misfire problem
 

I have a misfire that I just can't get rid of.(88 tII street port BNR stage 3 E-8) I checked my trigger and did find it falling apart at the high end of the rpm range. I added a little gain and reduced the filter and that seem fine now. That did clear up the problem of it falling on it's face,but there is still a miss. I will get new plugs and wires to rule that out, but I really doubt it will help. I am running the stock coils is there any way to test them ? What should the ignition set up look like? I have 3.5 charge time and 600 spark break.
How much can a misfire effect my 02 readings? I seem to have my injector durations higher than most of the base maps I have looked at. Even with my fuel curve my 02 reading creep to 12-12.3 under boost.
Any input would be greatly appreciated.
Dave Smith

3.5 ms if direct fire mode means there is plenty of time for more charge and a bigger spark..most coils will take more.. try 4.0 ms

if still wastespark leading .. ditch it..and go for 4 coils direct fire so you can use larger dwell periods

Its hard to tell at times checking misfires... 3.5ms is plenty.. try adding fuel to see if it get worse. If it does, try a different wideband and check your AFRs and lean it out carefully... Sometimes if its so rich it will read lean...

Always log trigger at last home. You mentioned having trigger issues at one time and that is always a likely suspect with the older boxes.

I will try logging trigger at last home tonight. I hate it when I miss the obvious. I have been watching it live and not logging it.
My other question is the placement of my o2 sensor. I think it is the stock location in the down pipe just down stream of the turbo. Should I weld in a new bung further downstream ?
I will try to borrow a wide band to verify mine.
I have started looking for a tuner. I am starting to doubt my ability to get this right
Thanks for the help and support.
Dave

ok logging trigger at last home works way better than using a timing light. I now have a nice straight line for trigger at last home. I will try more tuning this week end.
Dave

Just be patient.

Ok I now have a nice solid trigger. I have it running nice under no load. As soon as I put a load on it I get surges from lean to rich. I pulled fuel out and that wasn't the answer. I added fuel and it still surges just richer.
I would like to attach my datalog and maps but, I don't know how.
Dave

Email them to chris@lms-efi.com

ok I totally missed the obvious. The last time I was working on the car I cleaned and sealed the tank , replaced the pump, ran all new fuel lines. Of course this means no reason to check the fuel system. I noticed the wire to the pump was getting warm. So I got a relay and fuse to run larger wire. When I pulled the pump the coating on the tank had failed and both of my filters are jammed tight with rust and the coating. I ordered new filters and I'll see what I can do with the tank. I was pulling the failed coating out by the hand full.
Dave

Glad you've found it! I've never heard of good results from sealing a fuel tank.

ok I'm back to working on my problem child. I moved my 02 sensor to the back end of the test pipe. I still show lean and I am getting about 4 miles to the gallon so I have started pulling fuel. What is the formula to get a ball park pulse width ?
My most recent problem is I have no injector pulses. I drove it last night and parked it in the garage. This morning it wouldn't start. After I figured out what the problem was I checked the ecu ground, disconnected the battery for an hour then loaded a saved program from a couple of days ago. Still no pulses.
Dave

I wish I could just delete my previous post. My pulse width was to short to light the bulbs I was using to test. I cranked the pulse width up to 30 ms and they flashed. Now off to the garage to find the real problem.
Dave

^ Yes that happens. It's called learning...we understand. Keep it up and you'll get there, just don't overdrive your headlights.

Smitty- how far back is your 02 sensor from the back of the turbo. I have replaced my down-pipe and put in an 02 sensor. Just want to make sure I've placed if far enough away as I'm also getting a lean reading.

I moved it to the back of the test pipe. I actually had an exhaust leak at the manifold. Look real hard for leaks. I didn't find mine until I was pulling the motor. Be smarter than me and find your problem before it is to late.
Dave