Mitsubishi Galant GDI 2.4l

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hamz80 (hamz80) 2012-11-12 16:53:37 +0500 #1

Experts

The car in question is a galant GDI 2.4, my new purchase!
Took it for a long drive on motorway. It was a great run apart from a issue on which i need help.
You can push the car to any limit and it revs flawlessly, however, when it is brought back to 100-110 Km/hr, one can feel jerks. The rpm needle remains stable but it appears that the engine is missing.
My call is a choked fuel filter or clogged fuel injectors! Want the experts to share their views!
Thanks in advance

Xulfiqar (Xulfiqar) 2012-11-12 17:06:09 +0500 #2

the GDI is a royal PITA.

anyway - the jerks at very mild power is mainly due to carbonising of the piston tops, as you should already know about the way a GDI works, the air is compressed into a tiny tornado above the piston crown which is made possible by the crescent on top of the piston. Fuel is added at the end and finally ignited.

When carbon builds up on it the crescent loses shape and hence cannot make a good tight rolling effect for the air and when the part throttle response pulls back the mixture to about 20:1 the engine misfires.

A technique that helped was feeding the engine raw mixture of liqui moly intake valve cleaner from the PCV piping. But its a 1 out of 8 chance to work. The correct way is to use walnut shell blast media to scrape the pistons clean and vacuum out.

You can test the fuel pressure from the HP pump test ports but the gauges are expensive as you need to measure about 1750 psi of fuel pressure in the rail. You can try the filter change (its a generic mitsubishi filter) to see if it helped, but I doubt it.

btw - where did you find a 2.4 GDI? most GDI galants in Pakistan were 1.8

hamz80 (hamz80) 2012-11-12 17:20:49 +0500 #3

Well for now i am enjoying the drive! Lets c whether it turns out to be a royal PITA
It is a swapped motor on dewan import galant as you rightly pointed out that most are 1.8.
Can you elaborate on the walnut shell blast media thing. I am dead sure that no mechanic would be able to get that and i would like to explain it in simple words!
Will definitely be asking you more on the GDI. Will share pictures as well.

Xulfiqar (Xulfiqar) 2012-11-12 17:29:04 +0500 #4

Its quite hard to believe someone in their right minds would swap a 2.4 GDI engine into a Galant in Pakistan that was sold by Dewan motors, even why would someone swap a GDI into an older JDM Galant GDI anyway, its a known problematic engine in Pakistan. I have done many swaps in GDI Galants but the engines were

4G63
6A12
6A13

All were available quite easily, I used to get the rest of the "required' bits too like full wiring, AFM, airbox induction pipes etc. Correct swaps require part removal of the dashboard, full console removal and spidering some wiring for the "manual shift" autobox to work. Otherwise it behaves as a standard auto.

The walnut blast procedure is done via the spark plug holes and a vacuum attachment from the injector hole, the piston top is blasted with shell to dislodge all carbon and then vacuumed out. There are workshop tool adapters by Mitsubishi but not available in Pakistan, ME, Africa or any of the Americas.

hamz80 (hamz80) 2012-11-12 17:35:12 +0500 #5

Xulfiqar

It is a great swap with everything in order. The manual shift is in order as well. Have tried it today on motorway and pulled it to the max!
Coming back to the question: i would appreciate your guidance on either liqui moly treatment or wallnut blasting!
I guess liqui moly valve cleaner would be easy to find in Lahore. Can you guide me step by step so that i dont have to go to the mechanic for that and place where i can get it from Lahore.

Xulfiqar (Xulfiqar) 2012-11-12 17:41:33 +0500 #6

Dont know about Lahore, but you can do the procedure easily, doesnt take much effort, but you will create a lot of smoke. The mixture is fed at the PCV port of the intake manifold on the top while the throttle is held at 2000 rpm. Do not let the engine balk out. Another point to make sure is that you use a diesel rated oil in the engine, the CR of a GDI is quite high and produces a lot of soot like a diesel engine. Diesel oil has cleaning properties to keep the soot suspended in it.

can you post some pics.

hamz80 (hamz80) 2012-11-12 17:58:27 +0500 #7

You want me to post pictures of the engine bay? i have the pictures of the car right now but none of the engine.
I hope i am able to track the PCV correctly. Can you guide me on its positioning?
For oil, i am currently using ZIC-A, gasoline but after reading your post, i guess i have to shift to diesel grade. Should i use ZIC diesel oil and which grade? One more stupid question: i presume CR is carbon ratio?

hamz80 (hamz80) 2012-11-12 18:14:03 +0500 #8

Have gone through ZIC website! Should i choose Hi-flow 20-50 or shift to SD-5000 or SD-3000 Diesel specification?

