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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
 
#41 · (Edited)
It's been drastically reduced by reinstating the stock wiring do you have any more info I appreciate the comments however a point of reference to check or a lead in the right direction would be good

And the fuel pressure slightly higher than stock should be causing the Issues

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#44 ·
Thanks for your input Gary. The guy is asking for help & advice NOT for insults pointed at me as we have not done any work on this car apart from a basic Dyno run & fitted a fuel rail so he can check fuel pressure.. The map has not been changed by us in any way so no blame can be dealt there.
If you have any input to what the issue may be then sure the op will appreciate it rather than trying to put another Trader down.
It seems that your opinion may suggest that you know what this issue may be so please share as a few people may be interested in the diagnosis you have.

Please do Not point the finger when you have no idea what work has been done by us.
I suggest you read The whole thread before you chose your comments as the op has carried out the total restoration project himself.

I Do NOT appreciate your comments & will wait for your reply.
 
#48 ·
With the dremel today I have cleaned the following connections


Connections to fuse box adjacent air filter
Main Ecu earth's and bracket
Tightened alternator connection
Cleaned both battery terminals and connections

Left with all electrical load on ac,heater, fogs etc for 10 minutes

Went for a drive and still the same spluttering 6.7k onwards 😡

Cold startup voltage reading 14.5v
Warm idle voltage drops to 14.1 maybe weak alternator?

One thing to note the 3 pin connector on alternator is not clicking in place and become loose on the way home voltage dropped to 12.4 volts connected then back to 14.1/3


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#49 ·
thinking out loud here so please correct me if im wrong

so of If my ignition system is starting to fail could the issue be spark blowout as its only at very high rpms

say for instance if there is not enough energy going to the coils when the spark is required very quickly 6k+ could be the issue?

or am i totally wrong as its leaning out and spark blowout would cause rich as per dyno graph
 
#52 · (Edited)
complete long shot, but between the inlet manifold and the bulkhead, there is a small, multi wire earth wire, or at least there is on the 5. Say multi wire, i think it was 2 or 3 black wires all joined to single ring connectors each end, but cant remember exactly. Mine was making a poor connection, or disconnected, and made my 5 run funny at high revs. Maybe worth a look, assuming its meant to be there

Stu
 
#53 ·
complete long shot, but between the inlet manifold and the bulkhead, there is a small, multi wire earth wire, or at least there is on the 5. Say multi wire, i think it was 2 or 3 black wires all joined to single ring connectors each end, but cant remember exactly. Mine was making a poor connection, or disconnected, and made my 5 run funny at high revs. Maybe worth a look, assuming its meant to be there

Stu
Is it this wire you are talking about?,


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#58 · (Edited)
above are 0.55

put some old bkr7eix in and cleaned up the coil pack bolt holes not sure if there used as a earth but seems to run better altho now i have the 3 pin plug at the back of the alternator popping off after hard acceleration :wallbang:
will have to secure the plug and give another run, i did see 15v on my interior gauge for a short while before the plug popped off :goingmad:
 
#62 · (Edited)
I had these iridium plugs on my 8 for well over 20k with 0 issues without gapping them and the 6 seems to run better with the same 20k plugs!

Confused
Edit just to add I'll get the alternator plug in place and go for a longer run with them but initial results were good
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#65 ·
You mentioned faulty O2 sensor, did you have a chance of fixing it? Do you have EvoScan logs for fuel trims, ignition timing, O2 voltage (if fixed) and AFR?

From what I can read on the plugs (I am sure there are more experienced pros here!) are few things.
1. Good news is that your car is not burning oil and heat range of the plugs is good
2. Not so good news is that it is indeed running very lean and the top plug is showing the signs of detonation. I'd guess this is the pot which misfires - can EvoScan log misfire events per cylinder?

The ceramic part of the centre electrode should be ruddy brown really.
This is a simple plug reading guide.

Product Font Parallel Electric blue Diagram
 
#66 ·
You mentioned faulty O2 sensor, did you have a chance of fixing it? Do you have EvoScan logs for fuel trims, ignition timing, O2 voltage (if fixed) and AFR?

From what I can read on the plugs (I am sure there are more experienced pros here!) are few things.
1. Good news is that your car is not burning oil and heat range of the plugs is good
2. Not so good news is that it is indeed running very lean and the top plug is showing the signs of detonation. I'd guess this is the pot which misfires - can EvoScan log misfire events per cylinder?

The ceramic part of the centre electrode should be ruddy brown really.
This is a simple plug reading guide.

View attachment 279678
thanks for the reply buddy, so if you click the link above you should see a evoscan log of the run i logged today.. theres some weird readings i have been told :rotz:
 
#68 ·
No not fixed it as yet unfortunately running out of ideas
Could possibly swap the engine wiring loom but that's a bug job I'm not up for at the moment if it was running poor across the entire rpm range I would have done it already

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#72 ·
Couple of suggestions if not already done:
1) Flash a stock map back onto the ECU - does it still do it? Better / Worse?
2) Swap coil packs for a known good set - better / worse?
3) Check / replace HT leads
4) Ask Bob to map it for you to see if it can be rectified IF the above tests (2+3) show as ok.
 
#77 ·
need a evoscan 2.0 cable to reflash or read the map unfortunately i do not have this cable
coils and coil packs swapped from my 8 with 0 running issues inc old plugs - made no difference

found the fuel rail pressure is not holding above 3.5 bar approx (dropped 8 off to rich rg for undersealing explained problem and put a hand pump on fpr and its loosing pressure around 3.5:wallbang:

Part out time?
An Evo 6 should be running BR plugs not BPR plugs, this is recommended by NGK. I believe BPR's are for Evo 9 as they have a slightly different head design with a deeper dome.

The protruding tip of the BPR's have problems with spark blow out on 5-9's which is why people have to run tiny plug gaps.

I had issues at high RPM on my stock 5 with BPR's, but now i'm mapped with BR's at the factory gap running fine.
thanks for the info buddy ill look into this i would however say i have had the same plugs in my 8 for a long time with 0 running issues

NGK - PGR7A, platinum.
NGK - BPR7EIX, iridium.

That's from the evoscan site.

Platinum and iridium plugs give a better spark due to the finer electrodes.
So, they don't need as small a gap as copper plugs do.

What most people don't understand is that when the mixture is all wrong, it's harder to light.

The mixture is all wrong, as seen on the plug.
But that's now the third time I've mentioned it.
you have given an idea yes appreciated your input is but lacking in something there helpful but raise more questions sometimes :confused:
 
#75 · (Edited)
NGK - PGR7A, platinum.
NGK - BPR7EIX, iridium.

That's from the evoscan site.


Platinum and iridium plugs give a better spark due to the finer electrodes.
So, they don't need as small a gap as copper plugs do.


What most people don't understand is that when the mixture is all wrong, it's harder to light.

The mixture is all wrong, as seen on the plug.
But that's now the third time I've mentioned it.



edit just because I've run out of posts.


The manual says 3 bar pressure with vac line off.
33 PSI with vac line on.
The 3 bar with vac line off (43 PSI), that's only for setting it up unless you drive with no vac line.

So the only important number is 33 PSI.
 
#79 ·
looking at your last upload of the logfile something is definatly not right. id advise checking the setup is correct in evoscan. if all is ok the uninstall it completley and then reinstall it again with another version.
ill go back through the thread and see what was happening initially but the logs need sorted for definate to get a better idea of whats going on.
 
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