Euro 550 OBD plug . Yes it is there and I have found it. | FerrariChat

Euro 550 OBD plug . Yes it is there and I have found it.

Discussion in '456/550/575' started by Robbe, Nov 9, 2020.

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  1. Robbe

    Robbe Formula Junior

    Aug 22, 2013
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    #1 Robbe, Nov 9, 2020
    Last edited: Nov 9, 2020
    Somehow most of my cars the last 10 years are from the pre OBDII era, and that means that some have a 3 pin plug , like the 355 (behind the passenger seat in my spider), and for example on my old M3200GT it was a OBDII plug, on non-OBD or OBDII software.
    But that is the negative side of having a euro car in Europe, no obligatory OBDII around 1995-2002.

    So now that my freshly acquired 1998 550 is still not running well (after the fuel pump repairs, it worked fine for around 150km), I searched the whole net ( = mostly this forum..) for the location of the plug on my euro 550 LHD.

    I found that several people declared over the years that it has no plug at all, or that there are wires, so you can maybe make one yourself...

    But FBB insisted in another thread about the fuel pumps, that it really should be there, so I looked a bit better in my car.

    And yes, in the driver's footwell, behind the cover for the ECU, there was a plug which looked like the one on the 355. Connected it to my Fiat OBD to OBDII cable , connected to my Autel scanner (and a 12V source), and it worked!
    So that was 5 minutes of work, while I was expecting to have a lot of "fun" trying to make a connector myself.
    Sometimes it 's not all that hard.

    Now I just have to find out what the code means and if it is connected at all to the problems, and why the temperature indicated -40 degrees...
    (engine off, ignition on)_ (P0102 Mass or Volume Air Flow A Circuit Low it says, as a pending code without CEL. So I have my doubts it is the cause.
    Yesterday the car would not want to accelerate above say 3000 rpm, like there was yet another problem with the fuel pumps. Back in the garage, standing still, I could rev normally.. (because no load?).
    All plugs are carbon black, left bank as well as right bank...
    ordered nw plugs, NGK's, which will arrive tomorrow, so I can check the fuel pressures and the FPR's.
    Any further ideas? Vaccuum leaks?
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    and another question, what does this switch in the footwell, next to the dead pedal do?
    It is located on the cover of the ECU.
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  2. Robbe

    Robbe Formula Junior

    Aug 22, 2013
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    #2 Robbe, Nov 9, 2020
    Last edited: Nov 9, 2020
    Sounds logical that it is something that would affect both banks of engine.
    I had thought of the Throttle position sensor, but no codes about that stored.
    The coolant temp sensor, is that nr 33 in this diagram?
    Hope not, as it looks to be in the valley...


    Edit: looks like there are 2, one on each bank. Can I assume that each bank has its own? Or are the 2 connected, and the value to the Motronic is an average of the two?

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  3. Qavion

    Qavion F1 World Champ
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    #3 Qavion, Nov 9, 2020
    Last edited: Nov 9, 2020
    (EDIT) Sorry, had to delete my earlier responses. I realised you may have been talking about your inlet air temperature, not your coolant temperature values.

    The IAT (inlet air temperature) sensor is most likely a NTC (negative temperature coefficient) type similar to the coolant temperature sensors, so maybe you have an open circuit on the IAT. The IAT is used to apply correctins to injection time and ignition advance, so more fuel may be going into the the combustion chambers (hence the black soot).

    Check the connector on the IAT.
     
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  4. Qavion

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  5. Qavion

    Qavion F1 World Champ
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    If you were talking about coolant temperature, here is a chart of resistance versus temperature:

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    At 20C, the resistance seems to be around 2500 ohms.
     
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  6. Robbe

    Robbe Formula Junior

    Aug 22, 2013
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    I will have a look tomorrow, which temp exactly was -40. Makes more sense if it is the inlet temp!.
    Will report back, thanks sofar.
     
  7. Robbe

    Robbe Formula Junior

    Aug 22, 2013
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    Update:
    I connected the scanner again to the Left ECU (ign on, engine off, waiting for the new plugs to arrive) to see which temperature was -40 degrees. It was the ECT, which AFAIK is the coolant temperature. Not good, means removing the entire intake system.
    The ICT temp on the other hand was 17 C, so that one is working, or at least I thought so.
    Here is the picture of the scanner page:
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    Good news is the LTFT2 at 4,7, which is not perfect but not terrible from what I understood.
    FUELSYS2 - OL -fault is to be investigated. No idea yet what it means.

