Car leaning out on boost. WOT switch signal? Other causes ?
06-25-2015, 11:10 PM
#1
Three Wheelin'
Thread Starter
Car leaning out on boost. WOT switch signal? Other causes ?
OK have had car on dyno to try and sort it out and it is leaning out massively on boost.
The car was doing same with old ECU and AFM which have now been replaced with M tune/MAF. Mechanic is saying that it is FP not getting triggered to deliver more fuel. FP is fine(new LR HV unit, new fuel filter). FP was bench tested.
As this was happening with old ecu and afm, so I know MAP sensor isnt the issue.
All I can think of is that the TPS harness may be faulty ? TPS was resealed with arnworx kit. Connector was replaced. TPS sensor replaced
Everything has been replaced and I mean everything. New Turbo, new fuel lines, new rail, new inj with M tune. New speed and ref sensors and harness. New Inj harness, and probably anything else you can think of.
Anyway if anyone can think ofr another cause of FP not ramping up please let me know
cheers
The car was doing same with old ECU and AFM which have now been replaced with M tune/MAF. Mechanic is saying that it is FP not getting triggered to deliver more fuel. FP is fine(new LR HV unit, new fuel filter). FP was bench tested.
As this was happening with old ecu and afm, so I know MAP sensor isnt the issue.
All I can think of is that the TPS harness may be faulty ? TPS was resealed with arnworx kit. Connector was replaced. TPS sensor replaced
Everything has been replaced and I mean everything. New Turbo, new fuel lines, new rail, new inj with M tune. New speed and ref sensors and harness. New Inj harness, and probably anything else you can think of.
Anyway if anyone can think ofr another cause of FP not ramping up please let me know
cheers
Last edited by Cyberpunky; 06-26-2015 at 06:42 AM.
06-25-2015, 11:43 PM
#3
Rennlist Member
> fuel pump not being triggered to deliver more fuel
Is that a thing on turbo cars? I though the FPR was responsible for the fuel pressure based on vacuum. Seeing as how we have a return line and all. Shouldn't it be either 12V or 0V?
Is that a thing on turbo cars? I though the FPR was responsible for the fuel pressure based on vacuum. Seeing as how we have a return line and all. Shouldn't it be either 12V or 0V?
06-26-2015, 12:33 AM
#4
Rainman
Rennlist Member
Rennlist Member
wiring diagrams indicate theres no DME control of the fuel pump.
have you checked your tune at all? i had to add a lot of fuel with my MAF setup for the injectors i was running, like 20% more, vs the "out of the box" tune.
have you checked your tune at all? i had to add a lot of fuel with my MAF setup for the injectors i was running, like 20% more, vs the "out of the box" tune.
06-26-2015, 01:55 AM
#5
Nordschleife Master
The fuel pump is constant rate. Volume of fuel to the engine is changed with fuel pressure which is regulated by the fuel pressure regulator. First off, make sure the vacuum line is connected to it. The FPR will increase fuel pressure as it sees boost.
06-26-2015, 02:12 AM
#6
Freedom Enthusiast
Rennlist Member
Rennlist Member
The OP said he bench tested the fuel pump. Could a wiring issue to the FP cause it to run slow/intermittent which would cause low fuel pressure regardless of what the FPR does?
06-26-2015, 02:21 AM
#7
Nordschleife Master
You could get voltage drop at the pump due to insufficient wiring. If you put in an 044 pump its basically required to run it off a relay. Ive had no issues running the same high volume pump (same as Merc 460SL) on original wiring.
I think the first thing that needs to be checked with the fuel pressure regulator.
I think the first thing that needs to be checked with the fuel pressure regulator.
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06-26-2015, 02:38 AM
#8
Three Wheelin'
Thread Starter
that all makes sense so could it be the TPS(harness as plug and TPS sensor replaced) not triggering the WOT switch, which would change mapping for DME to increase injector output ?
The issue was happening with old DME/AFM/FPR(2.5baR) and hasn't changed with Rogue DME/M tune/3 bar FPR, so am skeptical FPR is issue. FPR has vacuum, no leaks in vacuum anywhere(tested)
The issue was happening with old DME/AFM/FPR(2.5baR) and hasn't changed with Rogue DME/M tune/3 bar FPR, so am skeptical FPR is issue. FPR has vacuum, no leaks in vacuum anywhere(tested)
06-26-2015, 03:08 AM
#9
Freedom Enthusiast
Rennlist Member
Rennlist Member
Do you have a fuel pressure gauge to see if fuel pressure is the issue. If you know that it is producing sufficient fuel pressure(via a gauge) then the issue is why the injectors are not dumping enough fuel.
From you first post, I am assuming that you are now running new 80# injectors with the M-tune.
From you first post, I am assuming that you are now running new 80# injectors with the M-tune.
06-26-2015, 06:35 AM
#11
Three Wheelin'
Thread Starter
Assuming I have proper pressure at fuel rail. What could be the cause of DME not ramping up fuel inj to supply enough fuel on WOT/boost ?
I believe the ECU isn't getting injectors to supply more fuel when on WOT/boost. I have replaced TPS sensor, rebuilt throttle body with new seals via arnworx kit and TPS connector but not harness. As DME has been replaced from a known good unit to a Rogue DME with M tune, and FPR was replaced at same time with 3 bar unit, I am ruling out DME and FPR. New injectors, new Inj harness, new S&R sensors and harness. Sorry for repeating myself but if anyone speed reads or skips posts we will be still on same page
I believe the ECU isn't getting injectors to supply more fuel when on WOT/boost. I have replaced TPS sensor, rebuilt throttle body with new seals via arnworx kit and TPS connector but not harness. As DME has been replaced from a known good unit to a Rogue DME with M tune, and FPR was replaced at same time with 3 bar unit, I am ruling out DME and FPR. New injectors, new Inj harness, new S&R sensors and harness. Sorry for repeating myself but if anyone speed reads or skips posts we will be still on same page
06-26-2015, 10:05 AM
#12
Rennlist Member
Glad to see that you're back on here, Bruce..How did everything go at the mechanic's shop that you took your car to? just wondering what the final outcome of your prior problem was...??
06-26-2015, 10:33 AM
#14
Rennlist Member
Are you using the right FPR? I'm not sure if there's a difference between the turbo one and the NA one, but maybe that has something to do with it.
On the NA the vacuum signal changes the resistance force against the diaphragm to keep the pressure in spec. It stands to reason that if that vacuum were changed to positive pressure, it would sway the pressure the opposite way (pressure in rail drops as boost increases). Does the 951 3 bar differ from the 944S 3 bar?
On the NA the vacuum signal changes the resistance force against the diaphragm to keep the pressure in spec. It stands to reason that if that vacuum were changed to positive pressure, it would sway the pressure the opposite way (pressure in rail drops as boost increases). Does the 951 3 bar differ from the 944S 3 bar?
