Asthmatic 350z
Discussion
I had time off last week and took my MR2 to Surrey Rolling Road. Charlie was his usual excellent self and our whole group had a great day.
While I was delighted at breaking the 250bhp barrier on an essentially bone-stock MR2 Rev 3, unfortunately not all the cars covered themselves in glory.
Probably the biggest surprise of the day was my mate's 350z. It's a UK car, low mileage, 2004, GT Spec with full Nissan service history. The car wants for nothing and it was only about 3 weeks ago that it was freshly serviced and received a brand new Nissan exhaust (mid and back box) in time for the MOT.
Charlie said he'd never seen one deliver less power. The average for standard cars is around 265-270 on his rollers. He gave my mate some contact details for people who'd look into it, but I figured it'd be helpful if I stuck the graphs up here and let the combined wisdom of PH have a think about it.
The car is mostly used for motorway work on weekends as he commutes by train. I thought that'd be ideal for keeping it healthy as it gets properly warm every time it gets driven?
Any thoughts?
While I was delighted at breaking the 250bhp barrier on an essentially bone-stock MR2 Rev 3, unfortunately not all the cars covered themselves in glory.
Probably the biggest surprise of the day was my mate's 350z. It's a UK car, low mileage, 2004, GT Spec with full Nissan service history. The car wants for nothing and it was only about 3 weeks ago that it was freshly serviced and received a brand new Nissan exhaust (mid and back box) in time for the MOT.
Charlie said he'd never seen one deliver less power. The average for standard cars is around 265-270 on his rollers. He gave my mate some contact details for people who'd look into it, but I figured it'd be helpful if I stuck the graphs up here and let the combined wisdom of PH have a think about it.
The car is mostly used for motorway work on weekends as he commutes by train. I thought that'd be ideal for keeping it healthy as it gets properly warm every time it gets driven?
Any thoughts?
It all starts off well enough and fueling richens to c.12.5 at 3200rpm where it should be, then it shoots up to c.13.4 and is all over the place till it settles down again to c.12.3 at 5800rpm which is more or less where he is making peak power.
In between 3200 and 5800rpm fueling is running way too lean for a proper pull, and all over the place too. From the point where it started off well at 3200rpm it should have been a fairly flat line hovering around 12.2-12.5AFR on a wide open throttle (WOT) right the way through this pull.
12.5AFR is where petrol delivers max power and with a normally aspirated car that is where you should be looking to run fueling when you're on it.
I'd like to know what timing it's running all the way through this pull.
Either the throttle pedal wasn't 100% wide open throttle(WOT) and was lifted during this pull or it may be an issue with either MAF sensor or Lambda sensor, or both, as there is something not quite right there.
In between 3200 and 5800rpm fueling is running way too lean for a proper pull, and all over the place too. From the point where it started off well at 3200rpm it should have been a fairly flat line hovering around 12.2-12.5AFR on a wide open throttle (WOT) right the way through this pull.
12.5AFR is where petrol delivers max power and with a normally aspirated car that is where you should be looking to run fueling when you're on it.
I'd like to know what timing it's running all the way through this pull.
Either the throttle pedal wasn't 100% wide open throttle(WOT) and was lifted during this pull or it may be an issue with either MAF sensor or Lambda sensor, or both, as there is something not quite right there.
The problem with MAF sensors is they rarely give you an error code when they start failing.
The way it normally works is as they get worse they read less and less airflow fooling the ECU into thinking it needs to run less fueling therefore it runs leaner and leaner.
Lambda sensors normally give up the ghost completely and then throw an error code. Also with OBD equipment a dead lambda sensor shows no AFR readings at all. It's not often they go the same way as MAF sensors with erroneous readings over an extended period of time. 9/10 times they just die.
If you have no error code for the Lambda sensor i'd be looking at the MAF sensor. Maybe it just needs a good clean, maybe it's faulty.
ETA a cheap OBD diagnostic reader off fleabay will read error codes and reset the ECU for code clearing.
The way it normally works is as they get worse they read less and less airflow fooling the ECU into thinking it needs to run less fueling therefore it runs leaner and leaner.
Lambda sensors normally give up the ghost completely and then throw an error code. Also with OBD equipment a dead lambda sensor shows no AFR readings at all. It's not often they go the same way as MAF sensors with erroneous readings over an extended period of time. 9/10 times they just die.
If you have no error code for the Lambda sensor i'd be looking at the MAF sensor. Maybe it just needs a good clean, maybe it's faulty.
ETA a cheap OBD diagnostic reader off fleabay will read error codes and reset the ECU for code clearing.
Something between £20-£30 will do the job. Most of them read live data too.
I'll give you an example of how cheap. I've got a Bluetooth enabled OBD2/EOBD reader that's paired to my HTC Flyer 3G. Works well enough for clearing codes and seeing live data. I paid less than £15 for it and small enough to carry around in the car glove box or in my pocket.
I've got other kit that cost a lot more and runs on my laptop with cable etc... Both of these i use for European and other compliant Jap vehicles depending on where i am and what i'm doing.
