Coilpack Problem

shaodome · Post by **shaodome** » Tue Jun 27, 2006 6:37 am

29q2 Running MS1 v3 and 3 VB921s in wasted spark mode.

Things replaced:

New Coilpack (tried two of them)
New Wires
New Plugs
New Coilpack Wiring
Tried two different known working Megasquirts as well

Car starts and runs great off boost or in spool. Works fine. When n/a I could got WOT and all was great. With the new setup, just as the turbo spools and I get to approx 130kPa, it sounds like it drops a cylinder entirely. AFR is ~11:1 until it starts to misfire, so I'm not running excessively rich. Dwell is currently at 3.8ms running (tried various other dwell with the same results).

Upon checking for a bad injector and just overall troubleshooting I was pulling individual plug wires with the motor running and when I got to cylinder 2, the car died.

V6 Layout:

1,3,5
2,4,6

Firing order 123456

None of the other cylinders exhibited this behavior. Upon further inspection, I repeated pullingout the #2 wire and noticed the spark arc from the coilB in the coilpack to the chassis. Right through the wires. Replaced both wires on that coil and still does it. I can't always see the spark arcing before the car dies, but I can hear it in the area of the coilpack. This is driving me mad. I"m hoping the boost dropout issue is related to spark.

The problem isn't related to the MS or the software on it because I can put that in a friends car and it works fine.

Post by **jsmcortina** » Tue Jun 27, 2006 10:03 am

Plug gap ?

James

shaodome · Post by **shaodome** » Tue Jun 27, 2006 10:32 am

.03 Its well within range. I have gone as low as .028. Same results.

Jon k · Post by **Jon k** » Tue Jun 27, 2006 11:14 am

shaodome wrote:.03 Its well within range. I have gone as low as .028. Same results.

.03 is very open for a FI car. I run downward of .022 - .025

shaodome · Post by **shaodome** » Tue Jun 27, 2006 11:42 am

It is NOT a plug gap issue. I ran with that gap all of last year, so I am confident it isn't that. The spark that the packs put out is more than enough to ignite the mixture when it works properly

Any idea about that plug jumping to the chassis?

Jon k · Post by **Jon k** » Tue Jun 27, 2006 11:54 am

shaodome wrote:It is NOT a plug gap issue. I ran with that gap all of last year, so I am confident it isn't that. The spark that the packs put out is more than enough to ignite the mixture when it works properly

Any idea about that plug jumping to the chassis?

I guess just check the plug boots and make sure theres no oil in the plug well. I had the same issue when my car was supercharged, I'd be ripping down the street and then when i hit X amount of PSI i'd get a misfire. Sounds most like spark blow out if you ask me. I'd gap them down just for the sake of doing it - NGK V-grove are only like $2.50 ea

shaodome · Post by **shaodome** » Tue Jun 27, 2006 12:01 pm

ok...tried .022. Same issue. I have also tried changing ALL the plug wires which were known good on my old boost setup. Car sat (garaged) for a few months while the details on this new one were worked out.

PSIG · Post by **PSIG** » Tue Jun 27, 2006 12:34 pm

Pulling a plug wire on a wasted spark system will kill 2 plugs unless the spark is leaking through somewhere. To verify which individual cylinder is misbehaving, pull the boots back at either the plug or coil and short directly to ground to kill that one plug instead of both on the coil.

Although you may be familiar, not everyone reading this is, so... Some use a screwdriver with a well insulated handle and TOUCH THE TIP TO GROUND FIRST and then lean it into the terminal to avoid a nasty shock. I prefer to clip a grounding jumper wire to the shaft and probe the terminals with the tip.

Be careful!

Jon k · Post by **Jon k** » Tue Jun 27, 2006 12:36 pm

shaodome wrote:ok...tried .022. Same issue. I have also tried changing ALL the plug wires which were known good on my old boost setup. Car sat (garaged) for a few months while the details on this new one were worked out.

Ok well what we can conclude is:

.03 misses, .022 misses... result is gap is fine.
You say the coil pack and wires are good (is this a VW VR6 btw?)
Dwell you say is 3.8 running have you tried to make it longer? Maybe the coil needs a little more juice with the boost.

The only other thing could be fuel cut...

Are the plugs new? They could be fouled - I had a horrible misfire when s/c'd and I swapped plugs and the miss was gone. I really don't know what else it could be - can you go part throttle (ie not boosting) past that RPM where ti starts to miss? That will give you an idea of whether or not its a CPS sensor or something. Why don't you datalog it?

Also if you're missing on one cylinder out of 6, it is my experience that it go quite lean during the miss. Post us a datalog.

Jon k · Post by **Jon k** » Tue Jun 27, 2006 12:37 pm

PSIG wrote:Pulling a plug wire on a wasted spark system will kill 2 plugs unless the spark is leaking through somewhere. To verify which individual cylinder is misbehaving, pull the boots back at either the plug or coil and short directly to ground to kill that one plug instead of both on the coil.

