KrazyLude

I have a 89 Prelude that has been recently boosted. I run a P06 with Hondata S200 for fuel management, and 450 cc injectors. T3 turbo...blah blah blah I was running 7-8 psi

The car was dynoed on Saturday, everything went very smooth. No problems.
I went out of town shortly after the dyno. The car has been driven all weekend, but not under any heavy load.

Monday I filled up with Citgo 93 Octane. Tuesday evening we started the car up to move it and heard that annoying Octane Knock for the first minute it ran, and then it just went away. We thought that it was a little weird.

Yesterday I went to go visit my tuner guys, my hot side intercooler pipe needed a bead. They fixed it and when we went to leave, we took it through the gears, and everygear at about 5000 rpms or so that detonation would come back. I would immeadiately stop accellearting.

All of the sudden my car sounds like a WRX, it didn't before. It cranks a few extra times before it starts each time. This morning it almost sounded like a car trying to start with a broken t-belt.

We checked the timing, its at 15 we changed out the plugs. Im thinking that its a spark issue. It seems as though when starting and full throttle its not getting enough spark causing detonation.

Does this seem right? Could it be a bad tank of gas? We did add octane boost incase it was bad gas. Im lost. It runs just fine if you are just driving around.

would a compression test tell me anything?

I heard from someone that because Im using MSD 8.5mm wires on stock coil with a stock coil wire that the resistance could wear out my coil prematurly.

I just need some direction I guess, help a girl out

Boltz

If it sounds like a WRX, your running on 3 cylinders. Did you try messing with the injector clips? What is your fuel pressure?

When did you last change your distributor cap and rotor?

Doesnt sound like bad compression, but if you have a tester you might as well.

I've seen cars run as lean as 19:1-20:1 at idle without problems. You can run very lean at idle without trouble.

What are your plugs gapped at?

Maine

If your car was knocking, then it was followed by the sound of running on 3 cyl. That's probably not going to be a good outcome. You should do a compression test immediately.

Detonation at idle is not a good sign, we usually associate any knocking at idle to be a trashed ring lands which is almost always the case.

Is this a gas station you often get fuel from?

Jermaine~

KrazyLude

the plugs are gapped at .030

the cap and rotor are less than a year old, with less than 10k miles upon them

the detonation is not a rod knock, its more of an octane ping. Im so sad.

Im at work now, were going to check the fuel pressure to make sure its not a fuel delivery issue, but thats not til im "off the clock"

fuel is 11.8:1 to 12:1


Modified by KrazyLude at 9:58 AM 5/26/2005

Maine

Sorry I relate knock/detonation together... We typically call it a count of detonation a "knock count".

kell211

Not getting enough spark won't cause detonation, that would be not enough fuel or octane. If the air fuel mix wasn't getting lit all the way, it would be like an overly rich condition. But it would cause it to run rough. Are all your plugs firing? Pull each one individually at idle, see if one of them doesn't change anything.