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Tuning Issue That Has Got Many Of The Best Minds Stumped.

D_Stirls

By D_Stirls,
in Engines & Forced Induction

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zebra Grand Master

zebra

Posted
Posted

Given the people involved, the diagnostics they have been resorting to and generally giving them credit I'd think (or hope) that its almost insulting to make these suggestions on the assumption they weren't the first points of call. It'd be very interesting to see a datalog file as the car warms up, however - if that were a possibility?

You would be suprised

ARTZ Grand Master

ARTZ

Posted
Posted

Amount of fuel to flow out of the injector is dependant on the opening time(For this purpose we will ignore injector lag times) and fuel pressure.

The more fuel pressure the more fuel will flow at the same opening time(This is also discounting changes in manifold pressure)

If you have a faulty FPR it could make the fuelling go all over the place.

That said if injectors are not getting a constant good voltage source, injector opening times will change, this will change the amount of fuel being injected but wont nessesarly change the pulsewidth's especially if the ECU is not seeing the same voltage drop

not sure if this is relevant

..but when i got my car tuned originally I had never changed the fuel filter. Must of been dirty, then i changed it oneday giving it a serivce and all of a sudden was running very rich .first got told it was a boost leak ,I thought it was FPR busted cause I had hooked fuel lines up wrong at first, but it was just a filter that changed pressures and threw my whole tune out.. :/

Trent fixed it I dunno how ...had him stumped for a while too...

T-Rex Enthusiast

T-Rex

Posted
Posted

Since most things have already been pointed out, what about the grounding of the engine to chassis, etc. I know the BA Falcon's have an issue where they would run rich and even stall, all caused by the chassis/motor grounding being installed wrong.

Rolls Grand Master

Rolls

Posted
Posted

Given the people involved, the diagnostics they have been resorting to and generally giving them credit I'd think (or hope) that its almost insulting to make these suggestions on the assumption they weren't the first points of call. It'd be very interesting to see a datalog file as the car warms up, however - if that were a possibility?

Well it basically has to be one of these things, how else does fuel magically get into the cylinder?

Amaru Veteran

Amaru

Posted
Posted

Tried another ECU that isn't a Haltech? I had a *very* similar issue along with some other "electrical gremlins" (intermittent misfiring and some other problems), the Haltech setup had been checked by many people whom could see nothing wrong with it - swapped it out for an Autronic ECU and the car has never run better.

Never did resolve the problems with the Haltech, as said many people had looked at it and said there was nothing wrong with the setup, it just would not work reliably in my car for whatever reason. Power FC had no problem, Autronic has no problem, Haltech had nothing but problems... *shrug* go figure.

Rolls Grand Master

Rolls

Posted
Posted

Yeah this isn't the first time I've heard of nondiagnosable problems with a haltech, most people end up fixing it by using another ECU.

Might not be the ECU, might be some weird combination throwing it out, but sometimes its just cheaper and less time to try another ECU.

Lithium Grand Master

Lithium

Posted
Posted

Yeah I was wondering about that too, ECU sounds like it CLAIMS its doing everything right - fuel pressure sounds right, something "lying" is the next most likely option.

Beer Baron Grand Master

Beer Baron

Posted
Posted

yes sadly if you are paying a workshop $100-$150 an hour to diagnose a problem it can often be cheaper to switch to another ecu if the problem is specific to that brand ECU... considering you're likely to recoup 50-70% of what you paid for it the changeover cost to a new ECU may not be too bad.

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