Vanos Rebuild Start Hesitation

[jamesfoley]

1. The mixture was on the rich side most of the time and this is why you have negative fuel trim, so maybe during status 8 moment the open loop injected fuel (based on the default look up table) was less than what the combustion needed, and so the exhaust gas was lean (0v o2 sensor). IOW, open loop is leaner than closed loop in your case.

Only reason I feel its weird is because isn't the range of the O2 sensors 0.1v to 1.0v? I didn't think they were supposed to go to 0v, but this is just me going off what I've read around the web. The graph makes it look like it's going open loop beacuse the O2 sensors are at 0v, however there are a handful of times where the fuel status is 8 and the O2 sensors are reading higher values.

3. I don't think so, as if it's then the injector should be weak with lean code. Also, the starter should be cranking weak or fails to crank.

That's a fair point, the car cranks fine every time and it's never failed to crank.

Also found this thread which you've replied to sapote which is extremely similar if not the same as what I am dealing with https://www.e46fanatics.com/threads/...sults.1304746/

[sapote]

1. Again, O2 sensors seem to just go to 0v during those sections,
2. not sure if they just report 0v when in open loop?
3. but could I be having a engine ground issue

1. The mixture was on the rich side most of the time and this is why you have negative fuel trim, so maybe during status 8 moment the open loop injected fuel (based on the default look up table) was less than what the combustion needed, and so the exhaust gas was lean (0v o2 sensor). IOW, open loop is leaner than closed loop in your case.
2. No, DME doesn't force o2 value to 0v during open loop, as you can see the value changed during cold start open loop with SAP running.
3. I don't think so, as if it's then the injector should be weak with lean code. Also, the starter should be cranking weak or fails to crank.

[jamesfoley]

Your money can buy a better USB based scope as it reuses many function of the PC already has, as opposed to standalone unit.

I guess the downside here is I'll need a reasonable laptop, the one I use currently is pretty terrible.

Just wanted to add this log which has some chunky sections where the fuel status was 8 for a bit longer. Again, O2 sensors seem to just go to 0v during those sections, not sure if they just report 0v when in open loop? Its both sensors as well so can't be a wiring issue surely?

https://datazap.me/u/jamesfoley/e46-...0&data=1-2-4-5

Might be a silly question, but could I be having a engine ground issue or would I have more issues than what I have currently?

[sapote]

Owon HDS242(S) (and also 272, 2102, 2202) are quite capable self contained scopes starting around USD120. Might be a bit easier than a laptop + USB scope.

Most portable standalone scope with screen too small and also lack many good features, and this is why I suggest to have a PC USB based scope. The Pico I use can decode many different serial buses such as CAN, USB, I2C, SPI, rs232, UART, etc. With the PC bigger screen and better resolution, the signal waveform is easier to analyze, and the waveform can be saved and shared. Portable scope is good for working on the field.

Your money can buy a better USB based scope as it reuses many function of the PC already has, as opposed to standalone unit.

[jamesfoley]

Without turning this into a DSO discussion...

Just be aware they are fairly basic devices but I think they have a place in between multimeters (these Owon units also have an OK one built in that's separate to the scope section) and a proper scope. They are limited to fairly basic triggering and have limited sample/memory depth. The automatic measurements are just the basic ones. They can't do any protocol decoding eg. CANbus.

A 40MHz unit should be plenty for pretty much anything car related. The higher bandwidth is relevant if you may want to use for any more serious electronics. Many microcontrollers are 100MHz+ these days.

Look up Kerry Wong on Youtube for some good reviews of them.

I have a 100MHz Owon and it does the job although I've not really used it in a car environment yet.

Thats cool, appreciate the advice. It will likely be a dedicated car scope as I have nothing else to use it for. Will pick one up with a set of back probes when my bank account recovers and give it a try.

[Shonky]

Without turning this into a DSO discussion...

Just be aware they are fairly basic devices but I think they have a place in between multimeters (these Owon units also have an OK one built in that's separate to the scope section) and a proper scope. They are limited to fairly basic triggering and have limited sample/memory depth. The automatic measurements are just the basic ones. They can't do any protocol decoding eg. CANbus.

A 40MHz unit should be plenty for pretty much anything car related. The higher bandwidth is relevant if you may want to use for any more serious electronics. Many microcontrollers are 100MHz+ these days.

Look up Kerry Wong on Youtube for some good reviews of them.

I have a 100MHz Owon and it does the job although I've not really used it in a car environment yet.

