The car will barely run, and it's acting like it has a large vacuum leak somewhere. I've investigated all of the usual suspects with no success. Intake tube is like new, all hoses are fine, but it will start, idle badly, then stall after a few seconds. if you pump the accelerator you can get it to rev to 2,000-2,500 rpm after which drops down to around 500 rpm and stalls. I had replaced the #4 coil pack and injector to fix a misfire and also changed out the cam cover on the right bank at the same time because it was damaged. After I put it back together is when this problem started. She's throwing P1646 and P1000 codes (obviously not concerned about the latter) and I have some questions:

Could the bad upper O2 sensor produce these symptoms? How about a clogged Cat? And finally, is there more than one cam cover for the right bank? The one I have seems identical to the original with the right opening for a VVT solenoid, and I assumed it was correct. Couldn't find any differences in the parts book except for VVT and non-VVT versions. Not sure where to go from here. Any help would be greatly appreciated.

 

Have you checked the fuel pressure at the schrader valve on the fuel rail?

 

Sounds like removing the flagged O2 sensor and peering at the cat using a borescope via the hole would be useful, then put in a new sensor.

Also may be worth looking at OBD live data very closely in case some clue is there (bad sensor or whatever).

 

I had already checked the fuel pressure which is a bit low (38-45 psi), but has been at the pressure for some time without a problem. Still wondering about a vacuum leak, just can't keep the running long enough to find it. Based on how the car is running, if it is a vacuum leak, it's probably pretty large so much so that the ECU can't compensate for it.

 

Could be clogged cat(s). It should throw lean codes if there is a vacuum leak.

 

I had something similar happen, mechanic said it was a loose wire that runs on top of the manifold somewhere. Sorry i don't have exact information, but he said it was a fairly common problem and fixed it for free.

 

Thanks,worth checking out. I moved wires to sensors around as well as the harness for the coil packs. Could be something I caused.

 

 

Hate to be repetitive, but did you check fuel pressure while the engine was running, or just static?

 

Thanks for the suggestions. Just came back from working on the car. It runs very rough and stalls under 1,000 rpm, But if you pump the gas a few times, it will rev up to 3,000 rpm and smooth out. Double-checked the snorkel, MAF connector and clamps so I'm sure there are no vacuum leaks. I've also checked the fuel pressure (with the engine running) and it ranged from about 40 to 46 psi. It did, however,, throw some codes: P1300 and P1316 as well as P1646 and P1000 which, it would seem, might point to an electrical problem rather than a vacuum leak. Not sure what the symptoms of a bad MAF sensor are, but I might have to change it out to eliminate that as the culprit (but I hate throwing parts at the problem).

 

That is confusing. I would expect to have individual cylinder misfire codes along with the 1316, and I'm not familiar with the 1300. It doesn't seem likely the right bank cat has collapsed, you would have trouble getting it to 3K, which is where the rev limiter kicks in. I agree that throwing a maf at it seems a waste.

 

It appears that this is problem is at least partially self-inflicted. This all started because of a miss in cylinder # 4 (according to the P0304 code which is rearmost cylinder in the right bank (according to diagrams provided to me). So I changed out the coil pack, miss remains. Next I changed the fuel injector for that cylinder which is when the problem got substantially worse. Turns out when i replaced the injector, it and an adjacent injector did not seat properly which caused the bigger problem and all of the codes. I just re-seated the injectors in that bank and I'm now back to the original problem; one cylinder still missing (although it hasn't thrown a code so far). I plan to take it out for a local drive to see if the car will give me an indication of the faulty cylinder and go from there. At least now it will start up idle, albeit a bit roughly. Overall, a lesson worth learning. TAKE YOUR TIME!

 

 

Jim, I don't think his car is supercharged.

 

It can't get fuel/air right with P1646.