easy

I will preface with some info about the mods done to the car.

-usdm h22a4 in a 98 base model.
-has cai, replica tri-y header, and straight through 3in exhaust. (no cat)
-p72 chipped (hondata s300)

The problem is... intermitent i would say, but is isolated to 3 ranges of opperation.

First is at idle when the car is warmed up. It idles perfectly fine, no surges or pinging. But, when i go to rev the car in neutral, i get what sounds like 2 or 3 mis fires as it starts to rev, and then it revs just fine. Also, it only happens if i rev wide open throttle. It does not happen if i go to launch and only rev with partial throttle.

Second range is around 15-1800 rpms cruising around in 3rd gear at 20-25 mph (i live on a military base, and this makes up a large portion of my normal daily driving) if i try to accelerate with anything more than 1/8th throttle in 3rd gear in that range, i get a stutter that feels like either, a non ignition or misfire of 2 cylinders (that is only a guess, i can't say that with full confidence) the tone from the exhaust is noticably more rough, and power is half what it normally would be at best. This will continue untill i let off the gas, and try again with less throttle, or until it very slowly climbs to about 2500rpm and then accelerates at what seems like a normal rate from there.

The third range i get it is in almost any gear, in vtec, around 7000-7200 rpm. At that time, i get almost the exact same sound change and power loss accompanied by the stutter feeling, only much more rapid as the motor is at a higher rpm. in this situation, i cannot lower the throttle in order to make it go away. I either have to let it slowly pull it's self out, or shift.

I will also submit that I am by no means very experianced with anything ecu wise. I know how to look at the data logs but, I am not 100% familiar with what readings should be vs what they are. I can watch the MAP sensor read anywhere from 20 +- 2 or so as i cruise around, and noticed the other day while driving around in what i described as the second problem range that when it occurs, the map drops to 0 or almost such at about half throttle. THat said, i'm not sure if that is ok or not :/

I may be able to get a recording of it happening if it would help more, and i may be able to record my data logging (although i don't have a wideband atm so i'm not sure if that will provide all of the info people might want to see) I am trying to figure this out as much as i can on my own, but i'm a little overwhelmed with where to start.

Easy

razorlude

back to the basic,spark plugs or plug cables?checked?

easy

I guess it would be helpful to list what i have tried already lol

I have tried all of these so far:

-checked spark plug wires
-new plugs
-cleaned IACV
-cleaned egr valve (not ports as i don't have the tools required on hand)
-cleaned the tb out
-checked for vacuum leaks till i ran out of carb cleaner

jdm_rb20

A stutter under light/regular operation can mean that your TPS needs calibrating or possibly replacing. I don't know what would result from a TPS problem under all those conditions. I guess I would calibrate the TPS and check it with an ohm-meter to make sure it is operating correctly.

hellifiknow

Have you checked to see if your injectors are all spraying? Could be a clogged injector. I'm having the same problem with my car and I'm curious to see how you solve this.

1funryd

Have you checked to see if the screw in the distributor came off or is loose and causing your rotor to spin out of control, which causes the stutter and loss of power.

It happened to me.

easy

Sorry for the slow reply, was TDY for a few days.

I did check the distributor and everything was clean and solid. nothing was loose or even dirty.

I have not checked the injectors yet, it was one of the things i was kind of leaning towards, just haven't had a lot of time to REALLY tear into it.

Something i am sort of leaning towards is possibly a valve adjustment. I can't find anywhere in the maintenance history where it was done, so valve lash might be off. If that is the case, would advancing the timing make the problem worse?

holmesnmanny

You should check your Throttle Position Sensor. Do a search for how to test it.