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.

  • Join the Community!

    DSMtuners is a massive archive of DSM information - but more importantly, it's a COMMUNITY! Join in and participate with other DSMers, and invite all of your DSM friends to make this place their home. Chat with others, create a build thread, post questions and answers. Get involved! Logging in will also remove many of the advertisements, along with this notice. ;) It will also allow you to view images in threads.

Please Support STM Tuned
Please Support Rix Racing

420A 97 Eagle talon 420a n/t misfiring (Video)

Natedizzle

Probationary Member
4
0
May 26, 2022
Stuart, Florida
Hey everyone,

I'm new to this 420a motor so not entirely sure what's going on with it. I have a weird misfire issue, when idling and under heavy acceleration it misfires and sputters. When accelerating slowly the misfires seem to go away.

Codes Reciving:
P1390 - Timming skipped one or more teeth (Tripple checked timing all good)
P0171 - lean bank 1 (Replaced both o2 sensors)
P0300 - multiple cylinder misfire
P0302 - Misfire cylinder #2
P0304 - Misfire cylinder #4
For these misfire codes:
-Pulled plug wires individually and rpms dropped except cylinder 4.
-Pulled injector harness connectors rpms dropped but barely on cylinder 4.
-Put screw driver on injectors to hear for pulses all seemed the same across.
-Volt reading at injector harness 13.5v across all 4 injectors.
- Ohm readings across all 4 injectors identical.
- Checked for vacuum leaks but didn't find anything.

Parts Replaced since November 2021:

Ecm
Iac valve
Tps
Cam sensor
Crank sensor
Map sensor
O2 sensors (upstream and downstream)
Fuel pump
Fuel filter
Egr delete
No AC
No PS

Next thing is to check compression. Gonna rent a storage soon if need be to tear this thing apart. As you here that knocking in the video but just not sure cause it goes away when I accelerate.
My other guess is maybe burnt valves causing improper combustion. Idk.
Not sure what's really going on since I got the car like this. The previous owner is no help as he as well purchased the vehicle with these issues with hopes of fixing it.
 

Natedizzle

Probationary Member
4
0
May 26, 2022
Stuart, Florida
Video

You must be logged in to view this image or video.
 
Last edited by a moderator:

BLACK'98DSM

Proven Member
3,504
1,232
Feb 9, 2019
Alabama
I noticed you didn't list the plugs, wires, or coil as parts that have been replaced. Not to say you should have without diagnosing the issue, but those are 3 important parts of the ignition system. And if fuel & timing are correct it's likely a spark issue. No need for assumptions though only conclusions.

What you need to do is check that cylinder #4 actually is or is not sparking. Pull the plug, connect it to the plug wire, ground it then see if it sparks while turning the engine over. If it's not then you need to find out why. Like testing the coil, checking for continuity and resistance of the plug wire, replacing the plug and adjusting gap... you get the point.
 

Natedizzle

Probationary Member
4
0
May 26, 2022
Stuart, Florida
I noticed you didn't list the plugs, wires, or coil as parts that have been replaced. Not to say you should have without diagnosing the issue, but those are 3 important parts of the ignition system. And if fuel & timing are correct it's likely a spark issue. No need for assumptions though only conclusions.

What you need to do is check that cylinder #4 actually is or is not sparking. Pull the plug, connect it to the plug wire, ground it then see if it sparks while turning the engine over. If it's not then you need to find out why. Like testing the coil, checking for continuity and resistance of the plug wire, replacing the plug and adjusting gap... you get the point.
Thanks for the reply I really appreciate it!

I didn't replace the wires or plugs but I forgot to mention I did replace the coil pack though. the previous owner said he replaced the plugs and wires. They looked new so I didn't bother to replace.

Went out and checked continuity also resistance through plug wires and all are inspect according to the service manual. Swapped plug wires 1 and 4 but same issue. Pulled plug wire from coil pack while running and 1-4 had strong arc across.

I will do as you mentioned above with removing the plug and checking spark and gap.
 
Last edited:

Natedizzle

Probationary Member
4
0
May 26, 2022
Stuart, Florida
Okay so went out at 5am (Woke up my wife LOL) pulled the plug and attached to plug wire then grounded. Had my wife crank the car while I watched the arc and adjusted distance to ensure I was receiving a strong spark which was the case. Proceeded same process on plugs 1-3. All good.

I attached the steps I've been following from the manual and everything seems to check out. unless I'm forgetting something?
Also pictures of plug pulled from cylinder 4.
Gonna swap out the Ngk Iridium for Ngk copper plugs today.

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


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


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


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


You must be logged in to view this image or video.
 
Last edited:
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned VR Speed Factory

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Top