Very slow spool up

[TSIkw]

I installed an EVOIII 16G, front mount, and GM Maf and translator running a blowthrough setup. I've calibrated the MAFT too.

The problem is the turbo will spool up to 10psi by around 3000rpm's and it stops there. Then around 4500rpm it will slowly start to build more pressure. It takes all the way to around 6000rpm to get it up to 16psi where is have it set.

I've done multiple boost leak tests and can't find any leaks. Even sprayed soapy water all over and I don't see any bubbles.

Any thoughts on how to fix this or what else to look for? I'm lost.

My Setup:
EvoIII 16G
FMIC
3" GM MAF and Translator
Denso 660's
DSM Link

 

[TSIkw]

I sealed the o-rings off after the turbo swap when i was doing my boost leak tests. I will try to peal off the rtv and see what it does. I was questioning that since i did it but I was just thinking it was the same as a boost leak so i sealed it.

 

[oldman]

I sealed the o-rings off after the turbo swap when i was doing my boost leak tests. I will try to peal off the rtv and see what it does. I was questioning that since i did it but I was just thinking it was the same as a boost leak so i sealed it.

It is a boost leak and the reason why disabling your MBC is always step 1 when leak testing, all MBC's are boost leaks including ball and spring types because they have a wastegate pressure relief hole, your bleeder MBC is just a bigger leak, the higher the boost you run, the more air needs to be bled, the bigger the boost leak. This is also the reason why no MBC's should be connected to the BOV line because it will greatly alter the pressure signal on the BOV line and affect the proper functioning of the BOV.

 

[daren_p]

Bleeder type MBC's do exactly that, they bleed off a certain amount of pressure so the WG actuator see's less pressure then your actually running & takes longer to open. MBC's leak during boost leak tests so you either have to ignore it or take it out for the test if your trying to see exactly how long it takes for the pressure to bleed down to zero, once you've removed the air source. I'd to take a guess that the RTV you put on has plugged the vent hole/holes.

Edit: Dammit, was beaten by an old man, opps I mean oldman

 

[linksys42]

It's game of give and take, someone like shapegsx doesn't need to to worry about boost creep because he's not running low boost.

As for slower spool, I would have to disagree, what he said is based on theory where as proper 3 piece porting has been proven over the years to help spool with real life results. Porting is an art, it's not just about making it bigger, and if you're looking for 11's, EVO3 16g would be a terrible choice to begin with anyway.

How much boost are you running anyway? Are you able to run 12 psi to redline? I suspect the tubular O2 (what I had on my old setup) is not what cured your boost creep, the combination of the 2.5" DP and running decent boost level is what did it.

When I first bolted the 16g on I was able to run 10psi all the way to red line. Did that for a couple of days then I just kept on turning it up till my Injector duty cycle was getting up there and kept a eye on knock, which brought me up to 16psi. I just don't think that porting is necessary. Back in the day in some of shape's post he had boost creep when he had the stock o2 housing on then he bought a tubular o2 housing and creep vanished he was also running a complete 3" from turbo back. At that time he was only running 17-18psi of boost. The thing is that in porting when you are trying to modify the direction of the flow to the wastegate opening (to eliminate creep) I believe that you are creating turbulence in the direction of the airflow. My plan is to turn up the boost as soon as I get my water/meth kit. Then later on 272's. Gut the interior and throw on a set of slicks see how fast I can get this 16g fwd 2g to go, see how far I can push this turbo then jump up to a larger turbo after I have done all I feel it will do.

 

[TSIkw]

That makes perfect sense. Thanks for the help oldman.

 

[oldman]

When I first bolted the 16g on I was able to run 10psi all the way to red line. Did that for a couple of days then I just kept on turning it up till my Injector duty cycle was getting up there and kept a eye on knock, which brought me up to 16psi. I just don’t think that porting is necessary. Back in the day in some of shape’s post he had boost creep when he had the stock o2 housing on then he bought a tubular o2 housing and creep vanished he was also running a complete 3” from turbo back. At that time he was only running 17-18psi of boost. The thing is that in porting when you are trying to modify the direction of the flow to the wastegate opening (to eliminate creep) I believe that you are creating turbulence in the direction of the airflow. My plan is to turn up the boost as soon as I get my water/meth kit. Then later on 272’s. Gut the interior and throw on a set of slicks see how fast I can get this 16g fwd 2g to go, see how far I can push this turbo then jump up to a larger turbo after I have done all I feel it will do.

