Heavy pinging/spark knock? out of no where!! loss of power

[gr8lover]

Hopefully this is just a gas issue, but I filled up for gas just before a 2 hr drive up to Lapeer for drag racing (never ended up going). But on the way everything was fine until a Brand New Mercedes V12 AMG pulled up wanted to race....ok I thought ---- nailed it and at 100mph it banged like you wouldnt believe and stopped accelerating!!! I let off and waved the Mercedes off.... I rn thru the gas till almost empty and drove easy... but now Exhaust sounds really different... more rocket like and also still pings on hard acceleration... (and restricts the power big time!!)... any thoughts? How long does bad gas effect this and can it change sound of exhaust? Thinking maybe something in the cat let go like G8GT594 but seems weird to have happened right when pinging started..... also, with dashhawk, when the pinging starts the spk adv goes way down to in the single digits...
thoughts??? (ps.. I checked all vacuum/pvc, etc lines and everything seems good.....)

[norm8332]

If you have cats they could be it. Sounds like the issue I had.

[gr8lover]

If you have cats they could be it. Sounds like the issue I had.

What was your issue? with the cats? did you get pinging and extreme loss of power when accelerating hard?

[vic2186]

Hope everything is ok..

[norm8332]

The cats went bad and were restricting flow at WOT. It would ping loud and loose power. Since cats gutted, no problems.

[gr8lover]

The cats went bad and were restricting flow at WOT. It would ping loud and loose power. Since cats gutted, no problems.

Thx for your help, I will try that. Dumb question: did you gut them yourself or someone nearby-- do you think any muffler shop can do it, or would you take it somewhere special?

[norm8332]

They were gutted when I took it in to a shop to get it checked. The tune has a lot of cat protection in it, if any is disabled then the cats go bad. At least that's what happened in my case I believe.

[todds87ss]

Thx for your help, I will try that. Dumb question: did you gut them yourself or someone nearby-- do you think any muffler shop can do it, or would you take it somewhere special?
no shop will gut cats at the risk of big federal fines. This is a DIY only!

[gr8lover]

Update: did a backpressure check on Cats and everything is fine.. looks like cats are still good.... but also found oil all over the bottom of my car that wasnt there before this issue.... so now there is a bigger issue I think and now I am really concerned. Going to get a compression test and a Leak down test done to see if it is something in the engine.... argggggggg...

Now I think my G8 is the slowest G8!!!!!! I think my Impala could beat it!!!!

[vic2186]

Oh man..probably bent a rod or piston blew..hope it's all ok you have one monster of a g8!!

[Seattle09GT]

Update: did a backpressure check on Cats and everything is fine.. looks like cats are still good.... but also found oil all over the bottom of my car that wasnt there before this issue.... so now there is a bigger issue I think and now I am really concerned. Going to get a compression test and a Leak down test done to see if it is something in the engine.... argggggggg...

Now I think my G8 is the slowest G8!!!!!! I think my Impala could beat it!!!!

Ahhhh man, this does not sound good at all.

[kayrunner]

Hi All,
I have a 2009 Pontiac G8 GT liquid red. I have not been able to make any modifications to this vehicle as it has given me trouble a month after buying it. With 3400 miles on it, while stopped at a red light, cylinder 7 blew with mild acceleration. Shop had it for week and a half. Since that time, anytime I accelerate with any enthusiasm, a total loss of power!!! It has been back to the shop since March of 2010, 8 times and they have it now. They cannot figure out what it is. At least they get a loss of power too when they drive it. Any suggestions out there????

[-Ray-]

What did the shop do to it?
What shop worked on it?
What state are you in?
Did you have a MIL?
Sorry about all the questions, but there isn't enough information to really help you.

[Seattle09GT]

Update: did a backpressure check on Cats and everything is fine.. looks like cats are still good.... but also found oil all over the bottom of my car that wasnt there before this issue.... so now there is a bigger issue I think and now I am really concerned. Going to get a compression test and a Leak down test done to see if it is something in the engine.... argggggggg...