Although you may be familiar, not everyone reading this is, so... Some use a screwdriver with a well insulated handle and TOUCH THE TIP TO GROUND FIRST and then lean it into the terminal to avoid a nasty shock. I prefer to clip a grounding jumper wire to the shaft and probe the terminals with the tip. Be careful!

The only prob with shorting a plug in his case is that it seems his misfire occurs under load

shaodome · Post by **shaodome** » Tue Jun 27, 2006 12:40 pm

The datalog can be seen in this thread:

http://www.msefi.com/viewtopic.php?t=20047

The engine is a 2.5L Mazda KLZE.

I can easily rev passed the point of boosting/misfire as long as i don't go over about 130kpa. It does show lean from the misfire if I say in it for a split second longer. Plugs come out fine...even if I boost and coast to the side of the road and check them. This is VERY frusterating.

Because the plugs look fine, I think it is still a spark issue.

I have tried up to 5.0ms worth of dwell and the same result still.

This entire ignition setup was working as it is previously a few months back

Jon k · Post by **Jon k** » Tue Jun 27, 2006 12:42 pm

shaodome wrote:The datalog can be seen in this thread:

http://www.msefi.com/viewtopic.php?t=20047

The engine is a 2.5L Mazda KLZE.

I can easily rev passed the point of boosting/misfire as long as i don't go over about 130kpa. It does show lean from the misfire if I say in it for a split second longer. Plugs come out fine...even if I boost and coast to the side of the road and check them. This is VERY frusterating.

Because the plugs look fine, I think it is still a spark issue.

I have tried up to 5.0ms worth of dwell and the same result still.

This entire ignition setup was working as it is previously a few months back

Ok well it's definitely a spark problem - I'd say anyway. The dwell up to 5.0ms is somewhat concerning. A coil that uses 3.8 up to 5 maybe jeopardize the coil. Can you find another coil pack - I know you said yours worked before, but just to be redundant?

shaodome · Post by **shaodome** » Tue Jun 27, 2006 12:50 pm

I know about the 5.0ms....kinda a despiration move. Oversaturation most likely.

I have tried two BRAND NEW coil packs, so I know the pack itself isn't the issue.

Edit: Thanks for taking the time to think about this problem!

Fastest95PGT · Post by **Fastest95PGT** » Tue Jun 27, 2006 1:04 pm

What's your minimum discharge?

shaodome · Post by **shaodome** » Tue Jun 27, 2006 1:09 pm

I've tried .1, .3, and .5

As previously mentioned. I know it isn't the actual coil pack itself, the MS, or the software settings on the box. Those all "were" working and ran great for a long time. There must be something stupid that I'm missing or a bad injector.

This only happnes in boost. When I had the car as is a few weeks ago (still n/a) it was fine at WOT all the way to redline. If I remove the wastegate...its still the same way. AFR remains solid and isn't twitchy.

Jon k · Post by **Jon k** » Tue Jun 27, 2006 2:50 pm

shaodome wrote:I've tried .1, .3, and .5

As previously mentioned. I know it isn't the actual coil pack itself, the MS, or the software settings on the box. Those all "were" working and ran great for a long time. There must be something stupid that I'm missing or a bad injector.

This only happnes in boost. When I had the car as is a few weeks ago (still n/a) it was fine at WOT all the way to redline. If I remove the wastegate...its still the same way. AFR remains solid and isn't twitchy.

Here's a question - what's your fuel pressure like on boost? Maybe you're running too high of fuel pressure and an old injector is getting pinned closed

shaodome · Post by **shaodome** » Tue Jun 27, 2006 2:52 pm

Nope. I actually built my fuel map with the FPR set at 44, so I've left it that way. It is static...not the "right" way to do it, I know, but I have compensated within the VE table. The fuel pressure is fine and no raising with boost.

PSIG · Post by **PSIG** » Tue Jun 27, 2006 4:56 pm

Jon k wrote:The only prob with shorting a plug in his case is that it seems his misfire occurs under load

Correct. I was addressing about half the original post that related to pulling plug wires - which is inconclusive when done in the method originally described.

Jon k · Post by **Jon k** » Tue Jun 27, 2006 7:35 pm

PSIG wrote:
Jon k wrote:The only prob with shorting a plug in his case is that it seems his misfire occurs under load
Correct. I was addressing about half the original post that related to pulling plug wires - which is inconclusive when done in the method originally described.

Yeah that was the hardest thing for me when I had issues - turned out I had a combination of fouled plugs at one point, and my valve cover leaked and let oil pool in the spark plug wells. Hard to diagnose because it was only at like 4500 rpm while under load.

shaodome · Post by **shaodome** » Fri Jun 30, 2006 5:58 am

I did discover a SMALL SMALL SMALL amount of oil in cylinder 2 yesterday from a valve cover leak, but nothing that should be causing this problem.

I went out yesterday and tried to mess with it some more. Boosted on it rather hard this time and immediately coasted to the side of the road. Pulled all the plugs again. They all looked the same (actually a little whitish on the ends) except #6. It was actually more tan and healthier looking then the rest. I'm still stumped. The dyno is reserved for tomorrow (hear that Jeff

) but the car doesn't run properly....GRRR!