Folks, Still working on solving the misfire/studder on my '86 22re. I'm using a NWOR header (please don't flame as it's been on for years) and it uses the #2 cylinder tube for the O2 bung... I know stock manifolds used combo #1 and #2 cylinder for the O2 sensor to operate off of. Do you think with the O2 sensor only sensing one cylinder could confuse the ECU and produce this type of side effect? One other thing I've tried is directly tied a vacuum line to the fuel pressure regulator (thus producing higher pressure to the injectors) This seems to mitigate the miss but doesn't cure it. <img src="/forums/images/graemlins/confused.gif" alt="" />

have you found out what cylinder is misfiring?

Well, when using a timing light, I'll see the #1 cylinder miss during the idle stage. I haven't hooked the timing light up to any other cylinder.

I run an early LC Engr. header and it has the O2 in one runner (#3 or #4 as I recall) and it works fine. No hesitation or stumbling. I think the ECU only adjust A/F mixture a little more than once per second, so unless you are hitting some special resonance point, it won't be able to see a single cylinder's exhaust pulse.

You could always have a flange for the sensor welded onto the main collector pipe and extend the O2 sensor wires down to that point.

Thanks Crawler. That's good info. to have and one less concern. A couple of other findings. The dist. pickup that goes over to the igniter ohms out at 220 ohms (the manual specs 140-180 ohms) Could the higher resistance cause an intermittent miss. In the past when it goes, you lose all ignition. I also mistyped the original post regarding the fuel pressure regulator. I REMOVED the vacuum line to it in order to keep the fuel pressure higher.

Not sure on the distr. If you can get another one to try, see how it works, I suppose.

You DO NOT want higher fuel pressure all the time, only when the engine manifold vacuum is down near 0" Hg (i.e. full engine load) do you want full fuel pressure. Why? Too much fuel will be injected into the engine at low loads. I found my 22RE really loaded up off idle until I fit around 2500 if I left the FPR open. I now just have it connected straight to the intake manifold:
- http://www.4crawler.com/4x4/CheapTricks/22RE_Engine_Pix/8.html

well dont feel bad i am still dealing with it also i just haven't had time yet to do any more diagnosing, but was ready someone elses post and they were having simular problems, ended up being maf sensor, what did yours ohm out at?

MAF is good. ( I did richen it up by adjusting it two teeth CCW). TPS is good at all points (fully closed, putting the shims in, etc..) Today, I took Crawler's advice and hooked the fuel pressure regulator straight up to the intake. It drives fine going down the freeway and such... just misses intermittently at idle and through the RPM's.

OK, got to spend some more time on this problem... Blanked off the EGR valve thinking it might be leaking... no difference. Then, I disconnected the O2 sensor wire and BAM, the miss goes away. Now, this is a new Denso O2 sensor, which replaced a OEM unit thinking it was bad.. So, now I'm thinking the NWOR header just doesn't want to work well with this setup... RV cam, cylinders bored .020. Is it time for a LC engineering header???? Do they place the O2 sensor in a more ideal location? Any other thoughts as to why the O2 sensor disconnected would make the misfire vanish? (other than without the signal, the ECU richens up the mixture)...perhaps?