Now I think my G8 is the slowest G8!!!!!! I think my Impala could beat it!!!!

Any updates? I've been thinking about you and hoping this isn't as bad as it sounds.

[Struggle]

I remember working on a vehicle a long time ago (Ford Explorer) and it had rthe same issue and several people looked at it and could not figure out what the issue was. I found the Mass Airflow sensor became contaminated and cleaning it resolved the issue. It would drive normal until you stepped on it and it would lean out and ping like crazy.

It ran great after a the MAF was cleaned.

Pinging is an issue of a lean condition which you probably already know.

[gr8lover]

found oil in the following areas:
Throttle body soaked, MAF soaked, Cold air intake flooded with oil, oil found in Cylinders by spark plugs.... and found rear main seal was blown out!!!!

Could the rear main seal issue that some G8's have cause the following items to be soaked with oil? WIth the MAF soaked with oil like Struggle mentioned i t makes sense to ping and run rough but would how did the oil get there? did the rear main seal blowing cause oil to be in places where it shouldnt be or is that not linked....

thoughts? Tomorrow looking to do compression test...

[norm8332]

How much oil in the cylinders? Hoping a hydrolock didn't happen. Good luck.

[gr8lover]

New update: Did compression test and found Cylinder #7 (It is the cylinder on the driver side towards the driver.... I think this is #7 if they havent changed cyl numbering conventions lately...) all the other cylinders read in the 160-180psi range.... didnt check the 3 cylinders cause after I got the 50psi reading I figured it would have to be pulled anyway.., Me and a buddy are going to pull it in a couple days and do a teardown to see what happened.... either way, I have decided to at least upgrade the pistons and the lower end so I dont need to worry about it and get it so it is built for a higher forced induction and/or nitrous.. I will probably get this one stroked to xxx??? or so depending on block... if block is bad then HELLO LSX....... If I go strked or so then I will have a Maggie for sale very shortly@!!!!!!

[VegasNate]

Wish you much luck Chuck. Why would you sell the Maggie? To pay for the new block?

[gr8lover]

Wish you much luck Chuck. Why would you sell the Maggie? To pay for the new block?

Thanks Nate... I would sell it cause I have a 1900 and it wont handle where I think I will be going..... I may have to go up to a 2300.... but if I go LSX I would probably do a 454 all NA.... or a smaller one and go large Procharger for that.... but not sure yet... very confused now and cant wait to see the internals.... probably wont know for about 1-2 weeks... good luck on your stuff-- you got to be getting close to be all back together I think? get trans back yet?

[GRRRR8]

Sounds like a piston failure due to detonation.

[norm8332]

Sorry to hear, Hope it works out. Please let us know what happened when you find out.

[VegasNate]

Thanks Nate... I would sell it cause I have a 1900 and it wont handle where I think I will be going..... I may have to go up to a 2300.... but if I go LSX I would probably do a 454 all NA.... or a smaller one and go large Procharger for that.... but not sure yet... very confused now and cant wait to see the internals.... probably wont know for about 1-2 weeks... good luck on your stuff-- you got to be getting close to be all back together I think? get trans back yet?

I'm STILL trying to get my car in the shop. I guess they don't like me or my money anymore...

[Struggle]

Did you do a wet compression test> It seems rather obvious that a piston is to blame though or rings/cyclinder wall failure.

Oil is blowing by the piston and back spraying it through the intake and on the MAF. It takes a pretty sizeable failure to blow oil that far.

I do nto see how the rear main seal would cuase any issues this bad on the upper end. YOu might a have a slight vacumm leak at the seal but I do not see how that could affect the other side.

The lean fuel condition can burn/blow a hole in a piston on detonation. It is the equivilant to taking a hammer and beating directly on the piston itself (pinging that is).

[gr8lover]

Did you do a wet compression test> It seems rather obvious that a piston is to blame though or rings/cyclinder wall failure.

Oil is blowing by the piston and back spraying it through the intake and on the MAF. It takes a pretty sizeable failure to blow oil that far.

