2001 Trans Am WS6 with A4, 35000 miles;
all stock, no mods (other than M-206 longer oil filter);

spark knock under medium to high load, and also when 1-2 or 2-3 shifts occur;
scan tool shows upto 7 degrees knock retard;
scan tool shows sensible values from MAF, MAP, ECT, IAT, TPS;
fuel pressure guage shows 59 psi at fuel rail;
using 91 octane (So. Cal., where else...);
seems to knock slightly less with 1/4 tank 100 octane added (but still knocks);
air filter and fuel filter recently changed;
still has original spark plugs (btw: was thinking of installing Bosch+4);
has been doing this for last 4 or 5 weeks, and seems to be getting worse;

could this be due to carbon deposits...?
or due to bad gas, or "oxygenated gas"...?
should I use top engine cleaner, and how do I apply it...?
is it harmful to O2S, MAF, injectors, intake manifold, or anything else...?
could this be due to oil being sucked thru the PCV...?
should I use octane booster...?
what else...?

on old cars spraying a quick shot of water mist down the carb while cracking the throttle wide open several times caused the carbon deposits to be cleared (puff of black smoke out the back)...
can you do this on new cars (the MAF is in the way, is it okay if it gets water mist thru it...?)...?

Thanks, I do appreciate it.

 

I would use the GM top end cleaner first since your car has 35,000 miles on it.All you do is start the car,pour it in the PVC intake fitting(use a hose)slowly and when you have 1/4 can left,dump it in as fast as you can then shut off car immediatly.Let car sit for 1/2 hour,then start up and drive.It will smoke very badly for about 10 minutes.

After that I would put in new plugs( NGKTR55's) and reset computer.

 

New plugs and swap out the fuel filter. Engine cleaner couldn't hurt either. Did you look at the inside of the intake for excessive oil. Look at the back of the throttle blade and check for build up. Use the ngk plugs.

 

yeah do ngk plugs and a top end cleaner, i used a mega power one we have at work and ran 2 gallons of 100 through with 1/4 tank of 93.....that will work out good just dont put any additive in the fuel tank, i dont think its a good idea....100 will work good....just did this on mine not only did the car run better but it cleaned off the o2 sensors also and they are reading a lot more consistent now...

 

Removed the MAF sensor and bellows;
throttle blade looks clean on both sides (used a mirror and flashlite to see the backside of the throttle blade);
intake manifold has a Large puddle of oil sitting inside it;

I'm going to replumb my PCV to prevent oil getting sucked;

just so I understand the problem better: how does oil cause spark knock...?

I should pull the spark plugs and check for oil fouling.

 

I meant to add:

does it matter if the direction of the PCV flow is reversed
(including reversing the PCV valve, and reversing the the two pcv hose connections at the throttle body)...?

(i.e. so that fresh filtered air enters the engine at the rear of the valve covers and exits at the front);

 

add a catchcan or do the ls6 pcv conversion at ls1howto.com
the ls6 sucks pressure from under the valley instead of the shallow valve covers

 

Oil burning/combustion results in Carbon build up in the chambers. Carbon deposits retain heat/energy and can act like glow plugs -> Detonation. FWIW.
joel

 

what can be done to prevent oil gettin sucked in the intake, and how much would it cost? i get oil in mine too, i can smell it too, smells like ****

 

I am going to reverse the pcv air flow direction so fresh air enters the rear valve covers and exits thru the oil filler cap and into the throttle body (I'm going to drill a hole in my oil cap and put a grommet and pcv valve there; I'm going to plug the front air fitting on the RHS valve cover where the fresh air originally enters).

 

Why (and how) can you reverse the PCV system - there is a vacuum at the TB, and air will flow INTO that port.

Also 7 deg of KR is not a major issue - for how long is the KR indicated - miliseconds or tens of seconds. Do you HEAR the knock, or is it based on the readings from the scanner?

Octane boost is a general no no in modern engines, and 92 should be fine.

Top end cleaner is OK as long as you follow directions.

Oil in the intake should have NO effect on knock unnless it is SO much that it has carbonized on valves and in cylinder, or as noted caused a carbon "hot spot". You'd notice the blue smoke long before it got this bad! How is your oil consumption?

Water on a RUNNING MAF will basically destroy it's calibration!

Link to Top End application:
http://corvetteforum.com/techtips/vi...=212&TopicID=1


Keep us posted!
MRK

 

1-joe said how and why. new idea on how to do it though.

2-seven degrees is quite a bit.

3-why no octane boost? it won't hurt anything unless it had lead in it.

4-they said how to use the top engine cleaner. i actually hydrolock my motor a bit by dumping the remiander of the can in at the end so it kills the motor.

5-you won't always see smoke.

6-those guys are on crack! there is NO need to use two cans.

 

at the cadillac dealer where i worked, i would heat the motor up, pull all the spark plugs, and pour equal amounts in each cylinder.

the cleaner sits on top of the hot pistons removing most of the carbon. easier to do on northstars though, with the easy access to the sparkplug holes. GM produced a special tool to actually squirt cleaner into the sparkplug hole.

smokes like hell when started. after it was done, they would be less noisy and burn alot less oil.