Every car is different, what solved your creep doesn't necessarily means it will work for others. If only solving creep was as easy as swapping in an O2 housing, in fact in most case, tubular O2 will worsen creep by making the turbine path even more free flowing, much like a 3" down pipe. If it worked for you, it means that you had a minor case of creep to begin with, upgrade to a full 3" DP and you will see what I mean. If you still have doubts, search the forums and see how many people still crept after tubular O2 dump, upgraded flapper, porting and sometimes external wastegate, yes I said external wastegate. You will also find some that never crept even with an unported stock O2 housing right off the bat. My old s16g for example had a tubular O2 and 2.5" CAT and it crept to 23psi, yes I said "s16g and 2.5" CAT" , who would have expected that?

 

[oldman]

Edit: Dammit, was beaten by an old man, opps I mean oldman

Slow ass kids.

That makes perfect sense. Thanks for the help oldman.

No problem. Get that fixed so you can follow what linksys42 said in post# 7. If you're lucky enough that it doesn't creep higher when you raise your boost to where your fuel system can sustain, you wouldn't have to worry about boost creep. Good luck.

 

[TSIkw]

Well getting the RTV off worked for the boost problem. It spooled right up to 20psi.

Still have to switch one line to the J-Pipe and fix my coolant temp issue. Then do some tuning.

 

[linksys42]

Every car is different, what solved your creep doesn't necessarily means it will work for others. If only solving creep was as easy as swapping in an O2 housing, in fact in most case, tubular O2 will worsen creep by making the turbine path even more free flowing, much like a 3" down pipe. If it worked for you, it means that you had a minor case of creep to begin with, upgrade to a full 3" DP and you will see what I mean. If you still have doubts, search the forums and see how many people still crept after tubular O2 dump, upgraded flapper, porting and sometimes external wastegate, yes I said external wastegate. You will also find some that never crept even with an unported stock O2 housing right off the bat. My old s16g for example had a tubular O2 and 2.5" CAT and it crept to 23psi, yes I said "s16g and 2.5" CAT" , who would have expected that?

I understand where your coming from on every car is different, when I bolted the 16g up I bolted the tubular o2 housing on at the same time because the waste gate passage just wasn’t going to cut it on the 2g. I don’t think that the 2.5” piping to the flex section on the down pipe is really going to make a difference because of the extreme heat of the gases (flowing much better) when it come off the turbo and o2 housing for the first couple of feet then it opens up to 3”. Before I decided on the set up I researched for years trying to decide what the best set up would be. I had a lot of second-guessing about the porting thing, and then I decided that if it does creep I would just tear it all back apart and throw on a recirculated external tial. But it works just great. On the upgraded flapper I truly think that is a bad idea because the larger the surface area the more pressure per square inch the boost is going to be able to crack the flapper open at higher boost pressure and then your going to have to shim the waste gate actuator to keep it closed till the proper pressure, them your just defeating the purpose of it too try to get rid of the creep. I truly think that the creep has to do with the exhaust flow/cam timing from the head at the beginning because of the velocity/flow from the duration of lift from the stock cam. And after market cams helping the problem tremendously.

 

[TSIkw]

One more question for you Oldman...

You said having the MBC hooked up to the BOV will cause a vaccuum leak at idle right? Would that cause my car to run lean at idle? It is very lean at idle and i have use DSM Link to compensate for alot of air at idle and I'm wondering if its because of the way the MBC is hooked up.

 

[oldman]

You said having the MBC hooked up to the BOV will cause a vaccuum leak at idle right? Would that cause my car to run lean at idle? It is very lean at idle and i have use DSM Link to compensate for alot of air at idle and I'm wondering if its because of the way the MBC is hooked up.

It certainly can because you're pulling unmetered air through the MBC, why are you still connected to the BOV line? Running lean at idle is the least of your problem, the bigger concern is open BOV under WOT and compressor surge after letting off. Furthermore, what was the results of your boost leak test? What is your vacuum reading at idle?