I do nto see how the rear main seal would cuase any issues this bad on the upper end. YOu might a have a slight vacumm leak at the seal but I do not see how that could affect the other side.

The lean fuel condition can burn/blow a hole in a piston on detonation. It is the equivilant to taking a hammer and beating directly on the piston itself (pinging that is).

This makes sense and exactly what I was thinking... just not sure how I got a lean fuel condition... not sure if BAP went bad or what happened... ??? worried I will get it all fixed up and happen again.. might look at a better fuel system setup also....

[Struggle]

Once you get this torn down take pictures of what you find if you can.

[gr8lover]

FINALLY TORN-DOWN-----

alot of you guys were right again!!!!!

all my pistons 1,3,5,7 were all damaged between the rings-- the lands were all cracked and broken!!!!! detonation...

even # pistons looked good...

Block and heads are damage free.... the broken pcs of the pistons didnt get free to roam around and didnt hurt block--- happy about that!!

so now I am off to build a stroker with all the best parts and go easier on the tune a bit...... I think I was pushing it a bit hard as I was getting 11.3's and 11.4's in 90 degree 2000+ da's..... and then not sure why it happened but it could have been BAD GAS!!!!!!!!! Need to investigate why but this is scary stuff to be tuned for 93 and maybe be 87 or something due to a gas station screwup or whatever then cost me a ton,....... not sure it was that but biy it makes me think about next time!!!!!

http://forum.grrrr8.net/attachment.php?attachmentid=9303

http://forum.grrrr8.net/attachment.php?attachmentid=9307

[norm8332]

Wow, at least the block is good. I wonder why only one side

[High Voltage]

What Air Fuel Ratio were you running?

[98aggie]

time to get Erik at HKE racing engines to build you a 468ci LS2 block to stick in there.

[gr8lover]

Wow, at least the block is good. I wonder why only one side

I was wondering the same thing? Not sure exactly what caused it, butI wonder if it all being on one side can lead me to the cause? anyone ever seem all one side pistons all break up and the other side is all good!@!!!! Seems very odd to me..... thoughts?

[gr8lover]

What Air Fuel Ratio were you running?

Good question.... my tuner could tell me I am sure but I do not know as of now....

[High Voltage]

AFR gauge might be cheap insurance for your new build. I have LM-1 by Innovate which was suggested by Patrick G.

[norm8332]

I'm also running an AFR gauge. Mine's a Autometer Ultra-lite. It makes me feel alot better knowing there is an alarm and you can glance at it and be assured it's not running lean during a run.

I'm guessing fuel pressure dropped. You had said before this that you had lost some power while driving a couple times before didn't you? Every time my fuel pump failed I had previously had the power loss issue. I believe as a matter of fact, if the stock fuel system was a little better there would be many more G8s in the tens.

Good luck with the new build!

[Struggle]

Awesome on following up on the pictures on this. Was thinking about it the other day. I find it hard to believe you can fail just on one side. Something is a miss but I cannot nail it down. Maybe Charlie will have a cause.

The only thing I can think of is if an O2 senosr on that bank was showing a rich fuel condition and leaning out that side which caused it to detonate when it was actaully lean and needed more fuel. Not sure if you are using the O2 sensors in your set up.

[todds87ss]

my guess...>500 hp and a sudden failure of BAP. Not sure of the oil on the CAI. I believe that the only way to get oil there is by putting it there. Over oiling can cause a lean condition, but it would be all cylinders. I have never seen an engine vomit oil to the extent that the air filter got covered. I suppose that the color of the oil on the filter would be a dead giveaway. I agree with others that over 500hp, an AFR gage is good insurance.

[Boostpatrol]

AFR s on a blower or turbo should be 11.0

[gr8lover]

AFR s on a blower or turbo should be 11.0

Was this something like what happened to your #7?

[-Ray-]

From what I've read, #7 is the 1st to go in these engines.

[Boostpatrol]

nope... mines from my trans slipping so bad, overrevving, letting off, and getting back in it. That crate LS3 at the shop did the same on number 7. Its a piston design flaw.