Nickp
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 posted on 10/3/17 at 04:41 PM |
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IVA fail
Car failed today at Nottingham
Main reason was the fast idle emissions. Few other minor things but they could've been sorted there on the day if it wasn't for the
emissions.
Emissions are fine at normal idle but the CO increases to around 2.5% as soon as the revs are raised to 2.5-3krpm.
The engine has a remapped ECU and M50 inlet manifold and passed the emissions in the donor when MOT'd but I'm pretty sure they
didn't do it at 'fast idle'.
The obvious thing to do is replace the ECU with a std one (which I have) but that has the BMW EWS security and I'd have to rejig all my wiring
Bit of a bummer, but I'll work it out and I'll be back!! 
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loggyboy
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| posted on 10/3/17 at 04:50 PM |
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Not too bad.
Can the ECU not be mapped to suit requirements?
Mistral Motorsport
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Nickp
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| posted on 10/3/17 at 04:56 PM |
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quote:
Originally posted by loggyboy
Not too bad.
Can the ECU not be mapped to suit requirements?
It's a BMW ECU that was remapped to suit the bigger inlet manifold and rev limit raised. At the same time had the EWS and ABS deleted. Problem
is I don't know if that is the issue TBH.
Any BMW gurus on here?
[Edited on 10/3/17 by Nickp]
[Edited on 10/3/17 by Nickp]
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Nickp
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| posted on 10/3/17 at 09:01 PM |
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Just been doing a bit of testing of the voltage from the lambdas (black signal wire).
They seems to start around 5v, works their way down to around 0.5v as it gets fully warm but then they both start fluctuating before ending up back at
5v. I've tried 4 different sensors with similar results, surely they're not all dodgy??
So, are the sensors reading correctly and the mixture is fluctuating due to something else? Or, are they giving a false signal leading to a rich
mixture? Bit of a chicken and egg one this
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obfripper
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| posted on 10/3/17 at 10:33 PM |
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You should have max 1v (assuming a narrowband zirconia type sensor), getting 5v at the signal wire indicates the lambda sensor is leaking current from
a faulty heater circuit, or there is an issue with the sensor wiring.
If the sensor is disconnected while the engine is hot and running it will still output a 0v lean 1v rich signal across ground-signal pins.
If you have a narrowband titania type sensor fitted, it is 0v lean 5v rich using a 5v reference supplied by the ecu, the sensor normally has a red or
yellow signal wire to indicate the different sensor type.
Have you got the obd socket (or bmw round 20pin diag socket )wired for use in your setup?
That would be the next port of call for both codes and live data, to check the recieved signals are correct and any fuel related codes that may be
relevant.
What is your donor car and engine code, this may help in narrowing down the fault.
Dave
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Nickp
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| posted on 11/3/17 at 04:09 AM |
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Thanks for the input Dave.
Sounds like I have the latter 5v type. 4 wire sensors with black, yellow, red and white wires IIRC. I've been measuring the black one as
I'd read this was the signal wire from the sensor, but might be wrong.
When I first started the engine it had an issue with the ICV. It would rev really high on a cold start (which I hate as it can cause engine wear) and
the revs were really slow to drop when you blipped the throttle. I cleaned out the ICV and the internals were moving freely but the problem remained.
So I tried disconnecting the plug and the problem went away completely and the engine seemed to run sweet so I left it like that. Now, is having that
disconnected causing it to go into 'limp mode' where it just dumps a set amount of fuel in at anything over tickover? BMWs of this
generation didn't have a CEL (check engine light) so I have no indication. I could reconnect it and see if my lambda voltages stabilise. If it
does then maybe I should block off the pipes to the ICV but leave the electrics connected? Or'try a new one? From what I understand the ICV is
mainly there to compensate for the extra load on the engine from the likes of A/C and PAS, neither of which my car has obviously. It does cold starts
too but tbh it's fine from cold and sits happily at 800rpm.
I've ordered an 20pin BMW adapter to see if my OBD reader will pick up any fault codes, should be here early next week.
Thanks again
Nick
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Toprivetguns
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| posted on 11/3/17 at 06:59 AM |
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Good to see the IVA tests appearing as the summer looms. Hope you manage to sort it and pass !
Only drive as fast as your angel can fly... !
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Nickp
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| posted on 11/3/17 at 07:03 AM |
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BTW- Donor was a '96 BMW 328i, M52B28 engine.
[Edited on 11/3/17 by Nickp]
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SteveWallace
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| posted on 11/3/17 at 09:13 AM |
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Have you checked to make sure that the lamda sensors are the right way to around. Each one looks at a bank of three cylinders and the wiring is not
interchangeable. The engine will run either way around, but it's rough if they are the wrong way
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Nickp
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| posted on 11/3/17 at 09:18 AM |
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quote:
Originally posted by SteveWallace
Have you checked to make sure that the lamda sensors are the right way to around. Each one looks at a bank of three cylinders and the wiring is not
interchangeable. The engine will run either way around, but it's rough if they are the wrong way
Yeah, which way round do they go Steve?
