Jump to content

missfire


Fordya42

Recommended Posts

I have a what i think is a miss fire not 100% but the engine certainly does not seem happy, i did have an issue where the car was cutting power at 3/4 to full throttle but found a split pipe from my turbo to actuator, can only presume it over boosted hence the cut in power and popping and banging but now with a new set of plugs and coils it seems to be missing at 6500 rpm, limiter is set at 6900 i have attached a log file can someone look and tell me if they see anything wrong, 

 

Thanks

Log 2021-06-23 7;50;18 pm.llg

Link to comment
Share on other sites

Your trigger error counter starts to climb pretty quickly above about 4700RPM so I would say you have a trigger issue.  You will need to find someone with an oscilloscope to get a capture of the crank/cam signals to see what is wrong.  If you know someone with a G4+ Storm or higher that you could borrow, then another option would be to plug that in and use the built-in scope.

Link to comment
Share on other sites

Sorry, not sure why I thought it was an Atom originally, I must have had someone elses map open at the time.  

So yes we can see the problem in that scope capture, the tooth after the missing tooth gap doesnt crosss the zero volt line, the the ecu will only see 57 teeth instead of 58.  This is typically caused by a poor gap design on the trigger wheel.  

What is the engine?  Is it a factory trigger wheel or some aftermarket kit?  Do any of the teeth around the missing tooth look damaged?

In the pic below the yellow line I have drawn is how the signal should look, but you can see the blue trace underneath doesnt cross the white 0V line like all the other teeth.

tQQ6npm.png

Link to comment
Share on other sites

Fantastic thank you its a focus st engine in an autograss car, its only been an issue since its been rebuilt, it runs a custom crank trigger wheel on the pulley end of the engine due to standard flywheel/pick up making it being to wide for the chassis. I will check the crank sensor and try again

Link to comment
Share on other sites

The common cause of this type of effect is the gap design of the trigger wheel.  An article from the help file attached below to explain.  If the wheel doesnt look damaged then you could increasing the sensor airgap which may help bring that voltage down.  If that doesnt help you are probably going to have to get a new trigger wheel cut with the correct design.

 WlF1Rkw.png

Link to comment
Share on other sites

ok so firmware has been updated successfully, but still have same issue, really weird as the car has been mapped fine on the rollers, but only had this issue since its been rebuilt ihave now replaced everything except the ecu

 

Link to comment
Share on other sites

So I have now fitted 3 different trigger wheels, and am now back on the original, the one thing I did that fixed it was to change out the crank sensor for one with a much smaller steel core to it, approx 3mm diameter my original sensor approx 5/6mm, no errors, no miss fire and back on original loom. The original sensor and replacements where all genuine Ford, its now on a magneti marelli sensor, after 14hours of chasing my backside, she's alive and kicking 

20210624_191424.jpg

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...