Knock/fuel pressure question

[BuickMike231]

Hey guys, I installed an adjustable wastegate acutator yesterday and got the boost where I want it, right in the 15-17psi range. Now I'm getting more knock since I was only running about 11 psi previously. I bumped the fuel pressure up to about 46 psi with the pressure regulator and the knock went down but is still there. It was reading around 2.8-4.0 knock retard with right around 800 for the O2's. My question is, what is too high for the fuel pressure? Should I keep bumping up the fuel pressure at the regulator until the knock goes away or am I getting too high with it? Thanks for any help!

 

[WS6]

Use the adjustability of the TT chip to add fuel at WOT,parameter 1.

 

[turbojd]

You said more knock, is downpipe hitting anywhere, check engine mounts.

 

[SCOOBY DOO]

Is it sustained knock?

 

[SCOOBY DOO]

What's your fuel pressure at 17 lbs of boost? You need to set your FP per Erics instructions.

 

[mikestertwo]

I would set the fuel pressure in the 43-45# range then pull a couple degrees of timing and check your O2's. Get your O2's where you want them with parameters 1 and 2 in the chip then adjust your timing for max with no knock.

 

[BuickMike231]

You said more knock, is downpipe hitting anywhere, check engine mounts.

I should have clarified at first, I did not have any knocking at 11 psi. Now there is some at the 15-17. The downpipe is clear of everything but I think the heatshield on it may contact the A-arm at times, the motor mounts are new in the car as well within the last 6 months. I will take some timing out like mentioned and try to fine tune the car with the Turbo Tweak chip like some of you have mentioned. Unfortunately I'm not sure what the fuel pressure is under boost because my fuel pressure gage is mounted to the end of the fuel rail. I know it's not the best way to do it since I can't see it while driving. Thanks for the advice guys, any other suggestions are always welcome and I will post back results today or tomorrow! Thanks!

 

[SCOOBY DOO]

It would be nice to be able to verify if your fuel pressure was rising with boost...if it isn't, then your fuel pump is on it's way out.

 

[BuickMike231]

The pump is not even a year old but I know there was all the problems with Walbros for a while. This one seems to be working, but you're right, I can't really verify the fuel pressure is rising right now.

 

[BuickMike231]

I would set the fuel pressure in the 43-45# range then pull a couple degrees of timing and check your O2's. Get your O2's where you want them with parameters 1 and 2 in the chip then adjust your timing for max with no knock.

Just wanted to clarify what you are saying. Are you saying pull back the timing to get the O2's where I want them, and then bump up the timing to get it maxed without knock? Also, I don't really like changing two things at once, so is it possible to eliminate the knock just by bumping up the fuel percentage far enough and not touching the timing? Or should I do the fuel up a few percentage points, then start bringing up the timing?

 

[8UWITH6]

Here is a great place to start............... what kind of fuel are you running? Octane rating? 15psi is about max on pump gas usually................

 

[bmackinnon]

...... I can't really verify the fuel pressure is rising right now.

I wouldn't do jack til I verified this.... not something that's optional or 'would be nice to know, but......' IMHO

 

[TurboDave]

Let me repeat what has been stated. You should NOT, I repeat NOT be tuning with fuel pressure. That's all we had in the 80's and was terribly crude at best.

You now have a TT chip that allows you to do all the tuning you need.

One of the easiest methods is to start taking out timing in the area the knock occurs. This is usually in 3rd and 4th gears. Pull a few degrees out and see how that affects your knock. Should be able to get rid of most of it with just a few degrees of timing pulled. You should have plenty of documentation with your chip to get you moving in the right direction.

 

[BuickMike231]

Sounds good thanks again for all of the help. I just wanted to clarify on whether fuel pressure or timing was the way to go. I will pull some timing out and see how it goes, and I will post back results once I get a chance. Thanks again for all the help guys!