 

just have to be careful that most of it is evaportated out of there or there isnt a lot. that fluid is not as compressable as gas and air mixture and you WILL bend a connecting rod. guy at work wouldnt listen to me and he found out the hard way

 

yeah i usually let it sit for 2 hours or more, sometimes overnight
then i start it and floor it, let it bounce off the rev limiter for a while
never caused any damage to customer vehicles
just make sure to be out of the garage, because it WILL smoke alot

 

hell yeah it will smoke like a SOB and the stuff we use burns yoru nose and eyes. see the stuff we use we run through with the car running, for about 10 min really slow, but if its too fast it bogs down and freaks everything up lol but yeah if u do it right its no problem, just have some morons at work and figured i would throw that out there for others sake that might not know...

 

Okay, questions and answers (>)...

1. Why (and how) can you reverse the PCV system - there is a vacuum at the TB, and air will flow INTO that port.
> swap the two air hoses at the throttle body, move the pcv valve and rubber parts from the lower hose to the upper hose (... but, actually, I want to move the pcv to the top of the oil filler cap since this is a high point on the engine); this means that the vacuum port at the TB will suck from the front of the RHS valve cover (or the oil cap), and fresh air will enter the valve covers at their rear (thru the existing plastic tube that the pcv valve is currently on); I am wondering if anyone foresees any problems with this reversal of flow...?
The reasoning is this: on acceleration, high rpm causes lots of oil to be pumped to rockers, and acceleration makes this oil accumulate at rear of valve covers... so suck the fumes from the front of the valve covers, or from some high point where oil can't get to; the idea is to not suck oil (since I'm using M1 synth I don't wan't to waste it (ping or no ping)); I don't really like the idea of a catch can;

2. Also 7 deg of KR is not a major issue - for how long is the KR indicated - miliseconds or tens of seconds. Do you HEAR the knock, or is it based on the readings from the scanner?
> The knock is Very audible, and lasts anywhere from 1 second upto 5 seconds (or more if I don't reduce throttle opening); scanner confirms this; 7 degrees is quite a bit, especially for a seond or more;

3. Octane boost is a general no no in modern engines, and 92 should be fine.
> That's funny since the GM dealer told me to use some for one tankful;
I don't trust the dealer very much anyway...;
I can't get 92 since So. Cal. is all screwed up;
what kind of bad effects can octane boost have...?

4. Top end cleaner is OK as long as you follow directions.
> Yes, I'll do this; thanks for the link regarding how to;
I read somewhere that GM recommends that top engine cleaner should not be used on cars with less than 50000 miles... I don't know what to make of this, but first I'll replumb the pcv plumbing and then I'll do top engine cleaner; what do I do about the large oil puddle inside the intake manifold...? And I'll use just one can.

5. Oil in the intake should have NO effect on knock unnless it is SO much that it has carbonized on valves and in cylinder, or as noted caused a carbon "hot spot". You'd notice the blue smoke long before it got this bad! How is your oil consumption?
> I don't see blue smoke, but my intake manifold has about 1/8th inch (or more) of oil sitting inside it; my oil consumption is about 1/2 quart per 3000 miles; pinging gets Worse after sitting in traffic for a 10 minutes or more (i.e. higher engine temp); can I get this oil out without removing the intake manifold, or should I remove it and clean it...?

6. Water on a RUNNING MAF will basically destroy it's calibration!
> Yes, I realized you can't spray water in and crack the throttle open, but I didn't realize that the MAF's calibration would get messed up;

7. Keep us posted!
> Yes I'll certainly do that (I won't be anywhere near the internet over Christmas, but I'll update this thread when I get back on the 8th of Jan); I'm hoping my wife'll get me a digital camera for Christmas so I can post some pics of this ("...we'll see..." says she...); so, as I see it, it always sucked oil which caused it to develop carbon deposits which now (after 35000 miles) causes it to ping (and it's much worse when hot);

I am also going to change spark plugs while I'm at it (this will show me if oil fouled or carbon fouled); I know there's a separate thread regarding choice of plugs, but do you have any comments on the Bosch+4 spark plugs...?

I'm also thinking of doing the thermostat mod (I'll go with 180 degrees), and getting a lid and [maybe or maybe not yet] short headers (I like long headers, but it must be able to pass visual here is So. Cal. where the cats must be in their original location...).

Thanks to all of you for your responses and ideas, I appreciate it; do enjoy Christmas.

 

ok so i wanna stop smellin oil getting burned whats the easiest thing that i can do NOW for it? and wahts the best thing in the long run to do?

 

can the lines be switched without any problems?

 

Your idea may work but you want to watch out that it does not reduce the amount of vaccum so that the fumes are not venting out well and being sucked back into the oil reducing it's life

The issue is the PCV laying on its side and when it opens oil also gets by so placing it in vertical position would reduce that.
Also the spring in PCV was a bit too weak and newer ones are better designed. They may be using the PCV used on GM pickups seem to have stronger internal spring.

Using a thicker oil will reduce what gets by PCV.
You could swap to a Z06 valley pan and its PCV location.

If you had high carbon buildup it would knock across the engine load and not just after idle so it points to a AFR issue. Using a higher octane such as Union 76 100 unleaded would prove if its carbon buildup or not.

If you ever took apart a knock sensor as I have you will see they are not designed well and would suspect the sensor(s) due to their age if the AFR and timing is correct.

Tuning the knock functions in the PCM would allow control of when knock occurs how fast the PCM attacks it and how fast it decays the knock and how much timing is yanked.
With Ca crapgas a PCM tune will allow good overall timing with no knock.
7 degrees yanked for that length of time is not the norm if AFR is correct.

Check heads for a problem if all else fails.