    But as there are 2 ECT sensors , one for left (shown) and one for right, where is the value for the right hand bank?
    So I dove into the passenger footwell, and behind the cover of the right ECU , I found another plug!
    So this car has an OBD plug for each side, had not expected that!

    It showed these 2 pages (no codes pending or solid)
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    ECT at 15 C , so this side is working. But it does not matter, if the intake has to be removed for replacing the left one, I better replace the right one at the same time.
    But more worrying is the LTFT at 25! definately a big problem on this side.
    Is the value shown what the ECU is TRYing to do, or what it has done? I mean, if there is yet another problem with a fuel pump, and it has not enough pressure (say 10psi instead of 50), the ECU would try to compensate the lean mixture by adding more fuel, but as the pressure is too low, that measure did not work, and the ECU increases further up to the max without actually more fuel injected. Is that correct?

    Then the next page:
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    IAT temperature -40! That is the sensor Qavion showed, and it is easy to check.
    It seems to be defective.
    So I measured the resistance, but instead of infinity, I got a reading of 3.17 , so 3170 ohms, which is exactly what a working one should give.
    But the scanner tells me it is defective?
    And the left ECU says it is working? Is there another one hidden somewhere?
    Does not compute at all...where do I make the mistake?
     
  8. franschman

    franschman Formula Junior

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    The sensor may be right but a wire can be broken, giving the same result.

    Suggest you go one step at a time here and take your time, although it's always tempting to immediately take the engine apart and change everything and hope for the best.
     
  9. F456M

    F456M F1 Rookie

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    Sorry to hear about your problems. I am sure you fix it soon. About your mystery switch... I is not original and might have to do with an alarm or something. I have a similar in my glove compartment and I installed to be able to cut off the power supply to my GPS tracker so that it will not drain the battery if the car is left for longer periods. On your car, it could aswell be an override for something. But I guess you have an original alarm? Might be a cut off for the brake light in case the previous owner wanted to outrun the police chasing him and did not want the police to see he was braking (to interrupt the radar or average speed measuring) :)
     
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  10. Qavion

    Qavion F1 World Champ
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    #10 Qavion, Nov 10, 2020
    Last edited: Nov 10, 2020
    Standby... I just remembered why you're why you're getting -40C on the Left bank. The left coolant temperature sensor is not hooked up to the corresponding ECU. As Bart says, don't start pulling the car to pieces. The left hand bank coolant sensor actually feeds the HVAC ECU.

    Give me an hour or so to look at the wiring diagrams...
     
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  11. Qavion

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    Well, it depends on what scale you had the meter on. If it was actually 3.17 ohms, then you have a problem. Did it say x1000 or Kohms?
     
  12. Qavion

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    #12 Qavion, Nov 10, 2020
    Last edited: Nov 10, 2020
    I had to edit my last message. I was getting my banks mixed up. The IAT (although on the right hand side of the engine) feeds into the left ECU. Again, the reason why you are getting -40C on the RH bank for the IAT is because it isn't hooked up to the right ECU.
     
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  13. Island Guy

    Island Guy Karting

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    -40 is a default reading for no sensor. All of the generic code readers will show this. Move on, this is not your problem. Focus on the LTFT. You're maxed out, so there's a serious problem on that bank.
     
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  14. Qavion

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    I think "FUELSYS1/2" is simply telling you if your engine management system is in open loop mode (OL) or closed loop mode (CL). Usually the system operates in open loop mode when the engine is cold, then when the coolant temperature reaches a certain value, the system goes into closed loop mode. On some cars, when you use full throttle will the car switch momentarily to open loop mode again. Also, loss of certain engine parameters may make the car switch back to open loop mode again.

    I think we are all getting to the point where we think your right bank LTFT value is your biggest concern. A positive value could indicate low fuel pressure or a vacuum leak.

    There is an excellent video (in english) on diagnosing fuel/air problems on YouTube:



    As the man says, you could have a vacuum leak or low fuel pressure.
     
