Need help with a Mysterious knock problem

[c&cgn]

My buddy is having a problem with KR (as much as 12*) at anything over 12 psi. It has been occuring since he took it out of winter storage this season. Here is what is not the cause of it:

He has gone through several tanks of Chevron 94 gas so it is not bad gas
O2's look decent on the OTC 4000 and they go up when we increase the FP (went up to 45 psi with no change)
FP goes up along with the boost so it is not the FP regulator
He is using an ATR pitbull chip but has been doing so for several years with no problems
Changed the plugs from AC 42's to Autolite 24's and still does it

We will be adding some racegas in the next day or 2 to see if that solves it. He says that he hears it pinging so I don't think it is false knock.

I am scratching my head on this one guys, any help here would be appreciated.

 

[c&cgn]

ttt

 

[blackbuick87]

Well we all know pitbull chips have high timing so I would try to talk him into a Thrasher since they are so cheap.

Use some GM top engine cleaner since this may be stg related, he may have one or more partially plugged injectors

Try some R43TS's to see if that helps. Definitely get the high octane in there to see if its real or not.

What are the O2 numbers and what are the mods on the car? When is the knock occurring? If he is getting 12* is must be starting earlier, probably below 10*

 

[c&cgn]

Sorry, I forgot to mention it is a stock combo with the basic fuel mods etc.

He has never had a problem with the Pitbull before, especially with 94 octane. He tried the stock chip with no difference. I can't find anyone else out here with a stock injector street chip. Everyone seems of have larger injectors

Nothing wrong with the new Autolite 24's they are the same thing as the AC 43's.

We will try the octane thing but I can't see how it would be false KR if it happens when he mashes the pedal or when he eases into it.

O2's are fine. We've tried everything from 760 to 850 on the OTC and the knock still occurs. KR is usually around 6-9* but he has seen as much as 12 or13*

Any more feedback?

 

[xlr8ngn]

12 PSI on the stock indicator or a real boost gauge? If on the stock indicator I would check with a gauge.

 

[Kid with a toy]

If he says he hears pinging...I'd start looking at fuel/electrical. Maybe time for a new chip or ECM. Bad battery cables. Checked the coil pack? I'd start looking at the goofy and stupid that leave our cars on the side of the road all too many times. It's the simple that is often over looked.

HTH
Erik

 

[blackbuick87]

It has to be related to the storage. The injectors will be gummed up if he didnt run stabilizer through them, or maybe a mouse ate something, who knows. I would send the injectors to Chuck Leeper and have them flowed and cleaned. I bet one is plugged

 

[c&cgn]

Originally posted by xlr8ngn
12 PSI on the stock indicator or a real boost gauge? If on the stock indicator I would check with a gauge.

Yes it's on a real boost gauge. I know better than that.

 

[turbolimited]

wiped cam lobe(s)??
That's what mine started doing when my 2 of my lobes went flat on all stock stuff.

 

[c&cgn]

Originally posted by turbolimited
wiped cam lobe(s)??
That's what mine started doing when my 2 of my lobes went flat on all stock stuff.

I hope not, but I'm trying to eliminate all of the non-internal engine stuff before the motor gets torn into. I was also thinking about the timing chain skipping a gear maybe??

Thanks for the input.

 

[steve hughes]

Is it useing oil? If the seals go out of the turbo or the oil rings are stuck causing it to drink oil could cause it.

 

[Kid with a toy]

I was also thinking about the timing chain skipping a gear maybe?? .........

Are you saying that it has the stock timing chain still on it? YIKES...
I wonder how many teeth the gear is missing

I kinda have to agree with black, storage is storage. How exactly was it stored? Climate controlled, inside/outside, started once a month/started once a year....

Erik

 

[John at J&S]

Yeah, I vote for oil in the intake, too.

 

[HRpartsNstuff]

It kinda sounds like it is false knock. Look for signs of the DP hitting the frame & such. Have you checked for a cracked motor mount? Not to sound like an infomercial, but that has been the cause more than a few times. If the stock rubber gets heat/cold cycled too many times, it will crack in storage & come apart under power. Do a brake torque & safely watch the motor for excessive movement & torque over. You may not see it hit unless you can hold it at 12 psi, but if it moves a bunch, it probably will hit something at WOT. Hope that helped.