Overfuelling Issues

[Jonny_FRS]

Hi all.

I’m currently battling an issue with my Focus where it is massively over fueling. Looking at the live data, it is learning (after an ECU reset)/running around -18 long term fuel trim (LTFT).

The car smells really rich on idle and is trimming fuel both on idle and whilst driving. When placing any load on the car, it feels lethargic and doesn’t always hit hitting peak boost which is what first alerted me to an issue.

I have checked all the usual things, and swapped out a load of parts but the fault remains the same unfortunately.

Here’s the extensive list of things I’ve tested/replaced:

• Fitted spare boost solenoid (pipes all look ok)
• Fitted forge actuator (car was on original)
• Serviced Forge DV with new piston and seals
• Fitted replacement Roose hose from chargecooler box to DV
• Checked turbo both sides and spins freely with little play
• Wastegate/penny washer ok
• Fitted Roose crank case hose (one way valve seems ok)
• Samco boost hoses pressure tested
• Roose turbo intake pipe already fitted
• Brand new MAF sensor fitted
• New plugs gapped to 0.7mm
• Fitted new HT leads
• Coil pack was new last year (tried spare - no change)
• Smoke tested inlet manifold and no visible leaks
• Boost pressure test - no evident leaks. Hissing from cam cover area
• No coolant in either boost hose from chargecooler
• Genuine ICV fitted. Seal replaced.
• Spare map sensor tested (I’m told the TDCI uses the same sensor)
• Fuel regulator vac pipe has no fuel in it
• Changed regulator vac pipe that runs to inlet
• Fitted new genuine lambda sensor
• Tried new crankcase hose one way valve (it’s pointing in right direction)
• Tried new PCV valve
• Tried used EVAP canister
• Swapped MAF back to old. Fuel trim and readings still the same.
• Isolated brake booster, no change.
• Brake booster one way valve working ok
• Fuel pump, filter and fuel changed
• FPR holds vac + pressure
• Manually operating FPR with hand pump adjusts fuel trim
• Used inlet manifold fitted along with new seals/gaskets
• Checked and cleaned all engine bay earths
• Injectors professionally cleaned/tested

I’m monitoring live data using Forscan. On idle the MAF is reading late 4g/s to early 5g/s which I believe is high. Fuel trim almost instantly jumps up to -18 STFT during the relearn process after a ECU reset then transfers to LTFT after an ignition cycle.

Car is mildly modded with Bluefin, FMS manifold, Milltek exhaust/decat and K&N Gen2. No recent changes and these mods have been on the car for around 20 years.

Has anyone ever had a similar issue who could offer any help/advice?

Thanks to those who have made it this far.

Cheers

Jonny

[S1_John]

From my experience the Bluefin map runs slightly rich. I get loads of fuel on mine on overrun and flames on track days.

[Jonny_FRS]

The amount of fuel mine is pulling is a massive amount. Another owner with bluefin has data logged their car and it’s getting somewhere around +3 to -3 STFT on average at idle with no LTFT.

[Johoo_NL]

i have Bluefin (AE map), Primary Design manifold and Sportscat with a BCS exhaust. I can check my STFT if you tell me how i could do this. Can i check it with Scangauge?

[Jonny_FRS]

i have Bluefin (AE map), primarydesign manifold and sportscat with a BCS exhaust. I can check my STFT if you tell me how i could do this. Can i check it with scangauge?

Thanks for this. You would need to use a tool which you can view live data/diagnostic info, like Forscan or something like a Texa unit or Snap on unit. Basically anything which allows you to view readings such as lambda and fuel readings etc.

[Johoo_NL]

Thanks for this. You would need to use a tool which you can view live data/diagnostic info, like Forscan or something like a Texa unit or Snap on unit. Basically anything which allows you to view readings such as lambda and fuel readings etc.

I am familiar with Forscan. I'll check in a few days. Have to install Forscan again.