Shinobi'sZ

I'm still having this strange loss of power while driving. I can produce a very light shudder between OD and 3rd if I lightly touch the pedal while under load and create a shudder, it feels like the tq converter. But what is strange is that the car still seems to be down on power and I hear what seems to be like a constant alternator sound, but the alternator is fine as I can have everything on lights, stereo, idles fine, and reads 14.59 vdc on the back of the alternator hot wire while idling. When I give it the gas it sounds like when you hear a large truck that has gotten warm with a clutch fan. Something is definitely causing a performance loss. I have checked vacuum, timing, fuel pressure, injectors, distributor, coil, wires, plugs, map, coolant sensor, TPS, IAC, Cats, IAT sensor, and the car otherwise fires right up and revs in P and N with no issues/runs fantastic. Trying to figure out if the tq converter or tranny is causing an issue, but I did smell a lot of fuel a couple of months ago before it got really cold and this issue started.

I read where if the purge canister gets full or goes bad it can cause some issues...but my only issue is under acceleration. Is there a way to check the charcoal o disconnect it for testing? I think the tank needs vacuum to help vent the fumes, gas cap always makes a noise just as it says it will "remove slowly" after the car has been ran.

I think if a head gasket or intake manifold gasket was blown that I would be seeing coolant loss and something in the oil. Perplexed for sure on this.

sofakingdom

iTrader: (1)

Sounds a bit like a clogged catalytic converter.

Vader

If the system is operating normally, the EVAP canister purge should only occur at part-throttle cruise, and it should never make a noticeable difference in engine operation while purging. The oxygen sensor will control mixture in that mode and adjust as necessary regardless of whether fuel vapor is being added or just air.

The converter is a plausible reason, and vacuum leaks (including the EGR) should also be considered.

Shinobi'sZ

Thanks Vader. I suspect the converter, checked for vacuum leaks, I took off the vacuum line from the TB and tested to see if I could hear the EGR diaphragm opening and closing, and it is pretty new replaced last summer (the original one wasn't bad). This thing is really bumming me out as it otherwise runs so good, it such a clean car and people compliment it all the time. Makes me want to tear out the motor and just replace everything.

Shinobi'sZ

I swapped in another mid pipe with dual cats from my old 91 Formula 350 I had saved from years ago, it only had 27K miles on it so I'm pretty sure the cats were fine in it.

Shinobi'sZ

Closing the loop on all of my threads regarding misfire under acceleration. The problem ended up being two fold.

First- my distributor hold down bolt loosened up and the distributor rotated clockwise and my timing was retarded at 4* ATDC. I re-timed it with a light and this resolved 90% of the issue. However something still felt off...down on power and not accelerating as it should from 2500-3500 rpms and really lazy to 5500 rpms (2nd -3rd shift).

Second- When I went to find TDC for re-installing the dizzy, I noticed the #1 plug had some insulation glazing, most likely from driving with retarded timing created some heat or something and glazed the plug. I never really have seen this before so I initially put the plug back in. After more thinking about it some more, and being convinced it was a spark issue, I pulled all of the plugs and they looked the same. I replaced the plugs and the car now does not miss.....imagine that. All is good. Thanks for everybody who chimed in.

Issue resolved.

KipMtn

I second on the plugged cat. All the symptoms point to it. Sometimes can be pinpointed by 02 activity or you could run a back pressure test on the cat, if you can get the 02s or air tube off. You will have to poke the pipe if not. Good Luck

Shinobi'sZ

Sorry it's probably buried in my previous response, but I replaced the mid-pipe section with another mid-pipe section I had stored. No change. The change was definitely spark related but the clogged cat and muffler check was on the list of checks.
Thanks