4.5 V8 max RPM ?
Discussion
Hi Guys
might seem a bit basic but can someone give me a bit of confidence about this- I was driving yesterday in and out of traffic temp. was reading 95ish saw a bit of straight and gave it full throttle in 2nd pulled nicely until what I think was just under 7000rpm when it all cut then recovered felt like the ECU hit rev cut?
I hadnt seen the shift light it works on start up but have never seen it in anger ( only had the car 300 miles.)
I dont think the tacho is very accurate it doesnt line up with speed whilst cruising ? gearing is approx 30miles per thousand revs Right? but at 60mph in top it is reading 2300ish rpm , The shift light is generated by the ECU isnt it? so is seperate from tacho reading?.
back to the story after my moment all seems OK no missing, no vibration but I dont think it ist pulling so well or am I paranoid?
would it help to reset the ECU? on previous cars I have unpowered the ECU to remove messages and adaptive learning would this work/help?
Sorry it so long, any of your experiences would be appreciated
RGDs Peter
might seem a bit basic but can someone give me a bit of confidence about this- I was driving yesterday in and out of traffic temp. was reading 95ish saw a bit of straight and gave it full throttle in 2nd pulled nicely until what I think was just under 7000rpm when it all cut then recovered felt like the ECU hit rev cut?
I hadnt seen the shift light it works on start up but have never seen it in anger ( only had the car 300 miles.)
I dont think the tacho is very accurate it doesnt line up with speed whilst cruising ? gearing is approx 30miles per thousand revs Right? but at 60mph in top it is reading 2300ish rpm , The shift light is generated by the ECU isnt it? so is seperate from tacho reading?.
back to the story after my moment all seems OK no missing, no vibration but I dont think it ist pulling so well or am I paranoid?
would it help to reset the ECU? on previous cars I have unpowered the ECU to remove messages and adaptive learning would this work/help?
Sorry it so long, any of your experiences would be appreciated
RGDs Peter
Joe
ref the gearing various roadtests in magazines quoted a higher figure (over 29)
as per the throttle pots? I dont understand why would the ECU go to a safe mode or whatever at a large throttle opening I dont know this ECU but others I have dealt with react to a knock or temp/pressure signal or the loss of a signal before they 'cut' anything. Large throttle openings normaly mean no feedback from Lambda? ie a fixed rich map.
Joospeed
if there is no rev cut then I have a problem? oops!
RGDs Peter
ref the gearing various roadtests in magazines quoted a higher figure (over 29)
as per the throttle pots? I dont understand why would the ECU go to a safe mode or whatever at a large throttle opening I dont know this ECU but others I have dealt with react to a knock or temp/pressure signal or the loss of a signal before they 'cut' anything. Large throttle openings normaly mean no feedback from Lambda? ie a fixed rich map.
Joospeed
if there is no rev cut then I have a problem? oops!
RGDs Peter
V8CER said:
Joe
ref the gearing various roadtests in magazines quoted a higher figure (over 29)
as per the throttle pots? I dont understand why would the ECU go to a safe mode or whatever at a large throttle opening I dont know this ECU but others I have dealt with react to a knock or temp/pressure signal or the loss of a signal before they 'cut' anything. Large throttle openings normaly mean no feedback from Lambda? ie a fixed rich map.
Joospeed
if there is no rev cut then I have a problem? oops!
RGDs Peter
Peter,
Was told example by dealer the other day. Customers trottle pedal was slightly bent, so at maxy chat, the throttles were opening past 94.7% and therefore going to safe mode. Probably not your problem, but just thought I would throw it out there. Autocar quotes a 29.8 gear ratio, but no idea how/why they do. I have checked my speedo against a gps to be almost spot on, and rev counter is fairly accurate according to the ecu software. I think there was a thread a while ago with most people showing about 26. Even the close ratio gear box doesn't have a higher 5th.
gazzab said:
Hitting 7k revs when you have only just got the car. Take it easy ! They are full of suprises!
I hit the 7000rpm in the Cerb repeatedly within my first few miles of driving it. Enjoying it from the moment you get in it is the best way to enter Cerb ownership - start as you mean to go on!!
