Still running lean any ideas??

[chris52]

Well I was hoping that I had this problem sorted with the adjustable fuel regulator and to a certain degree it did. But as soon as it gets anywhere near 4k rpm it leans out rapidly.
Below is the graph showing the AFR at different fuel pressure and although the BHP results are ok I realy need to get this fueling problem sorted.
While on the RR Iain from Torque V8 swapped the air flow meter which had no effect so that can be ruled out he also checked the voltages at the throttle pot and pulled out the chip and tested it for me all OK.
So what next
Injectors?
fuel pump? (holds pressure right through the rev range)
Lambda sensors?
ECU?
Wireing problem?
I dont want to go down the road of swapping out everything on a trial and error basis as I don't have very deep pockets at the momment so was hoping that maybe someone had seen this problem before and can point me in the right direction.
Many thanks Chris

[blitzracing]

You say the pressure holds out across the load range? Odd thing is you seem to end up with the same AF ratio whatever base pressure you set the fuel rail to under full load. The ECU cant do this as its all open loop, so its just running whatever the map tells it to with no feedback so it cant compensate for the different pressure, which would still lead me to believe you have a fuel supply issue as it looks like you are hitting the pumps maximum delivery through the fuel line and filter. What pressure where you getting at full power?

[chris52]

I didn't monitor the fuel pressure myself so I'm not sure but Iain said the pressure stayed constant even at full power. Could it be the injectors that are working at there max. The car has done 72k now so maybe they need a good clean. If you think this is just a fuel delivery problem then replacing the pump and having the injectors cleaned should solve the problem.
What fuel pump should I get? and could you suggest a good place for the injector cleaning?

Chris

[Mr MoJo]

Not really a technical type of guy as you know Chris, but would it be worth going the Mark Adams route to get the mapping right. From my limited knowledge (which could be a dangerous thing !! ) you seem to have the a similar problem to me. The advice I was given was to get MA to set the car up properly.
I know you are running the standard chip at the moment, but maybe it's worth going down the MA Tornado route and a session on the rollers ??
Should sort out your fueling problems, as apart from the chip I think you're running pretty much the same set up as me ??

[blitzracing]

Even if the injectors where flat out, Id expect the AF ratio still to alter acoss the range with pressure, as higher the presure, more fuel for the same opening time. Same with the fuel map, even if its wrong you will still get more peak fuel as the pressure goes up. What spec is the engine? Any mods?

[blitzracing]

Just a thought- Was the AFM swap a stock 5AM or a Torqueflow?

[chris52]

The AFM was a stock 5AM straight swap.
Upgrades are smoothbore pipes pre-cats out and carbon trumpets.
The car is running great no missfires, plenty of power but I am a little worried about any hard driving as I have been advised that running this lean can cause damage.
My only problem is that I have no way of knowing if the problem has been fixed until I get it on a RR. So the trial and error basis could work out very expensive.
Is their anyway to test the fuel flow without replacing everything? I can get a a pressure gauge that can be fit so I can read it in the car at full power. I presume if the pressure at the rail stays fairly steady throughout the rev range we can discount the fuel pump.
Is there a way of testing that the ecu is working correctly as I have looked back in the history of the car and although there has not been any notes of running lean it did have to have a full engine rebuild at 42k so maybe this has been here since new.

Chris

[blitzracing]

The fuel rail pressure should be about 38PSI at full throttle, and stay there as the rev's climb to peak, any lowering is going to be a delivery problem or a leaky regulator. The pressure will drop at idle or anything less than full throttle, which is quite normal and correct due to the way the fuel pressure is controled by the vacume in the plenum. I have gone down the route of fixing an FP gauge to the fuel rail on a pipe so I could read it through the windscreen. A bit hairy tring to read it a 6000 rpm, so you need a passenger to do it, but I think an electric gauge and sender would be a better option. You can tell if you still have an issue without a rolling road, by wiring a voltmeter on a long lead across the lambda probe output on one side (Black to white wire) and get a passenger to read the voltage. It should be between 1 and 1.3 volts at full power (The nearer 1.3 the better). If its lean it will drop to 0 volts when you hit 14.35:1 AF ratio. Also check you are getting at least 4.6 volts from the Throttle pot at WOT.(I think we have done that one). I dont see why an ECU fault would create a fault like that, but fouled injectors might. The rolling road will only show the overall fueling, but the V8 fuels each side independently, so one side might be lean, and not the other, so its worth pulling all 8 plugs out and look for variances in colour.

[chris52]

Cheers Mark will get the plugs out and check. I will also check the throttle pot at the ECU as its only been checked at the plenum which showed the nesacery 4.6v.

Simon I agree that MA chip and RR session would be a good step but I realy need to resolve the underlying problem first. If the injectors are at fault then no amount of remapping will sort it.

Chris

[blitzracing]

You will find a good proportion of Mark Adams time is spent checking the state of things to start with. After all no point in mapping it if something else is wrong. I know he frequently has problems with fouled injectors, and it can be seen by the plug colour being uneven around the ceramic plug tip. If the spray pattern is poor, then one side is "washed" clean, the otherside is OK, but this is checked after a full load run on the rollers, and then quickly kill the engine to check the colours once the engine has cooled (A plug chop). I suspect you would get different answers if you did a normal road test, and then checked having let the engine run at less than full load before you stopped it.

[blitzracing]

Another quick thought..I read somewhere that the fuel pumps overheat when they get covered in road muck, so it would be worth a check.

[spend]

Fuel cools the pump AFIK

[chromosome17]

No expert, but....one is, there are high performance fuel pumps out there which claim better performance, and the other is any kinks in the fuel line maybe where its copper pipe round the gearbox?

[blitzracing]

spend said:

Fuel cools the pump AFIK

Id agree with you on that, but this was from a TVR dealers web site saying it was a common problem so I thought it worth a mention. It does not happen to Ginetta's, but instead rust from the tank blocks the feed pipe to the pump as the filtration is (or was in my case ) poor between the tank and pump.

[spend]

Sure you read the site properly? The only thing like that I can recall was along the lines of internal muck jamming the pump around a discussion of the tank - pump plumbing?

[blitzracing]

I dont think so as it referred to road mud build up on the pump body, not the inside but Im not going to spend hours on Google looking for it just to prove a point however when its just a passing thought.