Im not sure if this happened to somebody else but i hope you can give a piece of advise:

It started the las week on a trip when traveling in high boost almost all the way long (2 hours trip). For any reason the engine started to cutting itself off when reaching 3500-4000rpm...no matter how hard and fast i tried to depress the throttle pedal it seemed like no more fuel was allowed to go into the engine when going at that rpm value. I though it was running without fuel because it felt like that, i mean, when the fuel pump started to suck air instead of fuel. Stopped the car, filled the tank full of fuel and noticed the engine was really really hot....as never before....the intercooler was really hot also. Started to move an happened the same thing, the engine was cutting the fuel delivery in the 3500-4000 range.
The next day everything was normal until a period of time of hard driving when the engine started to do the same ****.

After all that, the engine started to feel harsh and loud at mid and high rev and despite of the fact that turbo is generating the correct boost pressure (read on gauge) it seems that sometimes needs more rev to do it. Normally it was very clean and smooth, 0psi at 2000rpm and then 16psi in the 2800-3200 rpm range the made the car the feel like a rocket with a nice "ssssssssssss" sound. Now, when it feels harsh, do the same thing in the 3000-3500 rpm with a very loud engine sound...when the engine behaivor is like this, the engine hood is very hot.

There was no fault code displayed during engine tests but i think i´ll be replacing injectors harness in first place. If you guys have an idea on what could be happening with the car, im all ears...

P.S: the car is a Lancer EVO IV with MBC set to16psi of boost (std: 14psi). There is no more mods.

 

Honestly, since this is an older car, and I'm uncertain how similar it is to more current generations, I cant offer much input.. But the symptoms you are describing sound to me like Fuel Cut.. Does the earlier EVO have a similar MAF sensor to the Eclipse or later Evo??

I've always associated stumbling and rough driving with either fuel cut, or some form of misfire, so you can look at your coils, plugs, plug wires, and ignition harness also.. Poor performing fuel injectors, bad injectors (plugged), or a bad wiring harness can also be an issue, but your saying it doesnt happen all the time so I'm inclined to not think its really anything in the way of the injectors. You can always check the fuel pump also, it could be not providing enough fuel under certain circumstances. Not sure if this applies to earlier cars, but on the USDM Evo, the pump has a low and high output ECU Controlled using a relay, so under cruise the low setting is running, and under high, it boosts the fuel output slightly with more voltage.. if its similar you could check to make sure its not functioning inconsistently.

Almost anything electrical (if its a short or open circuit) "Should" trigger some sort of Check engine indicator. And an excessive timing, issue, lean condition, or misfire condition should also trigger the check engine (if its capable of detecting it)

Honestly, in the end, you may be looking at a closed loop drivability issue, in that case, check the front O2 sensor.. it may be reading incorrectly, or damaged/fouled, but not actually "Bad"

Sorry I couldn't help more, all of my experience is with USDM 4G63 engines..

 

Thanks for the "brain storm" i really found it very usefull.
The EVO IV 4G63 engine uses the same MAF sensor type than regular Lancer - Mirage 4G93 and later EVOs, not sure with the Eclipse´s series. This is a Japanesse spec EVO and its is supposed to run with +100 octane fuel but i allways used the regional available 97octane.

Yesterday i installed an A/F indicator but i have some doubst about if its working properly (= the O2 sensor is working properly):
After the first start of the day (cold engine at idle) it shows me the "Lean" zone until the engine gets warm but it doesn make any sense for me as it´s supposed the ECU progam perform rich mix configuration by default during cold starts, am i right? When warm at idle the indicator is constantly moving from the "Steich" zone to the "rich" zone and during hard accelaration is in the "rich" zone all the way long....perhaps i have it installed in the wrong way?

Yes, it is some sort of fuel Cut but what´s triggering it?
Because all this problem happen after long and hard driving it seems like an engine protection from higher temperatures...as i mentioned before i almost cannot touch the intercooler nor the engine hood when this happen. Can the I/C be so hot after hard driving?...i´ve never felt it before.
I´ll perform a CO, NOx and CO2 test again and compare it with former ones in order to know if more fuel is been delivered for any reason. If turbocharger is dying maybe the lack of proper air flow leads the engine to overheat...
I have to solve this one.

 

Oscar, sorry to hear about your problems, I wish I could help! Good luck!

 

Well, if you suspect the O2 sensor, it may take a long time to heat up, when the engine is cold it should run in open loop for a period of time, it could be related since open loop maps will infer fuel demand based on internal parameters and will do very little to adjust them environmentally (Throttle position, RPM, and Maf readings are referrenced for proportion, but the mixtures themselves are fixed in the map)

If the car NEVER goes into closed loop operation (Bad O2 sensor) then unpredictable fuel cuts are definitely possible at part throttle, boost spiking to a level where the car thinks there's a problem is another possibility and it will only be compounded by open loop maps (Generally rich)

FYI although an A/F indicator is not very accurate, when the car is in closed loop operation (and the O2 sensor is functioning correctly) you should see its voltage swing back and forth as its adjusting in closed loop.. If its not working, you should see its voltage either at a fixed level and never change (possibly excessively rich or lean, hence your fuel cut)

I'm almost certain that anything like this would trigger a check engine indicator though..

