Help?!? Thoughts?

Our RX7 race struggles under load. If you are parked and work your revs up, all is good unless you jab the throttle.

When driving if you try to accelerate to quickly it struggles and back fire.

We had an electrical short that fried the ECU. We had a surge problem and replaced the AFM. Both around the same time.

The motor pretty much runs off the AFM and TPS. Almost all the other stuff was removed years ago.

We tested the TPS, and adjusted properly. The pump has been changed to a high flow with constant high pressure. We've grounded the ECU ground wire.

Injectors are working, and we have spark. Plenty of fuel pressure.

Thoughts? Any sensors we should check?

 

how is the pump wired up? how are the filter(s)?

 

The pump is hard wired with a switch and a relay directly off the master kill switch. It’s a race car..

replacing filter this week.

 

did the filter make any difference or are you still having the issue?

 

I got busy with another race car. I'm heading down this weekend to do a few things, will post what I did, and hopefully an improvement.

Thanks for the follow-up.

 

That sounds like what my '80 did when I stabbed the distributor in 90 degrees out of alignment by accident.
I had direct fire leading ignition, so the leading didn't care. But the trailing was firing at 196BTDC.
Only time I'd ever got a nonturbo rotary to detonate!
When it wasn't detonating, it would buck and stumble and spit back through the carb at anything over about 1/3 throttle.

I'd double check your timing, especially trailing timing. On BOTH rotors if possible, my understanding of how the FC trailing system works is the computer gives a "flip" signal to the ignition module to tell it to switch to the other coil, if the flip signal is missing then it keeps firing the #1 trailing.

I'm assuming you are using the same spark plugs and all other hardware as when it had been running well. I also had an issue on my bridge port where it would break up under extended load, that I traced to #9 heat range plugs being too hot. Switched to 10s and the problem went away. Then we changed venues to where we didn't have looong straights and long run times, so the colder plugs weren't really needed anymore...

Also assuming that you are using an OE computer. I had an issue once on a Megasquirt computer on a friend's Miata... well two issues. The first issue was, I fried the ignition driver when I was trying to figure out how to make it run a tach. (weird combo of parts, he had a Mazdaspeed ignition system and an NA6 PNP, which means you have no tach) The other issue was, after I got it back from DIYAutotune, the tune was corrupted, and I had to go in and fix everything. I guess it didn't like being worked on.

ANOTHER thought. Did it run well with the high pressure in the fuel system or did the problem start with that? If you're on an untuned computer and stock injectors (making assumptions here), the engine runs super rich. If you crank the fuel pressure higher, it will run massively rich and possibly past the point of stable combustion.

 

Fuel filter didn't fix it.

Stock ECU. No, we moved it to high fuel.

Interesting that you bring up timing. I went to time it Friday, and I had to crank the ECPS/Dist all the way to one side to get the timing marks to line up. I may need to confirm TDC.

It was way off. Some "mechanic" worked on the car when all this happened. And supposedly knew what he was doing. It all started with a surging idle and a AFM swap. I'm not sure why he would reset it.

I've been undoing what he did since.

Now that I have the timing set, I want to triple check the TPS, and then take it out. That will be in a month, as it's 200 miles away.. It was up on a lift, with another race car under it being worked on.