Miata Turbo Forum - Boost cars, acquire cats.

- MEGAsquirt (https://www.miataturbo.net/megasquirt-18/)

- - No CLT Reading (https://www.miataturbo.net/megasquirt-18/no-clt-reading-18080/)

Quote:

Originally Posted by jsisco (Post 226259)

Alright I've got some interesting results.

With the connector for the CLT jumpered across both pins I got nothing in Megasquirt. With pin 21 from the Megasquirt jumpered to the engine I got a temprature. So bad ground right?

The plot thickens...The IAT was showing 43 degrees which is what it was showing yesterday and the MAF nor the IAT were plugged into the harness. Now that I think about it the IAT always shows 43 degrees regardless the outside temprature. The MAF and the CLT ground to the same point.

This car came with a JRSC with a smaller pulley to run more boost. Is it possible the PO changed the wiring harness to make sure the car always ran rich?

How else could the there be nothing plugged into the MAF connector and I still get a intake temprature in Megatune? Or do you think that is totally unrelated.

nope, these sensors are magic, you should know that.

I forgot Miatas have magic sensors. I need to light a fire and dance around it for hours to coax the little electric bolts with legs to run the right direction.

Oh I almost forgot the chanting... lots of chanting.

:)

I'm going to take a break from this for the next couple of days so my wife doesn't leave me. Then I'll pick it up with fresh eyes Friday. Thanks for all the help so far from everyone.

it really sounds like the harness got hacked up...just gotta retrace the leads...

Hell yeah.

Figured it out yesterday afternoon. I checked all the grounds again with the factory computer plugged in, and I could get continuity from which ever sensor to the head. So they were grounding to the engine. Then I unplugged the factory computer and I could no long get a ground to the head.

I was looking at the madracki diagrams and realized the junction connector does not ground, but goes back to the ECU for whatever reason. So I jumpered 3O on the ECU connector to Ground on the ECU connector and was then getting continuity from the sensors to the head. In the 94 and 95 madracki diagrams the sensors actually connect to a ground.

I just added a wire from 3O on the boomslang side of the MS harness to the two grounds on the boomslang side of harness. I was then getting a reading on all my sensors from Megasquirt. I imagine this was affecting the TPS and O2 as well.

The CLT and IAT were pretty close to right on. Car still ran like crap so I'll keep tinkering. I still have a narrowband, and the car is burning more oil than gas so that might have something to do with it (not really but its burning a lot of oil).

Yeah it's kind of important to use the sensor ground pin on the boomslang. Good trouble shooting.

Good catch. You're right, the TPS, IAT, and O2 sensors all would have been dead as well. If you had happened to notice that it would have been a dead giveaway as I've run into this during MSPNP prototyping ;).