Over heating could also be a problem, but you should at least see that on your temp gauge and indicator lamp.

Hmm.. heat can cause detonation which will definitely trigger the engine to run poorly.. you could have an obstruction in your intercooler causing problems, or something preventing the intercooler from performing correctly.

I have never run my car hard enough to not be able to touch the intercooler pipes, but they can easily get hot enough to burn you under very hard driving. Of course, under hard driving.. the turbo and exhaust manifold can get so hot that it transmits an obscene amount of heat to other things under the hood, and through the hood..

Also, check to make sure your radiator fans are kicking over, their not really needed while your moving at a constant speed, but if you stop, it will quickly cause the temps in the engine to rise, possibly triggering the car to limp..

Outside temp, humidity, or whatnot will have an effect also..

 

Oh.. let me add if your O2 sensor is working unpredictably, its possible that the car is running too lean on a regular basis (perhaps the o2 sensor is reporting rich and the car keeps removing fuel, reproducing what would be percieved as a fuel cut) Now, inferring that this is the issue, it will explain EXTREMELY high EGT temps, therefore the exhaust manifold, turbo, and everyhting under the hood can get extremely hot..

Thats about all I can think of at the moment.. FOcus on the O2 sensor for the time being..

 

Well, engine temp gauge didnt show anything abnormal in fact the needle was exactly the same place as allways. I´ll be looking for having a pyrometer installed in my car.
The I/C was disassembled and no problem was found other than small amounts of oil in all inlet line.
The CO readings are my concern. It resulted in 1.72ppm at idle (750rpm). Former test (3.5 months ago) showed 0.76 at idle..that means that more fuel is now burned in the engine, why? i dont know yet...
Unfortunatelly there is no O2 sensor available to swap but i´ll start checking inyectors and changing harness and all that stuff that i already got it.

Before doing this job we noticed something else: we tested the car again and the same problem started but with one more signal...the low fuel level warning light was ON despite of the fact that the gauge needle was in the 1/4 mark with proved fuel added yesterday.

It is well known that our fuel is one of the worst in S.America, in fact some japan-directly-imported car´s owners reported failures in O2 sensors and electronics fuel pumps but nothing compared with such symptoms (failure after long and hard driving).

 

Damb you get 97 octane and thats bad fuel?

 

Yes, mainly because of two reasons: knocking in some japanesse imported cars (specially subaru impreza WRX & lancer EVO designed for higher octane fuel spec) and high sulfur levels that really hurts sensors / electronic fuel pumps and engine parts as leads corrotion and affects some of the oil properties but i cant tell you too much about that.

 

Check your oil level, you probably burned it up.

 

Depends on what standard the fuel is measure in. This may not be as good as you think as different rating systems are used in different countries and so not all numbers mean the same thing. 97 RON (European standard) is only about 93 PON (US standard for measuring Octane). In the US service stations use the Pump Octane Number or PON rather than RON, this is the average of RON and MON and gives a much better grade.

 

Check for boost leaks. You could be overboosting your turbo and blowing 17psi of hot air into your engine making it more knock prone. Sounds like the ecu is going into a limp mode and almost inducing a fuel cut.

 

Yesterday in a closing inspection to inlet lines we noticed that one of the plastic hoses (the one that matches the throttle body) was really bad and we replaced it...after finishing the planned job we will test the car for air leaks as the high I/C temperature could mean that air has been getting really hot from the turbo (thank you Boosted).
We changed inyector # 1 as its black o´ring was damaged and some fuel could be leaking throug it into the combustion chamber. Perhaps the CO increase and some of the high engine temperature could be linked to that point.

Well, i let you know how this "little" problem is going...

 

Please keep us posted...

 

Ok, we finished our first test sesion.
We removed intercooler and have it tested (air at 35psi) finding AIR LEAKS from center panel (it was damaged time ago)...not too much but they were present. We replace the IC with one from an EVO V and swap the O2 sensor with a Lancer GSR 4G93 turbo: it takes more time to show that problem but it´s still present!!! The Lancer 4G93 started to have problems at idle when using our O2 sensor (we really dont know if they are EXACTLY the same or why we did not have the same problem but they looked pretty similar and fitted perfeclty).

The CO value decreased also. We noticed some oil leak through one gasket (the one located below camshafts cover) directly to the spark plugs compartments. When removing that cover we found that gasket with some damage i think due of overheat.

Removed the turbo and found one problem: wear in compressor bleeds as a result of slight contact between those bleeds and compressor housing....air leak at that point is possible, i´ve seen this before in an EVO VI but with different sympthoms including a sound that you´ll never forget but...
We´ll change turbo tomorrow and test it again.