Right after the collector. If its got a leak and sucking air that would cause the wideband to be off but not to lean pop if I let it go correct? Also, when I added the second pump I only added one, didn't replace the other 255 that I already had. Could the older one be allowing backflow when I start getting into the higher fuel pressure with boost? Just a thought someone had mentioned once. Anyone have any experience with anything like this?

 

Im still thinking its something with the tune, I know I've got the fuel system to handle it. And im also having issues returning to idle, some times I can put it in neutral and it will coast fine, and others it wont idle at all and have to keep it running by pedaling it. Agree or this give anyone else new ideas?

 

Going back to the basics, you need a set amount of fuel. If you fuel pressure gauge is getting into the mid 50's you are probable not having problems with the pumps. You have 80lb injectors, so there should be no problem there unless they are going static. I would look more at the tune to be sure you have those bugs worked out. Is the car having problems when you get into higher rpm's or are you just relying on the wideband?

 

Guy that was tuning it turned shady and pretty much can't rely on him to work on the tune. A friend just got tunercatz also but hasn't started with it yet. Right now im just relying on the sideband and shouting down if it gets ti 12:1 ish. But before the latest head gasket replacement, it lean popped on me if I didn't shut down...

 

Can you describe what you mean by lean popping and when it happens as you are driving? Are you describing popping when you are hard on the gas? or is this happening when you let off the gas?

 

Wideband*. Damn autocorrect... when im on the gas hard and the Wideband reads lean, pops...

 

You sure its not detonation you're talking about?

The other thing is maybe your ignition is breaking up or misfiring. All that will mess with your wideband readings.

What are you doing for plugs, and ignition? and what is your timing set at? Or are you pulling timing with boost?

 

I never saw if you checked the alternator to make sure its working properly. My issue with voltage felt like a little "pop" when it would breakup. Its free and easy to check.

 

You mean predetonation? I have an MSD 6al2 ignition. Running ngk tr60 plugs. Im not sure what the timing is set at because i wasn't doing the tuning myself... but he said reg is set pretty high close to where it was and right now he has a lot of timing pulled out when it goes into power enrichment until we get the issue resolved. I got on it today and stay in it for awhile. Kept climbing until I shut off at 13:1 on the Wideband. What could cause the injectors to go static? And I've had the battery and alternator checked recently and both came back great and are only a few years old with not many miles due to build time.

 

A weak injector can cause it to go static. My problem was the voltage issue was causing the injectors to not function properly because the voltage was dropping. I replaced my injectors when I suspected them to be the problem and did a quick wot test. The problem was still there, but it was way better and didn't happen until I got real high in the rpm's. Replacing the alternator has made it go away completely. I spent a lot of time cleaning every positive connection and ground that the car has and they needed it. Once again, you probably don't have the same problem as me, but someone suggested to me my problem and I waited till last to really check it out. The best way to check for weak injectors is to have a spare set that you can try and see if it happens again with them on. Not everyone has that though! Using Datamaster I was able to see a problem on one side of the engine and could have also swapped one at a time to different sides of the engine. That way if a bad injectors was moved the issue would follow. Gotta have a lap top, cable and the free program for that also.

 

Just had a chat with my friend that just got the tunercatz software, we will be plugging in Sunday hopefully and datalogging it to see if we can hopefully find something...

 

Ok, question, at what point is too lean on wot? Is "ideal" 14.7 still great or should it still be running more rich than that?

 

14.7 is fine for steady throttle/cruising.
Upon acceleration, especially in a forced induction but even in naturally aspirated mode, you want it to go sub-14. In N/A mode and moderate to slightly aggressive throttle, I would think 13.x would be ideal. With heavy throttle N/A, then 12.x and adding forced induction and WOT, it should not be anything greater than 11.5.

My own Turbo LT1 under WOT goes to 10.8 - 11.5 AFR using a PCMforLess tune by Bryan Herter. My fuel system is not optimised, using the stock 16 yr old orginal pump and a NOS 5176 kit's inline pump full time through stock lines/FPR. I have the Racetronix Walbro kit and will be installing that soon. At this time though, my fuel pressure is fine at WOT, with the stock pump and NOS pump.

What is your plug gap currently? I run .032 gaps on my Autolites. Have you pulled some/all of your plugs for a visual inspection? They can tell you a lot about what's happening. Are they all of uniform color? One(or two) dark/wet ones could indicate problem cylinders. Conversely, do 1 or 2 look extra white(lean)?

 

Dave - what kind of RWHP are you getting with that setup? And are you still running the stock filters (in-tank and inline)?

 

The only time I'd dyno'd it was on a 'Dynapack' chassis dyno which gives relatively (compared to Dynojet) pessimistic RWHP. This was when the motor was brand new, with 60# Mototrons and stock ported LT1 heads flowing 285/190 I/E. At 11 psi, it measured 574rwhp/571rwtq.



Since then, I've went to 95#delphi low Z injectors and ported TFS heads that flow 299/212 I/E and run typically 15psi but have run as high as 18 ps.

Based on things I've read, I assume my motor, naturally aspirated, would run about 300 hp. Then assuming 25hp per PSI, the power would build like this...

• At 1psi, the output would be 325 hp.
• At 2psi, the output would be 350 hp.
• At 3psi, the output would be 375 hp.
• At 4psi, the output would be 400 hp.
• At 5psi, the output would be 425 hp.
• At 6psi, the output would be 450 hp.
• At 7psi, the output would be 475 hp.
• At 8psi, the output would be 500 hp.
• At 9psi, the output would be 525 hp.
• At 10psi, the output would be 550 hp.
  
• At 11psi, the output would be 575 hp.
• At 12psi, the output would be 600 hp.
• At 13psi, the output would be 625 hp.
• At 14psi, the output would be 650 hp.
• At 15psi, the output would be 675 hp.
• At 16psi, the output would be 700 hp.
• At 17psi, the output would be 725 hp.
• At 18psi, the output would be 750 hp.

Note that the 11psi figure above pretty much coincides with the dynapack dyno's measurement.

And yes, I'm still running stock filters.