luffy

So here goes, I've been reading / searching etc. for the past 2 months, so bear with me.

The Car:
1998 Civic Si (canadian edition) 5spd, No A/C, 170k km / 110k miles. Stock everything.

The Problem:
When cold ---> the car is generally fine, quick starts and no real issues to speak of.
When warmed up
- Fluctuating idle when stopped, almost to the point of stalling
- At speed, when applying light throttle, car will drive normally. Revving freely up to 6k+.
- At speed, when applying a reasonable amount of throttle, the car will "stutter" or hesitate. If you stay into the throttle, the car will shudder more and throw a P300,301,302 & P1399 code.

What I've done
- Replaced spark plugs (twice, with factory NGK & bosch)
- Replaced ignition wires (NGK blues)
- Replaced cap & rotor
- Swapped distributor and resistance checked 3 sensors (all are ~350 ohms)
- Replaced ignition coil
- Replaced PCV valve
- Cleaned throttle body
- Replace air, oil and fuel filter.
- Checked for intake/ vaccuum leaks
- Adjusted / Calibrated TPS sensor
- Cleaned IACV
- Cursed the thing and contemplated rolling it into a lake...


I'm starting to think my cat might be plugged up, does anybody see something I'm missing?

Any help would be greatly appreciated!

-Adam

BaronvonOttobat

I'd check your MAP sensor, get one from a junkyard, auto stores usually charge around 80 for one.

Kohen

check the timing

quick86

Check your primary O2 sensor as well. Mine had a hesitation/stumble and it was just a wasted O2 sensor. Mine never threw a code though.....Replaced it and it made a WORLD of difference. I even picked up like 3mpg...

luffy

Should have mentioned it,

I had changed the O2 sensor and it had no effect.

-Adam

motegicivic

Try cleaning your IACV as well.

Also, are there NGK plugs in now? Check the gap.

EsotericImage

iTrader: (8)

might be the cat as well..

luffy

Cleaned the IACV, adjusted the TPS within spec. No change, problem persists.

Map sensor looked clean and tested fine.
Plugs have been gapped.

-Adam