I pulled the one on the top of the IM tonight and tried to blow through it.. it seems ok.. nothing going through but my car is jerking with it connected.. I just took it for a quick rip for a couple blocks with the electrical connector disconnected and it's running smooth again.. afr's are quite stable whereas lately they've been constantly jumping around from 13 to 15 afr just regular steady driving at light throttle. (Unfortunately, I can't see STFT's or LTFTs, but I can see and feel the difference anyways) Does this mean it's the one underneath the car that somebody said is behind a canister? If so, what part do I need to replace it with? Car's running beautiful with it disconnected though lol.. I think I'll leave it this way until a solution can be found.

 

Just an update on this:

Ran into clearance issues between the solenoid and bottom of the IM "bowl". There is a little less room between them than I anticipated when the solenoid is mounted and bolted down. This throws a wrench in my primary solution/idea I was going to test. I'm devising another plan, but it won't be as effective as the first idea I don't think though.

 

I've read this thread and replaced both the purge and vent solenoids. What now?

My AFRs sweep from 12 - 18. My car runs rough and surges occasionally.
My STFT was running right around 3-4. LTFT was -10.
No DTC's (Pending, current, history, or MIL req'd)
My car has done this since I've bought it and never thought twice until I read about it on here.

Is there any variables that have been tracked for cars with the problem vs. cars without?

 

Do you have the stock airbox? If not, are you tuned for the aftermarket intake?

 

I am guessing coked intake valves. do u have oil in your intercooler?

 

I have a modded airbox. I will check in my charge pipes tomorrow for oil. Thinking blown turbo seal? It smokes a little when I'm on it.

 

eventually the turbo seals can be harmed. coking is partly caused by the inabiliity of the pcv system to vent the crankcase well enough and a driving cycle which does not get intake valve temperature high enough.

Its also made worse by blow by from the pistons and rings, which get really worn on an LNF with crazy tunes, which provide too high combustion pressures, over fueling, and general deteroration from runaway detonation.

The LNF was sort of designed to accept some pooling of oil in the bottom of the intercooler. But its the old story of too much , is ...too much. The valves get coked in DI engines thats an industry wide fact, and once they coke up the spiral to a whole big heaping helping of nogoodatall.com is accelerated.
low ash motor oil, change in driving cycle, improved pcv, all are positive improvements needed. But if the valves are already coked up, that has to be fixed. Tune as well.

 

I verified I have ALOT of oil in my intake. When I took my SRI off to return to my stock airbox, the SRI was dry.

I ran my car on BG throttle body cleaner right into the intake, and it ran a little better (no surging, idle didn't feel rough) for about 50 miles. Will do further diagnostic this coming week. (Compression test, etc.) Any other tests I should do?

This will probably all be done under warranty because I work at a Chevy dealer. I do have a better than basic understanding of how vehicles run and work, I am no master technician by any means.

Already have a catch can on the way, and will be adding a vacuum pump soon, which I had planned to do as I am upgrading to full bolt-ons + a tune.

 

What intake are you talking about having ALOT of oil? Air intake, or intake manifold? I'm having some issues similar to yours.. just got both parts a few days ago, but haven't had time to install them yet; and I also have a catch can ready to go on as well. Hoping this solves the issues, but I'm wondering if it's something more serious like what yours sounds like. If I install all this stuff and it still does it, I'm going to be banging my head against the wall.
My purge solenoid seemed fine, I could blow through it, but I ordered a replacement anyways since they're only like $12 or $14 from Rockauto. I wish somebody could figure exactly what's causing these issues, instead of well could be this, this or this.. and still sometimes it's not that lol. Anyways.. I hope to put this **** on today and it works... wish me luck =P

 

The Intake Manifold actually has puddled oil. I really love this car but all these problems are going to be the death of me.

 

Well, update on mine.. didn't install catch can due to time limitations.. I'm working 6 days/week 75+ hrs so I have time to eat, sleep, and **** basically.. anything else is pure luck.

