Head temp sensor issue.

[jayzrocket]

Both of my 280zxt's are having an issue not responding correctly when getting on the throttle, poping, backfiring thru the afm and really bogging down. After systematicaly removing all of the connections in the engine bay one at a time, finally when i pulled the connection on what I believe is the head temp sensor the idle came up to a grand and no more poping or backfiring, with much more instant responce at the throttle. This was all done at temp in the driveway. Here's the thing, I went to auto store- baught new sensor and still same issue. this sensor I speak of is at the back of the p90 between the last two spark plugs and right above the block serial #'s. Does anyone know about this? And maybe the new sensor is bad out of the box (autoz**e).

I think it runs richer without being connected. Any input would be great.

Thanks.

[roger.svoboda]

well you got the right sensor. It is odd that you get the same response from both cars. There is an ohmeter check in the FSM which you can download and check that. I'd also look at the wiring. Friend of mine found someone put a resistor in the wire for CHTS. Is the sensor physically touching the block (which it needs to do) Careful putting it in if tightened too much it gets crushed. Download the fuel injection bible lots of tips in there. Try the new sensor in both cars. I assume you have checked the timing and the fuel pressure. Pull the main connector off the ECM in the driver compartment and see if it is clean. push in out a couple times make sure seating properly. Never had an issue on 280 but swapped out several on 300zxt which made a big difference. Luck

[jayzrocket]

Thanks, yea it is wierd. I didn't know about beeing too tight- thanks.

And I read on here in some of the other forums about the connection issues at the ECU. I had this issue first on my 355k zxt at about 350k. And the second zxt I bought last Oct., that had been sitting in storage at a shop. They had worked on the car for the customer for other maitinence, Hadn't been started since '96, just needed fuel pump. But anyhow there was a resistor on the connector as well where you mentioned. Thanks again, J.

[DuoWing]

Interestingly enough my ZXT had a problem like this, which is why the previous owner ended up selling it. CHTS went bad, he bought a new one which turned out to be bad, but he didn't know it. I discovered this myself. After I had done practically everything I was left at a standstill. I had the receipt and him pointing out that the CHTS was new. I swapped it with the CHTS from my 176k 280ZX and it ran good for a bit, but was on it's way out and shortly after went bad. I finally bought one from MSA and finally got one that worked. It was weird that it wasn't until the 4th CHTS that it was one that finally worked.

[roger.svoboda]

I got bit by the "but it is new" when I was seventeen and tuning up the 49 ford I owned. New points etc she wouldn't start. The dad walked out "whats wrong son?" smart mouth kid says don't know new points she wont run. dad HOW do you know they are good. Well they are brand new dad ask again how you know they are good. On close inspection found that NEW points were faulty manufacture. Never have trusted a new part since.

[jayzrocket]

Yea Iv'e had my fair share of "New parts", my luck has always been- if there is a bad one on the shelf, no matter what it is or where its from, if I were to bet on getting "it" I'd be rich! But then again, the way my luck truely is, if I were to bet on "it" I wouldn't get a bad one ever again. So figure that one out. Thanks for the input and the confrimation. J.