Tage Evanson

Okay, here's the deal. I've got a built 2.0L VTEC. The block and rings have just finished breaking in. I had piston to valve contact (leakdown test was indicating 30% leakdown through the intake valves) so I pulled the head and had Endyn repair it. It visually looked great and I have no reason not to trust Larry's work as he's done quite a bit of work for me without issue. This time around I use a thicker head gasket (.040" vs .027") to provide more valve/piston clearance. The engine fires right up and I'm able to drive around just fine but car doesn't feel as fast as it did previously. The motor previously put down 225whp on Locash's dynapack. I understand that the thicker head gasket will lower compression (now 11.8:1) as well as advance cam timing *about* 1 degree. I was expecting my numbers to be lower due to these items but something is definitely wrong the motor as the baseline run on Locash's (same) dyno was only around 140HP. Driving around on the street I felt less power but once we put it on the dyno and held the engine at a specific rpm (3000-4000) it became very clear that the engine was misfiring and/or running on 3 cylinders.

- Wideband A/F meter showed A/F ratio was fine
- We pulled plugs, they looked fine
- We tried new plugs, same result
- We tried a different set of verified good plug wires, same result
- We swapped plugs again, same result
- We swapped a different verified good distributor, same result
- We checking timing and changed timing (ignition and cam) until we were blue in the face
- We did a compression test (245-250psi across all cylinders)
- We did a leakdown test (showed 10%/good on Locash's SnapOn Unit)
- We tried a different ECU (Hondata S200), same result
- We tried a different ECU (w/Neptune), same result
- I tried a 3rd distributor when I got home from the dyno, same result
- I did a leakdown test with my generic leakdown tester and mine showed 1% across all cylinders

The engine is acting like it's misfiring or my valves are leaking or I've got a bad cylinder/rings but every test and troubleshooting step I've done doesn't point towards any of these things. I'll pull the head in a heartbeat if I thought the problem was in the head but I can't bring myself to pull the head on a perfectly healthy engine (according the compression and leakdown numbers). Joe from Locash Racing is completely stumpped and so am I. He's not sure what it could be but he's leaning towards valvetrain or cams. I think if it was a valve(s) issue that it would show up in the compression/leakdown test. I feel it's ignition related but there's no way that all those distributors/plugs/wires are bad. The distributor wiring harness looks visually okay. I'm almost wondering if I have a tank of bad gas??? If it's bad gas, wouldn't the wideband pick that up? I'd love to hear any other theories or opinions because I'm at a loss of what to try next.

RhdRicheeee

Tage Evanson

UPDATE: I had a Bosch 255lph fuel pump and I replaced it with my stock GSR fuel pump. No difference. I then drained the gas tank and put 5 gallons of premium fuel in. No difference. FYI - the fuel filter was changed about a 80 miles ago. Thinking of replacing the injectors and then the entire wiring harness next as I'm simply running out of ideas...

NJIN BUILDR

If you didn't have enough p to v and all you did was add .013" of head gasket you probably bent the valves again.Advancing the intake cam reduced your p to v.You must check the actual pocket clearance not just guess.Make sure the cams didn't move (adjustment).Do another compression or leakdown test.

Tage Evanson

Well after the engine was broken in I put about 700 street miles (<-- many VTEC miles) as well as about 20 dyno pulls to 9000rpm and 3 autoxes (<--30+ seconds in 2nd gear and VTEC) without issue. I bent the valves on the freeway while in 5th gear. I fail to see the difference of VTEC in 5th vs VTEC in 2nd or any other gear for that matter. I also made marks on the cam gears after my dyno session and they haven't moved. After banging my head against the wall several times I just accepted that something bad happened and I would give myself some additional clearance this time around with a thicker head gasket.

When I did bend my valves it clearly showed up on the leakdown test (30% through the intake valves). What's crazy is that the engine is running a ton better but still not right and like it's misfiring or running on 3.5 cylinders. I've done multiple compression and leakdown tests during this troubleshooting as it "feels" like one (or all) of the cylinders are bad but the tests don't indicate that at all.

#1 245psi 1% total leakdown
#2 245psi 1% total leakdown
#3 245psi 1% total leakdown
#4 245psi 1% total leakdown

NJIN BUILDR

You comp and leakdown numbers sound fine.Your a/f should show any fuel delivery problems.I've can't believe that you bent the valves in 5th , that's just bizarre.Are you running a MSD box?I've had those go "week".

Tage Evanson

Yeah I thought the compression and leakdown numbers didn't warrant me pulling the head. I figured the a/f ratio numbers would tell the whole story but I wasn't sure if the wideband was quick enough to indicate a stumbling problem due to fuel delivery. Hence the reason I swapped the fuel pump and drained/filled the tank. I'm running a stock ignition system. I've tried 3 different known good working units all with the same result.

NathanielH

do you have acess to an ignition scope? at least you could point it down to one cylinder, or verify when it is happening, ect...

Tage Evanson

I've never even heard of an ignition scope but I'll ask around to see if someone has one. Honestly I'm at the point where I'll pay for just about any tool to help me narrow this down.

I posted this problem on my local autox board as well and someone mentioned maybe a camshaft with a bad lobe/lobes which makes sense. Since that's an easy check, I'm going to go pull the cams right now...

EDIT: Update - I just finished inspecting the camshafts and they visually look like every other slightly used set of cams. The rockers and lobe pads look fine as well. Would it be worth trying a different set of cams for grins and giggles???


Modified by Tage Evanson at 9:25 PM 7/10/2006

RhdRicheeee

Tage Evanson

Okay, so like I said I've pulled the plugs a bunch of times and every time they looked normal. However, I just pulled them again and all but one is showing rich. I'm 99% sure it's not ignition/spark related so I'm thinking it's a intermittently bad injector. I'm not sure why the wideband wouldn't pick up on that but it's the most logical thing so far to try.

I'll be pulling the injectors tonight and sending them back to RC Engineering for analysis tomorrow.


Modified by Tage Evanson at 10:35 PM 7/11/2006

BuddhaSiR

you need to pinpoint which cylinder is mis-firing. Does it idle ok? Run smooth at idle? Does it miss only when you rev it? Does it miss only when you have a load on the engine?

NathanielH

with an ignition scope you can see wich cylinder is missfiring, and under what conditions, it has an inductive pick up that you put around the plugwire, and you can watch the "firing line" to figure out what is going on, really only a shop would have this tool, and im sure you dont want to pay someone to look at it.goodluck, hope you get it figured out

Tage Evanson

It consistently stumbles/misfires under load. It seems to idle okay, but sometimes will drop down pretty low. Static ignition timing was difficult to set because it was jumping all over the place sometimes, then other times it was rock solid.

I have no problem paying a shop to diagnose the car with an ignition scope but I'm going to try the injectors first. I'd imagine I'll hear back from RC by Friday or Monday and then go from there.

Tage Evanson

RC just called and they confirmed my assumptions. One of the injectors is fubar'd. I'd imagine all my problems will be solved once I get the new injector back and installed.

Horay!!!

Mr.OB*GYN_Rhett

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tage Evanson &raquo;</TD></TR><TR><TD CLASS="quote">RC just called and they confirmed my assumptions. One of the injectors is fubar'd. I'd imagine all my problems will be solved once I get the new injector back and installed.

Horay!!!</TD></TR></TABLE>
hell yeah man, congrats