Chasing problems

[87TIGN]

Ok so here it is. First off I have and 87 GN with mods listed below in the signature. Secondly I have read Julios chasing knock write-up (very-good!!)about a hundred times and have takin many of his suggestions but I am still havin a hell of a time... So I just recently parked the ride in the shop and took it all apart. The information I ended up with is this. After a very thorough compression test I got 130psi on each cylinder. Each plug that I pulled looked nice and tanish black but not terrible. Some of their threads had a little bit of oil but not alot. Next I pulled all old intake couplings and replaced them with brand new silicone couplings to eliminate any excess air coming in. I than proceded to clean the intercooler and leak test it. It held 40psi with no leaks and no water leaks with standing water in it so that is good. I also replaced the following sensors with ACDelco parts because they previously were not, Knock, TPS, O2, and the bottom half of the coil pack. The MAF is an original and seems to be ok. After doing all this I took the car for a run and I am still seeing kncok. I cannot hear any knock at all which is strange but when I drive the car and I boost at about 2-3 psi I start to knock up to about 5-6psi (I let off after that) and it goes like this... 0.0 .04 .07 1.4 3.4 4.0 4.9(4-5psi) (let off gas slow) 4.0 3.6 2.5 1.7 .09 .03 0.0 Another instance while I was trying to figure out what is going on I boosted to about 5psi and got up to 9.4 degrees knock in a similar pattern as before. As you probebly know this is irritating the S**T out of me. I have no idea what it could be. There are no wires bouncing around back there because I ty-raped them all so they wouldnt, and the huge kicker is that when I ran 104 at the track a little while ago i had NO KNOCK at all, all day long which just confuses me even more. If it dosent knock with high octane why the hell is it now with methanol and at such low boost?? Could it be a bad ESC and if so where is it and how do I replace it? I just put julios kit on and it still knocks. Someone PLEASE help me I am so sick of this. I just want my car to be ok and I WANT TO BOOST. I miss it. :frown:

 

[87TIGN]

Oh yeah and I am running 42-43psi of fuel vaccum off and I have stock injectors. Could the stock injectors be screwing me somehow? When I shut the car off they hold pressure for quite awhile so they arnt physically bad I guess??

 

[Razor]

Your car should run 10 PSI boost without any knock. Alky or not. If your getting knock at low boost levels.. you have other issues.

When you start getting into boost look at your O2's and make sure theyre coming up into the low 800's minimum. If your running lets say 8 psi boost with O2's in the 800's.. and you see knock.. its mechanical.

 

[jdsgnx]

try turning the alky off run 15/16lbs of boost clean before you turn the alky back on, also you can also be having over rich knock if there is too much alky to soon .

just my 2 cents , keep us informed , GOOD LUCK JD

 

[bsdlinux]

No oiling of the plenum ? ie PCV sucking oil. I've seen that cause knock at lower boost levels.

 

[87TIGN]

Thanks guys. I have a really bad feeling this motor is screwed. Even in park if i rev it when I get over 0 psi of boost it knocks a little. Dammit. Why did it stop knocking with 104 octane? Maybe it was recent damage? Why does it not show any knock until I get 1-2 psi of boost? If it was mechanical it would show knock all the time wouldn't it?

 

[Pronto]

So before you installed the kit you were able to run higher boost with no knock at all? What boost level and octain? I assume you changed chips when you installed the kit. Have you checked the chips parameters to make sure they are set to default? How about putting the old chip back in and not running alky to see if you still have knock.

 

[87TIGN]

I put a alky chip from Eric in when I got the kit. The parameters are changed just a little cause I wanted to see if it would help. Before the kit I could run between probably 7-10 with no knock on 91 octane. I ran 104 octane in the begining of July and had no knock at all for 7 runs and the remainder of the tank.

 

[Razor]

Baby steps. One answer at a time. I dont want to know what it was months ago.

Question.. Do your O2's go into the 800's as soon as you get into boost?

 

[87TIGN]

Ok so as soon as I get inot boost they are like 745-800 or so. So I tried putting it in 2nd and seeing what WOT looked like to see where they would be at. my scanmaster recorded 1.9 degrees knock and 046 O2 with the WOT record switch but I saw higher knock it just didn't record it for some reason. Should i add fuel on the chip and how much? or turn up the FP reg. and how much? Im at about 42-43psi right now. Should I buy some 42.5# injectors and see if that helps the flow of fuel? I have 28.5# stockers now.

 

[Pronto]

Where you able to run more boost with the 104? What fuel gauge are you using? I recently switched from a Kirbans one that I found had a 5%+/- accuracy. It was 3 lbs light compared to the new one that is 2% +/-.

 

[Razor]

Ok so as soon as I get inot boost they are like 745-800 or so. So I tried putting it in 2nd and seeing what WOT looked like to see where they would be at. my scanmaster recorded 1.9 degrees knock and 046 O2 with the WOT record switch but I saw higher knock it just didn't record it for some reason. Should i add fuel on the chip and how much? or turn up the FP reg. and how much? Im at about 42-43psi right now. Should I buy some 42.5# injectors and see if that helps the flow of fuel? I have 28.5# stockers now.

You have 20 year old injectors and are chasing knock..

Also..

You see any numbers in the 700's.. thats too low.

So pull the plugs and see if there is any abnormality with any cylinder.. if so, that injector is more than likely toast. Then start performing normal injector tests like how long it holds pressure on the fuel rail, plug readings, listen to them with scope, etc...

If you put your fuel pressure and your lower boost knock goes away.. then you def have a fueling issue. I mean put the FP to 52 PSI line off.. crank it up.

 

[87TIGN]

I have an autometer phantom FP gauge that seems to be ok. You heard any different Pronto? Razor i will check my injectors and probebly end up getting new 42's and i will try turnin up the FP see if it helps

 

[Pronto]

I would assume that it's better calibrated than the cheap plastic fuel rail style I had. Is it electric or mechanical?
Oh, just read your sig. Looks like it's a hood mount?

 

[1 RARE T]

If you're going to spend the money on injectors, I would'nt screw around with 42's. They are pig rich at idle and can be a bitch to tune with.

Mototron 60's all the way.

 

[87TIGN]

It is a mechanical FP gauge and and it is mounted on the hood. So mototron 60's huh? What is the difference between them and the 42's? Arnt they a bigger injector?

 

[Razor]

I personally like the MSD50's.. The motron 60's are a good injector as well.

Issue has to do with chips and tuning..

 

[87TIGN]

So razor you dont think my injectors could be fouled up and just not spraying enough fuel to keep knock down? seeing that they most likley are the OEMs

 

[86gn]

I put a alky chip from Eric in when I got the kit. The parameters are changed just a little cause I wanted to see if it would help. Before the kit I could run between probably 7-10 with no knock on 91 octane. I ran 104 octane in the begining of July and had no knock at all for 7 runs and the remainder of the tank.

Have you tried going back to your old chip to see if it still knocks, If you had the chiped burned for what you THINK are stock injectors and they have been changed that will cause problems.

just a thought....

 

[Pronto]

Forgot to ask if your fp is raising with boost too. Possible issue there.