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.
aleksanderk
Posts: 68
Joined: Fri Feb 01, 2019 4:36 pm
ECU Model: S80 Pro
Firmware Version: 6500

Re: Single misfire event every 3 seconds

Post by aleksanderk »

Went out in the garage again and did some adjustments.
The attached log are from a hot start and idle. A little bit too much fueling on startup on this one, so I revved it to clear it up.
Min duty for IAC was increased to prevent adjustments.
Fixed ignition advance at idle, since that got messed up somehow.
Did some more adjustments for fueling and that made a difference in the logs at least.
It it still misfiring though, but now it's harder to spot them in the logs.

Cooling fan kicks in at 90C, and hysteresis is 3C. I think the cooling fan turns off at 44.

If you look at 52, something made the MAP go higher, and so did the AFR. RPM dropped a little bit. It's hard to tell, but I will say that this is a misfire event.

Kind of irrelevant, but should I increase the filter value for the water temp sensor to get rid of the jitter? It's set to 5 at the moment. Same goes for other sensors as well if necessary. I'm new to all of this, and don't know if the logs are looking as they should. Although the latest log looke nicer than the previous ones IMO.
Attachments
hot idle 03.11 fixed IAC no closed loop. cooling fan kicked in several times. tuned fuel at idle.Dat
(435.09 KiB) Downloaded 142 times
Alex DTA
Posts: 1622
Joined: Fri Feb 28, 2014 1:03 pm
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79

Re: Single misfire event every 3 seconds

Post by Alex DTA »

Keep the diagnostic display open.
Check for any values counting up when the misfire event happens. Values counting means that something is not correct with the sensors.
That will tell you if it's an input issue, or a mechanical issue.
stevieturbo
Posts: 3578
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Single misfire event every 3 seconds

Post by stevieturbo »

I'd say nothing looks badly out of place. Although yes the water temperature does seem odd, with lots of noise. Maybe this implies there is also noise elsewhere that could cause a problem

coolant temp should be very slow and stable, as the sensors themselves are very slow.
Alex DTA
Posts: 1622
Joined: Fri Feb 28, 2014 1:03 pm
ECU Model: S40 Pro
Distributor: DTA
Firmware Version: 79

Re: Single misfire event every 3 seconds

Post by Alex DTA »

The water temperature is very noisy.
Compare it to your air temperature signal, that's roughly what the water temperature should look like.

You can try increasing the filter, but I would look at the root cause.
aleksanderk
Posts: 68
Joined: Fri Feb 01, 2019 4:36 pm
ECU Model: S80 Pro
Firmware Version: 6500

Re: Single misfire event every 3 seconds

Post by aleksanderk »

I don't recall any counters increasing in the diagnostics display. I will check next time i'm in the garage.

The wires for air and water temp are in the same harness, and wire length are almost the same. So I don't know what would cause the water temp to fluctuate.

How and where do I start my diagnosis? I will check the pins at the ECU, and the sensor ground to see if there is any obvious faults.
stevieturbo
Posts: 3578
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Single misfire event every 3 seconds

Post by stevieturbo »

What sensor are you using for coolant temp ?

Pretty sure the sensor on my old Volvo was a typical Minitimer plug....but the sensor had two outputs, one for gauge, one for ecu. One side of the sensor should not go to sensor ground as would normally be the case.
aleksanderk
Posts: 68
Joined: Fri Feb 01, 2019 4:36 pm
ECU Model: S80 Pro
Firmware Version: 6500

Re: Single misfire event every 3 seconds

Post by aleksanderk »

The engine has 2 coolant temp sensors. One for the instrument cluster, and one for ECU. It's a Bosch 0 280 130 032 which has the same characteristics as the preset 0 280 130 026 in Swin. It is indeed with a mini-timer plug as you mentioned.

When looking up the sensor, I can see that there is two outputs. This was new to me.
On the factory wiring diagram the other output from the sensor are just run to ground on the inlet manifold.
The temp seems to read fine, so I'm guessing that the sensor grounds through the engine, and the other side that goes to sensor GND is not actually needed. Should I get another sensor with only one output?

Could the fluctuations in the reading have something to do with engine grounding? Engine is grounded to BAT- and firewall. Can check to see if the signal is stable on key on, engine off.
JON-TEC-RALLYE
Posts: 38
Joined: Sat Jul 30, 2011 4:35 pm
ECU Model: S100 Pro
Distributor: JON-TEC-RALLYE
Firmware Version: 89
Location: Canary-Island

Re: Single misfire event every 3 seconds

Post by JON-TEC-RALLYE »

good morning. Some time ago I experienced a very similar fault, it only occurred at low revolutions and in an unpredictable way, on occasion sporadic, on another very often, the engine never stopped but it was not comfortable, it was a rapid engine failure accompanied by an incident in the crankshaft error counter.

search and change everything that occurred to me never discovered the fault. When the customer changed the spark plugs, he discovered that the fault disappeared, we did tests with the old spark plugs and the fault appeared again.

It was very strange that the spark plug itself made noise in the rpm sensor.
DTA--MoTec--Link--Ecumaster--HONDATA
stevieturbo
Posts: 3578
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Single misfire event every 3 seconds

Post by stevieturbo »

aleksanderk wrote: Mon Nov 07, 2022 5:37 pm The engine has 2 coolant temp sensors. One for the instrument cluster, and one for ECU. It's a Bosch 0 280 130 032 which has the same characteristics as the preset 0 280 130 026 in Swin. It is indeed with a mini-timer plug as you mentioned.

When looking up the sensor, I can see that there is two outputs. This was new to me.
On the factory wiring diagram the other output from the sensor are just run to ground on the inlet manifold.
The temp seems to read fine, so I'm guessing that the sensor grounds through the engine, and the other side that goes to sensor GND is not actually needed. Should I get another sensor with only one output?

Could the fluctuations in the reading have something to do with engine grounding? Engine is grounded to BAT- and firewall. Can check to see if the signal is stable on key on, engine off.
A sensor that is referenced to the ecu sensor ground would be preferred.

And as one of the pins is offering a variable resistance to ground....this may impact the ecu's sensor ground itself. So at a minimum I would not have the sensor ground connected to that sensor at all.

Ultimately yes ground is ground, or should be ground...but the whole point of the ecu only using it's ground for sensors, is so it can stay clean and stable.
If all sensor grounds are good and to ecu only etc....a poor engine ground should have minimal impact. But obviously all grounds should be good.
But ecu sensor grounds should always stay clean, never connect to a battery, chassis, engine ground anywhere.

The Volvo sensor is just a typical NTC output....I actually use the same sensor ( 1 wire only ) to feed a Hayabusa ecu...to drive the temperature gauge on my Hayabusa dash in the car.
Sounds extreme just to get a temp gauge working LOL. I only picked that sensor as it was a spare lying about.
stevieturbo
Posts: 3578
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Single misfire event every 3 seconds

Post by stevieturbo »

JON-TEC-RALLYE wrote: Tue Nov 08, 2022 5:44 am good morning. Some time ago I experienced a very similar fault, it only occurred at low revolutions and in an unpredictable way, on occasion sporadic, on another very often, the engine never stopped but it was not comfortable, it was a rapid engine failure accompanied by an incident in the crankshaft error counter.

search and change everything that occurred to me never discovered the fault. When the customer changed the spark plugs, he discovered that the fault disappeared, we did tests with the old spark plugs and the fault appeared again.

It was very strange that the spark plug itself made noise in the rpm sensor.
What make plugs ? where they resistor plugs or not ?
Post Reply