Introduction and Questions about 02 P5

[jw7783]

Hello everyone, my names Joe and I live in CT. My girlfriend has an 02 P5 Auto with 171K on it. I'm into older Chevy trucks so this car is a whole different world to me. About a week ago, I was driving it and the check engine light came on, but nothing seemed different. (It did this about a week prior but shut off after a bit). However, no if you come to a complete stop with it in gear, it will idle normal but then it starts to "chug"? like it is trying to die so you have to hit the gas to keep RPM's up. Autozone scanned it and it said it's running lean in Cylinder 4, which is probably bad injector. He unplugged the injector with it running and plugged it back in and it made no difference. Is this a common problem on these? I did some research and saw that the EGR's sometime's can do it but it seemed like the injector not changing it might be it also.
Also, not major at all, but when accelerating, mainly on inclines there is a rattling coming from the engine bay and the higher the RPM's the louder it is, but if you're just cruising a flat road at 45 it doesn't make noise. Any help is greatly appreciated!!

 

[Jackie chan]

Vacuum leak and the rattling is knock/detonation from being so lean.

 

[jw7783]

Vacuum leak and the rattling is knock/detonation from being so lean.

Any idea what area vacuum leak would be in? and the rattling has been going on for the past year or so, but maybe it just got worse now? Again I'm pretty clueless about these newer vehicles

 

[Maroon]

Check the accordion intake hose for cracks. I recommend pulling it out entirely to check. Cracks are not always easy to see.

Are there any exhaust leaks? Like on the J-pipe? Every time I get an exhaust leak there (which is all the time) it screws up the idle. These engines are very sensitive to exhaust leaks.

You should also consider cleaning the egr.

 

[kms1990]

check the coils and spark plug wires as well, common wear items on many cars including this one. as above check intake hose for rips and check for exhaust leaks. also check all your vacuum lines for rips as well. i would seafoam it as well, and watch the exhaust, its a good way to get it clean of any build up internally and also check for exhaust leaks at the same time, basically you warm it up park it shut it off take the vacuum line off the brake booster and then start it back up, pour about 1/3 to 1/2 the can through that line slowly and then shut the car off(while doing this watch for smoke rising in the engine bay, this could indicate exhaust leak). after doing all that let it sit 10-45 minutes and then go drive it around until no more smoke comes out the exhaust and then turn around.

 

[pkane]

Could the rattle be the exhaust heat shield (if yours still has one)?

 

[Hank3]

Could the rattle be the exhaust heat shield (if yours still has one)?

^^^
This would be the first thing I would troubleshoot if it's a metallic rattle that you're hearing. I recently got rid of a rattle I had on my P5:

http://www.mazdas247.com/forum/showthread.php?123840625-Metallic-rattle-when-accelerating-under-load