Thats the thing... the af's are correct. I swear I saw a 12.7 when I was running up there, but if it was that lean it would detonate. It sits at 11.7 when I am boosting at 7500rpm... and it sounds like popcorn. It feels like a rich spot... like its getting too much fuel, but even if I lean out the cells it still does it. The A/F will go rich and lean out when I adjust the cells, but the breakup still happens. THe plugs have maybe 500 miles of regular driving, and 200 miles of road tuning on them... The ignition system should be find for 10psi, and if the injectors were dirty, i'd be getting breakup across the board. I am going to check my grounds.

 

Even if setup perfectly, the meth injection is still a variable here. Remove the variable and see if the performance is the same. Do you have a map without the meth injection that you run too? Whose injectors are you using for the meth inj? Controller?

 

What is your base fuel pressure? Last time I saw something similiar was on a car running 30psi with a base rate set too high and a 1:1 RRFPR. Some injectors are more sensitive to higher pressures than others.

 

THe base fuel presure is 40psi, and thats where it likes it. We tried 30-35 and it wouldn't have it...

I don't have a map without the methanol at this time.

The methanol injectors are the dual 375ml made by snow performance.

Today I found my battery terminals had rust on them, my ground to the engine block was dirty and covered in oil, and the UIM ground needed replacing. I replaced all of them, cleaned all teh connectors with a wire brush, and reconnected everything. I ordered NGK wires from malloy along with a new coil harness. The new harness eliminates the seperate ground and gets it elsewhere.. I am going to install those tomorrow. After that, the only thing left for replacing is the ignition coils. If that doesn't fix my problem then I am going to try other things.


Even if i boost at 5psi... where the methanol is not active, i still get the 7500 rpm breakup. Maybe the grounds fixed it, I'll know tomorrow.

 

Oh yeah, grounds can cause that. I have 2 gauge running through the car and 10 gauge just tying the engine compartment grounds together. Some argue the benefits but without them I had a hiccup that only happened at the track at 6800rpm at the track.

Tony

 

I had a realy weird problem along time ago. The car ran fine on the dyno, but once off, it ran like crap with anything above 4,500rpms or so. I tore apart everything......checked coils, CAS, wiring harnesses, grounds....you name it, I swapped parts out trying to fix it. One day while driving around the water temp censor flashed for a breif second at me, in the censor check mode on the comander. So, I switched the WT censor out, and the car ran flawless.

You can read the detailed ramblings of a mad man here.

https://www.rx7club.com/forum/showth...hlight=problem

This probably won't be the cure...but you never know. CJ

 

Replaced my racing beat wires with stock NGK wires, and replaced the coil harness which elimintated the external ground, and I cleaned the 2 other grounds, one on engine block, one behind UIM. Works fine.. pulls great all the way to 8500.

=))))

Tuning for 21psi tomorrow, and dyno, w00t.

 

8500?

i didn't bridge port it

we'll do that to the next engine

 

oops, 8100. I got excited. I have my rev limiter at 8250, but I usually shift around 7800 anyway if I am doing dyno runs.

 

i gotta see the dyno sheets. you really don't see too many turbo engines with the stock manifold to peak that high. especially with your size porting.

 

Good troubleshooting..

 

I hate to bring this back from the dead...but replaced the coil harness? my car is doing the identical thing from what i understand. I have a 87 rx7 with rtek 1.7,fd fuel pump, new plugs, 8month old ngk wires. the werid thing is it only does it when i have my rtek installed. I have redone the grounds with 10 gauge wire. this has had me going in circles for months. any help would be aprecitated.