I've got a 2001 AP1 with 110,000 miles, stock except for HKS catback. I've been fighting issues galore on this car, started with the dreaded idle dip, progressed to misfires, major drivability issues, etc. I had the injectors cleaned and replaced the plugs, which fixed the individual cylinder misfire codes. I adjusted the valves, which cleaned up idle misfires. I replaced the cat, which was causing rattles and misfires everywhere. I had the TPS low voltage code, so I replaced it with an Omni Power TPS. The idle dips still remain, the car will still stall going back to idle, usually when it's humid. I cleaned the IACV, it works fine. I don't think the TPS/idle issues are caused by the MAP, but another electrical issue. I also get a pending P1457 (evap leak) which is also linked to voltage in some cases. My battery is good, and I don't get charging lights - does anyone know what else could cause the TPS low voltage code and idle dip?

 

With that many miles you should consider changing your coolant. It helped fixing my idle issues.

 

I don't doubt you... but how does this help the idle issues?

Just curious. Thanks!

 

It can't.

 

Coolant is coolant, it doesn't change the temperature that the CLT reads.

 

I should've been more specific, change your coolant if you suspect there is air in the system.

 

This thread is about idle dip.

It has nothing to do with coolant. Air in the coolant does not signify the need for replacement.

 

Anybody?
Rectifier in the alternator maybe?

 

Have you measured the static battery voltage. And the voltage when the engine is warmed up & idling?

 

I finally got around to checking this tonight (long story), but here's what I have:

Constant P0122 TPS low voltage code. It comes right back after clearing it, within seconds.
Getting P1457 EVAP code commonly, as well.
Emissions air pump is constantly turning on. I'd say it's on at least 50% of the time.
Car gets idle dip on a warm start. Idle fluctuates frequently, by 100-200 RPM, can hear a relay clicking near/under the radiator before the idle drops (I believe it's the relay that controls the air pump).
On warm starts, the car may buck, like it doesn't recognize the first 25% of the throttle input.
Battery voltage at 12.2v, ignition off.
Battery voltage at 14.2v loaded (lights, fan full blast) and unloaded. Dips to 13.6v as the car stumbles with the idle dip.

Somebody please help, I'm at wit's end here.