. After the car had sat for two weeks, it fired up after cranking for less than a second! I guess the sensors really ARE different since it would take at least 3 attempts with the old sensor. Lesson learned...

 

[CassMori]

any of you guys got a pic of this sensor(s) that's different? I'm having the same starting problem, but when I installed my JDM engine, I bought a brand-new engine harness, and all sensors plugged right in. CPT Furious, if this fixed your problem, I'll have to look into it as well, but I want to be sure to get the correct sensor. I'm guessing there may be a difference w/ 89+ models?