Problem started once I upgraded my intercooler. When I log, I start my rpms low in third gear so I can get a full range of data, so I start my 3rd gear run about 1500 rpms up to redline. During my first logging run, my car will start boosting normally, then at about 4K rpms I'll get this popping sound. It's not the intercooler hose blowing off because car will boost normally after that. This only occurs during the first run. All subsequent runs do not have this problem. What it looks like when you log is this:

3875 rpm
4031.25
3843.75
4687.5
4093.75
4218.75
4593.75

The rest of the log looks normal after that. Any ideas why it's happening? It's not the boost limiter as I have it set high, it just feels like there's some restriction and once it blows through it then it's fine. Question is, why is it always happening on the first run only on different days?

 

Spark? Is it sputtering right at peak boost? Do you have fresh plugs with a proper gap?

 

DITTO!

 

If it was the spark plugs, shouldn't it happen during every logging run? I only have about 25K miles on the car right now. I thought it was because the engine was still cold, but I made sure the needle was right in the middle when I did my runs so I don't think that was the case. I have a fresh set of plugs sitting in the garage so I'll throw them in and see if the problem goes away.

 

I have a feeling that it's the boost limiter because when I look at my logs, I'm seeing that the injector pulse width and injector duty cycle drop to zero. I'm going to try and raise the limiter up a little and I'll let you know what happens.

 

Sounds like fuel cut. If it were spark plugs, it would do it more than once and more than once per pulls. How much boost are you running? Try the tuning forum, there are alot of good *sticky's* there

 

Fuel cut happens at higher rpms and feels like hitting a brick wall - it is completely obvious when it occurs.

 

Yeah, that sounds like whats happening

fuel cut happens at peak boost

 

No, it doesn't.

 

Yeah, okay. Im not going to have a pissing match with you.
But I disagree