 

[TSIkw]

I can't find any boost leaks. I've checked many times and fixed a bunch but there doesn't seem to be any more.

Vacuum reading at idle is around 17 I believe.

And I just haven't had time to take the J-pipe off yet and switch the MBC setup. I plan on doing it in the next day or two but I haven't been driving it anyways.

 

[oldman]

I can't find any boost leaks. I've checked many times and fixed a bunch but there doesn't seem to be any more.

How much pressure were you able to introduce into the system via reading on the boost gauge while the air compressor is set to 20psi? How long did it take to bleed down to 0?

 

[TSIkw]

I was going off of the gauge that is on my boost leak tester and I was able to get up to 18psi or so. I didn't time how long it took to loose all the pressure but i would say it takes a couple minutes to get all the way to 0

 

[TSIkw]

Ok. I got the MBC hooked up properly now.

Vacuum at idle is 14. Did another boost leak test today and can't find any leaks.

I have no idea why it is running so lean at idle. At cruise and WOT it isn't lean but at idle i have to compensate the lowest Airflow slider on DSM Link to its max in order to get my Lo Fuel trim in range.

Any suggestions would be great

also this topic is starting to change from the title so I'm not sure if I should just post a new thread or continue here.

 

[oldman]

Ok. I got the MBC hooked up properly now.

Vacuum at idle is 14. Did another boost leak test today and can't find any leaks.

I have no idea why it is running so lean at idle. At cruise and WOT it isn't lean but at idle i have to compensate the lowest Airflow slider on DSM Link to its max in order to get my Lo Fuel trim in range.

Any suggestions would be great

also this topic is starting to change from the title so I'm not sure if I should just post a new thread or continue here.

Running lean + -14 inHG = vacuum leaks.

 

[c4uldr0n]

Or an aggressive cam

I found an addition to a BLT, blowing smoke (with a fogger) helped me track down some leaks that I couldn't find listening for air or bubbles.

-Korri / c4uldr0n

 

[oldman]

Or an aggressive cam

He has stock cams which should be pulling -18 to -20 inHG.

 

[TSIkw]

I'm not sure if i mentioned this either but I am running a 3' GM Maf in a blowthrough setup. That should mean the vacuum leak is one of the hoses off of the intake manifold since the engine is seeing more air than the MAS is reading?

 

[oldman]

I'm not sure if i mentioned this either but I am running a 3' GM Maf in a blowthrough setup. That should mean the vacuum leak is one of the hoses off of the intake manifold since the engine is seeing more air than the MAS is reading?

Vacuum only exit between your throttle plate and your intake valves, nothing to do with the type of maf you're using. Possible places for vacuum leaks are, going from TB to head, BISS o-ring, TB shaft seals, TB inner gasket, BOV line, brake booster line/check valve, FPR line/boost gauge, IM gasket, intake valve seals. PCV valve will also introduce unmetered air since you're running GM maf even if your breather is re-routed back to the intake pipe like you're suppose to. Lastly, have you calibrated your maft using either WB O2 sensor or MAP sensor?

 

[TSIkw]

I'm trying to get the maft calibrated but I don't have a wideband or map sensor. I'm going by some guidelines i've received from people on the DSM Link forums.

I just repleaced my TB shaft seals
the biss o-ring was replaced last summer
just put new gaskets (using RTV) on the TB when I put it back on from doing the shaft seals
Put a new BOV line on today
New line from PCV to Intake was done about a month ago

I'll do some searching on how to check for the other possible sources of the leak.

 

[oldman]

Another thing that will effect your vacuum reading, although will not introduce unmetered air, is your valve timing (timing belt marks).

 

[TSIkw]

I did crush the BOV a little bit. Could I have damaged it so that air is being sucked through it at vacuum and pushed into the intake?

Although I think there is a small amount of air blowing out of the BOV at idle.

 

[oldman]

I did crush the BOV a little bit. Could I have damaged it so that air is being sucked through it at vacuum and pushed into the intake?

Although I think there is a small amount of air blowing out of the BOV at idle.

If you're venting a 1G BOV, most likely you're pulling in unmetered air at idle.

 

[TSIkw]

I am venting at 1g BOV.

I'll hook it back up for recirculation tomorrow and see if it helps.