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Crasher
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R32, AMM analog or digital?

2007 Golf 5 R32, BUB engine.

I am fitting an FIC8 to this car which has had a turbo conversion in the past and also at least two different types of piggy back controller plus a remapped ECU and I have had to sort out a LOT of very poor wiring and strange bodges such as the AMM air temp wire having been disconnected and run off to a dead end!

This uses the 07D 906 461 Air Mass Meter (AKA MAF) which is a Bosch 0 280 218 073, a Hot-film air mass meter HFM-5-8.5. I cannot establish whether this is an analogue or digital AMM and I am struggling to make sense of the output from Pin 5, which I believe is the output.

With the signal going straight in to the FIC, the ECU immediately flags up a MAF error so Pyng Thai at AEM suggested a pull down resistor after studying the output of the AMM and the output from the FIC but even making sense of the signal has me puzzled as I have never had to do this before, does anyone have any advice?

 

AEM_NS
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Not sure what a Mk5 R32 has

Not sure what a Mk5 R32 has for a MAF but I know for sure that Mk5 2.0T FSI had digital MAFs. I've heard that Mk5 R32's are more like Mk4 R32's than other Mk5 chassis cars but who's to say that the Mk5 R32 didn't get a digital MAF like the 2.0T? Either way, looking at the signal on an oscilloscope should tell you exactly what it is. Also be aware that a digital MAF uses different input pins on the FIC than an analog MAF would use and you can't mix them up (digital MAF to analog MAF pins on FIC and vice versa).

Crasher
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This is my first AEM (but not

This is my first AEM (but not my last) and so I am still getting used to the differences to what I have used in the past. I was unsure about the AMM into the FIC but the instructions are not very clear on this, no mention of analogue or digital AMM’s, just in figure 16 the mention of a frequency based AMM so that could do with revising anyway. The signal I have been able to see from the AMM is a sine wave, not square, I will post a screen grab later. This is a wiring diagram of the AMM I was trying to post last night

NOW this has made me concerned about the lambda sensor, I have connected it up as per figure 9 but I think I have seen the LSU4.9 described as digital?

AEM_NS
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I'm guessing you're not

I'm guessing you're not scoping it correctly if you're seeing a sine wave. Sounds like the probe may not be properly grounded. Figure 6 in the instructions covers analog MAF connection. Unfortunately that diagram doesn't give any indication as to what the MAF sensor is. LSU4.9 sensors are not digital.

Crasher
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I will check the probes

I will check the probes grounding next week, thank you for your help.

Crasher
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After some fiddling around I

After some fiddling around I have thse results

Too high

Too low

At 21.8 Ohm

What do you chaps think?

AEM_NS
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If that 1us/div is right, I

If that 1us/div is right, I think you're way too far 'zoomed' in. Scope should be setup for like 10ms/div. You're zoomed in 10,000 times too much. You also don't mention what the two channels represent nor what 21.8ohms means.

Crasher
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I have just noticed the

I have just noticed the channels are on differnt divisions, start again!

Crasher
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Struugling to get this to

Struugling to get this to work, the diagnostic screen says no AMM flow.

I have tried a 0>2K resistor start to stop on the output of the FIC to earth and I can't get any sensible change to take place. The signals in and out of the FIC are masisvly different, roughly 1.5v in and a few mV out. Plug in the bridge and all is as it should be. What do you need me to show from the scope to help? Beginning to pull my hair out a bit, the customer wants his toy back.

AEM_NS
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Have you determined if the

Have you determined if the MAF is digital or analog yet? You've yet to provide a scope trace that concisely shows if the signal is digital or analog. In my eyes, you're just guessing and trying different (possibly wrong) things to see what they do. How can you know what to do and expect any kind of predictable outcome if you still don't know what the base signal is?

Crasher
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I am pretty sure the AMM is

I am pretty sure the AMM is analogue but as you say I need a conclusive trace from it which I will try and get the time to do later. Thankyou for you help so far.

Crasher
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I have to put this down for a

I have to put this down for a few days now, Mrs Crasher insists I take a few days holiday so back to it next Monday.

AEM_NS
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FWIW, after looking at some

FWIW, after looking at some diagrams on AllData, the R32 MAF is most likely analog. The Mk5 2.0T GTI MAF, which is digital, is shown as being a 3 wire setup whereas the Mk5 R32 is 5 wire. One thing to be aware of is that my AllData covers North American spec cars only. Being in the UK/EU may introduce other differences that I won't be aware of. Since it's likely that the MAF is analog, you don't really need a scope and should be able to check the voltages with a simple multimeter.

