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420A Needing Advice on random MisFire

Zeke05

Probationary Member
13
1
Apr 4, 2019
Dallas, Texas
Hey guys, looking for advice, I’ve gotten to the end of the rope in a sense.
I currently have a 1997 eclipse 420a
I have the basic modifications on it: Cold Air Intake, Headers, Straight Pipe (spacers on the O2 Sensors to fool the system).
About 4 years ago the Engine Blew and put in a New 420a in it, but then I got into a wreck, and the car sat for about a Year, it was repaired. After the repair was done, I decided to take it to a tech to make sure the engine was still good, and they did a Compression Check, all 4 cylinders are at 170 steady.
I have struggled with a CEL for 3 years now, and shows random MisFire on all Cylinders…
I have replaced the basics, Wires, plugs, Ignition Coil. And started from there from what I remember this is what I have also replaced:
Crank Sensor, Cam Sensor, MAP Sensor, Timing kit, Fuel Injectors, Intake and Exhaust Manifold Gaskets, Throttle Body, Fuel Pump, Fuel Pressure Regulator, EGR Valve, ECM (3 times now), knock sensors
Most parts have been replaced twice or more since I took it to a tech and they changed everything I had and have checked most of the Electrical to arrive to that the misfire comes and goes only at idle but couldn’t find the cause of the issue….
So now I’m at a lost and not sure where I go from here. Other options I have been told is to Tune the Car… (not sure if that would be something to consider since the Car does not have a Turbo)

Need to add that a smoke test has also been done to make sure it isn’t leaking air anywhere and all is sealed
 
Last edited:

CKOPOCT

Proven Member
90
50
May 27, 2017
North East, Maryland
Second going to stock copper plugs. A lot of car owners have put platinum iridium split fire mumbo jumbo stuff on their engines only to end up with ignition problems because the resistances, spark patterns, etc. cause problems in the combustion chamber.
 

Zeke05

Probationary Member
13
1
Apr 4, 2019
Dallas, Texas
Recommended plug gap on a non turbo 420a is .042 - .047

.045 is a good medium for the stock ignition system.

Start by fixing that.
Ok I’ll get some Plugs from Autozone and gap them to that and see how it runs
 

Zeke05

Probationary Member
13
1
Apr 4, 2019
Dallas, Texas
Update:
Ok here we go, I picked up the Car from the Tech (3rd one at this point) and took it home, decided to drive the car and go pick up plugs Today, since I have to work and I work at Autozone. When I turned over the car in the morning it Sputtered for about 3 secs and went back to normal idle (freaked out a bit since it’s never done that before) drove it to work and while I was driving it the CEL went off (first thought was that the bulb probably went out since it has been on for 3 yrs straight) got to work and decided to turn it back on to see if the CEL would illuminate, and it did.
So at this point, the car has fixed itself, and I’m thinking there could have been a Carbon Build up in the Egr Tube or some kind of Blockage that the Sputter could have cleared up a bit…
Any thoughts and advice would be appreciated
Will still replace Plugs to Copper and Gap them to .045
 

Zeke05

Probationary Member
13
1
Apr 4, 2019
Dallas, Texas
Update:
Ok here we go, I picked up the Car from the Tech (3rd one at this point) and took it home, decided to drive the car and go pick up plugs Today, since I have to work and I work at Autozone. When I turned over the car in the morning it Sputtered for about 3 secs and went back to normal idle (freaked out a bit since it’s never done that before) drove it to work and while I was driving it the CEL went off (first thought was that the bulb probably went out since it has been on for 3 yrs straight) got to work and decided to turn it back on to see if the CEL would illuminate, and it did.
So at this point, the car has fixed itself, and I’m thinking there could have been a Carbon Build up in the Egr Tube or some kind of Blockage that the Sputter could have cleared up a bit…
Any thoughts and advice would be appreciated
Will still replace Plugs to Copper and Gap them to .045
And Driving it back home the CEL turned back on, will check Codes and see what it says now
 
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