The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support ExtremePSI
Please Support Morrison Fabrication

2G $60 PayPal to whoever solves my issue

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

DSM's 4 life

10+ Year Contributor
649
14
Nov 13, 2011
Buffalo, New_York
Hey guys I am kinda at a loss as to what to do now ill start from the beginning in hopes that it will bring some insight to what happened and is going on with my car.

I have been building a Mitsubishi mighty max at my cousins house 4g64 2.4L bottom end with a 2g head, 2g ecu, harness etc. The car was complete and i was driving it around with no issues for a solid week just getting it dialed in with the maft. Changed the diff, and trans fluid making sure it received good maintenance. My cousin lives an hour and 20 min from my house and i was ready to bring it home about 30 min into driving it it sputtered a few times kinda like it dident have fuel when i pressed the gas just a blip though real quick then back on boost it was fine it began getting worse to the point my fuel trims started becoming off i bumped up my trims to richen it out 40 min in im on the highway all the sudden total loss in power wideband pegged lean i pull over immediately. I popped the hood and began inspecting i noticed my break booster had a huge vaccumme leak from where my intake manifold had punctured it after further inspection i saw that the intake was cracked as well. had the car towed home.
had the manifold welded i welded the booster. boost leak tested fixed two leaks in my pipeing also discovered my shaft seals were bad replaced them as well. car would no longer start i replaced the cam sensor 1997 style started finally. I discovered that it was running only on two cylinders. I replaced the transistor it began running on 4 cylinders. tested my isc discovered it failed and actually broke off inside my tb replaced that. changed my fuel pump bosh 44. changed my fuel filter. car sputters bad at low rpm and seems to fix itself in the higher end while revving it in my driveway. after taking it for a drive it seems like with the throttle held just cruseing it cuts out like fuel cut. I have an extra injector box and it runns better on the one than other for some reason. in addition runs better on my metal ecu than black box. and my ecu sensor ground pin 92? was grounding outside of the ecu It turned out to be my maft box so i cut cut the maf ground and just used a body ground.

Is it common to have this many failures at once and what is my current issue?
 
wired in a 1990 coil pack and saw no change. when i pull the wires of the spark plugs and have them arch on the valve cover cylinders 1 and 3 have to be less than 1/2'' away to arch while 2 and 4 can arch from almost 3"
 
Hey bro, I wish you success. I have the same issue, had other members stop by to tell me their in a hole and can't figure it out either. I have had zero success, changed and checked everything you did and more. Also in my own search I found a handful of dead threads with no resolve to similar issues. Seems to be one of those things. Best of luck , sorry I can't contribute.
 
wired in a 1990 coil pack and saw no change. when i pull the wires of the spark plugs and have them arch on the valve cover cylinders 1 and 3 have to be less than 1/2'' away to arch while 2 and 4 can arch from almost 3"


The TPS can cause some serious issues and am willing to bet is your issue. Make sure it is adjusted properly or do it like idiot me and turn it randomly until it runs right. My pocket logger says the throttle is open 12% at idle and that seems to be the sweet spot.

This is how you do it right:

http://www.dsmtuners.com/threads/how-to-adjust-the-throttle-position-sensor-tps.324431/
 
... and my ecu sensor ground pin 92? was grounding outside of the ecu It turned out to be my maft box so i cut cut the maf ground and just used a body ground.

Is it common to have this many failures at once and what is my current issue?

Yes, pin 92 is your sensor ground. The sensor ground is for the Maf, map, coolant, O2s, tps, and camshaft sensor. They all share the same 5v circuit to power them and are very sensitive to signal interference.

When you connected the Maf to a body ground, you made it harder for the Maf to be in sync with those other sensors. You need to find the Maf sensor ground wire problem and get that reconnected.

You may well have a fuel pressure problem that's masking itself as an ignition problem, but it doesn't' sound good to have the discrepancy on spark strength between the cylinders.
 
I disconnected the maft ground from the ecu ground because when pin 92 is unplugged from the ecu I was reading that it should not be grounding since ground loops. when the maft ground is unconnected i can probe pin 92 and it will only ground when plugged into the ecu like it should, correct?

here is a picture of my car
You must be logged in to view this image or video.


red wire goes from intake manifold stud to battery -
white wire goes from firewall to coil pack
black goes from battery neg to firewall

You must be logged in to view this image or video.



