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Need a Diagnostic Wizard


Philth
Newbie
1915/2000


Galant VR-4 org Post #: 1238864 posted 08/02/17 01:03 PM     Remind Me!  Send Private Message   Edit Post      
Hey everyone,

Recently acquired #1915/2000 up in Canada. It's a fun little car and get a lot of positive reactions to it.

A little history and introduction:

From what I understand of its history is it was brought up north, rally raced, and sold to various POs before me. It's obviously been a little abused in the past with some interesting modifications (not all bad). I'm slowly putting the TLC into it to restore it to its former glory and smooth out some of the rougher edges it has developed.

My New Problem:

It seems the engine has developed a stutter/violent loss of power above 4000RPM when pulling through the gears.
What I know: Off of boost there is no problem revving. In neutral I can rev to redline with no stutter whatsoever, which makes me believe this is related to the forced induction.
I have unfortunately yet to invest in various aftermarket gauges or sensors to help analyze this any deeper so all I have to go in is what I see and feel.
The stutter occurs just before 4000RPM and opening the throttle further will cause it to bog or choke while pushing full boost (based off the factory meter on the dash). I can milk it gently with the throttle above 4000 but as the turbo continues to wind up it'll eventually stutter and more throttle will cause it to bog and RPMS to drop (boost gauge still reads full though). Lot's of throttle causes it to start bucking as if about to stall.

Interestingly, within the first 5 minutes of coolant reaching normal operating temperatures I can pull through all the gears no problem. After about 10 minutes and the entire engine bay heating up is when this problem arises. If I shut the car down, let it cool, and start again, I can pull through all gears without stutter but then eventually run into the problem again.

The first thing I did was replace the plugs with BPR6ES and gapped to .028, thinking it was a spark blow out. That didn't fix it, so now I'm onto the next steps.

It'd be nice if someone has maybe seen this/had experience with this and has the surefire guaranteed answer, but I doubt that. So instead I'm hoping to get a little feedback as to where to go next and my best options.

My ideas:

When I got the motor it had a coil on plug setup which I converted back to the regular coilpacks and wires. My plan is to reinstall the coil on plug setup and, if that cures the problem, I know it's related to ignition and will continue to replace the wires and coilpacks to try and fix it.

If that doesn't work, my next option are to look towards air and fuel delivery, as I'm guessing there's something wonky happening there. Maybe if it's starving for fuel it'd cause that stuttering followed by the ECU retarding the timing drastically to avoid knocking. I'm thinking maybe fuel pump and fuel filter as next on the list to try and replace, followed by taking a look at the injectors.

It currently has a K&N cone filter on and that seems to be the only modifications on the intake side. I'm wondering if it could possibly be a MAF issue or TPS or TB issues on the intake side either letting too much air/not enough air in. I don't think a turbo leak would cause these problems and I can't hear any noticeable whine or leaking sound but I could always do a leak test to see if there is a savage leak causing these problems.

After that, I'm not sure. Maybe someone here has some ideas or more advice to get the ball rolling?

Posts: 7 | From: Ottawa, ON | Member Since: 07/10/17 | IP: (131.137.245.209) | Report this post to a Moderator

thomcasey
I ain't no puny human
1025/2000


Galant VR-4 org Post #: 1238865 posted 08/02/17 01:46 PM     Remind Me!  Send Private Message   Edit Post      
Check the PCM (flat connector, 7 pins, drivers side rear of intake manifold. Bolts to the head, below the coil plug stock location. These tend to show issues when they get hot. Seen it before, so it is a possible issue.



Thom
1991 GVR-4 1025/2000 (PTE 1200's, 16g, DSMLink v3, gm-maf, eagle/ross, .020 over, 272's)

Posts: 647 | From: Indianapolis, IN | Member Since: 09/24/14 | IP: (12.109.79.254) | Report this post to a Moderator

iceman69510
Turn Right Racing
855/2000
828/1000


Galant VR-4 org Post #: 1238866 posted 08/02/17 02:54 PM     Remind Me!  Send Private Message   Edit Post      
All stock parts as far as air and fuel control? Any chip or other aftermarket control system?