Anyways, went to buddy's shop, threw it up on the hoist, popped out the purge valve thingy (very easy with a hoist lol), popped in the new one. Lowered the car, popped in the purge solenoid and ran out of time. Hooked up the electronic sensor to it, cleared the CEL I had got for unplugging it, and fired her up. At first, not much better.. but driving home, it got better n better and is pretty smooth once again.. feels like new. It's still not perfect, but its WAY better. I still have the catch can to do, and a PcV valve as well, which from my understanding, is a Pita to get on. Might hafta take it to the dealer for that one, but I believe in maintenance
The fuel trims are much more stable now.. they were jumping probably 1-2 full points whenever they wanted to.. only time it was stable was basically under WoT. Now, they seem to only fluctuate like .1-.3 at most. I think it was the purge valve personally, although the spring still was functioning if I pushed on it. Solenoid was fine too.. couldn't blow through it.. obviously, one of those 2 things fixed her up though anyways. I can't read STFT's or LTFT's, but I can see my AFR gauge, which was bouncing around like a fkn yoyo before and is now pretty damn stable.

 

Does the PCV line that runs to the turbo serve a purpose at the turbo? Otherwise I'm thinking about blocking off the port at the turbo, and venting it into the air intake through a catch can.

 

my solenoid was actually making a knocking noise as if it was constantly opening and closing. once i unplugged it, the knocking stopped and my afr's stabalized pretty well. anyone else have this same thing happen?

 

The PCV system has nothing to do with the Evap system, so kinda confused why you asked here.

But no, that line doesn't have to be at the turbo, so you can move it to the intake. The idea was to have it come back into the intake stream somewhere before the turbo wheel.

 

The solenoid is pulsewidth modulated, meaning that by nature it's controlled by quickly alternating on-off power. You were therefore probably just hearing it operating. On the other hand if it was making an unusual amount of noise it may have been broken. It's kinda hard to tell.

 

well its a constant knocking and its actually pretty loud. the only time it stopped knocking was when i unplugged it. thanks for the info btw.

 

Car had been running rough lately. Replaced the evap canister purge solenoid (waited 'til she started throwing loose gas cap errors, unable to blow air through solenoid but replaced it anyway). Sheeee's BACK!. Started cold and took off smooth as silk, no lurching. Idled smoothly at the stoplight with the air going and ran like a scalded cat. Started getting rough at 15-20k miles. Has 30k now, 2 years old, Guessing the car's remaining life at 120k, she'll eat another 6-8 solenoids.

 

Agreed. first two on mine lasted 25k each. Not cool. Replacing every 18 months.

 

im sorry i tried to read all 13 pages but got burnt out.... is it safe for me to unpluge this if i have modded air box down pipe zzp intake pipe and BYT tune untill i can get my new one to come in im hearing the clicking nois also from it as its constanly turning on then off

 

in case anyone uses the search, then reads this far. Old part number was superseded. New part number is 12592015.

 

hey guys im having a problem with my 08 tc its hardcore stuttering at low rpms, but its fine if i WOT after 3500 rpms like no issues at all pulls awesome! i have a zzp tune for 22psi, hahn catless down pipe, ingen cold air intake(which is tuned) ingen upper charge pipe. gm s1 map sensors. the stuttering is really loud i will link a video, if anyone could help would be much appreciated if you could pm me! ( in the video i said it happens WOT at low rpms, but it happens at light throttle too.

 

I think that's a misfire code so see if zzp can look at your tune, unless it's a canned tune, in that case get a real tune from a local tuner. Oh and you probably shouldn't go wot anymore below 3500rpms, just saying.

 

its a canned tune!, but the thing is it was happeing before i got it tuned, i thought the tune would have fixed it lol

 

Well my car started doing this, will try to disconnect it today and see . All started after I cleaned evap canister filter by gas tank. Probably got something clogged up

 

Anyone used this one?