jicl55

No vacuum leaks, still get 2 codes: P202B-002 Idle speed control implausible: Short circuit to ground or open circuit. P20A2- Idle speed control implausible: Check system for unmetered air. Have had both of these codes since switching to the 80mm TB. Engine idles funny (up and down) sometimes. Sometimes it's fine. Sometimes it feels like it's going to stall at a stop light. Again, no vacuum leaks.... Had the throttle body knife edged (maybe sticking, but it seemed perfectly fine...) Also, had to drill a hole for the PCV vacuum and I noticed that it kind of sits under the throttle plate at idle position (3%) could this be the culprit? TPS sensor? Bad throttle body?

DChan415

You have more air going into the intake than the MAF see's. The idle surging is due to the ecu constantly overcompensating while trying to control idle speed. The most likely reason is a vacuum leak. Not necessarily manifold vacuum, anywhere behind the MAF. Intake boot?

jicl55

I think it might be the PCV hole that I had to drill. Question: if at idle, the plate is open 3% and the PCV vacuum hole is slightly underneath the throttle plate (where it shouldn't exactly be), could it suck that minimal air that is supposed to be going to the engine out and thus cause stall like characteristics because it's now not getting enough air? If this is the case, could I just temporarily plug that hole (on the throttle body) and see if it improves? Could this cause any damage to the engine to do a test run for a few days? Sorry, don't really know how that PCV hole works.... is that hole in the throttle for sucking air out or is it putting air in? If it's putting excess air in, could be the cause for slightly higher revs and the "unmetered air"? The PCV hole is suppose to be completely in front of the plate on the 80mm. The machinist that did mine tried to replicate the 74mm setup and put it behind the plate, but after looking at other 80mm setups, it's completely in front of the throttle plate. As a side note, was at a stop light last night and stalled out.... not good. I also notice that is runs good when the car is cold, but after driving for maybe 20 minutes and it starts to heat up, the jumpiness and erratic idle return.

chiromikey

even though it seems unlikely, i've also seen these symptoms caused by a poor fitting inlet over the tb. make sure your y-pipe is mated correctly to the tb inlet.

jicl55

It's on good.... even put an extra clamp on it to help hold it down.... checked for leaks everywhere.... no leaks.

jicl55

.... took off the throttle body, disconnected the PCV hose from the hole and just left it sitting in the engine, put a piece of high temp tape over the hole, drove it around all day today and coming back to the pad, the check engine light went off! It's the damn hole.... thinking that I'll have someone fill that hole with aluminum epoxy and have him redrill the hole for the PCV vacuum away from the butterfly plate like it should be..... should be problem solved.