Ignition Fail on Dyno!!! Help Please.
 

I couldn't get a full dyno run in today because the ignition kept falling off before the rev limiter was supposed to kick in. Rev limiter was initially set to 7000rpm, but the ignition was cutting out consistently at a much lower rpm. Changing the knock window seemed to drop the rpm this occurred, but it remained consistent after that at 5800rpm exactly - WTF? I'm running 3.0.3u firmware. Please look over my msq and tell me if there's another setting that could be doing this. Yes, I know the rev limiter is set to 5750rpm now. It was not while attempting to tune.

Power was about 200HP at 5800rpm and torque about 180ish just before ignition fell off.

Details: 96miata with 99 bottom and top end, 0.040in cometic head gasket, RC550cc injectors in sequential, DIYPNP, 3.0.3u, boost at 9.5psi or about 165kPa, new NGK 6 series spark plugs gapped to .028", blue plug wires with less than 5k miles, no issues other rpm, seems to be software limit related. AFRs about 11 and advance about 13deg when issue occurs. Let me know if any other info is relevant.

have a log of the event?

Will it freerev through 5800 if you aren't in boost? I.E. while stopped in neutral, can you rev it slowly past 5800rpm?

Here is a representative run where it seems to lean out briefly at about the 5800rpm mark, which might also be uncombusted fuel from missing spark. 14143.906 is the point I'm referencing.

Haven't tried free reving it - good thought. Too late now but I'll try tomorrow. I also noticed that the mapDOT goes a little bit crazy and map drops about 5kPa abruptly, but not sure if that's normal. Could this be as simple as my line from the manifold to the MS? Will check that line also.

While we're at it. Any explanation for the seemingly false "knock" I get intermittently. I'm not sure exactly the window for this particular run, but likely about 4000rpm to 5500rpm.

Alright. Doesn't happen when free revving - not in boost. What's that tell us? Does that make it appear to be a boost specific or load specific problem? BTW, I did a quick pull on the street after free revving with the limiter still set at 7000rpm and it did the same crap at 5800rpm in boost. I won't believe its knock cause my timing is so damn low up top. I wouldn't think it would be the spark getting blown out cause my plugs are gapped to .028. A buddy of mine suggested plug wires as he had a similar problem with new bosch wires on his turbo colt. Again, mine are NGK blues with 5k miles. What about coil packs? I've heard that the failures would be more random. Hoping to hear something back from the community soon. Thanks

Uh well are you sure that knock is false? How much timing are you running at what psi at 4000-5500RPM?

If your spark cut-out is load specific (in boost), then that means your spark is weak.

Can be:

plugs
wires
coils
dwell

or some wacky ass MS shiz

Do you have a dial-type timing light? Might be worthwhile to make sure you are actually sparking when you think you are. 13 degrees BTDC is plenty conservative . . . assuming it's right.

Nothing else really stands out. There are some wierd spikes in you PW plot, but not in the area of interest. All parameters other than AFR are smooth and continuous from surrounding values. It definitely looks like a misfire and excess O2.

I'd also recommend logging ignition advance.

13*???????????

Damn that is absolutely super weaksauce. You can run more timing than that.

You SHOULD run more timing than that.

That's a good point. If you confirm your timing is correct, just remember that the higher the cylinder pressure, the harder it is to jump that spark gap. So, overly delayed timing "could" generate a misfire if you're on the edge.

To put this in perspective, at 35psi, from 4500-5500 I run 14* This is super duper retard but 35psi on my turbo is WAYYYYYY more power than 9psi on GT2x. Also WAYYYYYYYY more catastophoploey detonation potential.

At 20psi I run 17*

and this is on same 93 octane as you with much more airflow and power. No WI.

also, never ever upload "CurrentTune.msq" unless you want to make us all crazy. File>Save As that junks.

Dead Fael, [feyl]

13° at 10psi is a bit low, but not the issue, if he were to run 17° at 20psi, his motor would blow. Please don't compare your built low CR motor to a stock High CR motor.

Love Brain.


SCCAAAAAX, where are you souring the map line from? Do you have MAPdot enabled?

Hmm? I ran more timing than that on my FM basemap for 11:1 uberstock 03 factory pistons.

I agree that the timing is not the cause of the case of "runlikecraps"

Has it run to red line in the past?

OK, to address some of the above and some additional info.

I didn't think about the CurrentTune issue. Haven't run into it myself yet. I'll be sure to rename prior to loading in the future.

Brain - boost is sourced from the back top of the manifold (99manifold on 99 motor in a 96). It is bridged to feed the boost guage on the interior side. It is possible some small amount of boost could leak somewhere in that line. MAPdot is not used for AE if that's the question. It's straight TPSdot, but I'm at 100% throttle the whole time, so AE won't matter on the top end. How else would I "enable MapDOT?"

I was actually a couple steps ahead of you guys in thinking my base timing might have been lost somewhere along the way and between having the motor in and out of the car. Just checked with a timing light and the timing is running right where I've got it in SW between 14 and 15deg at idle - I had the laptop sitting in the engine bay while checking timing.

I also went ahead and purchased another set of NGK6's - I'm running the V-Power BCPR6E-11 gaped to 0.028" as indicated several times. They're not the standard 6E-11s, but I should be OK with these, right?

I also went ahead and purchased another set of spark plug wires - NGK Blues just in case. Wires and plugs will get installed tomorrow night when I pick the wires up. Will let you know how that goes.

Just to verify, did you guys have a chance to look at my dwell settings? I don't think this is the issue because my battery voltage stays between 13.4 and 13.8 very consistently and I believe I've never touched these values from the base map. A confirmation from one or more of you would be good.

So, I called up flyin' miata to see what there thought was. Coils - there guess was coils. My wires don't really have enough miles on them to likely be the issue. Apparently this is extremely common. So much so that they keep a supply of coils for the '94 to '00 cars on-hand at all times. Mother F###! I hate paying more than $100 for maintenance items, but I guess I'm nickel and diming myself in spark plugs and wires. Not to mention the additional tuning time on the dyno. They stated only way to tell was to swap out a known good set of coils. The bench resistance check will tell you that the coils are good, but not the ignitors.

They also recommended to check the resistance of the wires. I have a really shitty multi-meter and measured 360 Ohm, 330Ohm, 299 Ohm, and 278 Ohm front to back. Please don't read into the actual values because my multi-meter is likely well out of cal and I took these relatively hot. However, I was happy to see the values in the same range. I'm thinking likely not the plug wires at this point. Also likely not the relatively new plugs.\

DAMN COILS!

Coils

or

DWELL

someone please look at his dwell values. Yes improper dwell will cause high rpm boost-only misfires.

Shoot me a pm. I might have coils.

resistance on wires should be 16k ohm per every 3.2ft.

anyways, increase your tpsDOT to 75%/s.

on your log where you said the event happened is exactly where you surpassed your 50%/s threshold.





you should really move your map line to off the fpr, the 4th runner is really noisy.

Brain,

Is that TPSdot in the AE settings? That's only thing that makes sense.

Shueind, not interested in used coils, but thanks for the offer. Don't plan to worry about this again in the future. I go all new on 99% of my stuff.