Crasher
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Thank you, with a scope, what

Thank you, with a scope, what sort of voltage and timebase would you recommend and with a multimeter, what sort of voltages would I expect? Other than using VCDS to view the ECU's interpretation of the flow I never test Air Mass Meters.

AEM_NS
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Voltage range will be 0-5v so

Voltage range will be 0-5v so setup scope for 1v or 2v per division. Time wise I'd stay "zoomed out" so something in the 10-50ms per division range would work. Having it super zoomed in in time and voltage will make tiny little changes in voltage look like crazy sine waves which sounds like what you were seeing before.

Crasher
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OK, will do that tommorow,

OK, will do that tommorow, too late now.

Crasher
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I think I was over analaysing

I think I was over analysing this, the output signals I am getting from the AMM look like this without the FIC plugged in so as you said, simple voltage signals. So, with channel 2 NOT showing, I need to match the two and ignore the sine wave aspect?

Engine stopped

Engine at idle

Engine at 2200 rpm

Engine at 3700 rpm

AEM_NS
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There was no sine wave. You

There was no sine wave. You have to decipher the data the scope is giving you in the frame of reference it's given. See those tiny little ripples in the voltage reading now that you're zoomed out and looking at the scope trace in a more reasonable time frame? When you're way zoomed in, those tiny little ripples will look like a sine wave. That's just the signal moving around and being a bit noisy - not a purposeful AC sine wave output.

Well now that you know you have an analog MAF for sure, you can do a MAF CLAMP.

Crasher
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I am glad you are on, I have

I am glad you are on, I have some more grabs, give me a moment

Crasher
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I am struggling to make sense

I am struggling to make sense of this, the result seems to be the exact opposite to what I want. As you American chaps would say, “this is way above my pay grade!”

NONE of my Photobucket links will now work!
Crasher
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Variable pull down resistor

I have tried all four different ways but either Photobucket is playing up or it is this site as it worked earlier!

Basically, at idle with channel 1 being the AMM feed into the FIC and channel 2 being the output from the FIC without a corrective resistor, CH1 shows around 1.5v and CH2 shows nothing. With a variable pull down resistor set at 0 - 2 Ω on an earth to the AMM output (FIC input) CH1, the FIC output signal is the same as CH2, laid on top of each other. With that resistor then turned up, CH1 starts to move up and at around 1200 Ohm it peaks at 1.5 volts, so exactly the same as if it is not there, this isn't right is it? I was expecting CH1 to stay at 1.5V and to be able to trim CH2 up to that but using my extremely small knowledge of electronics, that isn't going to happen with an earth fed resistor, wouldn't it need a pull up? The output from the FIC is basicaly 0 so I need to lift it to match the input???

 

Crasher
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http://i222.photobucket.com

This is the only way you can see them.

Variable pull down resistor set at 0 - 2 Ω from the signal earth to the Air Mass Meter output into the FIC8

http://i222.photobucket.com/albums/dd20/Crasher1964/Variable%20pull%20do...

With a Variable pull down resistor set at 1200 Ω from the signal earth to the Air Mass Meter output into the FIC8

http://i222.photobucket.com/albums/dd20/Crasher1964/With%20a%20Variable%...

AEM_NS
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First, stop using the

First, stop using the resistor. I'm not sure where you got the idea that one is needed but it isn't. It's another unnecessary variable that you've introduced into the equation that's only further complicating things. It's not that it's optional and that you don't need it in this case - it's that you flat out wouldn't ever use a pull up or pull down resistor at all on an analog MAF clamp. You have to understand that the FIC circuitry is not just a simple pass through. You the end user dictate the MAF voltage output be adjusting the table values in the software. If the table is in voltage mode and all cell values are zero, guess what voltage output you're going to see?

Crasher
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So to make the (extremely

So to make the (extremely important) MAF clamp function work I firstly need to log the Air Mass Meter output of a standard car and paste this into my MAF table. Do I need to add a voltage compensation to these signals to account for the drop acrooos the FIC Whebn I have done this and it is running, will I need to log the results and make adjsustmenst to the table using logging info? The AEM video tutorial on you tube “F/IC Software - MAF Clamp” says I need the logs from a standard car using the AEM internal logger. Now this is going to be a complete pain to do as I would need another car, unmodified, and then wire in the FIC8 to get the log, to be honest this is a next to impossible situation unless you were in the position to do this before converting the car, which is not. Would it be possible to use the system VCDS to make the log and then put this data into the FIC table, even if it had to be laboriously manually entered? Overall I am coming to the conclusion that where the MAF clamp function (which the advertising makes a big deal of) is concerned you could do with some caveats on the web site pages of the product to warn people that they need to obtain this log BEFORE modifying the car or they are stuffed! It isn’t even mentioned in the instructions, just a few seconds in a video.