neit_jnf

iTrader: (17)

here's the full story:

After changing the clutch, installing a light flywheel and bringing the car back to the streets I noticed that it started to misfire during boost at around 5500rpm and up, I thought I was injeting too much water but it still did the same without the water injection.

I went to a rotary drive around some rural streets in PR and suddenly the car lost power and shut off leaving me stranded. I found the rear half of the melted metal cat in the middle of the street! It came out of the tail pipe, thanks to a open 3.5" cat back.

I took out the midpipe and removed the leftover cat core and put the open pipe back but the car wouldn't start. I saw that the twinpower led was off so I put the ignition back to stock and the car started fine but wouln't hold idle and would shut off every time I let off the gas.

I did a compression test and it wasn't any different than last time I did it three weeks before, 270rpm, 95-97-100 psi front rotor and 105-105-106 rear rotor.

I reset the PFC and re-learned the idle but now the idle vacuum is less than it used to be and even though the car idles ok it still goes lower than the target idle, catches and goes back or sometimes shuts off when letting off the gas.

It feels rough during cruising below 3k rpm but I guess the open 3.5" exhaust is good since it wants to boost all the time now! I can get up to 17psi at 6k rpm with the boost controller OFF (stock seq twins)!!! I can get 15psi well before 3k rpm when I set the boost controller for it!

TPS voltages are within range, AAS is 4 turns out (used to be 2 but now it idles better), TAS is slightly opening the throttle, maybe one turn. Dashpot is all the way in.

Should I just re-tune all the map, logging and adjusting? Any recommendation as to have it go back smoothly to idle without going lower than target?

THANKS!

arghx

iTrader: (3)

What plugs are you running?

Where was the Twin Power mounted? Did you install it away from heat, and mount it on something to dampen vibration?

neit_jnf

iTrader: (17)

I was using BR10EIX but when the car was misfiring I changed them to some RX-8 Iridium 9's that I had laying around, no change.

The twinpower was mounted with velcro below the cruise/brake cylinder area.

K-Tune

iTrader: (26)

RX-8 plugs aren't the same length as rx-7 plugs. the threaded part is about 1/4" shorter...causing the electrode to sit further back from the combustion area.

put some RX-7 plugs in it and see what happens!

FD3S2005

iTrader: (11)

you reset the ecu wouldn't you of lost your tune then and with an open cat doing 15-17psi? Dont'cha think your engine may be in danger?

mdpalmer

iTrader: (24)

Any pics of that SMB chunk you lost? Also, how many miles are on the cat and what kind of AFRs you running (under boost, cruise, etc.). Street use car, track car? This is uncool, if it was a legitimate failure, you should let SMB know about it. I hope I don't fry mine

neit_jnf

iTrader: (17)

it's not misfiring anymore, I've used the RX-8 plugs before with good results I only went back to them because I thought I had bad plugs causing the misfires. Once I removed the twinpower the car is running ok, just rough during cruising.

Yes I reset the PFC, the car is running base map with the only change being the injector sizes and lag settings, and the timing split going from 0 in vacuum, 3 in P10 smoothly going to 12 in P19 and 15 in P20. I'm always watching everything, knock never goes above 45 in boost. I will tune it though, I'm just trying to fix the idle first.

I was cruising at 16 afr, and 10.5-10.8 in boost. Mostly street car, daily driver, with some track days and drag runs. Cat lasted about 10-15k miles

pics here:
https://www.rx7club.com/showpost.php...1&postcount=27

arghx

iTrader: (3)

From my firsthand experience with BR10EIX plugs, they have a big effect on the idle and require a different tune for idle.