Single misfire event every 3 seconds

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.

Re: Single misfire event every 3 seconds

Postby aleksanderk » Mon Sep 07, 2020 3:41 pm

Today I reset the diagnostics as stevieturbo suggested. I forgot to look at total resets yesterday, but looked at them today.
Went for a 30 minute drive, and took 3 screenshots at the diagnostics screen.
I had a pretty hard misfire that i suspect set the Rejected crank pulses. But the misfire is happening all the time without triggering any errors or resets. Only 5 rejected pulses can't explain all my problems?

(Click for full-size images)
Image
Image
Image

I also tried to pinch the fuel return line to see if higher fuel pressure would make the misfire go away at idle. It didn't.
Tried to richen up the mixture at cruise from 15 AFR to around 13. No significant difference.
At full boost (Peaks@1,6bar) it goes like a rocket, so this is very strange to me.
aleksanderk
 
Posts: 43
Joined: Fri Feb 01, 2019 4:36 pm
ECU Model: S80 Pro
Firmware Version: 6500

Re: Single misfire event every 3 seconds

Postby stevieturbo » Mon Sep 07, 2020 4:24 pm

That looks like a pretty solid crank/cam trigger setup, nothing there that would suggest a major problem.

As per posts from April, have you tried removing the case earth ? ( not power ground, just the earth to the case )

Also, what coil and dwell time ?
stevieturbo
 
Posts: 3251
Joined: Tue Aug 02, 2011 12:08 pm
Location: Norn Iron
ECU Model: No ECU

Re: Single misfire event every 3 seconds

Postby aleksanderk » Mon Sep 07, 2020 4:57 pm

No, I have completely forgot to test that. I will try that tomorrow if I get time.
I want to mention that the misfires are there regardless of the computer being connected or not. Since i talked about it in one of my previous posts.
I also see that the oil pressure, oil temp and fuel pressure are reading some odd values. I'm guessing that's because they are not connected and some electrical noise is interfering.

Coil is a KMS Dis-coil 4-post wasted spark. Same as some Audi's have OEM i think. Dwell is set to 2600 or 2800us. I have tried increasing or reducing but there is no difference. Too low dwell would cause high rpm/boost misfire right?
aleksanderk
 
Posts: 43
Joined: Fri Feb 01, 2019 4:36 pm
ECU Model: S80 Pro
Firmware Version: 6500

Re: Single misfire event every 3 seconds

Postby stevieturbo » Mon Sep 07, 2020 6:55 pm

I've seen a friend with a different ecu and the VW/Audi COP coils have light throttle misfires..yet be fine everywhere else, and that was from running too much dwell which seemed odd.
Seems those coils like very low dwell.

Although as always, best to test coils with a scope to see what they really want, or is too much.

Have you tried it at say 1500us ?

I'm sure I asked before, are any HT leads routed anywhere near crank or cam trigger wiring etc ?

The coil does just look like a common old VW type with the built in ignitor ( which can be removed and used as a regular inductive coil too )

Have you tried another coil pack ?

I know EFIParts sell it fairly cheap...lot cheaper than KMS anyway
https://efi-parts.co.uk/product/wasted- ... -ignitors/

Or try a regular inductive 4 tower Ford coil as DTA would sell ?

Or I know Subaru ones work very well, again available as either inductive ( 97/98 ) or built in triggers ( 99/00 )

Again I would always prefer actual OEM coils, than aftermarket.
stevieturbo
 
Posts: 3251
Joined: Tue Aug 02, 2011 12:08 pm
Location: Norn Iron
ECU Model: No ECU

Re: Single misfire event every 3 seconds

Postby aleksanderk » Tue Sep 08, 2020 8:41 am

Stevie: I have tried lowering dwell all the way to 1000us wich is the lowest DTA would let me, but the misfires are still there at idle. I don't see the point driving with it to test since the misfire is still present at idle.
I don't have a scope to test, but I contacted the reseller in Norway and they told me that 3000us should be ok but in high boost and hogh compression they would use 3500us. I think this seems a bit high though, but tried increasing gradually to 3000us with no success either.

The HT leads should not interfer with the wiring as the coil are temporarily mounted on the shock tower and the leads are zip-tied to the firefall to the plugs. There are 10-15cm (4-6 inches) clearance between the leads and the wiring.

