A Tuning Nightmare.

[andymoraitis]

I definitely agree with you there. Is there a way to test the fuel pump? Or a way to determine if it's good or bad? I'm going to try a new ECU tomorrow and see if somehow I can get a decent tune on it, which may be a little difficult tuning the 660s. It should at least give me an idea of what it is.

Kyle,

You can use a voltmeter to see if the pump's receiving constant voltage, however it may be petering out at higher RPM. It may also be that your FPR has issues and isn't getting enough fuel to the rail so checking pressure there would be a good idea.

As I mentioned earlier, while the tune is slightly aggressive, the fuel trims aren't out enough to indicate that it's lean enough to require that much fuel input. Getting the wideband hooked up would be a wise idea as suggested above. Also have you tried increasing fuel pressure to say 48 to see if knock goes down? I'm not a proponent of drowing the motor to stop it from knocking, but if you turn the pressure up and knock still persists in the same manner, then it's a fuel supply issue.

Andy

 

[BaddAssGst]

Kyle,

You can use a voltmeter to see if the pump's receiving constant voltage, however it may be petering out at higher RPM. It may also be that your FPR has issues and isn't getting enough fuel to the rail so checking pressure there would be a good idea.

As I mentioned earlier, while the tune is slightly aggressive, the fuel trims aren't out enough to indicate that it's lean enough to require that much fuel input. Getting the wideband hooked up would be a wise idea as suggested above. Also have you tried increasing fuel pressure to say 48 to see if knock goes down? I'm not a proponent of drowing the motor to stop it from knocking, but if you turn the pressure up and knock still persists in the same manner, then it's a fuel supply issue.

Andy

Andy,
thanks, I'll definitely try that. That was Jeff's idea as well to possibly set the fuel pressure 3psi higher and see if the knock goes down. Like you said, that way we know if it's a fuel supply issue or not.

I'm hoping to get my hands on a wideband for the weekend so I can make some use out of it and hopefully figure out what my problem is.

 

[andymoraitis]

Kyle,

I have very similar issues to yours since the stroker went in and I've been struggling with the tune so don't feel alone in this. I tried the FP experiment and my knock went down so although I know the pump is OK, I'm also sure that it's not keeping up and hasn't since the cams went in (a 255 HP goes in tomorrow).

Keep us posted. You've had some GREAT help in here and I'm sure between all of us, we'll get it figured out.

Andy

 

[BaddAssGst]

Andy,
Interesting talk we had the other night. I definitely think that your on to something. Unfortunately, it's been rainy here all day so I didn't have a chance to post some logs. I'm going to double checked the base timing in the morning and see what I come up with.

Another thing, Jeff is sending me a basic chip to try out (2g mas, 660s) to see if that's where I'm having trouble. He's trying to figure out if it's in the chip (which he doesn't think so and neither do I anymore) or if my problem lies somewhere else.

Updates coming..

 

[andymoraitis]

Kyle,

That certainly was fun talking into the wee hours. It just bugs me that we didn't think of checking base timing until them. If base timing was off a few degrees with the current chip having 18 advance, that would certainly explain the knock on 94 octane. Also, if you're not sure that you have a 255, I would certainly get one, or at least re-wire the current pump.

On this end, the 255 solved my problems. At base fuel pressure of 42psi, I have zero knock at 21psi and there's certainly more tuning room to go with one of my more aggressive chips and add a few more pounds of boost. I just hope the clutch holds it.

Shoot me an e-mail through the site and send me your cell number again so we can stay in touch. Being a little over an hour away from each other, we should get together and get a good tune on your ride so you can hit those 11's.

Keep in touch!

Andy

 

[firebirdvert305]

Whoa i hope i didnt join this thread to late. Badassgst are you running 14b? This is too weird to be true to read something like this. Last weekend i installed a set of 272's, 2g mas, 650FIC's, and my chip is burned to your exact specifications by a local tuner. The 1st chip he burned me turned out to be a bad one, afr's at low rpm was fine but soon as you went WOT the car just sputtered and backfired. Now ive got the "correct" chip in it,and its still running sluggish. Ive been experiencing the same problems you have been above as well. Im currently running a 190 but have no reason to think my problem lies there. Timing is at 5 degrees BTDC, i did a boost leak check, Im gonna try and throw a wideband on it this weekend if at all possible. I would log it but my datalogger cable is giving me problems so thats kinda useless for now. Im gonna try what you did and add 30% fuel 3k rpm and up and see is it changes anything. I tried putting the stock chip back in it, took out -18% of fuel as a baseline and for some odd reason the car ran pretty decent, something you might want to try? Lemme know how it goes for you, i will keep you updated as well on what happens here.

 

[BaddAssGst]

Whoa i hope i didnt join this thread to late. Badassgst are you running 14b? This is too weird to be true to read something like this. Last weekend i installed a set of 272's, 2g mas, 650FIC's, and my chip is burned to your exact specifications by a local tuner. The 1st chip he burned me turned out to be a bad one, afr's at low rpm was fine but soon as you went WOT the car just sputtered and backfired. Now ive got the "correct" chip in it,and its still running sluggish. Ive been experiencing the same problems you have been above as well. Im currently running a 190 but have no reason to think my problem lies there. Timing is at 5 degrees BTDC, i did a boost leak check, Im gonna try and throw a wideband on it this weekend if at all possible. I would log it but my datalogger cable is giving me problems so thats kinda useless for now. Im gonna try what you did and add 30% fuel 3k rpm and up and see is it changes anything. I tried putting the stock chip back in it, took out -18% of fuel as a baseline and for some odd reason the car ran pretty decent, something you might want to try? Lemme know how it goes for you, i will keep you updated as well on what happens here.

I'm actually running an 18g with what looks to be your same specs. I wasn't having the backfiring problem at all, it just felt "slow" for all the mods I have done.

I still have to verify it's a 255, check/reset my base timing and if that doesn't fix it, try the stock chip. I have feeling it's in the timing though. It makes all the sense in the world.

 

[andymoraitis]

I'm going with either a weak fuel pump or timing being off.