A datalog along with engine specs, your bin file and what ecm you are using would be a big step for someone to help you.
Brian
A datalog along with engine specs, your bin file and what ecm you are using would be a big step for someone to help you.
Brian
Last edited by sturgillbd; 09-23-2016 at 04:03 AM. Reason: added need for bin file
your assumption that it's going extremely lean may be a bad one?
consider that a gigantic series of misfires of some kind will show up as really lean on a wideband (your wideband probably maxes at 22:1 or something, it's probably reading pure air).
your ignition could be breaking up in a certain range or something, or something else might be completely messed up, hell you could have some kind of mechanical issue going on too
it makes no sense the injectors would fail to fuel mid-range then suddenly start fueling again at high rpm. you'd have to have an insanely large spike in volumetric efficiency in that 3000-3500rpm range -- engines generally move more air and hence require more fuel as RPM rises.
Thanks for the reply, I need all the help I can get. Prior to installing the WB, I assumed the lean condition because the motor had a "lean cough" when it was stumbling.
At first I thought it was ignition too. I replaced the dist. module, no help. I bought a new distributor (small cap hei), no help. Along the way I tried different coils, no help. I don't think it's an ignition problem. I had thought maybe there was some sort of weird reversion issue with the mini ram, but then it would seem like that or an ignition problem would result in a rich condition, not lean.
I agree, it seems like a mechanical issue is shutting off the injectors in that rpm band, but I cannot find it. Operation is fine in all other areas. I'll post more information when I have it, I'd value your opinion.
Now I understand, no ignition means no combustion, so no oxygen is consumed. My head was thinking since the bpw was high, too much fuel would be in the exhaust, causing rich condition...duh I bet a spark plug in the tail pipe would be cool (if I could get it to spark)
So now I have to find something that is cutting out ignition.
I went for a walk to clear my head. Ignition can't be failing completely, because the motor continues to run, it's just not making power. I don't see that there is any knock retard in that range, spark scatter inside the cap? (term from back in the day)
Last edited by htrdbmr; 09-23-2016 at 07:37 PM. Reason: more thoughts
still could be fuel, though... don't let me throw you too far off.
a great trick for that kind of thing (finding a spark miss while driving) is to get your inductive timing light, put the probe right near the plug boot of the suspected cylinder, and just point the damn light at your windshield. then go for a drive. if the flashing gets sketchy, you'll know what's up.
you can then track backwards to before the distributor cap to see if it's a distributor/plug wire cutting or the coil?
it's probably not the pickup or your ecm cutting spark, or you'd see your tachometer drop out in that range, wouldn't you? (assuming you have a fairly responsive tach)
a portable oscilloscope is a superior tool to diagnose any of these issues, of course
are you 100%+ sure you don't have a valve hanging up or something?
Have a look at the fuel and spark maps in that rpm/load range. Also, verify the distributor is set at 0*, the ecm pulls 9* iirc then adds per the cal. I can't see an injector going static at 3500 rpm then clearing up after. Double check that there is no spark knock detected during this hiccup. Does it act up in park, if you rev the engine to 3-3500 or is it only under load?
Buddrow
If it don't fit force it, if it don't force fit f&%@ it!
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