Here is a link to the coil I'm using: https://kms.vankronenburg.nl/kms-discoil-4-cylinder
I have not tried another coil pack, but I can revert back to distributor to test. But I am under the impression that it's not sufficiant enough to run a high boost application. I might be mistaken thoug. (Have been before :lol: )

The original coil is a Bosch 0 221 118 351 with an external ignitior module Bosch 0 227 100 124. Can I still use the coil without the igniter module?
What are the limitations of the original distributor setup?
aleksanderk
 
Posts: 43
Joined: Fri Feb 01, 2019 4:36 pm
ECU Model: S80 Pro
Firmware Version: 6500

Re: Single misfire event every 3 seconds

Postby Rob Stevens » Tue Sep 08, 2020 11:13 am

As Stevie suggests try using a dumb Ford coil just to really prove where the issue is. I kind of thought the dwell time was controlled by the coil with these amplified ones?
Rob Stevens
 
Posts: 1106
Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Single misfire event every 3 seconds

Postby stevieturbo » Tue Sep 08, 2020 11:45 am

Rob Stevens wrote:As Stevie suggests try using a dumb Ford coil just to really prove where the issue is. I kind of thought the dwell time was controlled by the coil with these amplified ones?


Very rarely is the dwell controlled within the coil itself....maybe something like that strange EDIS Ford and the Megasquirt guys use does ?

But keep it simple....keep a 4 tower coil.

But yes if you wanted you could revert back to a dizzy and single coil....I wouldnt bother though.
stevieturbo
 
Posts: 3251
Joined: Tue Aug 02, 2011 12:08 pm
Location: Norn Iron
ECU Model: No ECU

Re: Single misfire event every 3 seconds

Postby aleksanderk » Tue Sep 08, 2020 5:40 pm

So you suggest that I keep the coil I've already got? It's the same as you linked to at efi-parts.
Import taxes are expensive in Norway, but I could get a cheap one for £60 at a local shop that's similar to Autozone/Halfords. Don't know about the quality of it, but for testing I think it should be ok.
HT-leads are from the same store, and was a kit for an Audi with the same coil.

But I will try to disconnect the case earth first.
Could plug gap have any thing to do with this? Gapped them to .028" (.7mm) when building the engine. I have driven the car quite a bit since then, so I could probably check the gap as well. Are .028" good? When searching I find everything from .002" to .060". Plugs are NGK BPR7ES, wich is one "step" colder than the original BPR6ES that came on the engine originally (Originally N/A).
aleksanderk
 
Posts: 43
Joined: Fri Feb 01, 2019 4:36 pm
ECU Model: S80 Pro
Firmware Version: 6500

Re: Single misfire event every 3 seconds

Postby stevieturbo » Tue Sep 08, 2020 5:51 pm

aleksanderk wrote:So you suggest that I keep the coil I've already got? It's the same as you linked to at efi-parts.
Import taxes are expensive in Norway, but I could get a cheap one for £60 at a local shop that's similar to Autozone/Halfords. Don't know about the quality of it, but for testing I think it should be ok.
HT-leads are from the same store, and was a kit for an Audi with the same coil.

But I will try to disconnect the case earth first.
Could plug gap have any thing to do with this? Gapped them to .028" (.7mm) when building the engine. I have driven the car quite a bit since then, so I could probably check the gap as well. Are .028" good? When searching I find everything from .002" to .060". Plugs are NGK BPR7ES, wich is one "step" colder than the original BPR6ES that came on the engine originally (Originally N/A).


No. I did not say that. Both Rob and I said to try a different coil. And in the case of coils, I always prefer proper OEM coils, not spurious aftermarket items.

I only linked to the EFIParts to indicate it is the same VW coil you are using, just KMS charge nearly double.

But I'm sure there are plenty of cars in Norway with coils you could use or sourced in Norway. They're just coils, billions of cars have them, many can be used.
Although the VW copy KMS sell should be fine.

I doubt plugs or gaps are the issue here. And are you sure the coil is indeed wired correctly ? Although should be hard to get wrong

Maybe routing of leads if they are near any other wiring as said before, or perhaps if leads are routed and tied beside each other, and some crossfiring is occuring. Chances are low...but maybe it is possible.

Or can you move to a coil on plug, or coil near plug setup ?
stevieturbo
 
Posts: 3251
Joined: Tue Aug 02, 2011 12:08 pm
Location: Norn Iron
ECU Model: No ECU

Re: Single misfire event every 3 seconds

Postby aleksanderk » Tue Sep 08, 2020 6:43 pm

Ok, I misunderstood you then.
I will try to source another coil if removing the earth does not solve the problem. Totally agree with you on keeping as much OEM parts as possible. Someone at Bosch has spent more time on a part than I have existed on this planet. They know what they are doing.

The leads are tied together but very loosely. I will try to free them up to test as well.
aleksanderk
 
Posts: 43
Joined: Fri Feb 01, 2019 4:36 pm
ECU Model: S80 Pro
Firmware Version: 6500

Previous

Return to Tuning -- Tips and Tricks

Who is online

Users browsing this forum: No registered users and 3 guests

cron