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Sync/Cyl Ratio


Frank van Rouendal

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Hi, I have purchased a Link Engine Management system, type LPV14, for a Subaru H6 engine, model year 2003 (no adjustable camshafts). Trying to start the engine for the first time, I got no spark and no fuel. I have replaced the crankshaft sensor and the camshaft sensor, but no result. Running the "new" sensors (also from the same batch of engines, so maybe suspect) I got a big Sync/Cyl Error during starting. Also I have seen the needle of the RPM gauge in the PC display moving once or twice during starting on the starter motor, but I got no digital indication. Can you tell me what the Sync/Cyl Ratio should be for this engine (I have tried both 6 and 3 as indicated in your manual)? Can you tell me how to show trigger signals on the PC display, as indicated in Chapter 14 of the manual? This would help me checking for signal reception of each trigger. Hoping you know the answers, with thanks in advance. Frank van Rouendal

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Hello Frank.

Can you confirm the polarity of the reluctor sensors?  Quite often a reversed polarity can cause no end of problems.  Also ensure that you have the crank signal going to Trig1 and cam signal going to Trig2.  The sync/cyl ratio should be set to 6, as it is a 6 cylinder with the sync off the cam (it would be 3 if your sync was also on the crank).

We'll look a bit deeper while you get back to us and confirm that.

Jurgen

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Hello Jurgen, Tanks for your advice. I re-chekked polarity and connection to the ECU of both sensors, and all is OK. Also correct input of Trig1 and Trig2 in ECU is OK. Sync/Cyl ratio set to 6. Then I tried to start again. I noted engine speed signal coming up during prolonged cranking of the engine, indicating 200-500 RPM. Sync/Cyl error is quickly building up (after approx. 10 start efforts is is now at 124) Later starts gave erratic speed signals, sometimes indicating 5300 or 8700 RPM. Is this just caused by malreading of time-limited speed signal in the ECU? Hope you can help me any further. Thanks in advance, Frank van Rouendal

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Hi Frank.

I must say first of all there is not going to be an immediate answer, and we will have to go through a few logical steps to get this working for you.  For the first step, can you pleae lift the lid off the unit and take a photo of the sub-board for us.

Please make sure the photo is of reasonable quality, and in focus (eg.  Camera photo, not your phone).  This way we can determine what you have decoding the triggering and we will be able to feel a little more sure of the advice we give.

Jurgen

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Hi Jurgen, Please find attached picture of the sub-board. I have taken this at high-res, but compressed to low-res to fulfil your requirements. If needed, I can send high-res picture by e-mail. Also lid with serial number is included in the picture. Hope this will help you with finding out how to solve the problem. With kind regards, Frank van Rouendal

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  • 3 weeks later...

Hi Frank

ECU looks to be all configured with the correct hardware.

This is where its going to get had.

We are going to need a scope pattern taken from the cam and crank sensors. So will need a two channel scope so we can see both wave forms at the same time.

We can then check that the pattern and timing is correct.

Simon

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  • 4 weeks later...

Hello Simon, Please find enclosed screen dumps from 2-channel scope during starting attempt. Blue = channel 1 = crank sensor Red = channel 2 = cam sensor Scales of time and voltage can be seen on the screen dumps, and on Properties pallet in picture 001. Cam sensor triggers at gap in crank wheel teeth (pictures 001 and 002) but not always (picture 003). My guess is that no cylinder should fire in this case, but I am not so sure about this. Then also it seems that crank sensor is not always sending correct signals (picture 004)??? Hope you can solve the problem using these pictures. If needed, I can send high-res picture by e-mail. With kind regards, Frank van Rouendal

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Hi Simon, Please find enclosed an additional screen dump of the scope reading, generated with larger time scale. This shows several revolutions of the crankshaft during starting attempt. It should give us a better understanding of the relation between crank and cam sensor. Both are functioning well, apparently. By the way, the ECU still reports "Cyl/Sunc Error". Hope this will give you enough information to sort out the problem. With kind regards, Frank van Rouendal

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  • 1 month later...

Hello Simon, Thanks for your info. I have re-checked everything. 12 V power is available at both ignition and injection drives. I can trigger injectors individually by earthing the signal connection at the ECU connector, so this works fine. For ignition I cannot do the same, because I have no info. about the signal that drives the coil; no earthing here? Still thinking why I have an increasing Sync/Cyl Error upon starting. By the way, does the programme use any other input to block ignition and injection in case the signal is not OK? Like pressure/vacuum, temperature? Or did I adjust one or more settings incorrectly during set-up? Please find the settings file for this job, attached. In case you have no further possibility for solving this problem, please return the ECU to my address, and I will put all input and output signals on the oscilloscope to check for malfunctioning. Thanks for your efforts. With kind regards, Frank van Rouendal

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  • 3 weeks later...

Hello Simon, Noting that Sync/Cyl Error keeps adding up during start attempts, I have changed over the crank and cam trigger signals at the ECU input. This results in no more Sync/Cyl Error counts (!). However, still no starts. The injection signal shows no activity on the scope, so the ECU is still blocking the start action. Does the absence of Sync/Cyl Error counts in the new situation give you a clue about what is going on? Does the programme use any other input to block ignition and injection in case the signal is not OK? Please find the settings file for this job, attached. Could you confirm correct settings for this engine? Hope this will get us any further. With kind regards, Frank van Rouendal

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Hi Simon, With triggers swapped I see no errors, but I think this is due to the fact that no useful signals are received by the ECU at all. No indication of RPM on PC Link screen, but from the scope I calculate approx. 175 RPM during starting. Swapped back the triggers, as it seems not logic to foul the ECU. Resulting signals as per attached picture. I have hooked up a second separate battery for the starter motor, to keep voltage at ECU in the correct range, and to continue cranking longer than possible with the racing battery. Now voltage at ECU does not drop below 11.5 V, but still no results. Rising number of Sync/Cyl Errors still noted. Also I noted green and red LEDs on ECU steady after switching on, but red LED blinks about 5-6 times during each start attempt; not during whole start attempt. Does this indicate something? Can you confirm settings are OK (see attachment to Post dt. 18-09-2010)? With kind regards, Frank van Rouendal

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  • 2 weeks later...

Hello Simon, Funny: in my screen, Sync/Cyl ratio is still set to 6. More important, voltage of crank trigger signal was too low for ECU. See attachment "screen 041.jpg" at my reply dt. 01-10-2010. After finding out, I moved the sensor nearer to the crank, and got much higher voltage, see present attachment. After this modification engine started normally. Sync/Cyl error shows 0 or 1 at each start, which is normal. Also ignition and injection output signals look good on the scope. I'm glad to have solved the problem. Thanks for your co-operation. With kind regards, Frank van Rouendal

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