420A Repetitive Misfire codes P0300 to P0305

[ECLIPSEGS2]

I'm fairly new to DSM, just got a 99 gs 420a 5spd. However I noticed that the CEL/SES keeps coming on for multiple random misfires, and misfires on 1,2,3,and 4. I replaced plugs, wires, coil pack, and checked each cylinder for build up/ carbon. However whenever it pops these codes I dont feel any misfires but at low rpm below 3.5k rpm engine braking and light accel it pops alot. Im at my wits end for what could be wrong with it.
Codes P0300-P0305

 

[BLACK'98DSM]

Strongly sounds like the camshaft sensor to me. I just finished chasing down a similar issue and that's what it was.

 

[ECLIPSEGS2]

Strongly sounds like the camshaft sensor to me. I just finished chasing down a similar issue and that's what it was.

I have replaced camshaft sensor and the problem persisted

 

[BLACK'98DSM]

It's losing spark for some reason. Have you looked into the crankshaft position sensor?

 

[ECLIPSEGS2]

It's losing spark for some reason. Have you looked into the crankshaft position sensor?

But it doesnt feel like it is, it just pops and bangs at low rpms but still runs smoothly and o2s reading near normal fuel trims

 

[ECLIPSEGS2]

It's losing spark for some reason. Have you looked into the crankshaft position sensor?

I have one but havent installed it yet, PO said he replaced it but I haven't looked

 

[BLACK'98DSM]

o2s reading near normal fuel trims

How are you seeing that? Do you have an aftermarket wideband gauge and sensor? Or are you just viewing data from the stock sensor through the ecu? Trying to tap into the stock readings isn't very accurate and has a delay.

Whenever it pops you should get a quick spike in the reading. It should get lower for a quick moment because the fuel wasn't ignited.

 

[ECLIPSEGS2]

How are you seeing that? Do you have an aftermarket wideband gauge and sensor? Or are you just viewing data from the stock sensor through the ecu? Trying to tap into the stock readings isn't very accurate and has a delay.

Whenever it pops you should get a quick spike in the reading. It should get lower for a quick moment because the fuel wasn't ignited.

Snap on reader, I do see spikes in the in O2 when it starts popping and with misfires shouldnt you feel it, cause I get catalyst damaging misfire alot but never feel it happen.

 

[ECLIPSEGS2]

Update- sorry for the long delay but I finally got time to work on it. I have replaced the crank sensor. I'll update soon on if it comes back or not.

 

[ECLIPSEGS2]

Update after driving about 30 miles the codes are back, the only stutter I feel now is just low rpms 1500-2500. Spark plugs, coils, and wires new. New crank and cam sensor, new rear o2. Any ideas anyone?

 

[BLACK'98DSM]

Did you double check the connectors and wiring for each of the sensors? Need to make sure they've got good connection.

It's also possible that there's an issue with your cam magnet, but that's rare.

 

[ECLIPSEGS2]

Did you double check the connectors and wiring for each of the sensors? Need to make sure they've got good connection.

It's also possible that there's an issue with your cam magnet, but that's rare.

I believe it may be egr as it happens at the range egr should be opening so im going to pull the valve and check it

 

[ECLIPSEGS2]

I believe it may be egr as it happens at the range egr should be opening so im going to pull the valve and check it

And I used electrical contact cleaner on every connector ive unplugged

 

[BLACK'98DSM]

That is a good check. I haven't heard of the EGR causing multiple misfire codes vefore but I could see how that might happen. Our intake manifolds are prone to collecting carbon buildup near the throttle body area. After I deleted the EGR I took my intake manifold off and used multiple cans of cleaner

 

[ECLIPSEGS2]

That is a good check. I haven't heard of the EGR causing multiple misfire codes vefore but I could see how that might happen. Our intake manifolds are prone to collecting carbon buildup near the throttle body area. After I deleted the EGR I took my intake manifold off and used multiple cans of cleaner

It is deleted, egr was extremely dirty, I'll be thoroughly cleaning it when I have more time available to me

 

[ECLIPSEGS2]

It is deleted, egr was extremely dirty, I'll be thoroughly cleaning it when I have more time available to me

Also I noticed I had a little bit of oil that had comeback through and was in my intake piping. Not sure of the cause yet but thinking pcv related

 

[BLACK'98DSM]

Also I noticed I had a little bit of oil that had comeback through and was in my intake piping. Not sure of the cause yet but thinking pcv related

I would probably remove your valve cover and check the baffle under that breather. If it is damaged or missing it will let oil through (also not a good sign)

It's actually normal to have a small amount of oil in the intake manifold. As long as it's not pooling or leaking out anywhere. Our replacement options for PCV valves are garbage, unless you go with OEM. It will still let some through but much less than the reproductions.

There are ways to make it better like adding catch cans, but on a stock setup there's not much to do besides maintain your breathers.

Another thing that would cause oil in the intake is blow-by. From worn pistons/rings/cylinder walls. Unlikely though unless it's high mileage and popping the dipstick out too.

 

[ECLIPSEGS2]

I would probably remove your valve cover and check the baffle under that breather. If it is damaged or missing it will let oil through (also not a good sign)

It's actually normal to have a small amount of oil in the intake manifold. As long as it's not pooling or leaking out anywhere. Our replacement options for PCV valves are garbage, unless you go with OEM. It will still let some through but much less than the reproductions.

There are ways to make it better like adding catch cans, but on a stock setup there's not much to do besides maintain your breathers.

Another thing that would cause oil in the intake is blow-by. From worn pistons/rings/cylinder walls. Unlikely though unless it's high mileage and popping the dipstick out too.

Thanks for the bit of advice on what to check, I'll look when I can and check crankcase pressure to see if it's high

 

[ECLIPSEGS2]

I would probably remove your valve cover and check the baffle under that breather. If it is damaged or missing it will let oil through (also not a good sign)

It's actually normal to have a small amount of oil in the intake manifold. As long as it's not pooling or leaking out anywhere. Our replacement options for PCV valves are garbage, unless you go with OEM. It will still let some through but much less than the reproductions.

There are ways to make it better like adding catch cans, but on a stock setup there's not much to do besides maintain your breathers.

Another thing that would cause oil in the intake is blow-by. From worn pistons/rings/cylinder walls. Unlikely though unless it's high mileage and popping the dipstick out too.

There is relatively no positive crankcase pressure, burnt my hand a bit to figure that one out

 

[ECLIPSEGS2]

Cylinder 3 and 4 misfire came back with multiple cylinder misfire codes, did compression. Test but CC carbon build up and oil residue in 3/4 has me worried

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[BLACK'98DSM]

Does it smoke from the exhaust while running?

 

[ECLIPSEGS2]

Does it smoke from the exhaust while running?

It does not

 

[ECLIPSEGS2]

It does not

But from my look in each cylinder the carbon build up is atrocious and caked on each cylinder

 

[ECLIPSEGS2]

Does it smoke from the exhaust while running?

It does not

 

[BLACK'98DSM]

You need to determine how the oil is getting into the cylinders. How many miles are on the engine?