2003 vue 3.0 random misfire and cam position sensor codes

[Jmatt007]

So from the beginning this is my son's gf vehicle. It had a miss on cylinder 5 I pulled it apart put coil pack and all new ac delco rapid fires put back together with new gaskets and still didn't run like I thought it should. I then ran seafoam thru the vacuum lines let it heat soak for 30 mins or so and ran it it came alive and was running amazing.

Fast forward to this previous Monday the vue's belt tensioner pulley siezed up and burnt up the belt. I got a belt and put it on started it up and took for a 15 min drive. About 5 miles from the house ses light started flashing and lost all power except at very slight throttle. Pull codes and I have a cam positioning sensor code an 02 sensor bank 1 sensor 1,and random multiple misfires. I pulled intake and plugs and only 135 were firing 246 were wet as was the intake runner to cyl's 246. Cleaned plugs put it all back checking connections and vacuum lines. Once back together started and same thing checked coils on 246 and they are firing still getting random misfire and cam sensor codes. Racked my head trying to figure out why one side would run as it should and the other not at all picked up cam sensor as it was the first code that came up. Replaced it and nothing changed at all I can unplug the coil pack while running and nothing changes at all.no backfiring at all.

I am trying to not throw parts at it . But I am leaning toward ecm coil pack looks good and coil tester shows it is firing.

[Jmatt007]

So update i checked vacuum and it was very low kind of erratic hava snap on scan tool watching live data as well and it shows 135 not missing 2,4,6 missing then reconnect and it flipped saying my misfires were on 1,3,5 which is not true at all o2 showing it mimicking the downstream sensor 2 as well pulled intake and have quite a bit of sludge by the injectors of 2,4,6 but not on opposite side so I started taking intake apart. Any ideas would be great but for now I will be disassembling the intake and sealing it up before moving forward

[TJB63]

I'm dealing with the same issue, But since it's random on mine and really doesn't affect the performance when it throws a code, on top of this isn't a primary vehicle for me, I've kind of put it on the back burner for now until it warms up.

Some thoughts, Have you checked/replaced your timing belt? That's not one to let slide on these engines. - Do you have the means to smoke test it?

Like you, I addressed the obvious, Plugs, Coils etc...on mine, I plan to smoke it in Spring, replace all my vacuum lines and hope that fixes it, either way it can't hurt it. I have a feeling in the back of my mind that I'm either dealing with an intake/exhaust manifold gasket or even something as just an Old Computer showing it's age, once in a while I'll get a P0700 Trans code, P0171 Fuel trim, but mostly the P0300 misfire codes, usually on the Odd cylinders, in no case does the car run any worse than when it's running normally, that's what makes me think the PCM or whatever they call it on a VUE might be getting old, in my case mine is 20 years old.

I have an 06 Hummer (another GM product) that actually threw a code for the PCM, replaced it, cleaned the camshaft sensors and runs like new.

Good Luck, I'm hoping to resolve mine come spring, it's a fun car to drive, for now I just keep a cheap code reader with it and clear it as needed. it's more an annoyance than anything.

[Jmatt007]

Well i seem to have jumped time on front of motor not much but yes and after that found that there hasn't ever had a timing belt done so now after all this I have a saturn vue they are getting a new vehicle so soon I will be pulling it apart to assess how far off it is I feel it having 35-40 psi compression i may get lucky and be able to save it if not I will have head checked and replaced with new timing belt kit

[TJB63]

Good Luck, doing my timing belt the first time was a PITA, You will need to support the engine/transmission and remove the top engine mount. You'll also need the timing tools which you may be able to rent, I bought a set off Ebay. I've also seen videos where people make their own, I wouldn't trust myself doing that and besides the proper tool always makes the job easier. YMMV

There is a guy on Youtube that replaces a belt on a 3.0L Cadillac CTS -- His video is excellent, My first time I was relying on a Chilton's manual and needless to say, their instructions are very confusing, I ended up having to replace it again because I didn't do it correctly using the Chilton's. The CTS video showed me where I was going wrong and made the job 100% easier.

Also, recently I saw a video of a guy (Youtube) removing the front grill and side fenders off his Vue, this looked pretty easy to remove and would make doing the timing belt much easier I would think, Next time this is the route I think I'd go. A couple screws and some push pins and off it comes.

Remember to replace your water pump while you're in there. I hope that cures your problem, as these cars get older, I think we'll all get weird codes popping up, but fortunately you got to the timing belt before it snapped and cost you an engine.