(*car was already warm from dads runs, was at Harewood hillclimb in the wet)
Also had it sideways within my first mile of driving a Cerb. STUNNING cars, absolutely incredible to drive hard. ENJOY!!!!!!!!!!!!!!
Thanks Apprentice - Yes I will talk with Andy.
Took it out tonight and accelerated reasonably slowly up the rev range in 2nd all OK except the tacho drops back at 4K then restores after a moment? very strange.
it at least is consistant (did it 3 times) - also found the change light yes it comes on at 7K. Then tried a full throttle run up the range got to 7K no problem and all seems OK - so what happened the other day???
will keep fingers crossed (doesnt help when using the indicators)
RGDs Peter
Took it out tonight and accelerated reasonably slowly up the rev range in 2nd all OK except the tacho drops back at 4K then restores after a moment? very strange.
it at least is consistant (did it 3 times) - also found the change light yes it comes on at 7K. Then tried a full throttle run up the range got to 7K no problem and all seems OK - so what happened the other day???
will keep fingers crossed (doesnt help when using the indicators)
RGDs Peter
. Have to agree, go to Andy.
Andy changed my cams and fiddled with my bits about 8 months ago and ever since, whilst I have a 4.2 it revs all the way to the rev limiter which comes in at just over 8000 on mine, or did on Saturday at Lydden! Third in the open A3 class sprint, beaten only by a GT3 RS and a sorted Evo, 0.27 secs between 1st and 3rd, and I've done 54,000 miles.
I do have the alloy rads from Radtec which allows the car to run at between 75 and 90 on the track and I never go below 5500 rpm. Have to admit this has really helped changed the car's temperament at the limit. Cruising home it doersn't go over 80 c.
Don't know what magic Andy performs on a car but since he has taken over, the whole set up has made it a completely different animal!
Good bloke too, give him a call.
Jonny
Andy changed my cams and fiddled with my bits about 8 months ago and ever since, whilst I have a 4.2 it revs all the way to the rev limiter which comes in at just over 8000 on mine, or did on Saturday at Lydden! Third in the open A3 class sprint, beaten only by a GT3 RS and a sorted Evo, 0.27 secs between 1st and 3rd, and I've done 54,000 miles.
I do have the alloy rads from Radtec which allows the car to run at between 75 and 90 on the track and I never go below 5500 rpm. Have to admit this has really helped changed the car's temperament at the limit. Cruising home it doersn't go over 80 c.
Don't know what magic Andy performs on a car but since he has taken over, the whole set up has made it a completely different animal!
Good bloke too, give him a call.
Jonny
I'm with Gazzab - listen to his advice, I'm sure everyone else is a far better driver than me or something, and floors their Cerb constantly, and gets sideways on every roundabout, but I think that sooner or later it will catch them out in a very expensive way - plenty of time to go very fast, and you'll have a chance to see how you are with it sideways at some point ....
guydw said:
I'm with Gazzab - listen to his advice, I'm sure everyone else is a far better driver than me or something, and floors their Cerb constantly, and gets sideways on every roundabout, but I think that sooner or later it will catch them out in a very expensive way - plenty of time to go very fast, and you'll have a chance to see how you are with it sideways at some point ....
Im a crap driver, just never get behind the wheel of the Cerb unless its a safe environment off road atm (both for reasons of sanity and insurance)
I personally believe you are more likely to be caught out by the odd patch of oil or something if you *dont* know how your car behaves at the limit.
Agree entirely. I'd say that learning how any car handles near the limit is a good thing, though it is not the same as your car losing it unexpectedly on a wet roundabout etc. I think this has happened to us all - actually imho the Cerb handles it pretty well.
However my point was that even when "making progress" one should always be slightly defensive in how you drive. I'd say going out there and starting to push the car on public roads (doughnuts, power oversteer etc) is a sure way to end up embedded in a wall. Of course as you get better, you have more ocasions when you can get the back out or whatever - it's just that this will take a while for most of us mortals....
However my point was that even when "making progress" one should always be slightly defensive in how you drive. I'd say going out there and starting to push the car on public roads (doughnuts, power oversteer etc) is a sure way to end up embedded in a wall. Of course as you get better, you have more ocasions when you can get the back out or whatever - it's just that this will take a while for most of us mortals....
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