91 VR4 855 Nile Black
92 VR4 828 Belize Green-Daily driver status
91 VR4 115 Nile Black -SOLD

Posts: 10402 | From: Michigan | Member Since: 03/05/01 | IP: (205.144.100.200) | Report this post to a Moderator

Philth
Newbie
1915/2000


Galant VR-4 org Post #: 1238867 posted 08/02/17 06:05 PM     Remind Me!  Send Private Message   Edit Post      
All stock save for the K&N filter as far as I can see... I haven't dug too deep. There definitely was no mention of a different tune or chip when I got it.

Connected and reconnected the PCM with no results. Tried the COP setup again and still had the same issues, so I'm moving away from ignition problems and onto fuel/air.

I can try and snap a video with the RPM gauge and maybe it'll catch some of the stuttering/sputtering sound.

Could it be something exhaust side if it affects the engine only when it starts to run hot? On the exhaust side it looks like 3" straight back, so that's been modified. Maybe a cracked manifold or turbine issues that only appear under boosted load? But I feel like that would be a lot more... audible. Under any load.

Any recommendations for cleaning injectors if that's a possibility?

Posts: 7 | From: Ottawa, ON | Member Since: 07/10/17 | IP: (67.193.6.249) | Report this post to a Moderator

G
obsessed with the turds of others
486/1000


Galant VR-4 org Post #: 1238872 posted 08/02/17 07:34 PM     Remind Me!  Send Private Message   Edit Post      
Could be a clogged fuel pump strainer or a boost leak.



www.japanesenostalgiccar.com
www.nostalgic.co.jp

Posts: 8794 | From: zompton | Member Since: 02/24/04 | IP: (75.86.151.204) | Report this post to a Moderator

Philth
Newbie
1915/2000


Galant VR-4 org Post #: 1238874 posted 08/02/17 07:45 PM     Remind Me!  Send Private Message   Edit Post      
Just learned about the 4g63t "fuel cut" feature on the ECU... Is it possible that that's what the stuttering is? Still doesn't solve my problem but at least I can diagnose the symptoms.

Posts: 7 | From: Ottawa, ON | Member Since: 07/10/17 | IP: (2001:56b:9fff:9c) | Report this post to a Moderator

FlyingEagle
Doesn't Match Anything


Galant VR-4 org Post #: 1238880 posted 08/03/17 11:09 AM     Remind Me!  Send Private Message   Edit Post      
I'm busy this weekend but I should have some free times in the evening next week, back out of town on the weekend again.

I can swing by and see what "may" be up with your car if you like.

You have likely the only other "serviceable" Mitsubishi in town. I think that means that someone from this board will actually get to see my car in person.

Offer is on the table.



C53A 1 of the ~1500

Posts: 1494 | From: THE Ottawa | Member Since: 03/05/05 | IP: (108.63.97.28) | Report this post to a Moderator

Philth
Newbie
1915/2000


Galant VR-4 org Post #: 1238887 posted 08/03/17 05:55 PM     Remind Me!  Send Private Message   Edit Post      
Nice! I'm in Cornwall now but I'm to and from Ottawa all the time. Unfortunately I'm away all next week but I'll take you up on that offer after.

Might have found the problem: replacing the fuel filter and noticed the fuel line from the filter to the rail has been scabbed together with another piece of rubber hose that isn't very secure... could be sucking air or otherwise affecting it. I'll try and swap everything out tomorrow and try again.

Posts: 7 | From: Ottawa, ON | Member Since: 07/10/17 | IP: (67.193.6.249) | Report this post to a Moderator

FlyingEagle
Doesn't Match Anything


Galant VR-4 org Post #: 1238896 posted 08/04/17 11:28 AM     Remind Me!  Send Private Message   Edit Post      
Usually a leak would be present if a clamp was loose or not fitting properly, a fair bit of fuel pressure is ahead of the fuel pump.

