Need help, won't rev
 

Hello, all.
First off, I'm not new to turbos, wrenching, or tuning. I have an issue with my miata that has me scratching my head, though.
The car is a '90 that had been sitting for a number of years and basically fell in my lap. After draining the fuel, changing the oil, and replacing the dry-rotted tires, she ran great... for a couple of weeks. Then it started limiting itself to approx. 2200rpm once fully warmed up.
I checked the AFM and TPS signals. The TPS seemed fine and the AFM seems a little off through the door's range of travel. So I replace it with a used unit from ebay. The problem remained. So I bit the bullet and ordered a replacement TPS from rockauto. Getting that bugger adjusted was a PITA, but I was finally able to. And the problem remained. The carpet was damp from the top leaking, so I pulled it up and checked the ECU. There was no corrosion present on the connector (or the TPS and AFM connectors, either), but there was just a bit on the board itself, where the connector is soldered to it. So I cleaned that off with rubbing alcohol. The problem remains.
Where do I go from here? I don't want to keep throwing money at it, but I do want it to run properly before I megasquirt it.
It does give a code for the O2s. Does anyone know if that would set an artificial redline in the ECU?
Thanks in advance for any help.

TL: DR car won't rev past 2200rpm, replaced AFM and TPS. What next?

Megasquirt that thing and tune from there. Especially if you are already having ecu problems.


i have lots of spart 1.6 parts too if you need anything.

Fuel pressure? I'd pull the pump and look for varnish. I snagged a truck that had sat, did your basics and fuel filter, ran great for a few weeks. Then wouldn't rev. Yada yada, tank was corroded and clogged my new filter. Had to drop the tank and get it cleaned and sealed, been a great truck since.

That had occurred to me, and I need to do those things as well. But the fact that it runs great until fully warmed up leads me to believe it's ECU related. It doesn't act like its starving for fuel or low(er than normal) on power. It just hits a hard 2200rpm redline.

When i got my 90 miata it sat for 3 years and all i did was dump 5 gallons of fresh premium in and called it a day. It sounds like an electrical issue causing a limp mode to enable. And really a Megasquirt would be able to solve any ecu issue since you are the one setting all the limp mode safety features.

i might have a spare 1.6 stock ecu if you want to try it one day. I work in Kent and at the Snoqualimie fire station a few days a month

I might take you up on that offer. I live in Tenino, but my parents are in the Fairwood area and I get out there sometimes. The car is not my daily, so I'm not in a huge rush to get it fixed. In fact, I might just skip it and do the MS.