ECU reliability issues

Nistune topics related specifically to the 6303 cpu

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Junkie
 

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Joined: Sat Sep 26, 2009 11:07 am

ECU reliability issues

Post by Junkie »

Hi All,

RB26 with -7 aka R34 N1 turbos, 550 siemens injectors and early Type 2 board. Made 305kw @ 17psi. I was interested in pushing the boost up a little further, and added Nismo MAFs. Tuner had issues with the old boost controller not re-training, so it was replaced. Had issues with ignition and found a bad earth to the ignitor module so a new one was added.

Comments from tuner "suspect more wiring and possible noise interference with ignition system. Possible damaged ECU causing ECU sometimes to slow down during mapping and altering timing advance. Advised customer to invest in after market ECU and fix wiring to coilpacks/ignition module".

I'm happy with Nistune, but the comments are a concern. How should I troubleshoot the ECU side of this?
Matt
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Re: ECU reliability issues

Post by Matt »

The comments about the ECU 'slowing down during mapping' is a first and I wonder how the tuner came to that conclusion - and what the actual problems were that the tuner was seeing

When off idle, the ECU does a basic lookup of the main timing map, retards timing (if any knock count) and then looks at the dwell tables for charge times and then sets up the charge time and advance settings, The actual timing is done using a scheduler in a separate chip

The start of the charge time scheduled and duration done by the auxiliary chip, then trigger each ignition driver output in the ECU to subsequently charge and ignite the coil. If there was faulty ECU hardware (driver was dead) then the coil could either not work, or be stuck open. I've never seen a driver in the ECU work intermittently. However I have seen bad coils, issues with spark plugs and all the rest outside the ECU

What I would be interested so see is a trace of the actual timing (using the 'TRACE' button whilst in stream mode and compare against your timing map). If there was an issue, you would notice a 'lag'

You should notice that the timing in this window follows the actual timing map. Any 'slowness' would indicate a lag between timing shown in the trace vs the actual timing map.

There should be no slowness with the OEM firmware from Nissan. With feature pack there is an extra lookup done on the flex timing map, but only if the 'flex fuel' option is ticked in the software, otherwise it just skips the code

What are the actual problems displayed with the vehicle at the moment?
Junkie
 

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Joined: Sat Sep 26, 2009 11:07 am

Re: ECU reliability issues

Post by Junkie »

Thanks for your comments Matt - I suspected there may have been some misreading of the symptoms. It sounds you are sceptical that there's anything wrong with the ECU, as the description doesn't match the failures you've seen.

I wondered if the "slowing down" was just some intermittent rs232 comms, which of course could be unrelated to the ECU itself. I'll see if i can get any more specific info.
Matt
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Re: ECU reliability issues

Post by Matt »

It might be that the maptrace (in tuner mode) is laggy since the comms is bidirectional so the speed is slower

Stream mode is quicker for tracing and logging and would be best to use when monitoring a pull on the dyno
Junkie
 

Posts: 20
Joined: Sat Sep 26, 2009 11:07 am

Re: ECU reliability issues

Post by Junkie »

I asked the tuner:
"What was slowing down? Response in the Nistune GUI?
Re: the change in timing advance, did this occur at the same time as the slow down?
Was the timing change noticed by knock or via monitoring signal to the coils or some other way?
What's the PIN?"


He said; (i had asked in an earlier conversation if the timing issue could be CAS related)
"I had a few issues with the connection part and it kept asking for a pin. I made it 5500.

There were a number of times where the car would lose almost 20kw (across the whole rpm range) on the dyno without even touching a parameter. Seemed to me like the ignition was “retarding” then it would all of a sudden come back to normal.

I noticed on the logs on the test drive that the car would knock sometimes then not, again the log was showing the same timing numbers and I hadn’t changed anything yet.

This makes me sceptical that there is something wrong. If it were a CAS, it would be either consistent or it would show up on the logged runs.

Timing changes were noticed by audible knock."
Matt
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Re: ECU reliability issues

Post by Matt »

The connection part is to do with electrical noise in the vehicle affecting communications. When you first connect, it requests a PIN. If the message or response is garbled then the message about an error will come up. The default is 0000

If you watch the 'ignition time' parameter whilst in stream mode on the 'Trace' window you can monitor the actual timing and confirm if this is the case. This is better than "seems" that it was retarding since you will actually know what the ECU is going. You can also do this for 'injection time' to see if this varies at all between runs

If the log was showing the same timing numbers, then it was not retarding timing (even if you could hear knocking). Consult timing numbers displayed are final (even after knock filtering). Seems to be something else but its not timing. You can confirm timing at the crank with a light
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