When turbo fully spools, rpms stop rising.

[B-lackGSX99]

Okay, so if I go for a solid speed run, I noticed that as soon as I hit max. boost (set to 16lbs in my car) and the wastegate opens up, my rpms no longer want to increase. Typically, this happens at around 4500rpms. Is this normal??

What kinds of things can I do to adjust the boost so that it allows me to get to redline? I feel like i'm missing out on almost all of the powerband that I worked really hard to achieve with my 272/272 HKS's. For the time being, i'm going to re-read the vfaq on tuning with the SAFC-ii and see if there is anything I can do from that end. I've also heard about using different trims, but have no idea what this is...

I look forward to your ideas/comments/suggestions.

 

[zippyshoe]

Thats strange. How does your timing advance look as boost builds - does it increase steadily with RPM's or do you see it leveling-off or decreasing which may indicate the presence of knock?

 

[tom04841]

Have you checked for a boost leak?

 

[T9S1i]

I second the idea for checking timing. every time that my car had a power issue, or a slow-spooling slow-revving condition either my base timing was off, i was knocking, or had a boost leak.

 

[damnslowtsi]

How fresh is your clutch? May be it is on its way out.

 

[dsm-onster]

Ok, let's see. . .

What is your injector duty cycle when this occurs?

What does your timing do?

What hertz is your maf reading?

How are your plugs? What heat range? how old are they and the wires? To what are the gaps set?

What is you pretty wideband telling you when this happens?

 

[TSG59_Steve]

How fresh is your clutch? May be it is on its way out.

That's what I was thinking too...

 

[xveganxcowboyx]

I second the boost leak test idea. If you're running really rich this can happen which can come from either a boost leak or from bad tuning. Of course there are plenty of other potential reasons. Answer dsm-onster's questions and you'll know a lot more.

 

[roni-wan]

My car used to do that near 7k rpms it was my clutch

 

[B-lackGSX99]

Okay, installed a new set of spark plugs (the recommended NGK BPR6ES's) and the car runs perfectly now!! The set I pulled out where the BK's from NGK, and appeared to be quite fouled. I had no idea that spark plugs could make such a big difference!! Why is it that they could cause the car to be behaving the way it was?? Thank you all for your help!

 

[tkelly27]

Under higher engine loads the energy required to arc the gap goes up. The more fouled they are, the less efficient spark you will get. Glad you fixed it.