Thread: Misfire at idle and partial throttle

This has been driving me CRAAAZZZY
I have an issue that I can't get rid of - it misfires every couple of seconds while idling, and at partial throttle, between 3,000 RPM and 4,000 RPM, it misfires a LOT. This gets better when it warms up, but is definitely still present.

This is a 93 Highport SR20DE
Here's the list of what I've done so far:

• MAF tested good
• One of the injectors was leaking, but has been replaced. They all test good with the ohmeter
• Timing is set at 17* BTDC
• Fuel pressure is at 38psi at idle, 44psi at WOT
• Vacuum pressure is at 15psi at idle, and pretty steady *this should be between 17 and 22 psi according to the book, but I have 8.5:1 pistons in it, which explains this I believe, though it may still be causing part of this issue*
• All grounds have been cleaned
• Set TPS to 0.44v closed *note: it reports over 5 volts at WOT - I believe it should be no more than 4.00v, right?*
• IAC and AAC valves have been tested and confirmed working properly
  EGR system was cleaned, and certain components were replaced. After that, I removed the whole system today - EGR, BPT, and the two thingies on the front of the engine related to it (AIR valve, right?). All vacuum and exhaust ports have been plugged/rerouted appropriately. Both of the EGR control solenoids were removed (the one on top of the intake manifold, and the one below it). The steel vacuum routing system bolted to the intake has also been removed during this process.
• Charcoal canister was also removed at the same time.
• I checked all the other vacuum lines at the same time, and they all checked out just fine.
• Spark plugs are wearing a little bit dark.
  

List of relevant mods:

• Stroked to 91mm
• Bored to 89mm
• 8.5:1 pistons
• Lightweight flywheel
• Cat-back exhaust, straight-piped cat
• Intake is the old stocky right now - an accident destroyed the CAI
• Solid lifters, solid-style cam - 272* duration with a 10.5mm lift
• +1mm oversized valves
  

I'm stumped, frustrated, and almost ready to take it to the professionals
Please help me

check plug gap. If it is lower than .032 then it could just be that. Check AFRs too because I notice a lean miss every now and then. Pretty much same issues you have.

could definitly be a lean or rich misfire depending on the air fuels at idle and part throtle

by AFRs do you mean Air Fuel Ratio or Adjustable Fuel Pressure Regulator? I'll check plug gap and let you guys know...

air fuel ratios, you cojuld be getting a lean spot in your fuel map for one reason or another, either it could be too lean or too rich. or that could not be the problem at all, but iwould check that

I guess that means it's time to buy a wideband O2 sensor...

or try to borrow one from a friend or something, its easier to do that then to spend xxx on a wideband they are good to have though

OK totally just figured this out and feel like a moron.
The battery in my ohmmeter was dying - it dropped to 7 volts (it's a 12 volt battery)
Because it had dropped, it was giving me incorrect readings - it said my car battery was at 19volts... lol
So I put a new battery in the ohmmeter, and started re-checking things. I found that my TPS was actually at about .25v closed throttle. I adjusted it, and it runs like a dream now.