Heat generally leads me looking for electrical issues like MAS, sensors, etc.
Time being a factor can relate to, as others said, stuff clogging the fuel filter sock, dropping off and rinse repeat.
Sometimes rubbers expand with heat and either lose their seal or it gets better - O-rings in the TB, air snorkel equipment, vacuum hoses, etc.
The other thing that happens when you get to operating temp, is the system should be running much leaner/stoich and can have a piss poor time running correctly when underlying issues come to light.
Getting a cap/plug that fits the inlet at the turbo and performing a boost leak test (with a car rim valve stem drilled and sealed into the center of it), just don't go beyond 15-20 PSI regulated PSI due to seals in the system having issues with high pressure amongst other things!

All seals on the engine could be suspect with boost and heat coming into play, as you say 10 mins down the road.

I have a datalogger setup that with some AAA batteries can be brought to life (I hope) and maybe we could see some data in real time with MMC datalogger or whichever program I can hopefully reload onto it. The Palms lose all data when battery power is removed. I might be able to hook it into my old PC to achieve this. Not many things have 15 pin serial ports anymore ...



C53A 1 of the ~1500

Posts: 1494 | From: THE Ottawa | Member Since: 03/05/05 | IP: (108.63.97.28) | Report this post to a Moderator

Philth
Newbie
1915/2000


Galant VR-4 org Post #: 1238897 posted 08/04/17 08:37 PM     Remind Me!  Send Private Message   Edit Post      
Replaced the fuel filter, seems to have helped the issues a little bit... stutters a lot less/less aggressively, I have a longer warm-up time before issues occur... Leads me to believe it's a combo of things which is probably even worse?

FlyingEagle I'll definitely take you up on your data logger. I'll be back in town on the 14th.

Posts: 7 | From: Ottawa, ON | Member Since: 07/10/17 | IP: (67.193.6.249) | Report this post to a Moderator

FlyingEagle
Doesn't Match Anything


Galant VR-4 org Post #: 1238898 posted 08/04/17 09:25 PM     Remind Me!  Send Private Message   Edit Post      
The other thing that does have issues with heat and pin grip/contamination of the green death are the pins at the Power Transistor setup. IF they are corroded, heat will be their enemy and severely reduce the current output to your coil pack. Check there too, the coil pack connections, but be especially critical of the plug at the Power transistor and the case around the transistor setup.



C53A 1 of the ~1500

Posts: 1494 | From: THE Ottawa | Member Since: 03/05/05 | IP: (68.171.77.46) | Report this post to a Moderator

thomcasey
I ain't no puny human
1025/2000


Galant VR-4 org Post #: 1238903 posted 08/05/17 11:48 AM     Remind Me!  Send Private Message   Edit Post      
^^^^ This is why i suggested swapping it out for a test.



Thom
1991 GVR-4 1025/2000 (PTE 1200's, 16g, DSMLink v3, gm-maf, eagle/ross, .020 over, 272's)

Posts: 647 | From: Indianapolis, IN | Member Since: 09/24/14 | IP: (68.45.230.24) | Report this post to a Moderator

FlyingEagle
Doesn't Match Anything


Galant VR-4 org Post #: 1238910 posted 08/05/17 11:17 PM     Remind Me!  Send Private Message   Edit Post   
Ah, I went back and re-read that Thom, I was thrown off by the term PCM (usually means power train control module, which in newer cars could be the engine ECU and transmission control on Auto cars). I hate my phone for autocorrect as it sometimes changes what I was hoping to write too.

The green death is finicky, and lurks anywhere and everywhere!

Also, be doubly sure the wires at the CTS (coolant temp sensor) on the top of the head, are not broken open at the jackets just as they twist down off the sensor into the harness. This is mounted on the top of the coolant housing, top most position, as this give the ECU coolant readings and can be way off as things corrode or lose proper connectivity. We usually see an ECU getting an invalid input thinking the world is now -40C and you would have a very rich start condition ... and be well aware of it. Great place to check anyways and deal with now, and add some extra strain relieve with some appropriately sized layers of heat shrink, before it does become a plague type issue.



C53A 1 of the ~1500

Posts: 1494 | From: THE Ottawa | Member Since: 03/05/05 | IP: (68.171.77.46) | Report this post to a Moderator


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