shunting till 300rpm after cam change
Discussion
hi guys just need some advice before i go back to the indy garage had cam done picked it up drove home thought it would settle down mild shunting till 3000rpm then woooooosh so smooth and lots of torque power better than it was before... the car has done 102,000 so i thought new cam kit time1 car was running fine beforehand no shunting ever had it 5 years.. i presume when it was reassembled something has failed or not put back right|not set up/tweeked Will a fault code reader see it? i need a few ideas so i can go to the garage and point them in the right direction to put it right(at their cost i hope).. my thoughts are air flow meter? HT leads??
any thoughts?
any thoughts?
Also look for air leaks - I've once had a Stealth cam kit delivered to a customer of mine who had huge shunting/low rpm driveability problesm afterwards and was questioning the validity of the cam choice (it was a 500) - turned out there was a duff valley gasket with the kit that drew false air from inbetween the steel and plastic/rubber layers...
Shunting?
If you mean the power delivery feels sticky and unpredictable then safety says plug chop for running mixtures, as the settings would have to be awol to give symptoms up to 3000.
If the mixture is ok and you are sure it is not a misfire then the symptoms are
present for possible valvetrain or valveseat issues.
If you mean the power delivery feels sticky and unpredictable then safety says plug chop for running mixtures, as the settings would have to be awol to give symptoms up to 3000.
If the mixture is ok and you are sure it is not a misfire then the symptoms are
present for possible valvetrain or valveseat issues.
just been out for half hour in it there is a mis fire not the pop and bang you usually get i cant drive it below 3000rpm without adding more right foot to the pedal before the cam change i had no issues at all... when i say shunt it feels like its hesitant fuelling??? then off it goes after 3000rpm there doesnt seem to be a leak as when i first bought the car i became an air leak expert!!!!!!
the valley gasket i supplied... it came from TVR Power
the valley gasket i supplied... it came from TVR Power
The ECU should reset the long term fuel trim within a couple of minutes of idle on a warm engine. The typical shunting that effects the cars is normally lower than 3000 rpm, nearer 1700 rpm under light throttle in high gears. The ECU can cause shunting at higher RPM if its trying to correct a fueling issue, but you will need a fault code reader / ECUmate / Rovergauge / Fault code reader to see whats going on. Id trust the Indie would have such hardware if they are a TVR specialist.
The cam timing can be precision set with an adjustable vernier to allow for the vagaries of cam grinds.
The spec will be something like:
25thou @ 4'ATDC
This will probably be on the Kent site.
The dial gauge measures the lift.
You need to check this b4 thinking about valvetrain inspection & gauging.
The spec will be something like:
25thou @ 4'ATDC
This will probably be on the Kent site.
The dial gauge measures the lift.
You need to check this b4 thinking about valvetrain inspection & gauging.
blitzracing said:
The ECU should reset the long term fuel trim within a couple of minutes of idle on a warm engine. The typical shunting that effects the cars is normally lower than 3000 rpm, nearer 1700 rpm under light throttle in high gears. The ECU can cause shunting at higher RPM if its trying to correct a fueling issue, but you will need a fault code reader / ECUmate / Rovergauge / Fault code reader to see whats going on. Id trust the Indie would have such hardware if they are a TVR specialist.
yes that was the next step to get over there i think they have Steve Heath code reader so time to get over there and plug it in i do think its a fuelling issue have reset ECU its probably something easy to fix ..i kept the original cam and vernier etc should post pics they wasnt in too bad condition for 102,000 miles
I have a Griff 500 which shunts even with MS2Extra/EDIS and I have been trying to fix the problem for nearly two years! Still have not fixed it, and now I've become pretty obsessive and depressed about fixing it. Like you I never had a problem until a rebuild, and change of cam. I thought I would be able to tune it out with MS, but 2 time consuming years later still have the problem. I would post what I have tried, but it would fill the page!! Simpler to say you name it or any combination thereof, Ive tried it. My last option appears to be to revert back to original cam profile. Boy is it annoying.
For those intrigued by the symptoms I will attach a snapshot. , a datalog and my msq. The snapshots show RpmDot because this highlights the changing rpm 'shunt' (between 60-120rpm) variations. It occurs mainly when cruising on a light throttle but can also occur on initial acceleration, anywhere from idle up to 2300 rpm. If anyone wishes to know more, email me and I can forward more snapshots, datalog and .msq.
For those intrigued by the symptoms I will attach a snapshot. , a datalog and my msq. The snapshots show RpmDot because this highlights the changing rpm 'shunt' (between 60-120rpm) variations. It occurs mainly when cruising on a light throttle but can also occur on initial acceleration, anywhere from idle up to 2300 rpm. If anyone wishes to know more, email me and I can forward more snapshots, datalog and .msq.
DaveG said:
I have a Griff 500 which shunts even with MS2Extra/EDIS and I have been trying to fix the problem for nearly two years! Still have not fixed it, and now I've become pretty obsessive and depressed about fixing it. Like you I never had a problem until a rebuild, and change of cam. I thought I would be able to tune it out with MS, but 2 time consuming years later still have the problem. I would post what I have tried, but it would fill the page!! Simpler to say you name it or any combination thereof, Ive tried it. My last option appears to be to revert back to original cam profile. Boy is it annoying.
For those intrigued by the symptoms I will attach a snapshot. , a datalog and my msq. The snapshots show RpmDot because this highlights the changing rpm 'shunt' (between 60-120rpm) variations. It occurs mainly when cruising on a light throttle but can also occur on initial acceleration, anywhere from idle up to 2300 rpm. If anyone wishes to know more, email me and I can forward more snapshots, datalog and .msq.
What cam are you running. For those intrigued by the symptoms I will attach a snapshot. , a datalog and my msq. The snapshots show RpmDot because this highlights the changing rpm 'shunt' (between 60-120rpm) variations. It occurs mainly when cruising on a light throttle but can also occur on initial acceleration, anywhere from idle up to 2300 rpm. If anyone wishes to know more, email me and I can forward more snapshots, datalog and .msq.
rigga said:
What was the cam that was in there before ? at 102k i doubt it was the original,could it have been a different spec to the one you have now ?
Looks like the original camshaft.... has TVR stamped on the side so not aftermarket bought the car 5 years ago with 71,000 on the clockGassing Station | Chimaera | Top of Page | What's New | My Stuff