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[TheBoy]

Reply from Bro, who read this thread yesterday...

I've not look yet. It is returning fuel. I connected a short length of pipe and container to the fuel rail outlet and it filled a 200ml (approx.) container in approx. 5 sec.
Turned the engine of just in time before it over flowed.
 
Another thought is could the purge valve be stuck open?  Looked inside the throttle body and the chamber appears to be wet?
 
Would burning oil cause long fuel trims and high emissions. Sometimes when I remove the EGR valve (especially as it is blanked off at present) a small amount of oil runs out of the inlet manifold.

[TheBoy]

Ah the standard "I've been rumbled" response.

If it was a standard run of the mill engine, the parameters you've checked would mean all was well on a normal engine. There for, it's not a "normal" engine. There for the model and engine details might help. Just saying. Like.

What have you been smoking, I want need some

LTFTs at anything other than 0% is NOT normal on ANY petrol injected car (with closed loop capability). You know that. So still in realms of standard petrol diagnosis.

[TheBoy]

http://pages.suddenlink.net/daydreamer/Coupe%20TSBs/Fuel%20System/10-FL-009%202.0L%20AND%202.4L%20THETA%20ENGINE%20ETC%20THROTTLE%20BODY%20CLEANING.pdf

worth a try,coolant temperature sensors can also cause issues not unlike what you describe

Thanks, I'll get him to check. I know he's cleaned the idle valve, not sure if a different item on his engine, or if he's done your procedure

[chrisgixer]

Right, so he still doesn't know what car it is.

[TheBoy]

Right, so he still doesn't know what car it is.

Reply #18 

[TheBoy]

Further update from Bro

It's a Hyundai santa fe 2.4ltr petrol  2002
The fuel filter is an in tank type. The fuel pump sits inside the filter and can only fit one way. When it arrived I thought it was a star wars toy.
There is only one ECT that does both dash and ECU. As I get a reading on the dash temp gauge and approx. correct reading on code reader I think it's ok.
FPR vacuum connection and pipe look ok. (doesn't mean it's not faulty)
new O2 sensors fitted.
 
Some good news I swapped over the fuel return and 2nd tank connections and the LTFT is much improved whilst driving, still in the minus range but sometimes goes back to 0% and the car fells more lively. Unfortunately at idle the LTFT goes back to -12.5% and if the STFT is a high minus the O2 sensors just reads rich. If you lightly rev it and get the STFT down the O2 sensors start switching again.

[chrisgixer]

If it helps, its a Hyundai Santa Fe 2.4 (I think)

Ah, so TB is evasive because TB doesn't know.

I'm pretty certain. Well reasonably

It was more as the car wasn't relevant, as virtually all petrol injection systems are identical in operation.

Ar you sure this time?  Absolutely certain?


No idea about these, sorry.

[chrisgixer]

So its rich, yes? (Being serious for a minute)
So not fuel restriction.

Temp sensor correct? As Al said.

[TheBoy]

And...

When I block the FPR vacuum hose there's no change in fuel trims or O2 switching. I'd expect the fuel to go rich(er)

[TheBoy]

So its rich, yes? (Being serious for a minute)
So not fuel restriction.

Temp sensor correct? As Al said.

As above, live data shows ECU coolant temp reads approx. dash temp.

[Entwood]

And...

When I block the FPR vacuum hose there's no change in fuel trims or O2 switching. I'd expect the fuel to go rich(er)

If the FPR is knackered, could it be supplying fuel at way too high a pressure thus causing mahoosive overfuelling ?? which the fuel trims are desperately trying to cut back, hence the high minus values ??

[Kevin Wood]

So, something's causing it to go pig rich at idle. Guessing if the lambda sensors were lying, by the time the fuel trim has got to -12% it's be idling pretty rough.

Could be purge valve stuck open, I suppose, but wouldn't have thought it would draw that much vapour in. Easily eliminated by clamping the hose to the carbon canister.

Leaking fuel injector, perhaps? Is it worth jury rigging the fuel pump to run and looking down the manifold to see if one of them is dribbling?

After a bit of idling, cut the engine and inspect each spark plug? Are they showing signs of running rich? Are they all looking the same or is one especially sooty / wet?

How does it run if you disconnect the lambda(s)? Guessing it'll revert to 0% trim in some kind of limp-home strategy. If it really was rich, it'll idle grumpy. Ditto if disconnecting the MAF, I suppose.

[TheBoy]

So, something's causing it to go pig rich at idle. Guessing if the lambda sensors were lying, by the time the fuel trim has got to -12% it's be idling pretty rough.

Could be purge valve stuck open, I suppose, but wouldn't have thought it would draw that much vapour in. Easily eliminated by clamping the hose to the carbon canister.

Leaking fuel injector, perhaps? Is it worth jury rigging the fuel pump to run and looking down the manifold to see if one of them is dribbling?

After a bit of idling, cut the engine and inspect each spark plug? Are they showing signs of running rich? Are they all looking the same or is one especially sooty / wet?

How does it run if you disconnect the lambda(s)? Guessing it'll revert to 0% trim in some kind of limp-home strategy. If it really was rich, it'll idle grumpy. Ditto if disconnecting the MAF, I suppose.

LTFTs on this ECU max out at -12 or +12, so impossible to say how far beyond this its actually going (to be absolutely accurate, for Mr Pedantic Gixer Bloke, its 12.5%, which is what bro is seeing.