hidious noise at full spool

[kams1gsx]

Ive been messing around with this maft/afc crap for a few months now,and i feel like a monkey f@$#ing a football.I cant for the life of me get the fuel trims right.low=139 mid=107 high=100,sometimes my timing is 40 while crusing,I turned the boost way down,(9psi)and it still knocks up to 20 counts and I here a repeated chirping noise.No boost leaks,compression #1=132 #2=136#3=148 #4=140 mods are in my profile.Are my rings fried?

 

[dsm-onster]

compression #1=132 #2=136#3=148 #4=140 mods are in my profile.Are my rings fried?

Hmm, your compression seams low but with in service limits.

My 1992 Factors Service Manual: Standard value is 164 psi w/ a minimum value of 121 psi; pressure diference btween each cylinder of no more than 14 psi. So you seam to be fine there. How many miles on the bottem end? 160-180K?

Your perpetual knock may in fact be phantom knock. Where is the "chirping" coming from? Is the chirping the "hidious noise at full spool"?

About the fuel trims, I have PTE 650s and I could NEVER get my low trims to even out w/ MAFt. It ran decent and my gas milage didn't suffer. My fuel trims were 135-140(low), 100-105(mid), and 100(high). That's the best I could do until I got DSMLink. I think that you'll be fine with your fuel trims like that. Flip over to the RPM mode and start having fun tuning for power now. Stop humping the frickin' football, ok !

 

[andymoraitis]

One of the best things to do would be to post a log of a third gear pull. 40 degrees of timing while cruising is normal, but the 20 counts of knock is pretty hellatious at WOT. Get us one showing RPM, timing, knock, O2 and TPS so we can have a look. Anything else would be speculation at this point as to what's causing that much knock at such low boost levels.

Andy

 

[kams1gsx]

I cant post a log now ( pc problems)but the car has 69k orignal miles on it,the crazy noise is coming from the drivers side of engine and it seems like it only happens at wot.There is an exhaust leak,(mani to turbo) it leaks out the sides between front and rear bolts bolts.I need to find a way to seal that.everything was new when i put it all together,7cm,mani,turbo. and torqed it down.

 

[andymoraitis]

You just clued us in on something huge. A leak before the O2 sensor will cause an extreme rich condition, in addition to the noise and the 02 will dump plenty of fuel. Depending on the severity of the leak, you may be running into rich knock which would make more sense considering the boost is so low. If your bolts are backing out, torque them with the motor cold and then do a retorque after running it at full operating temp. The additional tightening when hot will allow the bolts to shrink into place and stay tight so they don't keep backing out.

I'd get on that leak right away as it's likely the source of your problem. While you're at, it wouldn't be a bad idea to replace the 02 and downpipe gaskets to keep the system tight and functioning properly.

Andy

 

[kams1gsx]

The bolts are tight. It seems like somthing is warped.I can hold a flashlight on one side of the header base and see light coming through is there a softer gasket i can use here or some kind of high temp sealer.I know it sounds a little cheesy but the 7cm is not going to do it.thanks andy. Kam

 

[andymoraitis]

Kam,

If something warped then you need to get the manifold and turbo off so that you can have both planed flat by a machine shop to ensure a stronger seal. It won't matter what kind of gasket you throw in there since if the surfaces don't mate properly the seal will eventually blow. I know that's not what you wanted to hear, but I want you to be able to fix the problem and move on to enjoying the car instead of trying any kind of quick fix.

Hang in there!

Andy

 

[kams1gsx]

Yea, that would be the right way to do it,it wont be the first time I tore it all apart and put it back together no biggie.Ill just wait until I get my turbo back exhaust.That noise is still a mystery though, the car bucks all crazy when I hear it chirping.Is this what knock sounds like