I got all wires and tubing routed for temp and boost gauge...thank again for the suggestion about the 2 holes inside the driver fenderwell.

Now, I am in process of connecting the water temp gauge sensor to the filter neck...originally my plan was to remove the filter neck and tap it for the sensor. However I see there are two plugged holes already there, the one on the side is not good because the air pump pulley's on the way. The other one is on top next to the cap...is this a good route out? Seem like there are RX7 owners took this route for connecting the sensor instead of remove/drill/tap the water neck.

Would I experience false reading using this method?

TIA

 

No, but it does interfere with the filler neck cap.

 

doesnt a little bit of air get trapped up there? and wouldnt that cause a false reading?

 

Never had a problem. The only false reading you'll get is if your sensor gets grounded out for some strange reason....

 

so it would be ok if I can mod the cap to fit?

 

Yes, depending on your sending unit, you might have to cut off one of the "ears" on the cap so you turn it as you close it.

 

I did mine that way, and didn't need to remove any ears.

Just look directly over it and remove the cap - if it sweeps over that spot, it will need modified.

The only issue is that it won't read a coolant temp until the engine warms up and the thermostat opens. But that takes 2 min and nobody in their right mind will push the car before that event.

Dave

 

there was a thread a while back about someone who installed the sensor in the hose that goes to the thottle body with better results than sensors located at the filler neck. Can't seem to find it right now though. Try searching maybe.

 

https://www.rx7club.com/showthread.p...ht=temp+sender

I think this is what your talking about, and yes, it's a WAY easier install. No drilling or taping, gives accurate readings w/o evening waiting for the T-stat to open. And (though I don't know why you'd want to), it's completely reversable. Check post #36 for a complete list of what's needed. Kudos again to DaleClark

 

Just to present the other side of things....the throttle body location does NOT represent the hottest coolant flow and does not react nearly as quickly as the t-stat location.

 

In terms of accuracy and quick response, my experience is identical to what DamonB described in post #28 of the same thread I linked too.

 

With all due respect to you and Damon, I find that the temp gauge with the sensor in the t-stat housing reacts FAR faster than the stock-in-block temp sensor (as read by the PFC Commander). If the throttle body line location reacts similarly to the stock-in-block sensor (as it appears to given Damon's statements), then it reacts more slowly than the t-stat location and does definitely NOT show how hot the coolant leaving the engine truly is.

It's really not a big deal and I'm sure that the throttle body line location works well enough, I just felt the need to point out what I see as the benefits of the t-stat location...

 

OK. Your right to give both sides and I was probably over-selling the TB install. He can make up his own mind.

 

I thought the same thing, but I've been running my car for a while now with both the T in the TB coolant hose and watching the temp on the PowerFC, which reads from the ECU's temp sensor right at the back of the thermostat housing. Readings are IDENTICAL - during warm up, full throttle, you name it.

The water goes from the back of the engine block, to the throttle body, then to the thermostat housing. The water has already been through the motor and represents full water temps.

Dale

 

well just to give another opinion, i have my sensore in the throttle body line and have had NO problems with readings, it was a very easy install, and its right by the firewall to run the lines into the cabin.

Im not saying this method is better or worse but it works and it was my choice of installing it. (i have a VDO and i would have had to tap something if i wanted to install it elsewhere)

 

But that's precisely my point, Dale. The t-stat location temps change much faster than the ECU temp sensor's do.....For example, the t-stat may show the temps hitting 92-93C while the PFC reads 90C, then the fans kick on, t-stat shows temps drop to 88C for as much as a minute before the PFC temp reading actually drops to 88C (assumes you have PFC set to turn on fans at 90C).

The point is, that the t-stat location accurately reads the hottest part of the coolant and does so more quickly than other locations. Like I said above, the throttle body line location is an easy install and seems to work just fine, but it is not the PERFECT mounting condition either.

 

My problem is finding an operator who looks at the water temp gauge often enough to take advantage of the faster response

Dave

 

I've had my greddy temp gauge on the top of the tstat housing and on the housing by the low coolant sensor. I never had a problem with it on top but i ended up putting it on the front of the tstat housing. I also drilled a few holes on my tstat, so my gague works from 30C and on. The readings react quickly, right when it hits about 98C it starts to drop. When the sensor was at the top, it read the same temperatures but it would react slower.

 

Just wanted to add my 2 cents. I bought the fd with the temp sensor already installed onto the filler neck. The ears on the cap always rubs right where the wire connects to the sensor and has been wearing on the wire every time I open the cap. When I first got the car the temp seemed to be accurate, but now I think somethings wrong because now my readings read "Lo" almost all the time. At start up I get 80 F and slowly climbs, but when I start to drive the temp dives all the way back to "Lo and stays there. It reads "Lo" at 70 F. My guess is that it's grounding, so if you do install it on the filler neck, make sure you route the wire well.