Dyno run AFR & detonation
Discussion
My car is a totally stock engine 500 Griffith, 103k miles with a top end rebuild including cam around 6000 miles ago.
I've just had a dyno run to see where dogs lie and the concern is detonation where the two dips occur on the AFR graph at around 3800rpm & at 4750rpm. Both the dyno knock sensor detected it & it could also be heard.
AFR seems to be heading in the wrong direction after it goes lambda open loop above 3250rpm and the operator's opinion was a lean burn induced knock.
What is the opinion of the plots from those people with experience of this engine?
Kev
I've just had a dyno run to see where dogs lie and the concern is detonation where the two dips occur on the AFR graph at around 3800rpm & at 4750rpm. Both the dyno knock sensor detected it & it could also be heard.
AFR seems to be heading in the wrong direction after it goes lambda open loop above 3250rpm and the operator's opinion was a lean burn induced knock.
What is the opinion of the plots from those people with experience of this engine?
Kev
carsy said:
Motorsport developments in Bispham by any chance ?
That does look to be running weak. 12.5 - 12.8. Would be more where you’d want to be at wide open throttle.
Have you checked your ignition timing re the pinking.
Your down a fair bit on bhp as well.
Yes, I'm local to the area. That does look to be running weak. 12.5 - 12.8. Would be more where you’d want to be at wide open throttle.
Have you checked your ignition timing re the pinking.
Your down a fair bit on bhp as well.
Edited by carsy on Friday 13th July 13:59
Timing was also suggested so will pull the timing light out of hibernation.
Yes, power isn't quite what I had hoped but the curves seem the right shape and it's a high miler. Oh & just discovered on RoverGauge that throttle pot is only opening to 75% on the pedal but pulls to 96% under the bonnet. Think the throttle stop requires a small adjustment
Just plugged in RoverGauge and fault 23 seems to point to fuel supply/pressure.
Edited by Kev Bamber on Friday 13th July 16:45
That's the easy job done, now getting full throttle.
Thanks for the guidance, will check for leaks first, then the pressure regulator with vac pipe both on & off, & if that checks out okay, then rig up a fuel pressure gauge in the car so can see what happening at WOT. Then some AFM volt checks.
So from what you described, probably lots lambda fuelling correction being added whilst closed loop <3250rpm then when goes open loop, leans off even more after switching to map only?
Thanks for the guidance, will check for leaks first, then the pressure regulator with vac pipe both on & off, & if that checks out okay, then rig up a fuel pressure gauge in the car so can see what happening at WOT. Then some AFM volt checks.
So from what you described, probably lots lambda fuelling correction being added whilst closed loop <3250rpm then when goes open loop, leans off even more after switching to map only?
I've run up to 5500rpm at WOT and fuel pressure is dropping from 2.5 to 2.4 bar (1.5psi drop)
Should it hold rock-solid or is a slight drop expected?
Fault code 23 is no longer appearing since correcting the static test fuel pressure up to 2.5bar.
Should it hold rock-solid or is a slight drop expected?
Fault code 23 is no longer appearing since correcting the static test fuel pressure up to 2.5bar.
Edited by Kev Bamber on Monday 23 July 21:24
That's the fuel filter changed and checked for crimped fuel & return lines.
Whilst under there did some voltage checks. I'm seeing around a 2.75 volt drop between battery & fuel pump. So, around 9.5 volts at pump engine off & 11.2 volts engine running.
Cleaned & remade obvious connectors and terminals, no significant difference but think getting closer to the root cause.
Whilst under there did some voltage checks. I'm seeing around a 2.75 volt drop between battery & fuel pump. So, around 9.5 volts at pump engine off & 11.2 volts engine running.
Cleaned & remade obvious connectors and terminals, no significant difference but think getting closer to the root cause.
Cleaned all terminals and connectors I can access. The only one I can't locate is described as being a brown plug/socket on the bulkhead under heater control unit. I guess part of the dash has to come out to access that.
On the Bertram Hill wiring schematic the pump -ve is just shown earthed, but I presume earths come back on the loom to the front of the car. My earth disappears off into the boot with the +ve.
If no improvement after this, will then consider pulling some thicker wire.
On the Bertram Hill wiring schematic the pump -ve is just shown earthed, but I presume earths come back on the loom to the front of the car. My earth disappears off into the boot with the +ve.
If no improvement after this, will then consider pulling some thicker wire.
Adding an additional earth and cleaning remaining contacts has got me down to a 2v fuel pump volt drop
Time to run a 30amp +ve cable, so unless advised otherwise, I'll run it from the inertia switch.
Before I start, how do I remove the glove box to access the inertia switch, and also any advise of cable routing? I'd like to avoid ripping out the interior if possible
Time to run a 30amp +ve cable, so unless advised otherwise, I'll run it from the inertia switch.
Before I start, how do I remove the glove box to access the inertia switch, and also any advise of cable routing? I'd like to avoid ripping out the interior if possible
As an outcome to this topic:-
Fuel pressure increased by 3.5psi to 36psi
Fuel pump rewired to maintain pressure at WOT
timing corrected to 28Deg BTDC
Throttle pedal stop adjusted so pot at 96% rather than 75%
AFR corrected and detonation cured by extra fuelling and power/torque significantly improved, both by numbers and shape.
Thank you for the inputs.
Fuel pressure increased by 3.5psi to 36psi
Fuel pump rewired to maintain pressure at WOT
timing corrected to 28Deg BTDC
Throttle pedal stop adjusted so pot at 96% rather than 75%
AFR corrected and detonation cured by extra fuelling and power/torque significantly improved, both by numbers and shape.
Thank you for the inputs.
eliot said:
500’s run std 3.9 rover injectors, there’s much debate - but there’s essentially no headroom at wot and run pretty much 100% duty cycle.
I know this from megasquirting a 500 on the oem injectors with dual widebands.
If you paid a pro a pro for a fuel injection setup in the aftermarket they wouldn’t let it leave premises with anything over 80% duty cycle.
So whilst you have your horses back thankfully, like all 500s that left the factory - it’s a ‘that will do’ approach rather than doing what needed to be done, which was bigger injectors. (and proper trumpets rather than some 45mm offcut mild steel tubes but that’s another story)
I haven't just wound up fuel pressure to meet the required AFR, I've returned it to hold the correct 36psi (2.5bar) Rover standard, it was running 3.5psi low. With everything set back to the correct standard, duty cycle never exceeds 80% and AFRs in the mid 12's.I know this from megasquirting a 500 on the oem injectors with dual widebands.
If you paid a pro a pro for a fuel injection setup in the aftermarket they wouldn’t let it leave premises with anything over 80% duty cycle.
So whilst you have your horses back thankfully, like all 500s that left the factory - it’s a ‘that will do’ approach rather than doing what needed to be done, which was bigger injectors. (and proper trumpets rather than some 45mm offcut mild steel tubes but that’s another story)
Yes, considering the plenum & trumpet mod.
Edited by Kev Bamber on Saturday 25th August 10:00
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