Hi there. I've been having issues with my car bouncing like no tomorrow then stalling out. I've been on I-95 during rush hour traffic and the car will suddenly lose power and stall out. It's a serious safety issue.

Two days ago when I went to test the alternator the car wouldn't start at all. I tested the battery and suspected there were dead cells because it was reading 14 volts but would drop to 9 volts within hours. After having Napa test the battery as expected there were bad cells. After replacing the battery I was able to start the car and this happened: It's very loud and the car shakes violently.

the engine was bouncing with such power that I thought it might actually go airborn and out of the car. The video was taken after the car had been running for about 5 minutes and is not as awe inspiring as the initial bounce. I have questions specifically about the 2004 1/2. The engine is designed much different than the 2004 and earlier and resembles nothing of the 2005 or later. I was trying to find the air control valves after watching, "How to Fix Engine Idling Problems (Rough Idle) in Your Car - DIY with Scotty Kilmer" on Youtube but for as hard as I searched I have no idea where it's located. I ended up opening the short, big black hose located just above the battery, to the right of the actual engine and sprayed Sea Foam Spray in it. The car was suddenly idling smooth and drove like it did when I first bought it in 2005. This morning though, I started the car to see if it would bounce after sitting over night. It did not bounce until I did the "air flow check" by stepping hard on the break like I would if I were on the road and coming to an abrupt stop. The engine started to bounce and the idle was all over the place.

Does anybody know where the air flow/intake/control valves/throttle plate is on the 2004 1/2 S40?

 

This is what I am trying to find and do: It's not visible to me on the 2004 1/2 s40.

 

First, that is a 2004, not 2004.5.

Do you have a check engine light on or flashing?

 

It seems you have a cylinder out of work.Check the coils,the feeders to the coils and the plugs.If all checks out you have a fuel delivery problem.Unplug one injector at a time and see which one doesn't make it worse.

 

The sticker on the door says 2004.5 as does the title that came with the car. Are these clerical errors? You might be right because I just Googled engine pics and the engine looks more like a 2003 s80. How strange!

OMG you are right! It is a 2004!

https://images.search.yahoo.com/sear...g&action=click

 

I did this. There's only 2 of them but 4 slots. Both of them cut off the car completely when I disconnected them. It didn't continue running when I did it. Stalled out. I disconnected each one with the other connected.

 

In the US, that 4 cylinder only came in the 2000 to 2004 S40 and V40.

Was the check engine light on before disconnecting the coils?

 

Well I didn't say to disconnect the coil but the injectors.Of course the engine will stall if you take out 2 cylinder at a time which happens upon pulling the feed to one coil while it would run with 3.The connectors on the coils are known to fall apart and loose connection causing intermittent ignition issues..

 

I took out one at a time. I always thought the car was a 4 cylinder. It was surprising to see only two slots filled. My ex was in charge of taking the car for maintenance so I am not 100% positive but I'm pretty sure that's the way we bought it, with 2 cylinders.

The wires seemed fine. There was a bit of cracking to the outer tubes that hold the wires but the wires seem fine. I'll look closer.

Should I be checking the fuel injectors?

Thank you VERY much. I am most appreciative that you took the time to respond.

There's other issues (electrical). I don't know if this would have anything to do with it and it's hard to know because it's giving me false messages. The seatbelt light will be on when I'm wearing it, the door light will be on when I know it's closed tight. The brake light is on, air bag light is on, check engine, service... the back windows suddenly don't work, the back speakers suddenly don't work, the a/c spontaneously works. I know it's time to replace the car because I can't afford the upkeep (my ex did that) but I can't afford a new car either so I'm stuck with it, doing my best.

 

Each ignition coil fires 2 cylinders. The cylinder it's physically on top of and the cylinder with the spark plug wire attached. Misfires are usually caused by a hairline crack in the plastic of either the coil or it's associated cylinder where the plastic fits down over the spark plug. The high voltage spark jumps to the cylinder head instead of jumping the gap at the spark plug. High temp RTV spread on the cracks sometimes can be a cheap fix.

Too much engine movement is normally a sign of busted motor mounts. There are 4 but the bottom 2 will go first.

I would not replace fuel injectors. Normally they are fine. They can go bad or clog but is more rare than the common cracked plastic on the coils or spark plugs.

And check all your fuses first. You have a ton of warning lights lit.

 

I'm not really sure what to check/do at this point.

 

Disconnect the injectors one at a time and see if any of them makes it run worse.Engine will jump if a cylinder is a miss no matter if the mounts are brand new even.Injectors get clogged supplying no fuel or they wont close flooding the cylinder preventing the plug to ignite the mixture.You are looking for the one which makes no difference when you unplug it.

 

Thank you. I've tried this. I have tried this. With either disconnected the car shuts down. I appreciate your input and know the answer is out there somewhere.

 

What I have see what you have said is that you did disconnect the coils not the injectors.

 

 

OK I understand. I have not gone near the injectors. I will try that next.

 

If you don't know whether your car has two cylinders or four, close the bonnet and take it to a mechanic.

 

It was the mass airflow sensor. What I learned:

To diagnose the problem, disconnect it and start the car. Drive it long enough to step on the brakes and head back home. If the car doesn't stall, this is the problem. It needs to be replaced.

 

Thank you for coming back and telling us what you found.