Resolved 420A Check engine light flicker

[1st_ride98]

Check engine light was on - Misfire cyl#4 code (P0304). Changed plugs, plug wires & coil, still came on. Replaced #4 injector and light was off for 3 days. Today, flickered while backing out of driveway and then went off. Any idea as to what this means? (1998 Eclipse GS 2.0L non-turbo)

 

[Chumpaumpalumpa]

Bad connection or if you have link that the coolant was approaching the temp you have it set to come on and then it cooled back down.

 

[1st_ride98]

Flicker was when engine was stone cold, just after staring up. Not sure what you mean about coolant approaching temp and bad connection? Have not had a lot of experience.

 

[96WhiteTSi]

He is saying if you have DSMLINK that you can have the settings turn on your check engine light when your coolant reaches a temp .. He was suggesting that the car reached said temp and flickered on and off because the coolant cooled down before the check engine light stayed on solid. As for bad connection... Beats me

 

[2gmitsueclipse]

1998 Eclipse 2.0L non-turbo

Gentlemen, this is for a non-turbo DSM. The OP likely doesn't have ECMLink.

 

[1st_ride98]

Yeh, non-turbo. Guess I'll check for code, but if light is not on chances are no code. I just don't want to burn up my cat. Car runs good - maybe a little off at lights ocassionally, but nothing that noticable

 

[1g Cam]

Maybe something wrong with the catalyst

 

[tondar]

May be completely unrelated but I had this in my MR2 and it was a bad alternator regulator that was letting voltage vary too much

 

[1st_ride98]

Thanks, it's a thought. I was thinking maybe some kind of short so maybe.

 

[1g Cam]

Maybe a coil pack

 

[ceedawg]

Bad connection or if you have link that the coolant was approaching the temp you have it set to come on and then it cooled back down.

How could that be when he has a non turbo eclipse!

 

[GST Jeremy]

If you suspect its the charging system go to your local auto parts store they can test it for free in the parking lot

 

[PlanZero]

Well since the CEL was for misfire you should definitely rent a compression tester from autozone . I had a similar problem on a GS a few years ago. Wasted $ on wires, coil pack, etc. Just to find out I had no compression on that cylinder. Ironically the car felt and drove fine, compared to another 420a I had. I just realized how bad that is

 

[1st_ride98]

So you can have bad compression in a cylinder and it still runs smoothly?

 

[cmehlxl]

had the same issue- was a loose ground connection from the negative battery terminal.

 

[1st_ride98]

Thanks. Will check it out

 

[Chumpaumpalumpa]

My bet is on a loose connection or some gradual change that's just starting to set it off then goes away but most likely just a bad ground or short to ground somewhere.

 

[1st_ride98]

In case anyone has this issue - Intake manifold gasket was de-laminated on the corner by cylinder #4.

Did a smoke test and showed intake gasket leaking. Took it apart, pulled the gasket and saw it was separating. Replaced gasket and idles and runs smoothly.

I threw quite a few parts at it that seemed more logical, but in the end, the smoke showed the way. Hope this in some way may help someone else. It was very frustrating not being able to track this down for so long.