Greetings.
I pray that you all can point me in the right direction. I have a 2006 s40 2.4 with 115K miles. During the last month I have been experiencing some major issues while starting the car and some performance issues while driving. I took it in for service and had the oil changed, and the car was diagnosed with an engine misfire. I had all the spark plugs changed. The issue seemed to be gone for a few days and then the rough starting began to occur again. The computer once again reported that there was an engine misfire. So I now all the ignition coils were replaced and the issue once again seemed to be fixed but then about a week later the issue resumed. Once again an engine misfire code came up. Now I had the engines wiring harness replaced about two weeks ago. Yesterday the issue resumed and now its worse than ever. I can't even keep the engine running unless I am pressing the gas at the same time I am starting the engine. It will sometimes rev high and a warning will appear saying "Try slowing down or shifting up". If I don't keep my foot on the gas while turning the ignition then the car will sputter and die. The car also now has a rough idle at times.

Tonight, a new message appeared: "Engine System Service Required"
I checked the codes on my s40 and the following codes came up:
P0304: Cylinder 4 misfire detected
P0300: Random/Multiple cylinder misfire detected
P0607: Control module performance

I am very short on funds and I am hoping that you all can give me an idea on what I need to do to fix this once and for all or at least give me something that gives me a better place to look. I will attach some photos of what my code reader is showing. Hopefully someone can make sense of it.

 

check vacuum lines/intake tubing. Then inspect the MAF and throttle body for any dirt.

 

Welcome to VF nappiiroots

 

Thank you. I will check, the vacuum lines and throttle body in the morning and update the post. Please pardon me, but I am not familiar with where the MAF is and how to check it for dirt. Can someone recommend a video or provide any instructions on how I can do this?

 

Thank you for the warm welcome.

 

I haven't been able to clean the MAF or vacuum lines yet because the weather here has been terrible but hopefully before the weeks end, I will be able to take care of this.

 

Okay, so I cleaned MAF and the throttle body and I have noticed an improvement in the way the engine is running but there is still something wrong. I am still experiencing a rough idle and start. Anybody have any other ideas?

 

Are you sure that the battery is good? A low battery causes really wonky behaviour on these cars. Also see:

 

Have you checked fuel pressure? The 2006 has a fuel pressure sensor instead of a fuel pressure regulator like on the older 1.9L engine. The FPS controls fuel pressure through voltage changes to the fuel pump. It's kind of expensive but super easy to replace.

It's located on the pax side of the engine at the end of the fuel injector rail. One wiring connector and one bolt hold it on the rail.

Failure of the FPS causes misfires and poor performance due to incorrect fuel pressure.

 

Battery is good but, yes I have heard about the crazy issues that come from weak batteries.

 

How can I check to see if that is the problem without actually replacing it first? I am kind of a novice.

 

Does anyone know if a coolant leak could cause some of the issues I am experiencing? I have had to refill my coolant tank quite often lately and I have found that the cap on the tank is not screwing down tightly anymore. I have a feeling this is causing some kind of pressure issue. I don't too much about this but I am hoping someone can shine some light on to this.

 

Check the fuel pressure with a fuel pressure tester. Harbor Freight sells a cheap unit that is good for the home mechanic.

 

Leaking coolant is a warning sign for a couple of things. Not all bad either.

One is a cracked coolant tank. You should see and smell coolant on the outside of the tank. My 2005 had a crack on the top center that only spewed coolant under pressure (engine running). I would address this with either a new cap or tank or both. They are not expensive online.

There are also two small rubber lines running across the front of the car to the coolant tank. I found a large crack in one while searching for a coolant leak.

If coolant is leaking from the main hose assembly then it's more work to replace. You have to remove a bunch of parts on the front of the engine to access it. Not overly complicated, just have to put things together the opposite of how you took it apart.

If you find coolant soaking into your interior carpet then it's the heater core o-rings. I spent 2 lousy days on my knees and crushing my ribs to replace mine. This one isn't expensive but it's a PITA to replace.

Now the worst place for a coolant leak is a head gasket. This one is bad news. There are a couple of tests with the easiest being a visual inspection of the oil. Is it milky? This would be water and oil mixing. The 2nd is to pull the spark plugs and look for one that is bright white. Literally "steam cleaned" by coolant being burned in a leaking cylinder. The last is a chemical being added to your coolant to check if combustion gases have entered the cooling system. This failure can lead to misfires and rough running.

 

I have not been able to drive or do much with my car in almost two weeks due to personal issues but I am healthy enough to drive again and I tried to start the engine and the idle was extremely rough but smoothed out eventually. I drove literally just two miles up the road the car stalled on me once I stopped at a light. I opened the hood to find the coolant was completely drained. The temp gauge was just slightly higher than normal but the car began smoking very heavily from the exhaust. I was not able to get the car home. I needed a tow. I checked the coolant before leaving and the level was nearly to the top. I checked the oil after getting the car home and it looks like chocolate milk. I just changed my oil three weeks ago. I think I blew the head gasket.

My question is, is it even worth fixing at this point? Its looking like it is going to cost around $2,600 and that is just if the head gasket needs replacing. Other issues could start to add up quickly. Does this price sound fair for this issue?

 

 

I agree with pierremcalpine, get a used engine or sell the car for parts. Head gasket failures usually don't just happen. It's normally the result of an overheated engine that warps the head. Much more rare is a cracked block.

With a warped head you can have it resurfaced or buy a new head but the labor costs are very high if someone else does the work for you.

 

 

thank you for sharing .