Na99Si

First the details. B17 with CTR pistons (11.3:1), stock head gasket, B16 head, 99 Si intake mani, first gen 58mm tb, r valvetrain, 99 Si cams, 14 degrees timing, stock P61 B17 ecu.

Here is the problem. I am getting some hesitation around 3,000rpms up to around 6,000rpms. You can feel the car trying to go, but its backing off. I am running 91 octane and have full 2.5" exhaust on the car as well. After 6k when Vtec hits the car seems ok (can't go completely full throttle yet) and makes good power. The knock sensor is hooked up so perhaps its pulling timing? The fuel pressure is set to 54 with the line off, 44 with the line on. I tried increasing it with no change. The PCV system is not completely hooked up, still need to pop the valve into the canister. The canister is open, the connection on the intake is plugged. Do you think this is a vacuum issue, or a problem with perhaps detonation? I have heard the knock doesn't work after a certain RPM. Can anyone confirm this? Any help would be appreciated.

lazy bum shaughn

Just a thought, maybe you have a bad fuel filter or dirty injectors.

Na99Si

I plan to change the fuel filter here shortly. I will check the injectors as well, but the came from my SOHC Vtec which ran with no problems. I don't suspect they are the problem. Then again, who knows? I have no codes or anything to help me along.

Na99Si

I checked the timing today and it was now slightly advanced. I pulled some timing from it (about 2 degrees retarded) and dropped in some octane booster. Problem is still there, in fact it seems worse. Could it be ECU or possibly the wires/plugs? The plugs are left overs from my 99 SI so they are Plats... Heat range 6.

Katman

nice engine setup .
Should be fun *ahem* will be fun, once its broken in.
I use to have this setup long ago (until my car got jizzacked).

The PCV isn't causing your hesitation. Hesitation in power has to do with something ignition or physical cam/crank timing related.

The KS could be the culprit.
You might wanna have your ecu reprogrammed w/a disabled knock sensor program; that would fix that issue. (hit me up if you need this done..heh). The stock KS is pretty crappy to begin with when building up a high-comp engine setup, it kicks back the timing way too much.

You probably want to keep your fuel pressure near stock or within the 35-44psi range; and you'll want to use a 7 heat range plug, as those are better for a high compression (11.0+) engine. But 6 range should suffice...and shouldn't be causing hesitation either.

Is your cam timing perfectly set at TDC?
if its not, then your car will run like its on stupid juice.
You'll want to keep you ignition timing pretty close to stock for now....don't advance it too much (no more than 2 degrees) as you could enhance knocking.

....as some added info, when I had my high-comp B17 setup (st.CTR pistons), I ran a knock sensorless program (mugen) on my P28 ecu and had no problems whatsoever. When I would go on a long drive to conserve fuel mileage, I'd pop in a stock DOHC VTEC ecu and boy did it suck! It was pulling back on timing big time.



[Modified by Katman, 2:33 PM 3/27/2003]

Na99Si

Ecu was chipped with a Spoon program but when I fired up the engine for the first time there were some problems. As process of elimination I cut the jumper to resort back to the stock ecu setup. This seemed to help things along. I fear running the Spoon chip as it might be too aggressive on the timing. I am fearfull of destroying the engine as the gas out here does suck. I was planning on hitting up the dyno once its all broken in to see if its possibly the fuel curve on the ECU. Problem is the dyno can't show you if the engine is indeed detonating or not. Does the stock ECU ignore the knock sensor after a certain rpm? If so, do you know what RPM this change take place at with a P61?

Katman

I don't believe the stock programming *stops* looking at the KS at any point in time when the engine is running, unless its disabled in the programming. It's more of a sensitivity thing. So, I'd say if you were easy on the throttle there's less chance of knocking, yet when you get ON the throttle, you're dropping the hammer (sort a' speak) building up the sensitivity of knocking because of the air/fuel building up...

Personally, the Spoon program sucks. I tried it and dyno tested it and it blows in comparison to the mugen program. I have a stock euro B16A program w/disabled knock sensor if you're interested in something like that. hit me up on IM.

Na99Si

Well. I put the jumper back on the ECU last night and tried the Spoon program. It seemed to make the idle a LOT higher and made the car very jerky down low... Like it would not go anywhere when you tried to accelerate and then all of a sudden it was like BAM and the car jerked and shot off. The hesitation was still there, seemed a little worse. The only thing I noticed was that the Vtec point was (obviously) lowered 1,000rpms. I don't think the issue lies in the ECU anymore, do you? Seems like its something fuel/timing related.

Katman

that almost sounds (cam) timing related. When the camshafts are off by a tooth or two, the car has a jerky throttle response and feels like it revs up slow/weird...

do you know if your cam timing is off or not (TDC)? Do you know how to set the cams at TDC, to begin with?

Na99Si

Yes, I certainly do. I am far from a novice. Keep in mind I built this engine by myself from just a block. As well as working on tons of other cars before this, I have more then enough experience to handle the job!

Katman

good...
think your cam timings off? peep it out..