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  15. Qavion

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    #15 Qavion, Nov 10, 2020
    Last edited: Nov 10, 2020
    Did each ECU test port have a blanking cap or were the connectors plugged into something? Normally on the 550, the left and right ECUs talk to each other via these type of connectors. If someone has disconnected your connectors, then you could have a problem with data sharing. i.e. if the left bank ECU normally gets coolant temperature data from the right bank sensor via the databus, then maybe this could be the cause of your unknown messages and rich running/high LTFT.

    Unfortunately, with these plugs connected (on Euro 550's without OBD2 ports), you won't be able to analyse the data using your scanner.
     
  16. Qavion

    Qavion F1 World Champ
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    Have you tried cleaning the MAF sensors and MAF electrical connectors anyway?
     
  17. Robbe

    Robbe Formula Junior

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    Wow, thanks for all the support and suggestions and info, really great. I will watch the total video later on, but a masterclass in Fuel trims is really helpful to understand what the engine is doing.
    About the questions:
    - the ohm meter was on position "200" I believe. But the value was correct comparing the ambient temp against the table, so I am confident it is ok.
    And as there is only one, giving data to the left ECU, it seems logical that the left side is showing a correct temperature, and the right ECU is showing a -40 as it has no value. So not part of the problem

    - About CL and OL, since I can't start the engine now (new plugs should arrive later today), I have to wait till the engine can be started to see if the info stays the same or switch to a CL. Hope at least that the scanner does show that.

    - Both plugs were plugged in already, so to connect , I had to disconnect the plug from the loom.
    The measurements on the right ECU were done with the left still disconnected
    (the earlier info from the left ECU was with the right connector connected)
    So I hope they did share data up to yesterday...

    - Have not cleaned the MAF's yet, need to buy the special cleaner (brake cleaner is a NO, correct? As it leaves a residu?)

    So the only thing I could check at the moment, was the fuel pressure on the rails. The left side gives 54-55, and when I connect a tube to the FPR (instead of the vaccuum), and suck hard, it lowers to 51 or so. That sounds correct to me.
    But the right side...it only gave 25 psi pressure, so again is a problem (was it before I bought the car, was half replaced by a sh*tty garage(return hose + valve missing, connectors loose etc), was repaired by me with the addition of a return hose+ valve, worked for say 125km, but broke down again it seems.
    Maybe it had picked up some more debris, I do not know.
    Time to drain the tank again. Too bad I just filled her up 25 km ago...
     
  18. Qavion

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    #18 Qavion, Nov 10, 2020
    Last edited: Nov 10, 2020
    Correct. Only use MAF cleaner. It shouldn't be too expensive. With the engine running, the MAF values on your scanner should be similar on both banks. The manual may give a tolerance between them. On the Ferrari 360 for example, the split should not be more than 5kg/hour at idle. Your display shows g/s, so you will have to use a correction factor. e.g. 5Kg/hr is 1.39 g/s.

    Anyway, it sounds like you've found at least one of your problems (fuel supply) :confused:
     
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  19. Robbe

    Robbe Formula Junior

    Aug 22, 2013
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    Update.
    One the right hand side pump, one of the fuel hoses had worked itself partially lose (again), so that was easily found, and the clip was tightened a bit more.
    It is the side where the rubber hose goes over the plastic pump-pipe, so you can't tighten it too much...
    Fuel pressure back to normal, and since I cleaned the injectors, it is keeping pressure long after the engine has been shut down, so that is good. Removing the vacuum shows small rise to 3.8 bar on both sides, so that is good.

    What is not so good, is that the long term fuel trim has only dropped from 25 (max) to 16.8, and not below 10 as it should.
    (during first test, 10 minutes at idle, it remained at 25...I switched the MAF's left/right, no difference)
    During my test drive, LTFT only lowered to 16.8 , and the car had problems, sometimes not reacting at all to the throttle input (severe hesitation), and then suddenly lurching forward and reacting more or less normally. The difference between driving well and not well is big, so I do not think it is a misfire on a cylinder or so.
    So must be something like the Throttle position sensor , or maybe both MAF's? They are equally old...

    During the test drive I had the scanner installed to monitor the TP and MAF values, but during hesitation, no spikes or drops in values were visible.