I don't think that's the issue tbh though Steve as I've tried them both ways and they still end up fluctuating and back at 5v
whichever way around I have them
[Edited on 11/3/17 by Nickp]
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rodgling
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| posted on 11/3/17 at 12:26 PM |
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I also had a lot of emissions issues when I had the 328 and spent a lot of time trying to sort this. I think part of it was having to extend the loom
so the sensors would reach - I did a poor job of this initially which really hurt emissions. Also the engine had nikasil issues which caused to burn
oil with obvious results on emissions - hopefully that's not your issue though! One thing I realised when searching the internet - the US 328
engine used a different, incompatible type of lambda sensor, so be sure you have the right type.
You can test the lambdas off the car with a blowtorch, that might be worth a go.
On the car at idle, They should normally fluctuate from 0 - (I think) 1V at around 1-2 Hz. The engine loom is labelled 1 and 2, plug 1 is the front
(nose) of the engine.
I think I have a spare 328 ecu, Ews etc if you want to try going that route. Also spare set of lambdas.
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Nickp
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| posted on 11/3/17 at 12:36 PM |
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quote:
Originally posted by rodgling
I also had a lot of emissions issues when I had the 328 and spent a lot of time trying to sort this. I think part of it was having to extend the loom
so the sensors would reach - I did a poor job of this initially which really hurt emissions. Also the engine had nikasil issues which caused to burn
oil with obvious results on emissions - hopefully that's not your issue though! One thing I realised when searching the internet - the US 328
engine used a different, incompatible type of lambda sensor, so be sure you have the right type.
You can test the lambdas off the car with a blowtorch, that might be worth a go.
On the car at idle, They should normally fluctuate from 0 - (I think) 1V at around 1-2 Hz. The engine loom is labelled 1 and 2, plug 1 is the front
(nose) of the engine.
I think I have a spare 328 ecu, Ews etc if you want to try going that route. Also spare set of lambdas.
It's deffo a fueling issue mate, fine on tickover 0.2%. CO just shoots up anything above that, it's like it's in 'limp'
mode adding a set amount of fuel at anything above tickover.
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owelly
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| posted on 11/3/17 at 12:42 PM |
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What is the ECU seeing as the coolant temp? Is the coolant sensor playing tricks?
http://www.ppcmag.co.uk
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rodgling
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| posted on 11/3/17 at 12:42 PM |
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Could also be a bad MAF, you can test this by seeing if emissions improve when it's unplugged. Emissions etc should be ok but not as good as
closed loop with it unplugged (not sure if it would be good enough to pass)
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rodgling
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| posted on 11/3/17 at 12:43 PM |
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quote:
Originally posted by owelly
What is the ECU seeing as the coolant temp? Is the coolant sensor playing tricks?
I think this has only a very minor influence on fuelling, doubt this is the issue
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Nickp
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| posted on 11/3/17 at 12:47 PM |
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quote:
Originally posted by owelly
What is the ECU seeing as the coolant temp? Is the coolant sensor playing tricks?
Can't see any codes yet mate, just ordered a BMW 20pin to OBD adapter to try and get a looksy
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Nickp
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| posted on 11/3/17 at 02:11 PM |
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quote:
Originally posted by rodgling
Could also be a bad MAF, you can test this by seeing if emissions improve when it's unplugged. Emissions etc should be ok but not as good as
closed loop with it unplugged (not sure if it would be good enough to pass)
Ok will do, gonna try the ICV first but tbh not sure if this has any effect on fuelling.
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rodgling
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| posted on 11/3/17 at 02:30 PM |
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quote:
Originally posted by Nickp
quote:
Originally posted by rodgling
Could also be a bad MAF, you can test this by seeing if emissions improve when it's unplugged. Emissions etc should be ok but not as good as
closed loop with it unplugged (not sure if it would be good enough to pass)
Ok will do, gonna try the ICV first but tbh not sure if this has any effect on fuelling.
It shouldn't do (unless the hoses are leaking), it's just an extra throttle body really. I probably have a spare if you want to replace it
though.
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Nickp
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| posted on 11/3/17 at 04:06 PM |
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quote:
Originally posted by rodgling
quote:
Originally posted by Nickp
quote:
Originally posted by rodgling
Could also be a bad MAF, you can test this by seeing if emissions improve when it's unplugged. Emissions etc should be ok but not as good as
closed loop with it unplugged (not sure if it would be good enough to pass)
Ok will do, gonna try the ICV first but tbh not sure if this has any effect on fuelling.
It shouldn't do (unless the hoses are leaking), it's just an extra throttle body really. I probably have a spare if you want to replace it
though.
Interesting discovery. Lambda volts were still all over the place. But when I disconnected the maf they stabilised. Still high 1.5-2v but stable.
Reckon it could be the issue? I may owe you a pint if it is
Didn't realise they were so cheap - Mass Air Flow Meter Sensor For BMW 323i, 328i, 523i, 528i 5WK9600----OE Quality
Probably cheap for a reason, they go for between £112 and £275 from EuroCarParts  Probably worth a try though, I might get lucky.
