Yea i used that foam directly in throttle for a good cleaning ,let it sit 20 min an drove .There may be a temporary code or 2 after you 1st start it up once foam is done sitting a bit.-normal..
After the hard drive then it smooths out reset computer .
This foam seems to give it a deeper clean!

 

I'll do the spray tonight. Since I'm spraying through the intake tube, any concern that it will get into the IAC, TPS or MAF sensor?

 

MAF might take offense at it...... the others just won't care.

 

3.9 has MAP, not MAF. Won't care.

 

Got it, thanks for the info. I'll use the spray tonight and see if I can get rid of the cylinder #4 misfire code.

I guess the best route for the computer is to purchase online for about $200 with Vin programming and 1 year warranty. Hate to even go that way if it just means something else is giving me this issue.

 

Im going on 2 months now..no code again.

.make new ecm last resort.
Try used one with same specs 1st.
But i dont think its the ecm.

An no issues with the map sensor after my foam spray..Just 02 code because of all the spray..
It did change the cylinder # code once too but after that hard drive an the full key reset ..NO codes.
If it does reset ,switch injectors an rerun it an see if it went to that injector ..

 

Used the sea foam spray through the throttle body and seem to help for a week for so but got the same cylinder #4 misfire error again.

Replaced the throttle body and MAP sensor. Used the new TPS and IAC I had before and still having the P0304 error.

I ordered a set of O2 sensors to replace all 4. Will be doing that this weekend. Beside the O2 sensors I don't believe their is anything else that I haven't done beside replace the computer.

 

UPDATE:
I'm running out of ideas on why my Dak is crying about a p0304 misfire on cylinder 4. Any advice much appreciated.

Things I have done:
New fuel pump (was having long startups)
New cap and rotor
New fuel injectors
New Sparkplug cables
New Sparkplugs
Compression test (pass all either equal or 1 to 3 PSI difference)
Replaced #4 Fuel Injector Connector
Replaced Crankshaft Positioning Sensor (Mopar)
Sea Foam - 1/3 in engine oil, 1/3 in brake booster and 1/3 in gas tank
- directly in throttle for a good cleaning ,let it sit 20 min an drove
Replaced the throttle body and MAP sensor. Used the new TPS and IAC I had before
Replaced all 4 O2 Sensors
Replaced ECM - from carcomputerexchange.com
- Now I am getting P0300, P0301, P0304 (Random misfire's)

The check engine light will clear itself randomly once in a while, like today. But I can feel the truck is misfiring.

Next to do:
Vacuum Leak - From reading other posts and research this could also be the problem (Sigh), ready to run it into a ditch...

If you can suggest anything else for me to check I would appreciate it.

Thanks,
Peter

 

What brands on the 02 sensors an map ?
Hopefully not bosch.
If vacuum leak I'd think it wouldnt jump from 1 code to 3 after 02 change.

Try the vac leak test on the lines .an cam sensor.
Check fuel pressure there at engine also.
Leaky intake manifold/plenum can set it too.

 

Heres info off another one with same engine .another person replaced pcv valve an it helped.


Message:
I finaly found out what was causing this issue after many part and dealers looking at my truck. It turns out it is the Intake gasket set that needed replaced. Oil was leaking into the manafold after running and when you restarted it blew the oil into the valves and caused the misfires and ruff idle till the oil burned off. my codes were 301, 303 & 304. Hope this helps other Dodge 3.9 owners.