pl_obeny86

Hi guys!

Recently I've discovered very annoying behavior of my car. First of all is poppling tacho needle. Under high load tacho needle is jumping between 6 and 10k rpms when engine runs at no more than 7k rpms. This is almost always reproducible, whenever engine runs at high loads or WOT. Moreover in similar conditions engine tends to snort (I don't know how to call that thing). I mean sound is similar as during large ingintion retard with flooding engine with fuel. Some times explosions are heard from the exhaust. Engine loses it's power when described behavior occurs. But when revs are higher 7k rpms or more explosions stops but tacho is still freaking out. I don't know whether tacho and explosions are related, some times only explosions/snorting are heard, some times tacho freaks out and other times both things happens at the same time. Engine not always looses the power during explosions. No clicking/pinging/knocking sound heard (even with det can/stetoscope). No metalic sounds at all only these explosions and loosing power. My exhaust system is quite silent so working engine is well heard. Everything begins to happen when manifold pressure exceeds 0,5 bar of boost

I'm fighting with this problem for over a week and cannot find the solution. All hints are welcome.

Shortened engine specs:
- B18C6 with forged CP pistons (machined - no sharp edges) and Eagle rods
- machined head combustion chamber and milled 0,7mm (0.027")
- compression pressure is about 13,5 bar at hot engine
- aem fuel rail with B&M fuel pressure regulator ( about 80psi, 5,5bar)
- MSD ignition coil, rotor and dizzy cap, new Vision spark wires
- tuned with crome gold (pro license)
- engine doesn't overheat (90 celsius degrees,194 Farenheit of oil and water during load)
- IAT doesn't exceed 45 celsius degrees, 113 Farenheit
- Intake camshaft is advanced 1 degree and exhaust is 2 degrees retarded.

Previously engine was running on 1,3 bar of boost and everything was fine. It has a 6 month pause during which some parts mentioned above were changed:
- stock fuel rail to aem with B&M and increased fuel pressure
- spark plugs and wires
- fuel tank
- MSD ignition coil and related dizzy stuff added

Problem still occurs after restoring stock dizzy (ignition module changed too - NEC), previously used spark plugs and fuel pressure, changing ECU, changing program to this which was running at 1,3 bar of boost. It doesn't matter whether engine runs at lean mixture (about 13) or rich (10), retarding and advancing the ignition doesn't have bigger influence. I think that problem isn't used map related. Even restoring stock fuel pressure and using P30 code still generates those f*cking explosions.

I've used two different and propperly working in other cars (N/A spec) distributors. With second one I've used Hitachi and NEC ICMs. No changes observed.
What about LSA (lobe separation angle)? Does the changes made (+1 intake, -2 exhaust) have any influence?
I've got Vision spark wires. Is resistance of spark wires important for Honda ignition system? OEM ones went to trash, so I can't compare the behavior...

Plans for today is to replace the spark wires to OEM one if someone have a set. Restore stock fuel pressure regulator and change the ECU with previously used map.

I want to install fuel pressure gauge because I think that fuel pressure may fluctuate. On idle when I'm opening the throttle fuel pressure gets lower for over 10 psi (not during closing throttle when vaccum changes regulators membrane tension).

I've got no clue what the hell is going on. Have you got any ideas what to check, what to change, whatever?

Former User

I'd start with plugs and wires.

Have you replaced the fuel filter? Measuring the fuel pressure and testing the FPR is a good idea.

CEL codes?

pl_obeny86

hmmmm fuel filter may be perfect guess!

I've been running car on pure methanol for a while so maybe my filter didn't like it...

A friend of mine had exactly the same problem when fuel filter was damaged after using some kind of shitty fuel.

No CEL codes.