Xulfiqar (Xulfiqar) 2012-11-12 18:18:53 +0500 #9

cr = compression ratio, for excellent cleaning properties I have found Caltex Delo 400 to be great and cheaply available, ZIC also must have something like that, call them up and ask for it and also ask where to buy it from.

Also ask if they have a synthetic diesel engine oil. It would be much nicer. But much more pricey too.

hamz80 (hamz80) 2012-11-12 18:30:37 +0500 #10

They have a synthetic diesel oil as per their website!:: MAS GROUP ::
i will shift to it asap!
Can you guide on the PCV positioning as well! Thanking you in advance!

Xulfiqar (Xulfiqar) 2012-11-12 22:15:17 +0500 #11

the PCV would be mounted on top of the valve cover going to the manifold, you need to use the manifold side.

hamz80 (hamz80) 2012-11-13 01:38:13 +0500 #12

Thanks Xulfiqar for the usual help
Highly appreciated!

hamz80 (hamz80) 2012-11-13 08:17:38 +0500 #13

Xulfiqar

There is one more thing i want your views on. My mechanic opened the tappet cover and found those jammed. As you are aware that GDI runs hydraulic tappets, those were polished and were moving nicely after that. The issue that has came up is that they are making sound which wasnt there before. I have been told that since the tappets were jammed and now they are working fine, they would adjust and the sound would vanish. I have run it good 700km after that and still feel the sound pretty loud.
Please share your expertise!

Xulfiqar (Xulfiqar) 2012-11-13 12:22:50 +0500 #14

All modern Mistu DOHC engines have hydraulic lash adjusters for the valve tappets, They are recommended to be washed in diesel fuel and then are installed partially primed with engine oil, they should go dead silent after about 10 minutes on idle, you may hear an occasional tick like the lancer EVO 4g63 engine.

If they are not silent then they are worn out (excessively high mileage with bad engine oil) or your oil is too thick to quickly move or the oiling galleries are plugged with sludge, Replace the oil with synthetic and replace or clean the PCV valve also. The recommended viscosity for such mitsu engines is 5W30 so the adjusters can pump up quickly.

btw can you explain the polish part?

hamz80 (hamz80) 2012-11-13 12:48:30 +0500 #15

By polishing i meant that we washed them in petrol and also used sand paper to remove the carbon sludge on them. They are not silent but i presume that the galleries are sludged as well as they were not making any sound earlier.
So what i get is that i should opt for 5W30 viscosity oil and that too diesel specification?

atif11 (atif11) 2012-11-13 12:55:59 +0500 #16

can it also be done by sand blasting to dislodge carbon ?

Xulfiqar (Xulfiqar) 2012-11-13 13:48:59 +0500 #17

sand is too abrasive and will wear out the cylinder walls in less than 1 hour from the left over dust, walnut shells are softer compared to sand.

Xulfiqar (Xulfiqar) 2012-11-13 13:51:27 +0500 #18

Any abrasive material should never be used on their inner parts, they are hand selected parts with extemely tiny clearances, A wash in acetone mixed with ATF can dislodge the caramelised oil sludge. If your mechanic used sand paper, I would suggest you buy all new ones. When cleaning them they are recommended to be done one at a time so different parts dont get mixed. That also upsets them.

atif11 (atif11) 2012-11-14 17:36:02 +0500 #19

no no sand blasting is just the name , in actual baking soda is used which i think is very soft nonabrasive

Xulfiqar (Xulfiqar) 2012-11-14 18:25:39 +0500 #20

oh you mean soda blasting, It will take a boat load of soda to move the carbon and it is amorphous in state which then will easily lock itself into the upper ring lands. walnut shells are very good for this job.

Please remember this job is done with head in place, and the only access you have is the spark plug hole and the injector hole into the combustion chamber.