2005 S-type R. Starting happening last night, I started the car and it ran really rough, rpms jumped around and car felt like it was going to shut off. I revved it a few times and eventually it stabilized and then I was able to drive it.

No CEL light, however I checked pending codes and got P0300 and P1316 the first time and when I turned the car off and re-ran the pending codes I got P0300, P0301, P0302, P0303, P0304, P0305 and P1316.

Any ideas on what the issue may be?

 

Sounds like an air leak. Hot engine, check fuel trims (LTFTs) at idle and about 2500rpm. An elm327 will do - very cheap

 

Perfect, I have the ELM, will do.

 

I've got a similar problem, and will be curious to hear what you find.

My problem is more of a lumpy/wobbly idle at 1200-1300 rpm, not dramatically fluctating rpms. It evens out on its own after approx 30-45 seconds to a fairly smooth 800 rpm idle.

I'm a rank amateur, but speculate that is when it goes into closed loop as O2 sensors reach temp and trim kicks in and can add fuel. I did noticed fuel trims max out both banks +25 at idle which I had not seen before. I need to recheck at 2,500 rpm.

 

I doubt it's when it goes CL. You can tell by having someone watch OBD.

Could well be a TC (TQ conv) problem or low autobox oil.

 

Hey gents not really sure how to check fuel trims using the elm and my torque app? And I just got restricted performance now.

 

Hunt round it.

Check you battery isn't failing as it's #1 suspect.

 

With Torque you need to be looking at Short term fuel trims using STFT1 and STFT2 and Long term trims using LTFT1 and LTFT2.

I have Torque Pro: you can set set up displays in Realtime Information menu/display find it best to use histogram as it builds over time and retains data.

 

Yeah at first I thought maybe battery, however mine is only about 6 months old. I have the Magnaflow 59975 hi flow cats. A friend of mine suggested that they only last about 4 years or so (which is about the age of mine). He thinks its a failing cat, any thoughts?

 

Well the problem with that is you have no cat codes??

You have a number of cylinder misfires which points to coils and/or battery. But you said you battery is pretty new.

Have you inspected the spark plug wells for oil/water?
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Hey guys, still trying to figure out how to check fuel trims. Haven't had a chance to check the spark plug wells yet also. Parked the car for now until family friend (mechanic) is back in town to properly diagnose. I ran the codes again last night P0300, P1316 and P0171.

 

Ok so visited my indy mechanic. Confirmed that there is a vacuum leak on the left side (not sure just where yet). He didn't have time to do the smoke test, however that is the next step next week. Didn't seem like it was coming from a hose as he checked them all. Any other common areas for vacuum leaks on these engines?