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evo 6 suddenly running lean at high rpm

28K views 150 replies 26 participants last post by  Gary @ APT 
#1 · (Edited)
So had my 6 at dynotech today having issues with the car suddenly running lean high rpms 6.5k+ at 0.7bar (ish)

have changed the fuel pump wiring to nevereverman hardwire kit
changed to new walbro pump
changed to known good fpr
tested injector resistor pack all resistance is coming back 6ohms so all good
new 8mr bov
new sas gasket
new fuel filter's
new avcr solenoid

will be looking into the condition of the main fuel lines from tank to engine bay as the cars had shell swap and possibly slightly bent in the process
also has evo 4 fuel tank

will be doing boost leak smoke test & checking fuel lines from tank to engine bay
thought id ask the mlr massive advise where else to look :smthumbup
 
#82 ·
Taking into account of how important a role spark plugs play I do not think there is point in saving on them at all and you can get a set of HKS Superfire Racing plugs for £55 or so.

I will Pm you re Tactrix when I get a minute to find links.
 
#111 ·
Going on last nights testing it seems the fuel pump pressure relief valve is opening at around 50psi

I believe the 255 pump I have is rated at 80psi

Clamping the fuel return hose found the pressure in the rail raised to 5 bar but quickly dropped back to 3.5 bar in the space of a second

Does anybody have a stock fuel pump laying around i could borrow to test this?

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#114 ·
So fitted a new walbro 255 pump today also connected the hardwire kit checked fuel lines around the fuel pipe and along the underside to the bulkhead

Still have the same issue.

One thing to notice I removed the fuel return pipe underside of the car at rear pumped 2 bar into the fuel rail and in 1 minute the return pushed back 2.5litres of petrol with some air mixed in possible it was running the tank dry as not much left inside

Thoughts welcome

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#115 · (Edited)
Have you fitted a pressure gauge yet?

Too hard?


edit, running short of posts again.

Don't know why you're wasting your effort swapping pumps again when it's obvious that by fitting a walbro, your idle pressure has gone up by 6 ish PSI.
It makes the fuel trims try to lean it out at low load then it's too lean at high load and the plugs end up sooty on the body.


"Opinion" doesn't factor into it.
It's FACT.


A stock pump idles at 33 PSI.
A walbro will idle at 38 or 39 ish PSI.
As you can see from the gauge.


It doesn't take an Einstien to figure out that you fkcued it up.
But it's not the only problem because it never is.


By eliminating the "known" problems, you only get left with the "unknown" problems to sort out.
 
#129 · (Edited)
So Fred, how is a larger pump overcome on the later models then? You've still not answered my question? Edit the post above if it's posts you don't have. I think a lot of what you say on some of these threads is good advice. But you sometimes seem to ramble. Would you mind also updating your opinion on the forged piston thread. Many thanks

This one - http://www.lancerregister.com/showthread.php?t=538467&page=3
 
#132 · (Edited)
I would add the cold start pictire was taken so presumably the cold start valve would have been active. Maybe that increases the pressure

I have another fuel line to try and a set of injectors to fit will update thread when I have time to do the above work

Edit would replacing the 3 injector seals be advisable when fitting another set of used injectors?
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#143 ·
The 'norm' is to fit a hardwire kit as grants suggested as it just means you know you always have a nice constant feed of battery power, rather than the stock voltage switching one.

I normally make a hard wire kit to fit next to the pump wiring under the carpet on the offside rear just by the rear bench. Then it's easy to pick up the stock power feed as a trigger for the relay :smthumbup
 
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