Hope this posts in the right section!
I have a 2008 Dodge Grand Caravan 38 SXT.
Had a faulty injector at cylinder #2.
Replaced all cylinders and now it throws a P0300.
No apparent major vacuum leaks.
Replaced the EGR to tube gasket,
Replaces the intake manifold cover gaskets.
Nothing seems to help, engine funs just a little rough.
Drives okay at low speeds and even better at high speeds.
Any advice is appreciated.
Thanks

 

1) Double check vacuum and intake connections. Make sure all hoses are routed properly with no cracks and snug or clamped fittings on the manifold. Make sure the air filter housing to throttle body tubing is seated squarely on each end and the clamps are snug but not over tight (60 in-lbs is enough).

When i replaced the plugs on my GC a while back, the vac hose for the EVAP had been unintentionally stuffed down behind the manifold during reassembly. I noticed it ran a little rough but seemed ok when under load so I didn’t discover the error until it threw a code for the purge valve.

2) Verify all the plug wires are snug and snap onto the plugs and that the coil connector is clean with good terminal tension.

 

Thank you so much for taking the time to assist with my issue - i have looked at all of this but I will look again.

Cheers

 

Okay, onto other questions and suggestions:

1) Did you have the battery disconnected when you replaced the injectors?

2) Have you tried to determine whether or not the EGR valve is partially stuck open?

3) Have you tried tapping on the IAC valve at idle to see if it smooths out?

4) Using the handle of a screwdriver, tap lightly on the MAF sensor at idle and see if it smooths out.

5) How far have you driven the van since replacing the injectors?

Sometimes after a project like this, the computer needs time to relearn idle speed, air flow, O2 sensor values, etc. This can take 5 miles or 50 depending on how it's driven. If none of the above suggestions results in a fix, try disconnecting the battery for 10 minutes and then get it on the highway and cruise for at least 10 miles.

 

1) I did have the battery disconnected when I replaced the injectors.

2) Yes, it seems to be working properly.

3) Yes, no change.

4) Yes, no change.

5) I have driven the van approximately 25 miles

 

One more thing I can think of before more advanced diagnosis may be necessary- when you pulled the fuel rail, did you disconnect the primary connector on the left side of the engine (feeds the injectors and coil) or disconnect each injector individually?

In either case, you may want to disconnect it for inspection. Unhook the negative battery cable first. Check for corrosion on the terminals and whether or not any terminals look like they may have spread out. Clean both sides thoroughly using electronic contact cleaner (MAF sensor cleaner is essentially the same if you have some on hand), blow dry with compressed air, then spread a light coat of dielectric grease on the female side before reconnection.

If you desire, it would be a good time to measure the resistance of each injector and circuit while it’s apart. That might indicate the new injector being faulty or connection problem at the injector or coil. If you need the wire colors I can look them up for you.

 

GumbyRT,

Thank you for taking the time - your efforts have saved me time and potentially lost monies.
I took all of your advice and repeated them again.
After running through all of the steps you provided the engine seems to be running a lot smoother at idle and throughout.
Thanks again!

 

Good to know. Occasionally I guess my way through a problem and make it sound good.