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Posted by: McMark Nov 25 2014, 07:32 PM

While playing with my MicroSquirt kits I found that the stock CHT has a quite frequent failure rate. I used a stock unit on the motor I installed and on my trip to Portland I realized it was giving lots of erroneous readings. When I got back I installed another one, and it was fine for awhile, but eventually started giving the same erroneous readings. I found a modern electronic component which replicates the stock resistance/temp curve of the CHT sensor and isn't prone to vibration/heat damage like the stock unit (including new replacements). I would like to find someone who drives their car enough to notice if there is a difference.

Who's got stock D-Jet installed on their system, drives somewhat regularly and is willing to do some testing?

Posted by: rick 918-S Nov 25 2014, 07:37 PM

Not in the snow But Cool!

Posted by: 914_teener Nov 25 2014, 07:40 PM

I.ll help.

Posted by: ConeDodger Nov 25 2014, 07:48 PM

For once, this isn't me...

Posted by: BeatNavy Nov 25 2014, 07:57 PM

I may be able to help. 72, 1.7L with stock D-Jet. I just installed the MPS repair/tuning kit and haven't had a chance to "dial it in," but it's still running ok and I could do some before/after stuff. My CHT was replaced about a year ago and I put one of Brad's spacers on it earlier this year.

What are we trying to fix? CHT behavior or just find a better replacement?

Posted by: McMark Nov 25 2014, 07:57 PM

Sweet PM sent so I know where to ship it.

Posted by: eyesright Nov 25 2014, 08:00 PM

Me?

I have a '76 2.0L (weren't they all that year?) DJet that is a DD. Has nearly 30K on my rebuild.

Send me a PM

Posted by: hot_shoe914 Nov 25 2014, 09:54 PM

I have a 73 and a 74 if you need more help.


Shoe

Posted by: The Cabinetmaker Nov 26 2014, 05:27 AM

I run djet and at the present time is my only transportation, so it gets driven everyday. I too have noticed a large failure rate of chts in the last few years. Would love to see an alternative. Be more the glad to help out with this

Posted by: ClayPerrine Nov 26 2014, 05:53 AM

If you are willing to use an L-Jet system, I can put one on Betty's car. It definitely gets driven all the time.

Posted by: McMark Nov 26 2014, 11:33 AM

Cool, four testers should be sufficient to know if it's a good upgrade.

Thanks guys!

Posted by: rdauenhauer Nov 26 2014, 11:57 AM

Mark can you elaborate?
Were these variances something you noticed looking at a map or glitches in drivability that led you to the CHT & observe issues with their resistance/temp curve?

Posted by: Marty Yeoman Nov 26 2014, 03:09 PM

Mark,
You can send one my way if you want one more data point. My car gets about 150 to 200 miles a week added on the odometer.
Marty

Posted by: McMark Nov 26 2014, 03:51 PM

Since I'm running MicroSquirt I can graph the readings. I was getting a bit of bucking, each time the reading jumped it would squirt a bunch of fuel. The first one stopped reading all together and just had high resistance, so the engine always thought it was cold. Thankfully I had my laptop with me so I just turned off the cold-start enrichment and ignored the sensor. The second failure was similar, but never got to the worst case scenario. It would buck occasionally - just a quick miss and then back to normal.

Posted by: Jake Raby Nov 26 2014, 06:00 PM

I've observed this with newer sensors as well.. The old ones seem to hold up much longer and to be much more stable.

Posted by: Chris Pincetich Nov 27 2014, 10:22 PM

WHAT?!?!? You mean chasing the TPS and vacuum leaks isn't the only thing that might be causing my D-jet to experience the mysterious buck n hesitate during the normal driving commute?

Very interested in seeing the outcome here. Been upgrading bits in the engine bay to help make my 914 a more reliable commuter

Posted by: Jake Raby Nov 27 2014, 11:24 PM

Something else I noted with the stock CHT is the resolution is very notchy.. It may be unresponsive for 20-40 degrees of engine temperature differential, then all of a sudden it'll change. This makes it very difficult to build a MAP of engine temp values in regard to enrichment.