cruiser

Long story short. I dynoed my car 280rwhp@10psi. Then upped the boost to 13psi and dynoed around 270rwhp due to bucking in higher revs (6000-6500RPM). Between runs I let the dyno vent cool down the IC so it was cold to touch (about 10mins between runs).

What can cause this ?

I have had new plugs, new plug wired and new grounds.

I got this hesistation both on M2 Stage3 ECU and Pettit Unlimited.

I'm thinking HKS TP will cure this, but someone suggested that I may just be curing a problem which actually lies elsewhere.

So I'd need a few pointers where to look and what to check.

Thanks!

SomeGuy_sg

Mm... Good question . What really cause ignition blow out as boost is raised ? Is it the higher boost blowing out the spark ? Any Gurus wanna spread some knowledge.

Railgun

My understanding is as pressures increase, the need for a stronger spark increases. Though YMMV. A local here is running stock ignition with 13 PSI no problem. As soon as he brings it to 15, it breaks up on him. Same thing with me, which is why I run an amp.

The density of the a/f I think at higher boost pressures causes the spark not to jump across the electrodes or at least avery weak spark. The voltage from the ignitor to the coils in stock form is too weak to do the job (in most higher boos cases).

cruiser

But I already get this breakup at 12psi. At 10psi its perfect.
Could a bad coil cause this ? Can coils wear out and work at 80% of their capability ?
I'm no electritian mind you

tcb100

Yeah, a bad coil could cause this problem & there is no good way to test it under load. In theory coils can wear out and these cars are old.

There is a procedure to test the resistance of the coil in the manual but that is not under load so by the time you get in there to check it you might as well replace them.

You can't go wrong with a twinpower though. It takes 10 or 15 minutes to install and it will probably "paper over" any weakness in a coil just fine. I had high rpm breakup that went away with the Twinpower.

rotorbrain

test your coils. . . i have some laying around if you need them.

paul

cruiser

I already have a very nice offer for T2 leading coils, thanks

And I'm also getting HKS TP, but if only the coil is the problem, then I'd rahter not spend on TwinPower

adam c

iTrader: (2)

I have an M2 stage 3 ECU. The problem may be inherent in the ECU itself, and may not be a "problem" at all. I have found that I will get some "break up" at higher rpms if my water temps are under around 200 degrees F. Over 200 F, and the breakup seems to go away.

I suggest that you try the test with your water temps around 210F.

John Magnuson

Same here! If I'm cruising on a cool night on the freeway and then get on it when the engine is nice and cool then I get some high RPM break up (even at 10psi with an HKS Twin Spark). However, if I'm cruising around on the street or at the track I don't have this problem. I thought maybe it was related to air intake temps but maybe you're right and it's engine temps. Hmmmm...

HotWheel

I had a similar problem when I was at Nazerath speedway at WOT in 4th
at high rpms running at 10 and 12 boost, I ajusted my fuel boost and add 2%
fuel at my higher rpms problem solved ! I have the PFS FMS ( piggyback purple
fuel mang. system )

Hope this helps!

mecman

iTrader: (11)

I have M2 Stage 3 ECU and I purchased a Crane Fireball ignition amp off a forum member and put them on my leading coils. I still get the 3K hesitation when the engine is cold but it goes away after 5 minutes. On the high RPMs I do not notice any ignition break up at all.

I recently switched back to the stock ECU with the price of premium going up to $2.65/gal just to gain mileage.

ducktape

Good question. Stock coils alone would cause break-up at around 13psi.

I've been using a Crane HI6 Capacitive and it has a very limited ceiling. It seemed to work for a while, but I still get break up at 6500-to-8000rpm, on ~19psi of boost, with race fuel. I think I'm going to try to sell off the HI6 and grab an MSD 6AL, as I've heard very good things. For those that are considering it, the HI6 does work... But it seems a little too 'mickey-mouse' for heavy-duty.

Kento

Um..."test it under load"? A coil is basically several sets of wire windings and an iron core encased in insulating material. It either has the correct resistance or it doesn't, regardless of voltage.
I'm thinking that the chipped ECU is dumping more fuel at the lower engine temps at WOT, which causes an excessively rich a/f mixture that the stock ignition has difficulty dealing with.

adam c

iTrader: (2)

Yup!

Fatman0203

Im running with the petit unlimited and I have had to lower the boost from 13 down to 10 to 12 because I get the same thing. Im thinking of doing the grounds better, possibly checking the altenator, and battery, plugs, and if none of that woks HKS TP time.

Mahjik

iTrader: (1)

Yep, the stock ECU (and rechips based off of it) will change the amount of fuel being used based on temp (using the water thermosensor). IIRC, the PFC uses the fuel thermosensor to add in about 2% but I think the stock ECU only used the fuel thermosensor for hot starts. I'll have to look that up in the FSM tonight.

Montego

iTrader: (1)

so what does ignition break up feel like?

Cuz I'm thinking I had it too...

When it was cool (I had F_CON ECU then) and I would boost past 10 psi @ WOT, I would get a 'hesitation' or a 'studder' at around 5.9K RPMs and again at 6.5K RPMs. Was that ignition break up?

Railgun

A single stutter like that, probably not. It's more consistant and frequent. You have a general loss of power and the exhaust note sounds really choppy.

Montego

iTrader: (1)

Ok... thanks

I guess I'll deal with the problem once I'm ready to up the boost again.

adam c

iTrader: (2)

For me, the issue was a bit of hesitation.

Montego

iTrader: (1)

^^ lol... Now I don't know what to think. I'll find out soon enough I guess

G's 3rd Gen

iTrader: (11)

Yup..To me it sounded like the exhaust note was choppy w/ noticeable power loss...Twin power solved it..15psi now no probs..

cruiser

Yes, these are the typical RPM points where ignition breakup occurs. It feels like you'd get off the throttle and back on it in a split second. Engine looses its momentum and thus produces less power.

cruiser

Interestingly, on the racetrack where I turn up the boost if its cold enough, I dont experience this. Could well be something related to water temps, which are obviously higher then usual in those conditions.

badddrx7

iTrader: (7)

As boost goes up so does fuel..pull your spark plugs and check/and or install a new set and try it again. I bet your current ignition system does not have the umph to bridge that gap and the least bit of fouling sends it to ground. Try new plugs and see what happens - nothing else. Autolite AR3933 are cheap and work really good for my application/