    Some observations:
    -Throttle position is only like 65% at full throttle. Should that be 100%?
    - MAF values at 3000 rpm are around 20-25 , but do not change when the hesitation time is over, and the car accelerates a bit by itself on light throttle
    - increase in MAF value is not linear when engine has no real load (driveway/garage revving):
    from 950 to 2400 rpm in equal rpm steps: it goes from 7,1(950) to 8,5 at 1100, 9 at 1300 , 10.7 at 1600, 11.8 at 1900, 12.1 at 2200. But that is without load.
    During the test drive I saw values of 25 most of the time. Did not look during full acceleration...
    I read that MAP values should be rather lineair, but here it looks like the MAF is underreading? creating a lean situation which shows as a high positive number of the LTFT?
    Is it time to throw new parts against it like sensors and MAF's, or is there still more to investigate?
    Still no solid nor pending codes by the way.
     
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  20. Island Guy

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  21. Island Guy

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    Clear your fuel trim numbers...and start the car. LTFT takes a while to recalculate, so I'm not sure what you're seeing is relevant. What's the STFT? This will tell you what's happen now. Have you smoke tested the intake? Plenty of Bosch info on MAFs. Scope it and see how it's responding. What is your injector "on time" at idle. As I recall it should be 3.2-3.5ms....

    It would be very useful to find someone with a SD tool. I have my doubts as to what your reading....If your absolute FT (ST+LT) is at 20, the CEL will be on. No ifs or buts about it!
     
  22. Robbe

    Robbe Formula Junior

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    Thanks for reacting.
    STFT is around 0, between -10 and +10 depending on rpm and throttle, so behaving normally. O2 sensors ok? Looks like it.
    I had expected the LTFT to come down from 25 fast, as the STFT started out at -10 with the engine still luke warm and idling, and slowly creeping up to 0. But no effect on the LTFT, still 25 on idle. Only after I drove off, it came down to 16, where it remained. I drove for 20 minutes, no difference.

    - erasing the trims, is by shutting off the battery for 20 minutes, correct?
    - I have not smoke tested the intake, can do that, I have a paint tin -type 100 usd smoke machine... but a vacuum leak is getting more and more unlikely, as the problems occur during driving, at say 3000 rpm. But good to eliminate it anyway.
    - I have no oscilloscope unfortunately. Same for an SD, very rare over here...nearest is 45 minutes away, and I do not want to drive that far in these conditions...
    - injector "on time" at idle, is that a value I can look for in the scanner? Any idea what the abbreviation would be? I do see spark adv (ance)
    - The total Fuel trim sometimes exceeds 20 , but only for a moment, but ( ;)) still no stored or pending codes. I had expected pending codes , but nothing...at least on this side of the car. Will check the other side as well. Last time the LTFT on the other side was 4,7, so within reasonable expectations for a 80000 mile 550 I think.
     
  23. Island Guy

    Island Guy Karting

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    Without an SD tool, we're limited in what we can see....
    I doubt that you can see injector pulse time.
    Ignition timing on a 550 as I recall is 4.5 degrees at idle
    So, disconnect the battery for 30 minutes or so and then watch the LTFT. Ideally, it should be 5% or less.
    Does the engine run like it is rich?
    Have you tried simply disconnecting both MAF sensors? This will force the Motronic to use default values, to get you home. Although I doubt you have both MAFs failing, it's a simple enough test to do.
    Have you measure the IAT sensor? RH side air box. Easy to do...

    550s have a long, rich history of leaking intake and plenum gaskets. Look closely at cylinders #1 and #12. If the gasket is a greenish color, there is a 100% chance that it is leaking. The revised gasket from the 575 is black and is a much better alternative. If she's coming apart, definitely replace those plenum side gaskets.

    I'm not sure using the ALDL connectors (versus a proper OBD connector) if a generic code reader will show a proper code.
     
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  24. Qavion

    Qavion F1 World Champ
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    #24 Qavion, Nov 18, 2020
    Last edited: Nov 18, 2020
    I'm not sure you should be doing any driving tests with the scanner hooked up. It's still not clear what data is shared between the ECUs. Because the MAFs on 550's seem to be wired up to the wrong ECUs for a crossflow engine, the ECUs may share correct MAF data on the 3 pin data plugs (?)
     
  25. Qavion

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    Having said that, there is also a 12 pin connector connecting the two ECUs, which includes a databus.
     

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