Im having an issue with the boost bouncing between 4-7 psi when undle partial throttle in 3rd gear between 2800-4000 rpm. When this happens, the car is jerky and the afrs are all over from 11-14. The jerkyness isnt ridiculous, but noticeable enough to annoy me. I checked out what the FIC was doing during these conditions and noticed that the active cells were bouncing around with the boost... which is normal. But they were bouncing up past the 23psia which doesnt make sense because its only bounces up to 7 psi in actuality. So since my max boost is 8.5 psi, I copied the 23 psia row and pasted it in every higher row all the way up to the top (for both the igniton and fuel map). I did this so even if the active cell bounced higher than what the FIC was acutally tuned for, it would still tune the same as if it were 8.5 psi..... This helped it a little bit, where it happens a little less often, but not a true fix.
So Im trying to figure out a way to stop the boost from fluttering so much under this specific condition. If Im in 4th gear under the same throttle position, it fine... and the same for 5th. I checked for boost leaks and everything else I could think of. Im thinking about changing my wastegate, but Im not sure if that will really make this issue any better. Anyone have any ideas on how to stop this?

 

Sounds like a tuning issue or a issue with your piggyback.

 

I dont think its necesarily a tuning issue only because the FIC is doing what its supposed to be doing.... its just the boost bounces so fast during that 1,200 rpm range that I dont think the FIC reacts fast enough to hone onto the correct cells.

I think if the boost creeped up in a smooth, linear manner... like it does in all the other gears, there would be no problem.

 

For some reason, I am wondering if there is an issue with the wastegate. If it is really slow, it could cause spiking and the low boost back and forth while it opens. That is just a guess though. Check your vacuum lines too and look for any kinked lines. Otherwise, you may need to go somewhere and get a good tune put on it.

 

What size spring do you have in your WG? Unplug your vacuum line and cap it off. Only do this temporary and don't let the boost get too high to damage the engine watch your afr. Try to go again only getting to 8-10psi and letting off and see what happens. Then you will know if its your wastegate.

 

There def arent any kinked or leaking vacuum lines. As fas as the tune... its been tuned professionally, but he only used the lower 3/4 of the fuel and ignition maps. So I just changed the upper 1/4 of these 2 maps to mimic the max boost row (23psia).

I dont think the problem is in the tune.... I mean you could prob sit there for hours trying to tune out this specific problem, which isnt consistent. But I think the real problem is the boost bouncing. Remember, I dont see this problem in any other gear other than 3rd. In 4th, between 2800-4000 rpm, its smooth from 4 psi all the way up to 8 psi. Its just in 3rd, the boost comes up really inconsistent. Im thinking its the WG causing this problem. Anyone else have any suggestions?

 

Sounds like something leaking as it's trying to build up boost. I'd check the WG and the BOV.

 

Its a .6 bar spring... the same spring that came with the kit. But I see what your saying, Ill give this a try later on tonight when I get home from work.

 

what size wastegate are you using? 38mm?

 

Yea, its a 38mm, tnetics evolution wg. Its basically a tnetics kit with a different turbo, and a synapse bov.

 

So let me ask you guys.... do you notice how much boost builds up in your ride at around 20-40% throttle, in the lower rpm range? If you do, let me know. Id like to compare what everyone else is getting around this rpm range under partial throttle. Thanks

 

So this occurs just at partial throttle? Not WOT?

 

Correct, only at partial throttle.
If I go WOT at 2000rpm, no problems. Its smooth boosting and accelerating up to 8.5psi and AFRs are fine... start at like 10.7 and end up about 11.4-11.5.
This bouncing only happens at like 20-40% throttle.

 

perhaps you need a 44mm wastegate.

Read about it in the post about half way down the page. informative.

http://www.verociousmotorsportsblog....mpaign=vmsblog

 

Which post on which page are you talking about?

 

the post about wastegate selection.

http://www.verociousmotorsportsblog....mpaign=vmsblog

 

is there a link im not seeing somewhere on this thread?

 

this might work better for you.

http://www.verociousmotorsportsblog....stegate-sizing

 

It was weird... it took like 3 posts later for the link to finally show up.

So yea I read it. And it makes perfect sense. But everything I have is configured for a 38mm.... my mainfold, and the dump tube. Im thinking about just spending the 250$ and getting a synapse wg. I hear there superb.

 

we sell a 38mm to 44mm adapter flange if your interested. Also I use Tial wastegates, and we use them on all of our cars in the shop. Never had a problem with one.

Here is a link to the adapter.

http://www.verociousmotorsports.com/...Flange-T304-SS