OBD Codes Help P1319 P0302 P0306 P0150

Hello,

I have the opportunity to buy an 03 SE3 with 93k at a great price, but it has the following codes:

P1319 - misfire, low fuel
P0302 - misfire cylinder 2
P0306 - misfire cylinder 6
P0150 - O2 sensor bank 2 sensor 1

It starts up fine, transmission shifts good, but runs very rough. It's definitely an active misfire, not random.

First owner reportedly overheated it driving to the dealer to get diagnosed. A line of dried oil scum can be seen in the coolant overflow from when it happened.

Second owner (current seller) did the following to fix the damage from overheating: new heads, valves, headgaskets, water pump.

Seller has removed the muffler because he says it runs better... "backpressure issue" was his words.

Seller says they think it's an electrical issue, probably ECM, and that a LR mechanic told him that over the phone. Plastic cover to the ECM was unscrewed and sitting loose on top, like someone was poking around in there.

I have some thoughts but would like to get un-influenced opinions on what may be the cause. Trying to come up with the most likely causes to see if the total to buy and fix it makes sense.

Thanks!

If you don't know what you're doing... run a mile.

The KV6 is an engine that runs on a fine line between being a lovely sweet engine and disaster!

Plenty of good mechanics have failed to fix KV6 engines once they start going wrong.

How long has this 2nd owner owned the car? After he did his work, has it run sweet for any length of time?

I doubt the ECM is kaput. Its working to run the engine, and it is running to communicate with the diag kit and respond with the types of codes that correspond with the running issues. There will be people waking up in the UK who may be able to give you possible reasons for those codes.

There was a guy rebuilding his KV6 on here that had issues once he put it together and it turned out his exhaust was completely blocked. That was in Bahrain, or somewhere near there, I dunno if it got blocked on the engine or from a sand storm while in 'storage' - but it corresponds with what the seller is saying. It may also just be that removing the exhaust gives the car just enough power to be 'usable' given the current problems.

Have you searched on here fore those error codes?

I would start with checking the coil packs on the plugs (reset the codes and swap them around to see if the errors follow) and that weird variable intake VIS motor on the plenum, I'd be surprised if they didn't already check this, but you never know

The O2 sensor on bank 2 could have been damaged by expensive coolant contamination.

The cylinders 2 and 6 (both bank 1) misfiring could be a number of things.

A bad plug would cause it, as would in incorrectly fitted coil. If the coil primary windings were fauly, the ECU would flag a bad coil code. It's not so it's using its misfire detection function to flag the cylinders responsible.

Personally, unless you trust the repair work done has been done to better than factory spec, I'd not touch it and I know and love the KV6.

Thanks for all the quick input. I've decided to walk away from it. I don't think it's as likely, but there's a possibility of it being something major in the top end.

Given the codes, I'm thinking the main issue is probably something having to do with individual cylinders, like injectors or coils. The possibility of a plugged cat crossed my mind, but I think that would cause a random misfire.

The fact that both misfires are on the same bank worries me it could be something with that head though, which would result in more time and money that it's worth. That chance is just too high for me to take the risk.

Your options in USAland are pretty limited because I think the V6 was the only F1 offered over there, which is a shame. If you get a good one offered at a good price, worth buying it, I'm sure you'll enjoy it... and cross your fingers it stays good!