hey guys
so basically iv had some horrible luck with a misfire i cant seem to find

the car has stock ecu and a brand new link ecu right next to it ready to be fitted

mods

2.3 stroker
PTE6466
GSC S2
ID2000 injectors
sparktech COP

the car basically broke the wastegate off the manifold
had it rewelded during the process we damanged the cam sensor plug

we replaced both the plug and the sensor

we have replaced coils
injectors have been cleaned and tested
multiple sets of plugs and plug gaps
vac line check
boost leak test

the car misfires at baout 2k rpm on part throttle

just goes pig rich as it misfires

nothing has been changed or added since the wastegate issue

car ran perfect all day everyday


car shows no fault codes at all even tho its missing

HELP!!!!


Misfire only at part throttle. Revs up well with WOT

 

Did cleaning the injectors alter the rich spot at all? Have you tried pulling fuel out of the tune where it goes rich?

 

cleaning did nothing at all

map has not changed in a year. ran perfect

 

Well, true misfire will show lean due to unused oxygen in the exhaust. Pulling fuel from the tune will confirm it's getting too much fuel, and we can go from there. Or you can datalog and see what IPW is doing vs load, etc.


Is the car on speed density? Possible it's a bad Omni 4 bar..

 

By the way you describe things, the engine is indeed misfiring. It will not show lean in the exhaust on an afr gauge as the excess unburnt fuel self ignites in the exhaust system, most possibly just right after the exhaust wheel.




Check if the crank sensor is getting the right voltage, if it does, switch it with a brand new one.








Marios

 

If your car is running fine WOT (open loop) your issue may be limited to closed loop only.

The difference between closed loop, and open loop is that the PCM uses the oxygen sensor only in closed loop.

I'm wondering if you damaged the oxygen sensor too, and for whatever reason it is sending a lower than 450mv signal to the PCM telling it "hey, I am running lean, add fuel to the trim".

This is what I call a "false lean".

In my situation I would put my oscilliscope on the oxygen sensor signal and look at the voltage and observe if the signal is greater than 450mv at any one point in time. Fluttering the throttle at idle should drive it rich from time to time, and you can observe this on the oxygen sensor. Also, if you spray gas propane into the intake, you should be able to observe a change in the sensors reading.

Also, if the heater circuit on your oxygen sensor is shot, it will have a very high internal resistance which causes it to read lean all of the time regardless of the actual mixture. This causes the PCM to want to add fuel.

I hope this gives you a few things you can troubleshoot that will either confirm they are, or arent a problem.

 

It is unlikely to be the oem o2 sensor as firstly there is no way of damaging it, at least without knowing it. Secondly if it sends the wrong millivolts it would for sure greatly affect the closed loop idle conditions with the first indication having from a slightly rough idle to a heavily rough idle, very indicative of evos, and the way the evo stock ecu works in accordance to the o2 sensor as it relies completely on it without any other way of correcting and adjusting idle afr.





My experience with evos has shown me that when their idle slightly suffers due to a faulty o2 sensor, the part throttle and wot is fine, when the idle suffers heavily that is when part/light throttle mostly low load low revs up to 5K usually develops a rough misfiring stuttering condition.














Marios