Page 1 of 1

Random misfire

Posted: Fri Aug 06, 2021 10:29 pm
by HunterJones02
What to do? Can someone dingos a misfire? 02 Bonneville 3800 series 2

So far replaced..

Spark plugs
Wires
Ignition control module
Coil pack (all 3)
Downstream o2 sensor
Fuel filter
MAF sensor
Throttle position sensor
Catalytic converter is not clogged, it’s been deleted replaced with straight pipe

I’m leaning more towards a fuel problem? Maybe injectors, but from what I’ve read I’ve done a couple tests and doesn’t seem to stand out.

Jumpy at idle, when accelerating it feels to cut out, I can go full throttle and it will just slowly accelerate. Misfire code P0300 (random misfire or multiple misfires)

Re: Random misfire

Posted: Sat Aug 07, 2021 12:48 pm
by nos4blood70
Are you losing coolant? Have you ever changed your upper intake manifold?

Re: Random misfire

Posted: Sat Aug 07, 2021 2:07 pm
by HunterJones02
Not losing any coolant, sprayed starter fluid around upper intake. No leak

Re: Random misfire

Posted: Sun Aug 08, 2021 2:36 pm
by AJT2004
As asked earlier, has the upper intake manifold and gasket been replaced?
How many miles?
Did the random misfire start randomly or after a repair?
After changing all the parts listed, was there any change?

Re: Random misfire

Posted: Sun Aug 08, 2021 2:39 pm
by HunterJones02
Fixed the original misfire with the ICM, after sparks wires and coil packs, fuel filter. Changed o2 sensor TPS, Camshaft position sensor. The gasket has not been replaced, but it doesn’t leak coolant, and I spray starter fluid around the whole area and it doesn’t change anything

Re: Random misfire

Posted: Sun Aug 08, 2021 5:44 pm
by HunterJones02
No its not been replaced but it doesn't leak coolant, even tried spraying starter fluid around it.
130k miles
happened about the same time the cat went out and i just replaced w/straight pipe
they fixed a previous misfire, haven't seen any improvement.. could a small exhaust leak cause a mis?

Re: Random misfire

Posted: Mon Aug 09, 2021 1:36 am
by AJT2004
An exhaust leak will not cause a misfire.
Did you use OEM equivalent wires and plugs?
Confirm firing order is correct and wires are fully seated.