I'll give you an example of how cheap. I've got a Bluetooth enabled OBD2/EOBD reader that's paired to my HTC Flyer 3G. Works well enough for clearing codes and seeing live data. I paid less than £15 for it and small enough to carry around in the car glove box or in my pocket.
I've got other kit that cost a lot more and runs on my laptop with cable etc... Both of these i use for European and other compliant Jap vehicles depending on where i am and what i'm doing.
I have to say i wouldn't have expected quite such a deviation from rich to lean and then back again on a wide open throttle between 2500-4200rpm if it was running 100%. It's normally aspirated so i expect there to be a lot less deviation and a more linear fuelling curve.
I'd of expected the fuelling to start off lean at 13.0AFR then gradually slope down with little variation up and down till it hits peak power at 12.3AFR, if it was fuelling properly.
If the car is 30+ bhp down on what the manufacturer quotes either the manufacturer is a liar or there's something not quite right with the car wouldn't you say.
I'd of expected the fuelling to start off lean at 13.0AFR then gradually slope down with little variation up and down till it hits peak power at 12.3AFR, if it was fuelling properly.
If the car is 30+ bhp down on what the manufacturer quotes either the manufacturer is a liar or there's something not quite right with the car wouldn't you say.
ScoobieWRX said:
I have to say i wouldn't have expected quite such a deviation from rich to lean and then back again on a wide open throttle between 2500-4200rpm if it was running 100%. It's normally aspirated so i expect there to be a lot less deviation and a more linear fuelling curve.
I'd of expected the fuelling to start off lean at 13.0AFR then gradually slope down with little variation up and down till it hits peak power at 12.3AFR, if it was fuelling properly.
If the car is 30+ bhp down on what the manufacturer quotes either the manufacturer is a liar or there's something not quite right with the car wouldn't you say.
I know there is something wrong with the car, as its the lowest one i've ever done, I've also done enough of these to know what the standard car's fueling curve looks like!I'd of expected the fuelling to start off lean at 13.0AFR then gradually slope down with little variation up and down till it hits peak power at 12.3AFR, if it was fuelling properly.
If the car is 30+ bhp down on what the manufacturer quotes either the manufacturer is a liar or there's something not quite right with the car wouldn't you say.
I recomended the Chap visit Jez at H-Dev, he does alot of work with these.ScoobieWRX said:
If the car is 30+ bhp down on what the manufacturer quotes either the manufacturer is a liar or there's something not quite right with the car wouldn't you say.
Well, that wouldn't be that unusual! I recall Mountune saying that they had never seen a factory stock mk2 Focus RS making more than 269hp when it came to them! A good 30bhp down on what Ford quote!Baryonyx said:
ScoobieWRX said:
If the car is 30+ bhp down on what the manufacturer quotes either the manufacturer is a liar or there's something not quite right with the car wouldn't you say.
Well, that wouldn't be that unusual! I recall Mountune saying that they had never seen a factory stock mk2 Focus RS making more than 269hp when it came to them! A good 30bhp down on what Ford quote!Mr MXT said:
I know the car and the owner that the OP is referring to and the way it is driven.
Is there any evidence to suggest "the italian tune up" actually produces results? The car is never, ever, driven hard.
(P.S. Al - first dibs if he ever wants to sell it)
I'm interested to hear what everyone thinks about this. Could a good thrash unblock its lungs a bit? Russ speaks the truth. I'm honestly not sure it's ever been over 4,000rpm. Certainly not for more than a few seconds.Is there any evidence to suggest "the italian tune up" actually produces results? The car is never, ever, driven hard.
(P.S. Al - first dibs if he ever wants to sell it)
P.s. You can have SECOND dibs. I'm quite taken by it myself....
Vixpy1 said:
Most i do seem to make 285bhp to 300bhp
Indeed, I've read and heard (though have not owned and dyno'd one myself) that the RS MK2 is a consistent under-performer, making anywhere from 265-280bhp. I suppose Ford had a real battle on their hands to convince people that it was a real jump up from the competition and yet still suffered the horrendous fuel consumption issues that plagued the ST, so had to strike a happy mid-point. Underpowered from the factory but probably up on the MPG, CO2 output and engine longevity fronts.. There is a price to be paid for the extra cylinder I suppose, but the way they gulp fuel is shocking. Mastodon2 said:
Vixpy1 said:
Most i do seem to make 285bhp to 300bhp
Indeed, I've read and heard (though have not owned and dyno'd one myself) that the RS MK2 is a consistent under-performer, making anywhere from 265-280bhp. I suppose Ford had a real battle on their hands to convince people that it was a real jump up from the competition and yet still suffered the horrendous fuel consumption issues that plagued the ST, so had to strike a happy mid-point. Underpowered from the factory but probably up on the MPG, CO2 output and engine longevity fronts.. There is a price to be paid for the extra cylinder I suppose, but the way they gulp fuel is shocking. Gassing Station | Japanese Chat | Top of Page | What's New | My Stuff