You must be logged in to view this image or video.
 
Glad to see you've got an FPR so you can be sure the fuel pressure is steady.

The two ecus you're using are from a 4G63 platform. Pin #8, to the fuel pump, on those ecus goes to ground, whereas pin #8 on a 4G64 ecu goes to 5v. You must have done some rewiring to get the 4G63 ecus to work to control the fuel pump.

As for the maf, the wire colors and functions are:

Pin 1 Green w. Yellow Pin #81 5v
Pin 2 Orange Pin #85
Pin 3 Blue w. Yellow Pin #90
Pin 4 Red Pin #9 12v
Pin 5 Black Pin #92 Sensor Ground
Pin 6 Red w. Blue Pin #72
Pin 7 Red w. White Pin #19

Test each wire between the maf plug and the ecu plug. The colors will stay the same all the way.

The sensor group (I listed in my above post) share the same sensor ground, they also share the same power source, Pin#4 12v.

It can be painfully slow sometimes to verify all the wires to all of the sensors, but as you can see, all it takes is one sensor wire in the group to screw up the sensor ground or not get 12v power, to make a no-start, or run-bad condition.

Rerun any bad wires you find. A repair in the middle of a wire harness can lead to shorting out other wires later, if it wears through other wire insulation, or even worse problems, like melting, etc.
 
Glad to see you've got an FPR so you can be sure the fuel pressure is steady.

The two ecus you're using are from a 4G63 platform. Pin #8, to the fuel pump, on those ecus goes to ground, whereas pin #8 on a 4G64 ecu goes to 5v. You must have done some rewiring to get the 4G63 ecus to work to control the fuel pump.

As for the maf, the wire colors and functions are:

Pin 1 Green w. Yellow Pin #81 5v
Pin 2 Orange Pin #85
Pin 3 Blue w. Yellow Pin #90
Pin 4 Red Pin #9 12v
Pin 5 Black Pin #92 Sensor Ground
Pin 6 Red w. Blue Pin #72
Pin 7 Red w. White Pin #19

Test each wire between the maf plug and the ecu plug. The colors will stay the same all the way.

The sensor group (I listed in my above post) share the same sensor ground, they also share the same power source, Pin#4 12v.

It can be painfully slow sometimes to verify all the wires to all of the sensors, but as you can see, all it takes is one sensor wire in the group to screw up the sensor ground or not get 12v power, to make a no-start, or run-bad condition.

Rerun any bad wires you find. A repair in the middle of a wire harness can lead to shorting out other wires later, if it wears through other wire insulation, or even worse problems, like melting, etc.




all the wires i tested ran to the pins you listed other than "Pin 4 Red Pin #9 12v" runs to pin 12 in the ecu after looking it up it goes to a 12v source so prob just a type on your end.

maybe my maft is wired wrong i wired a 1g maft into my harness so it wasent plug and play, but my car was running fine for a week
my maft is hooked up to the following wires

maft -------------------------stock wires

pink red
black black
brown blue/red
green blue/yellow
gray orange

green yellow is not hooked up
red white is not hooked up
 
Do you have the ability to datalog this thing? I think thats your first task. Then you can verify that all the sensors are giving valid outputs. Otherwise you are shooting in the dark.

I have that black box ecu and a obd2 to usb cable and wanted to download Clanzer's Mut Monitor but I dont think i have any obd ports in my car since I swapped it can a obd2 be wired in?
 
Just an opinion on your grounds.. I think their not the best or not enougg off the bat. You should have 2 main ground leads one to firewall one to block one off of intake to fore wall and I'd run coil packs straight off negative terminal ubtill problem is resolved to assure you getting a good ground.. grounds can cause a mess of problems this may not be the answer but you will eliminate chasing your tail around.. best of luck man and as always check for shorts and bad wiring
 
I would be pulling the cover off that PCM and checking for leaking capacitors. You said that your ISC went bad adn that is the number one cause for PCM failure. Its four screws, probobly worth a shot.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top