4G15 GDI Mysterious Problem

[Sampson10]

I have a Mitsubishi lancer (2002 model) with a 4G15 (CVT) GDI engine. Lately I have been experiencing some problems that seems very difficult to identify. When AC is off car works perfectly, but when AC is on car stutters, loses power and cuts off when stopped or slowed down. Checked coil packs, changed spark plugs, serviced throttle body, serviced air intake sensor etc. Still experienced same problems so mechanic said to check AC. Took car to AC guy, was told that AC is in perfect working condition. Then took it to an electrician who told me that the alternator was charging fine to take it back to mechanic. Does anyone know what the heck is wrong with this car?

[trini iceman]

If it is stalling can you keep it running by stepping on the gas? Is it difficult to restart? What happens if you just put on the blower?

[racedriverpro]

Idle air control valve or idle step up unit...

[VLDS]

I went through the very similar problems with a 4g94 GDI. Turned out to be the GDI fuel pump after months of trial and error.

[nissan4life]

GDI doesnt carry a iacv as this is controlled by the ecu nor is it the fuel pump as the car would not be idling on at a stop.

Sampson i experienced this recently, when the ac is on the car is under added load. My idle use to drop extremely low especially at a stop and cut off with ac on.
One of the poor designs in gdi technology is the carbon build up caused by the exhaust gas re circulation.

Contact ryotech on the forum, he ran two services on my car, a intake manifold cleaning and a injector cleaner.
GDI injectors are built into the combustion chamber so the typical injector cleaner wont work as it would on a normal port fuel injector that sits on a rail.There is a product he used called BG44k gdi injector cleaner
This is a in tank solution and the intake solution he used was done through a machine. My car has been working great after the service, i suggest you give him a call.

Only distributor i have seen carrying the BG products locally is AUSCO, but i sure there are others.

[tdaisley]

Was experiencing same problem no one knew what was going on check throttle cable there's two ten bolts adjust and make sure cable is tense not to pull butterfly make sure cable has no play

[leo0816]

Good day Gentlemen, I'm having this same problem with my lancer and I believe is what nissan4Life is commenting about. Does anyone have any contact information for ROYTECH? I'm unable to look at his information.

[Sjnerro]

I have a 2001 lancer Cedia, ok so when I start it it revs high then after a while it tones down but when u leave it an watch it then it goes lower and lower till it shuts off, I have to drive with two foot one one has an one on brake, it just don’t throttle on its own, installed back the ac and it even worst, omg can someone just help me and tell me what’s going on cause here in Jamaica they just telling me to throw the engine away an I love my car there must be a way to fix this issue, please help me or contact me via WhatsApp with info on how to get it fixed at 8764842959 I beg of this assistance

[kmarchan9]

I have a gdi 4g15. It's idling low I got it scan they said
It's the throttle body. I change it & getting the same
thing. Can anybody tell me how this problem could be solve.

[ZeroOne]

Might need to to another engine scan for error codes and perhaps a compression test.

Is the engine cutting off?

[kmarchan9]

No it isn't

[ZeroOne]

Ok check your high fuel pressure supposed to be 5, also check your fuel trims

[kmarchan9]

I want to clean my gdi 4g15 intake valve. What to use and how to clean it.

[Dave]

A throttle body spray is adequate. Amsoil power foam is one of the best.
Drive a few days them do an oil change. If plugs are also due then coincide all of the above.

[kmarchan9]

Can I use crc intake valve & turbo cleaner to clean my 4g15 gdi engine

[EvoofRome]

Hey any update my cs2 2002 4g15 gdi getting same issue I went a in a some dry pothole and it happen then also I did a full service except injectors....so after that I started to get the idle problem

[EvoofRome]

It was a hose connected to the ivac

[DemiCelph]

Can I use crc intake valve & turbo cleaner to clean my 4g15 gdi engine

Using CRC intake valve and turbo cleaner on your 4G15 GDI engine might help remove deposits and carbon buildup. However, ensure it's compatible and follow instructions precisely. Consult a mechanic for guidance if unsure.

[deltagulf]

Can I use crc intake valve & turbo cleaner to clean my 4g15 gdi engine

Using CRC intake valve and turbo cleaner on your 4G15 GDI engine might help remove deposits and carbon buildup. However, ensure it's compatible and follow instructions precisely. Consult a mechanic for guidance if unsure.

It's also a good idea to use high-quality fuel and oil to reduce future buildup since premium fuels often have detergents that help keep things clean by stopping carbon deposits from forming. Good quality oils come with better additives that reduce engine wear and sludge. Regular oil changes and using top-tier fuel can really help extend the life of your engine and make it run more efficiently

[lancer3]

Wow, it sounds like you've really been dealing with a frustrating issue with your Mitsubishi Lancer. It must be so annoying to have it stutter and lose power like that. Since you've already checked so many things, maybe it's worth looking into the AC compressor or its connections, like you said. It's great that you've already had it checked by both a mechanic and an electrician, but sometimes these issues can be tricky to pin down.