lets try this again. Blldogg if you would?

[Camaro Dom]

ok, so this has been an ongoing problem since i bought the car at 60k miles and now i'm at 105k and havent figured it out. so... lets start out with a clean PCM (no trouble codes)... i'll drive around town all day long and it'll stay trouble free, accelerate smartly and generally drive well. If i take it on the highway and i gun it hard to pass people or merge or w/e *for an extended period of time* say from 35 mph to 70 (or basically all the way thru 2nd gear), it'll gimme the SES light. ok so i scan it and i get (i forget the #'s but) o2 sensor voltage low bank 1 sensor 1 and then same for bank 1 sensor 2 and bank 2 sensor 1. and all three of the codes hit twice so i total 6 codes but 3 of them are duplicates. the car still drives fine but i still have the codes.
everyone told me to replace them all, and against my better judgement (y would all of them go bad at the same time) i did. well, now i'm out like 150 bucks and the problem remains. the cat seems to be running well, throwing in injector cleaner has done nothing, and i'm starting to get worried b/c low volts tells me something's lean, and lean makes things go boom (in the summer i gotta run 89 or 92 to get rid of KR... ON A N/A ENGINE!!!) why the hell is it running lean, and what can i do to fix it?
compression test came out fine when i checked it last summer, vacuum shakes b/w 20 and 22 mmHg rather erratically and fluids are all up to date.
The ONLY thing that isnt in order is a small exhaust leak at the mainfold to head junction on both sides. i get a small ticking sound when i start it up but it goes away once its at operating temp which leads me to believe it seals itself and thus shouldn't be causing a problem.
Can someone PLEASE help me thru this? this is probably the 3rd or 4th thread i've started on it in the past like year and a half and every time people wind up giving up on it and me. Blldogg, if you could pull up flowcharts from the tech database that would help like no other!
Thanks in advance!

[BLLDOGG]

Re: lets try this again. Blldogg if you would?

that exhaust leak could be the problem. low of weak fuel pressure could cause you to go lean under load. some type of trash on the inlet screen. contaminated or faulty injectors. I don't particularly like the normal in tank injector cleaners. could be your MAF. try cleaning it. you might have the K&N oil on it.

[BLLDOGG]

Re: lets try this again. Blldogg if you would?

also, that detonation/spark knock you mentioned, is also an issue that can be caused by lean issue or incorrect spark plug application. also, some pinging during hard acceleration and loading the engine like up hills is normal and does not require upgrading your fuel. it is the loud and consistent knock that causes damage.

[BLLDOGG]

Re: lets try this again. Blldogg if you would?

tell me more about the vacuum test you did. can you in more detail describe what you were doing and the gauge? the reading is suppose to stay steady at idle.

Tell me what your compression readings were and how exactly you performed the test.

[Camaro Dom]

Re: lets try this again. Blldogg if you would?

ok... sorry its taken me a bit to get back here... i've been at my computer for all of an hour in the last 2 days.

Seriously doubt its the MAF. Used to blow a MAF code till i cleaned it (b/c of the K&N) and havent had to reoil since yet so i doubt more oil has gotten sucked thru. havent blown a maf code since.

i dont actually get knocking per se... i've just noticed that in the summer, if i give it gas when i'm close to lugging it (like if i'm going 35 and gun it starts out low in 2nd gear) it'll generate very little power... kinda like a mix b/w hesitation and trans slipping. i'll get some higher rpm's but power will come gradually. i pinned it on KR cuz a trans would give me a sudden change from no power to power and hesitation would mean i wouldn't get the rpms right off or stumbling... neither of which i get. it feels like a plugged exhaust or intake more than anything but once cold weather hits its like its this speed demon ready to eat something ricey.

vacuum test: i hooked into the brake booster line (same as how you seafoam) and started the car. tested reasonably well, no exhaust restrictions or anything. it was twitching b/w 19 and 21 or something like that like mad. i couldnt identify a pattern or regularity, it was just twitching really fast, like with each little exhaust putt.
compression test: did that last summer. dont remember the readings exactly but i remember looking them up in the little booklet that came with it and they were ok and reletively around each other. i had one of those screw in ones. not a piece of crap hold in place tester. i should probably do it again just to see cuz its been a while like i said.

[Vanquish]

Re: lets try this again. Blldogg if you would?

Have you checked your EGR valve and hose and your PCV valve and the hose that connects to it?

Also, the SES light you are getting(and during the same instances that you mentioned) happens to my wife's LHS. All 4 of the o2's are fine, and practically new, so I really don't know what to make of it. I am wanting to actually get started on trying to figure out what it could be, but everytime I open the hood and remember that it's a FWD v6 and realize there isn't enough room in the engine bay to blow smoke through to the bottom I usually give up.

[Camaro Dom]

Re: lets try this again. Blldogg if you would?

havent touched the EGR, and the PCV is only like 5000 miles old.

i'm gonna try and see i cant scrounge some money together... theres a place right across from the GM tech center that is really good with wiring and they might be able to take a gander at it if we cant figure it out here first.

EDIT: its a 3800... i dont think there IS a tube leading to the PCV...

[iGoRa]

Re: lets try this again. Blldogg if you would?

You have a bad ground connection. All 3 sensors using same ground point at the rear of left cylinder head.
Make sure you have this wire grounded well. run another wire to the battery ground just in case.
And post codes please.

[Camaro Dom]

Re: lets try this again. Blldogg if you would?

P0131 02 Sensor Circuit Low Voltage (Bank I Sensor I)
P0137 02 Sensor Circuit Low Voltage (Bank I Sensor 2)
P0151 02 Sensor Circuit Low Voltage (Bank 2 Sensor I)

Those are them...
I thought about grounding but i wrote that off. like i said, ONLY happens when its under big load for a long time like a pull all the way thru 2nd gear (its an auto so thats pretty much 40-75 mph)

[iGoRa]

Re: lets try this again. Blldogg if you would?

P0131 02 Sensor Circuit Low Voltage (Bank I Sensor I)
P0137 02 Sensor Circuit Low Voltage (Bank I Sensor 2)
P0151 02 Sensor Circuit Low Voltage (Bank 2 Sensor I)

Those are them...
I thought about grounding but i wrote that off.

I would reconsider that.

like i said, ONLY happens when its under big load for a long time like a pull all the way thru 2nd gear (its an auto so thats pretty much 40-75 mph)

I have same thing: Logging with HPT and under big load voltage in the system drops, and if you have poor ground you are getting an errors

[Camaro Dom]

Re: lets try this again. Blldogg if you would?

ok... makes sense. where exactly is that ground you're referring to then? if you can, tell me the color of the wire and it'll make my life a ton easier.

[iGoRa]

Re: lets try this again. Blldogg if you would?

black wire , running from joint S108 to the rear of left cylinder head ground point G114

[Camaro Dom]

Re: lets try this again. Blldogg if you would?

wait... what? joint s108?? where the hell do find those locations? GM tech book?

[iGoRa]

Re: lets try this again. Blldogg if you would?

lol , yes , in system wiring diagram , ground points , sensors , everything is there. You can download it , I remember I saw it hosted.

Its gonna be pita , as this wire runs behing the engine. , when you find s108, just run speaker wire to the fat battery ground.

[Camaro Dom]

Re: lets try this again. Blldogg if you would?

speaker wire is like gold. i use it to wire up EVERYTHING! i'll try to look for it but if you find that schematic post it up for me.... or maybe a page # in the book or something... you gotta have it, theres no way you remember joint s108 without it being right in front of you. send that bad boy over here! share the wealth!