All: Thanks for the ideas, please keep them coming.

Rechecked spark plug wire routing for a 4th time against all three (agreeing sources: 1) reply above, photo copy of service manual, dist cap markings). All wiring correct.

Spark plugs were pulled and cleaned earlier this week. They did have black residue. Did not replace as they have less than 500 miles on them.

Verified the MAF connector to be fully seated and not damaged. Tried running it with MAF disconnected. It would start would attempt to idle but would die if you did not give it gas.

Removed air intake filter assembly and inspected for loose debris. All inspected TB and plenum past the butterfly valve. No extra parts found.

Tried running it with the air filter removed & MAF connected to see if that was restricting the breathing but no change in acceleration.

CEL codes 24 and 31 are set.
24 IAT Sensor Signal
31 Air Flow Meter Signal

Seeing conflicting info on IAT location. Some say integrated into MAF some say elsewhere. If integrated, both may be from when I tried running w/o the MAF connected. Will clear the codes and drive this afternoon to see if they will trigger with MAF connected. Will try this: http://ww2.justanswer.com/uploads/sn..._lexus_IAT.pdf

Will also try the remove one plug wire at a time to see if one has no change. I think runs too well for one to be totally out but not ruling anything out without data.

Repaired a small vac leak where the PSP vac valve used to tie into the intake air tube. I had removed the PSP vac valve some time before all of this started to eliminate the smoke from the tailpipe problems most have had. The port that was leaking is tied directly to the vac port on the front of the engine that used to go to the PSP valve.

Current status: Idle is fair but not factory smooth. Tack is jumpy at idle. Grandma's walker acceleration & RPM increase (i.e. not high rev slow MPH tranny slippage), valve clatter initially when flooring it from a dead-stop. Transmission does wait to 3k to shift even under light pedal takeoffs.

 

I would get another MAF/AFM/whatever you call it and try it again. If it's throwing that code, then it may be bad.

 

Sometimes cleaning a maf will kill it, causing the code 24. They are VERY sensitive, Karman Vortex units with easily breakable parts inside.

Most likely, the maf is dead or the connection to it is dead.

Now, try adding supplemental fuel and see if it wants to run better. You need to double check your spark and spark timing as well.

You can also get a code 31 from a leaking power steering pressure switch, oddly enough.


Lastly..you absolutely positively did not replace or move the timing belt at any time of this, have you? It is extremely common to accidentally miss the timing marks OR have the belt jump a tooth, and it causes these codes (due to improper vacuum), and of course horrible driving.

The intake air temp sensor should be in the MAF, btw. Some people have fixed this air temp code by installing an external iat with similar specs, which the computer can use in lieu of the oem one.

 

PROBLEM SOLVED!! Never would have guessed this one. I was sniffing around for a vacuum leak with my stethoscope. The light in the garage happened to be off because I was about to get cleaned up to go to jury duty. I noticed a faint flashing out of the corner of my eye on the left-hand fuse box. My first thought was that it was a relay arcing in the box then realized that I as seeing a reflection of something on the side of the engine. I moved over to see what it was and here's what I found...The left-hand coil-to-distributor wire had gotten sandwiched between the distributor/sparkplug cover and the engine. Not a problem until I started test driving it around the neighborhood and getting the engine up to temp. Just like pressing down on a hamburger in a skillet, the pressure and heat melted away the insulation, exposed the core, and broke the wire. Basically, it went from the coil to shorting out to the block, the block shorting out to the other side of the break in the wire and on to the distributor. The block (i.e, ground) was sinking all of the current from the coil and the distributor was getting ground instead of kVolts. It's amazing it would run at all. The fun part was that when I discovered this, I had about 15 minutes to get it operational before getting cleaned up and driving it to jury duty. The wire measured open from end to end so the tiny coil winding wire had a break. Get ready to laugh but here was my temp fix. Since it is next to impossible to solder to this enamel coated wire, I took an inch long piece of stranded 20 gauge, tinned it with solder to make it stout enough, and clamped it to either side of the break with hog rings, wrapped it with a healthy portion of electrical tape and threw a 5" section of 3/8" hose split down the side over it. It measured just under 500'ohms even when shaking it around to test the connection. I reinstalled the doctored up wire and being careful (this time) to make sure I routed the wire through the window on the sided of the distributor/sparkplug cover and took it for a test drive. The result, more power than it had before this journey began. Thanks for all of the support along the way. None of us could have guessed this odd-ball ending but you kept me trying and your ideas made a noticeable improvement in pep and probably mileage as well. THANKS! O'Reiley's sells single wires so I will have the replacement in the morning. We drove it around quite a bit tonight with no problems, except the temp gauge started shooting up to the red zone a couple of times then back to normal. Not sure if it is the sensor, thermostat or just low on coolant. I will do a radiator flush and swap the t-stat out tomorrow and go from there.

 

Just saw this but having had a similar experience I was about to tell you that you were not firing on all 8.

 

Hmmmm,,seems like I read somewhere that there was a possible coil problem. LOL!! Granted, you had a problem with the wire going to them but coil problem none the less; time for all new wires and might as well do plugs while you're at it for peace of mind. Good to know that you found the problem.

 

you also threw a ton of raw fuel through the cats so check on them

 

Yep, in a roundabout way, the coil was not getting the job done. I replaced the plugs last month and the wires 2wks ago. Actually, replacing the wires is where I started the problem. The drivers side coil wire must pass through a window cut-out in the side of the distributor cover. I failed to do this when reinstalling the cover. I just replaced the bad wire with a single new one. $12 vs. an instant repeat of $100 for another set of wires. My only remaining problem is that the cold idle is way too low (300-400 RPM). It kicks up to 600 once warmed but but wants to die until then. Thanks for the advice on the cats. I checked them out and replaced the gaskets (needed anyway). No blockage so far. Any ideas?