[jamesfoley]

sapote Shonky Yea, the Owon scope is what I was going to go for. I’m a complete noob when it comes to oscilloscopes though, I know how they work in principle but never actually used one. From the small bit of reading I’d done in the past I read that it’s worth the investment on one with a higher sample rate as it’ll be more useful in the future.

[Shonky]

Owon HDS242(S) (and also 272, 2102, 2202) are quite capable self contained scopes starting around USD120. Might be a bit easier than a laptop + USB scope.

[sapote]

"Just not 100% sure how I get readings from those while driving the car…"
No need to drive as the fuel status 8 will show up with rpm higher than 2000.
This seems to be an nice digital storage scope for less than $70. max input voltage is 35v perfect for car electronic. The o2 sensor signal is a slow signal, way below 20Mhz of this scope bandwidth. Which scope that you're looking with 40Mhz?

I use a Pico scope 3000 series and like it, but it's more expensive.

[jamesfoley]

On the post cat sensors: as soon as the rpm was over 2000rpm, the cats seem not able to treat the exhaust gas and the sensor signals dropped below 0.5V -- a sign of aging cats?

Aging cats is a possibility but not really one I’m too worried about right now. As far as I know the post-cat sensors have no influence on the mixture, and it’s currently passing emissions so it can be a problem for another day.

On the fuel status 8 bad open fault, it is hard to trouble shoot as the open loop is just a short moment and so no error codes. I would expect that during status 8 -- open loop should cause rich mixture but then why the pre cat o2 switched to lean, below 0.5v?

At this point I honesty have no idea what could be wrong here, every Google adventure I go on just gives me the usual E46 fuel pump stuff. Being a fuel status error it kinda makes sense it’s fuel, and the last link in that chain is injectors, so will probably get those checked. However what doesn’t make sense is that fuel trims and pre-cat o2 readings look “normal”. Oil does smell kinda fuel contaminated, though I’ve been to a couple of places now that have told me it smells fine 🤷

On the same log, looking at the pre cat sensor switching pattern, notice the during the high rpm that the sensor seems to switch less often than during idling instead of faster proportional with rpm. I think this is caused by the slow sampling of the reader, as if the oscilloscope was used then the switching frequency should be faster during higher rpm. This means we cannot tell what mixture that the sensor sensed during the higher rpm with fuel status 8 -- rich or lean.
You might want to look at the sensor signal with a oscilloscope.

I could pull all PIDs apart from pre-cat, fuel status, and rpm? Would result in a higher resolution log in theory.

I don’t currently own an oscilloscope, though I’m happy to buy one of the cheaper 40MHz ones from Amazon and back probs the O2 sensor plugs. Just not 100% sure how I get readings from those while driving the car…

[sapote]

On the same log, looking at the pre cat sensor switching pattern, notice the during the high rpm that the sensor seems to switch less often than during idling instead of faster proportional with rpm. I think this is caused by the slow sampling of the reader, as if the oscilloscope was used then the switching frequency should be faster during higher rpm. This means we cannot tell what mixture that the sensor sensed during the higher rpm with fuel status 8 -- rich or lean.
You might want to look at the sensor signal with a oscilloscope.

[sapote]

On the post cat sensors: as soon as the rpm was over 2000rpm, the cats seem not able to treat the exhaust gas and the sensor signals dropped below 0.5V -- a sign of aging cats?

On the fuel status 8 bad open fault, it is hard to trouble shoot as the open loop is just a short moment and so no error codes. I would expect that during status 8 -- open loop should cause rich mixture but then why the pre cat o2 switched to lean, below 0.5v?

[jamesfoley]

Please don't turn on the AC for the test. Do hot idle again to confirm MAF is around 4g/s at idle and not 6.

Warm log with no accessories turned on: https://datazap.me/u/jamesfoley/e46-...s?log=0&data=2

The only thing I can see is the status 8 peaks are around the times where the pre-cat o2 sensors are below 0.1v, or 0v

[Slideways]

So I could get another DME, have the EWS removed and it will just work?

Does the milage / VIN / FA coding not matter? Not doubting you, just trying to understand what data is stored in what modules

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/195737-dme-ecu-swap-change-process

[jamesfoley]

After disabling the EWS, it should just be plug and play with another DME.

So I could get another DME, have the EWS removed and it will just work?

Does the milage / VIN / FA coding not matter? Not doubting you, just trying to understand what data is stored in what modules