FIXED: Unknown issues in primary ignition

Hi guys,

Already had this posted on the Pico group on facebook as well and no good conclusive reactions came from it:

I have a car here, a Peugeot 207, year 2008, 5FV EP6 engine with both inlet and outlet VVT as well as variable valve height lift system

Following is a copy of the info I already posted on facebook:

Hi guys (and gals if any in this group). Gotta little question. Have a Peugeot 207 which I have some scope images of primary that I can't figure out a 100%. It's a miss on cylinder 3 and that cylinder gives me low firing KV on a little higher amp ramp. When starting it still has little spark, after a while it messes up completely. Trying to understand what I'm seeing here.

Got some talk with collegues's in the field and they share the opinion it's ECU but can't really put the finger on it 100%. ECU repair company say it's not ECU and send me picture of it running with what they see as descent scope images but they run test with plugs in the open (no compression, low demand from ECU) and so little detail on their scope I feel sorry for them (almost).

Any of you have a good explanation of what is hapening here. It's not coil and plug (changed it from good cylinder and have exactly same situation). I'm trying to get the grips on an explanation of what the images are telling.

Also got a bit of extra info from the customer (garage) on the history of things. The ECU has been send in to the ECU repair company 2 times before. First time they repaired (driver) and send it back, the garage did not listen to the advice given and did not replaced coil.. it went extremely hot and I guess driver burned out again which tells me the changes of a shortend coil are moving towards 100%... send it back again, got it returned repaired... now changed all coils and plugs. Got the thing running but still cylinder 3 is dead though coil not going hot anymore. This is the point they drop the car with me (did not know of the car or situation before that point in time).

first image - cylinder 2, a good one

second image - cylinder 3 (bad) just after restart (also just erased codes) - ramp sloping up slightly different and already low firing KV and not 100% falling after colapsing the field (still som amp right of the end)

third image - cylinder 3 after short running, amp don't fall to zero after closing 100%, I measure on driver wire so from ECU. I thought this means still amp from ecu, so driver not closing 100% correctly, some internal issue otherwise or are there more possibilities. Also no firing KV really, only a weird 'hump'

fourth image - did cranking compression in cylinder but how many mechanical issues there might be with these engines, the compression won't care really regarding spark I think.. too high, too low compression would still give spark (shorter, longer, higher or low starting KV point but still.)

I think you may have more than one issue.

I, definitely, don't like the coil turn off in the 3rd image. I don't know what, besides the coil driver, could cause that.

I, also, don't like the vacuum pocket between the intake and exhaust strokes, of your in-cylinder. It looks like the intake valve is opening late, causing the cylinder to draw into a deep vacuum, until the valve opens at 65° ATDC. Can you take a capture of a GOOD cylinder, to compare valve timings?



You, also, have "Leaning Towers".





Can you post the .psdata files? I'd like to see RC, too.

Chad thanks for your response

My major concern first of all is that ignition issue on nr 3. Both of the pressure images are from different cylinders, 1 is a good one, the first one is the bad one. So yes, I am very curious to what his can cause but it's key issue to get iginition back online

Uploaded 2 cranking compression ones and also a running / idle one (if I have it in file size below the max cap of your server)

Had 2 images on idle as well combined in one shot
left cylinder 3, the bad one, right a good one.

However, this left me with a compression issue. The problem is, you don't make these images in exactly the same situation. One image is made when a good cylinder is cut off whilst the pressure transducer is in the cylinder. The other capture is when you take a bad cylinder out of the equation. The engine uses active valve lift AND inlet and exhaust VVT... and might very well act differently. So I took the connector of the valve lift system off to get this system out of the way and took another idle picture (the last one) of the bad cylinder... now we have 9.2 bar, is it perfect, don't know, but not THE issue it seems.

As an update: this issue was fixed some time ago by replacing the ECU. The other issues with in cylinder pressures seem to be non problematic or even standard on this engine.