[Edited on 11/3/17 by Nickp]
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rodgling
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| posted on 11/3/17 at 09:31 PM |
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Sorry if you already know all this: lambdas are *supposed* to fluctuate at idle. If they report oxygen in the exhaust stream, the ECU will enrich the
mix slightly, and if they don't, it will lean it out. So it constantly cycles just slightly rich/lean, around twice a second.
If you unplug the MAF, it goes open loop (i.e. doesn't use the MAF or the lambdas, just estimates fuelling based on RPM & throttle position)
- this is less accurate so it runs a little bit rich to be safe. So, you see a fixed value (i.e. slightly rich) when you do this.
The problem seems to be that your lambdas start out cycling (which is what you want) but then end up a bit rich? It's odd that you get 1.5-2V -
as someone else said, normal output should be (I think) 0 - 1V. Is this the same for both sensors? If it is it would be a bit of a coincidence for
both sensors to fail the same way.
Excess CO (as opposed to CO2) on your emissions readings means incomplete oxidisation of the fuel because there wasn't enough oxygen, i.e.
it's too rich. Which is also what the lambda sensors are telling you - so that doesn't really suggest that the lambda sensors are bad.
Also you've seen consistent results from four sensors... so it's not the lambda sensors.
Could be the MAF, if it's reporting more air than is actually present then the ECU will obviously over-fuel to match the amount of air it thinks
is present. In my experience buying third party MAFs didn't go well... I'd go OEM on that one if you need to replace it.
Do you have the exact numbers from the emissions test?
I think I'd be tempted to point the finger at the remapped ECU at this point but that's just a guess.
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Nickp
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| posted on 11/3/17 at 09:54 PM |
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When I say they fluctuate, I don't mean slightly, I mean from 0.3v all the way back to 5v. All over the place tbh. All sensors react in a
similar manner. As soon as I disconnected the MAF they stabilised at 1.5-2v. Seemed to point to the MAF to me. I should probably wait to try and read
the codes but want to get it retested ASAP. I don't mind paying for an OEM one but only if it's definitely the problem. Might have to try
a cheapo one for now just to see if it changes things.
At the IVA it had 0.2% at tickover and 2.5-3% at fast idle (2.5-3krpm)
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gremlin1234
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| posted on 11/3/17 at 10:07 PM |
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quote:
Could be the MAF, if it's reporting more air than is actually present then the ECU will obviously over-fuel to match the amount of air it
thinks is present.
could also be too high fuel pressure
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rodgling
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| posted on 11/3/17 at 10:11 PM |
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I think you have titania sensors on that engine, apparently output voltage for these can be 0.5 - 4V or wider range, so fluctuating in the 0.3 - 5V
sounds like normal behaviour. Your multimeter might be a bit too slow to keep up so it may not be obvious if it's cycling in a regular
pattern.
I don't think it does indicate the MAF particularly. With the MAF removed, it will be slightly rich, so you would expect the lambdas to have a
stable rich reading (although 1.5 - 2V is strangely in the middle which seems odd). It could still be the MAF but this doesn't help prove it
IMO.
[Edited on 11/3/17 by rodgling]
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Nickp
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| posted on 12/3/17 at 02:55 AM |
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quote:
Originally posted by rodgling
I think you have titania sensors on that engine, apparently output voltage for these can be 0.5 - 4V or wider range, so fluctuating in the 0.3 - 5V
sounds like normal behaviour. Your multimeter might be a bit too slow to keep up so it may not be obvious if it's cycling in a regular
pattern.
I don't think it does indicate the MAF particularly. With the MAF removed, it will be slightly rich, so you would expect the lambdas to have a
stable rich reading (although 1.5 - 2V is strangely in the middle which seems odd). It could still be the MAF but this doesn't help prove it
IMO.
[Edited on 11/3/17 by rodgling]
Would it be normal behavior to go from full rich (5v?) to full lean (0.5v) within seconds at the same revs and temp? Shouldn't I expect it to
fluctuate slightly as it tweaks the mixture?
It'd be nice to know what actual CO reading the 1.5-2v equates to but unfortunately I don't have a meter If this is normal then surely
I have to try the MAF first?
Also, when it's ticking over and i disconnect the MAF it improves the idle. When I plug it back in it stalls.
[Edited on 12/3/17 by Nickp]
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Nickp
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| posted on 12/3/17 at 03:02 AM |
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quote:
Originally posted by gremlin1234
quote:
Could be the MAF, if it's reporting more air than is actually present then the ECU will obviously over-fuel to match the amount of air it
thinks is present.
could also be too high fuel pressure
Cheers, yes that's something I'd considered too. I'd kind of dismissed it because it passed Ok at normal tickover and wouldn't
it be at its richest then as it needs the least fuel? This is controlled by the OEM regulator on the fuel rail which has a vac pipe connected to the
underside of the inlet manifold, presumingly increasing the pressure as the throttle opens and the vac drops?
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