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Author: Subject: Omex ecu buzzing
martinnitram

posted on 2/12/17 at 04:55 PM Reply With Quote
Omex ecu buzzing

It's done this since I've owned the car.
It's an omex 600, seems to make most noise on part or coming off throttle, there are other relays under the dash near the ecu but getting your head down there while driving is a bit awkward !
Do they make noise ? Or is this more likely a relay.
Everything works fine it's just an annoying noise.

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leon51274

posted on 2/12/17 at 05:13 PM Reply With Quote
Can't say I've ever heard mine buzzing
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jeffw

posted on 2/12/17 at 05:17 PM Reply With Quote
solid state device so nothing to 'buzz' unless the case is loose.





623BHP @ 10200 rpm with 1.75Bar of boost. 2Bar coming soon

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40inches

posted on 2/12/17 at 05:21 PM Reply With Quote
quote:
Originally posted by jeffw
solid state device so nothing to 'buzz' unless the case is loose.


I was going to say a Cap,but the ones I have had let go usually whistle.

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perksy

posted on 2/12/17 at 05:36 PM Reply With Quote
It shouldn't buzz


Sounds more like a relay?

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martinnitram

posted on 2/12/17 at 06:43 PM Reply With Quote
Thanks
I didn't know if these ecu's had relays in them, must be a relay then, only does it while on the move so I can't Rev and look on the driveway.

Wonder what relay would likely do that, part or lifting off throttle makes a " Bzzzzzerrrtt" noise, lol, lasts a few seconds or until I give it more gas.

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perksy

posted on 2/12/17 at 06:47 PM Reply With Quote
I Bought a stethoscope off amazon, Wasn't expensive and has paid for itself several times over

Even diagnosed an over tightened drive belt on a dry sump pump


Might be worth looking into?

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martinnitram

posted on 2/12/17 at 07:08 PM Reply With Quote
quote:
Originally posted by perksy
I Bought a stethoscope off amazon, Wasn't expensive and has paid for itself several times over

Even diagnosed an over tightened drive belt on a dry sump pump


Might be worth looking into?



That's a good idea

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ken555

posted on 2/12/17 at 07:53 PM Reply With Quote
quote:
Originally posted by perksy
I Bought a stethoscope off amazon, Wasn't expensive and has paid for itself several times over
Might be worth looking into?


If your looking into it, then its a telescope not a stethoscope






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arrow-engineering

posted on 2/12/17 at 10:04 PM Reply With Quote
that is funny.
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martinnitram

posted on 24/7/18 at 06:38 PM Reply With Quote
Any clever folk around

Thought I would update this thread.
Ive got the dash out to get at the relays and have a proper look and listen.

The engine is a 20v 4AGE silver top with OMEX 600 ecu. BTW

The buzzing is the valve timing relay, which ive swapped and the replacement did exactly the same thing, grrrr.

What i have learned so far is that the valve timing on this silver top engine is RPM activated, the ecu turns on the relay at around 3000 rpm which in turn powers a VVT solonoid which controls the timing, and then off again around 6000 rpm.

Now what ive noticed is this.

If i rev the engine firmly and quickly blipping the throttle you can hear the relay clicking in and out.


If i rev the engine to the point that the relay would click and hold the revs steady the relay buzzes. If then you press throttle further it stops buzzing, you can hear it positively click, its like the relay is not quite getting the signal and can't decide what to do.


Seems to me that throttle position is the factor that causes the buzzing not necessarily engine rpm.

But according to what ive read the silvertop engine didn't have throttle position input to control valve timing.

Hope i've described this in a way thats understandable.


Thanks.

ps the engine runs fine, its just a very annoying noise...

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obfripper

posted on 24/7/18 at 08:18 PM Reply With Quote
Is it a case that the vvt requires a pwm signal to operate correctly, the output from the omex 600 is only low amperage, so it has a relay to up the output and that is what you can hear buzzing?
It would be possible to replace this with a correctly rated transistor to get rid if the noise.

Dave

[Edited on 24/7/18 by obfripper]

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martinnitram

posted on 25/7/18 at 10:33 AM Reply With Quote
quote:
Originally posted by obfripper
Is it a case that the vvt requires a pwm signal to operate correctly, the output from the omex 600 is only low amperage, so it has a relay to up the output and that is what you can hear buzzing?
It would be possible to replace this with a correctly rated transistor to get rid if the noise.

Dave

[Edited on 24/7/18 by obfripper]


As far as I can tell the VVT solenoid requires a switched earth to operate via the ecu / relay, as you say the ecu output would be low amp and requires the relay to send power to the VVT solenoid.

I don't actually know if the ecu puts out a pmw signal or not, if it did would this be the cause of the relay buzzing ? and if so I don't know why it would alter as the throttle is pressed more. ?

What i'm trying to figure out is if this is normal operation or something not working as it should ?


Thanks again.

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peter030371

posted on 25/7/18 at 11:21 AM Reply With Quote
quote:
Originally posted by martinnitram

If i rev the engine to the point that the relay would click and hold the revs steady the relay buzzes. If then you press throttle further it stops buzzing, you can hear it positively click, its like the relay is not quite getting the signal and can't decide what to do.



Sounds like you are on the edge of a threshold to switch the relay on or off and its flicking backwards and forwards between the two states. I don't know much about VVT but surely its not throttle position switched anyway? Should it be mapped to RPM and load?

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obfripper

posted on 25/7/18 at 01:14 PM Reply With Quote
I've now looked at the oe setup, it is just a plain on/off switching with no pwm using 2 advance states of 0 and +30, and is controlled by rpm and map signal on the oe ecu.
As Peter has suggested, it is likely that the load threshold has been incorrectly set, if the omex is using alpha-n then the only load parameter used is throttle position and must be close to cruising throttle position. It may be possible to adjust this value to allow cleaner switching which would prolong the relay's life.
It could still be using pwm on crossing the threshold to damp the transition, this would be in the omex configuration if used.

Dave

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martinnitram

posted on 26/7/18 at 03:52 PM Reply With Quote
Your correct, the throttle position causing the buzz is at cruising speed which makes it all the more irritating!

Would i be right in thinking that the original toyota ECU controlled the VVT on RPM, and that the OMEX ECU takes account of throttle position also?

Im going to get the engine mapped properly at some point in the near future as i have no record of it being done before, so will ring a few mappers local

Thanks again

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martinnitram

posted on 5/8/18 at 03:29 PM Reply With Quote
Bit more info on this.

Apparently the later silvertop engines did have an input from the TP sensor, im also now more sure this buzzing is happening from throttle position rather than engine revs.

Now booked in for a mapping and rolling road session so im sure i will soon find out for sure whats going on.

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