Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: X30XE on 20 March 2016, 18:47:35

Title: Rev limiter
Post by: X30XE on 20 March 2016, 18:47:35
3.0 Auto Facelift, new to me...

If you floor it, Rev counter shows revs climbing to 7krpm (into red) with no hint that a limiter is about to kick in [then I back off for fear of causing damage]. 

Is the Engine ECU responsible for rev limit or is it left to autobox ECU to change up?  :-\

Title: Re: Rev limiter
Post by: Nick W on 20 March 2016, 18:53:37
3.0 Auto Facelift, new to me...

If you floor it, Rev counter shows revs climbing to 7krpm (into red) with no hint that a limiter is about to kick in [then I back off for fear of causing damage]. 

Is the Engine ECU responsible for rev limit or is it left to autobox ECU to change up?  :-\





Both. The rev counter is likely to be a bit slow if accelerating hard. I saw 7000rpm several times overtaking on the way home last Sunday.
Title: Re: Rev limiter
Post by: serek on 20 March 2016, 19:01:40
when last time I check with "My Naff Code Reader" was showing  6890 rpm at cut off
Title: Re: Rev limiter
Post by: X30XE on 20 March 2016, 20:08:19
Hmm. I shall have to carry out further investigations  :y
Title: Re: Rev limiter
Post by: serek on 20 March 2016, 20:21:21
Hmm. I shall have to carry out further investigations  :y
maybe you have non standard ecu , but even then wont go over 7200 as think thats limit for standard valve springs
Title: Re: Rev limiter
Post by: X30XE on 20 March 2016, 20:43:11
Hmm. I shall have to carry out further investigations  :y
maybe you have non standard ecu , but even then wont go over 7200 as think thats limit for standard valve springs

Lets hope the previous custodian didn't "customise" the ECU without knowledge of that fact eh.  :o
Title: Re: Rev limiter
Post by: X30XE on 03 April 2016, 19:18:07
Is there any reason why the rev counter would misreport the actual engine rpm?
Presumably it takes it's feed from the crank position sensor; and if that were lying the engine wouldn't run...  :-\

Gauge goes off the scale long before the rpm's stop.

Does the omega support live data on OBD as I can't get the thing to work with my Elm scanner?
Title: Re: Rev limiter
Post by: Nick W on 03 April 2016, 19:36:17
Is there any reason why the rev counter would misreport the actual engine rpm?
Presumably it takes it's feed from the crank position sensor; and if that were lying the engine wouldn't run...  :-\

Gauge goes off the scale long before the rpm's stop.

Does the omega support live data on OBD as I can't get the thing to work with my Elm scanner?


The rev counter needle is driven by a stepper motor from the crank position sensor, and if accelerating hard might not keep up with the signal, or stop moving quick enough. Or, the gauge is damaged in some way, loose needle perhaps? None of the gauges are intended to be precision instruments, they are a representation of what is happening. The rev-limiter is an integral part of the ecu and can be trusted.


3.0l are not OBD compliant. You need more specialised equipment to read them.
Title: Re: Rev limiter
Post by: STEMO on 03 April 2016, 19:45:16
Rev it as hard as possible in first gear. If the engine cuts out at the top end of the revs, then the limiter is kicking in.
If the engine explodes in a cloud of smoke and a metallic crunching noise is heard, the limiter has not done its job.

HTH.  :)
Title: Re: Rev limiter
Post by: X30XE on 03 April 2016, 19:51:20
Rev it as hard as possible in first gear. If the engine cuts out at the top end of the revs, then the limiter is kicking in.
If the engine explodes in a cloud of smoke and a metallic crunching noise is heard, the limiter has not done its job.

HTH.  :)

 ;D It's an auto  :P
Title: Re: Rev limiter
Post by: X30XE on 03 April 2016, 19:53:57
Is there any reason why the rev counter would misreport the actual engine rpm?
Presumably it takes it's feed from the crank position sensor; and if that were lying the engine wouldn't run...  :-\

Gauge goes off the scale long before the rpm's stop.

Does the omega support live data on OBD as I can't get the thing to work with my Elm scanner?


The rev counter needle is driven by a stepper motor from the crank position sensor, and if accelerating hard might not keep up with the signal, or stop moving quick enough. Or, the gauge is damaged in some way, loose needle perhaps? None of the gauges are intended to be precision instruments, they are a representation of what is happening. The rev-limiter is an integral part of the ecu and can be trusted.


3.0l are not OBD compliant. You need more specialised equipment to read them.

Needle doesn't bounce, jitter or stick so I'm not suspecting it's loose.  Must just be really badly calibrated.  Unless as previously suggested someone has tampered with the factory set rev limiter.

And as it's not OBD compliant I ain't gonna know which any time soon  ::) 
I'm glad I'm not going mad; I was sure my old 3.2 was obd  :)
Title: Re: Rev limiter
Post by: STEMO on 03 April 2016, 19:55:18
Rev it as hard as possible in first gear. If the engine cuts out at the top end of the revs, then the limiter is kicking in.
If the engine explodes in a cloud of smoke and a metallic crunching noise is heard, the limiter has not done its job.

HTH.  :)

 ;D It's an auto  :P
Oh dear.......so lock it in first.  ;D
Title: Re: Rev limiter
Post by: X30XE on 03 April 2016, 19:59:41
Rev it as hard as possible in first gear. If the engine cuts out at the top end of the revs, then the limiter is kicking in.
If the engine explodes in a cloud of smoke and a metallic crunching noise is heard, the limiter has not done its job.

HTH.  :)

 ;D It's an auto  :P
Oh dear.......so lock it in first.  ;D

Are you high??  :o An AR35 doing as it's told??  :D As if!  ;D
Title: Re: Rev limiter
Post by: zirk on 03 April 2016, 20:00:25
Rev it as hard as possible in first gear. If the engine cuts out at the top end of the revs, then the limiter is kicking in.
If the engine explodes in a cloud of smoke and a metallic crunching noise is heard, the limiter has not done its job.

HTH.  :)
I reckon you need to upgrade your Public Liability Insurance with some of your 'Stemo's Omega easy Fixes'.  ;D
Title: Re: Rev limiter
Post by: Nick W on 03 April 2016, 20:01:00


And as it's not OBD compliant I ain't gonna know which any time soon  ::) 
I'm glad I'm not going mad; I was sure my old 3.2 was OBD  :)


It was.
Title: Re: Rev limiter
Post by: X30XE on 03 April 2016, 20:02:59
Rev it as hard as possible in first gear. If the engine cuts out at the top end of the revs, then the limiter is kicking in.
If the engine explodes in a cloud of smoke and a metallic crunching noise is heard, the limiter has not done its job.

HTH.  :)
I reckon you need to upgrade your Public Liability Insurance with some of your 'Stemo's Omega easy Fixes'.  ;D

Technically probably not, given he did clearly state the outcome that would befall anyone daft enough to try  :D
Title: Re: Rev limiter
Post by: X30XE on 04 April 2016, 17:38:33
https://youtu.be/RTK7GYmxwrk

About as much use as a chocolate fire guard  ::)