the hks dli II? bad move from what ive been told by several of the site sponsors that sell them is it will fry coils pretty quickly because the coils arnt set up to run something like that.

 

so i'm confused, how is he seeing a misfire on the computer if he's not displaying knock? what other sensor can you monitor that will show a misfire?

and if it doesn't alter a/f or can't be felt then it's just a false reading so it actually doesn't exist. I still would like to know what they are using to detect this false misfire.

 

it's a band aid fix anyways. People love to throw parts on a problem to try to fix it without actually fixing the underlying problem. crazy how that works. Usually the crappy shops will do this.

We know that a stock ignition system in good working order will support near 1000hp cars without issues so to say you need to upgrade to support 550hp is just plain wrong. If the ignition can't support it then there is something wrong with this specific car.

i'm just agreeing with you jerry.

 

The shop didn't mention the hks to me. I was just wondering about it. As far as the knock or misfire I'm not sure. Il get more answers on Tuesday. They really think its the coils. If not they will keep the car till they find the cause.

 

crank position sensor determines misfire

 

I was just using that as an example not implying that this shop is trying to patch a problem with another part.

With a misfire there are 3 things leading to the problem: spark, fuel, air

i doubt it's air flow.
spark either plug or coil
fuel would be from injector


Ask them what they are "seeing" a misfire with. Computer is not a good enough answer. I want to know what sensor they are monitoring and how they are thinking this is a misfire if there are no symptoms at all.

 

str8dum1 is correct. Per the FSM, when a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crankshaft position (CKP) sensor signal to vary, ECM can determine that a misfire is occurring.

 

Misfire is easy to see on dyno plots, not a whole lot of guesswork there.

 

I have no idea about tuning cars. I just put the damn thing together and gave it to the shop to tune. So I can't really answer for anything there doing at the momment. Il take the information you guys have gave me about it and ask them on Tuesday and let u know.

 

I was able to talk to them today for a min. They said they monitor knock and nothing showed up. They said its not a timing issue and that only at 5500 rpm does it break up. The rest of the rpm range is fine. They said its most likely an electrICal Issue. That is all I know. The new coilS are going on today. If its not that they are checking wiring next.

 

IC, so how would it know if there is actually something going wrong or if it's not just a faulty position sensor? With as many that fail on these cars and the fact that the car has no other symptoms (can't feel the misfire) I wouldn't use the crank position sensor to tell me it is misfiring.

so if the timing is messed up you probably have a bad crank position sensor or it's at least starting to fail. Timing should be exactly what is commanded in the ecu map when WOT.

 

Well I have an extra crank Position sensor so might as well swaP it over.

 

This is only true for an EMS that has Dwell control, which Osiris unfortunately does not. I ran out of spark at around 580rwhp on pump, and have come across a handful of other stock ECU high HP cars with such blowout. An HKS Ignition amp solved my issue, I then pushed that setup to 633rwhp/667ft-lb until I recently switched to Haltech.

 

what is the dwell on the stock ECU?

 

Was it similar to my problem with one 5500 rpms having an issuer or was it a certain rpm and then all the way from there on? What is ur success with the hks. Coils die out?

 

Not sure, I believe Hal did some testing with Dwell, He may know.

Mine occurred between 6-6.1k every pull, the only way to make it rev higher was to pull the boost back. I ran the HKS amp for probably 6 months with no coil pack problems. We have several customers who have been running it for years without issue.

If you can't find one, I have a brand new one I might part with. I happened to come across a used one while I was waiting for the new one to arrive. I've held on to it in case I decided to run it along with the Haltech.

Edit: I remember Jesse having a similar problem before he ditched the stock ECU also.
https://my350z.com/forum/8817812-post64.html

 

How much are u willing to part with it? I'm not having the same issue though. I can take it all the way to redline. Can't tell there's a problem with misfire

 

Well I suppose I "could" have taken my car higher, but when it began misfiring I got out of it. If you repeatedly misfire at WOT, that can harm the turbos quick.

As far as my amp, i'll have to try to dig up what I paid for it. I'll PM you once I find out.

 

Ok so it ended up being the coil packs that were bad. They swapped em out and there is no more misfire. Final dyno numbers were. 565 whp and 580tq at 17 psi. I told them to hold off on taking it any higher until I get a twin pump and more injector even though there was room to go. Il post dyno sheet later when they email it to me.

 

Good stuff. Glad it's sorted and Osiris is working out at that power level.