help please iat issues mspnp
 

trying to install a PNP on a friends miata, got it all installed and it runs on the supplied stock AFM map. idle is a little weird but that will be fixed...I put in the GM iat to the right pins. (1 and 6) put it in the intake trac, and its showing air temp so its working. burned the supplied NO AFM base map, and now the car won't start....any ideas would be appriecated

ok so update

reinstalled firmware. had ignitor out, and 10amp fuse like like i should.

narrowed the problem down to the fuel pump

with stock ecu and afm car runs fine.

MS and afm - no running
MS, afm, fuel pump jumped via paperclip - car runs
Ms, no afm, iat hooked up correctly - no run
Ms, no afm, iat, fuel pump jumped - no run

seems like there would be a problem with the ms board? opened up the ms, everything looks fine, and no burning smell....

any ideas?

I think you have burned the fuel pump transistor inside the MSPNP, you should have take the ST_SIG fuse in the first time, when you started with the AFM.

With the AFM it stills works because the AFM triggers the fuel pump.
Without as the transistor is burned, the MSPNP is not able anymore to trigger the fuel pump.

I think you will have to send back the MSPNP to DIYautotune....

The AFM triggers the relay that turns on the fuel pump on 90-93 Miatas. AFAIK, it's a simple fix you have to wire around. I'm pretty sure there's a thread on it here, and if not, Brain will chime in with the right way to do it.

I took the cover off the MS and do not see any damage.

At some point the MSPNP was installed in the car and the ignition was turned on, but the ST_SIG fuse was not removed from the fuse box as stated in the instructions. So what happened was the transistor inside the MSPNP that powers the fuel pump circuit fried. Your options are to

• Send the MSPNP back for repair (recommended)
• Hard wire a fuel pump jumper at the AFM harness or diagnostic connector

A hard wired fuel pump will not shut off in the event of an accident, so while electrically it will work fine, the best option for safety is to repair the ECU. Send an email to us at websales@diyautotune.com to set up the RMA. It's an inexpensive repair.

I will email you, but it's strange as the fuse was out when we installed the MS and it ran, and was definitely left out for the AFM delete map install as well.

Spock is correct (its his car we were installing on) the unit itself has only been on 2 cars. my own, which worked fine and installed properly, and his which we installed properly as well, but hasn't been working right.

If it has the stock TPS (switch type), it will also prevent the fuel pump to switch on if the MSPNP was configured for variable TPS no? (I'm just thinking out loud as I experienced a similar thing before)

Have you tried starting without the TPS plugged in?

Have not tried, but it ran on the stock basemap at first, and after the AFM delete fiasco the car would not run with the same first basemap again.

1.6 never had a varibale tps on 94+.Also i never modded the pnp for it. so that wouldn't be the issue. thanx for the input though