94 with VVT engine - won't run on stock ecu

[chriscar]

Hey guys,

I'm trying to get my Miata to run on the stock ecu temporarily in order to get it inspected. It's a 94 R with a VVT engine, and I usually run it with an MSPNP, wideband o2, and an IAT (no MAF). I swapped the stock maf and ecu back in, and it'll start but only run for a few seconds. Jumpering the FP to GND makes no difference, and plugging in the stock o2 sensor doesn't either (I didn't think they would, but figured I'd try anyway).

The car originally had 4 wire coils, and when I swapped in the VVT engine which uses 3 wire coils, I had to configure the MSPNP to send the signal to the tach. So I'm thinking that maybe that's where the problem lies. Does the stock ECU need a signal back from the coils? And does that signal come in on the missing 4th wire?

If anyone has an OBDI inspection hookup, shoot me a PM, and I'll skip this whole stock ECU excercise.

Here's a video, don't mind the mess, the car has been sitting in the driveway for 6+ months. Oh, and it starts and runs fine on the MSPNP.


C

[Gmrlocal1]

If it is obd1 you should be able to pass with the megasquirt in place. You are just going to need the right tune and a catalytic converter. Trey once mentioned to me that he even passed his car without a cat.

[MoonieGT]

Why do you need the stock ECU? I thought with a 94 you only need to pass the sniffer? With my 99 I have to put the stock ECU back in because the MS won't report OBDII codes via the diagnostic port, which is a fail on its own.

[OZMDD]

Yep, no obd2, so it just needs to run well. A good mspnp tune should have better emissions than most 20 year old cars anyway.

[chriscar]

Yeah, you guys are right. Nate even gave me a smackdown IM on FaceBook after I posted this. Brainfart I s'pose, or just nervous about getting it inspected. The cat is back in place, so I'll take a crack at it.

:fingers crossed:

C