as some of the peeps know i went to SGP yesterday and got tuned, we are having an issue while tuning with my afr's at 4000-4500 rpms. at that point it spikes up and down between 11-13afr about 4 times in that short of an rpm range. first thought was running out of injectors and or fuel pressure (550cc injectors and stock fuel pump) but as we continued to watch it and as the car got hotter it would smooth out a little more with each run. now when we let the car cool down in prep for more runs and continued our endevour it was more aperant with sharp jumps in afr's at the same rpm, of course as the car got hotter it would smooth out a little. we then noticed that at that point in the rpm range the wastgate was opening fully, but seemed to be a sudden opening, as if it was sticking and loosing pressure at the diaphragm. well i decided to open the wastgate open and take a look at it. the outer side of the diaphragm was clean but the underside was pitch black with carbon build up, i also noticed that the valve had just a slight bit of play from side to side when i jiggled it (very slight but noticeable). so my question is this, is the wastgate ok and operating as it should or should i look into a new one?

 

what kind of wastegate do u have?

 

hmm that an interesting problem you got right there.. But could it be the boost controller? Do you by any chance have the afr graph and boost graph on your dyno sheet? I just want to see how consistent was your boost at that rpm range... If your boost is pretty much consistent, i dont think its the WG prolly more on fueling and tuning issue or could be piggyback issue related..

 

i have the tial 38mm. this issue was happening before tune and i thought it was the boost controller at first because every time i had the boost controller on and boosted past 7psi it had a nasty stutter, but one cold day i had the boost controller off and running off of just the wastgate spring and it stuttered. it did it when it boosted past 7psi and continued till it eventually got past 9psi and everything was gravy. this whole issue just came out of the blue one day and didn't stop. i also thought that maybe it was my ignition map cause i had been playing around with it so i changed it back to the way i had it from day one and still did the same thing. i also changed my spark plugs out but still had the same problem. after tune the stutter is gone but you can still see the problem on the afr graph. now on the dyno we initially started out with 7psi and got the afrs pretty damn smooth but as soon as we went higher that's where we started to see the problem.

 

i dont have the afr graph on me, i need to talk to my tuner and bring him my wastgate so i can get his 2cents. the good thing about SGP they are pretty fair about ish, Mark (tuner) told me to come back for a tune clean up (after i solve this issue) for an extra 50 bux.......so i cant complain, not to mention he didn't even charge me full price for tune either, i guess its for appreciation for all the dyno runs i bought in the past............lol

 

Can you verify if it was not an injector problem and your injectors arent closed to max out above 7 psi.. I checked out that that other guys thread tuned by ptuning he maxing out his fuel injectors a bit too early.. and is that stuttering you mentioned sounds like the wastegate repeatedly shutting on and off? I notice that on mine usually if im boosting at the borderline of my wg spring around 6-7 psi..

 

im pretty sure im running out of injectors (fuel pressure) so yeah thats still a possibility but just trying to rule out the wastgate.

 

yeah with 550s i imagine 11 psi is at least 85-90 duty cycle.. what was your wastegate spring again? I hope you'll get it figured out.. as for now, just observe your boost if its consistent doesnt spike or fluctuate then i doubt its your wg or boost controller..

 

NM reread your other post. You have an issue here and it sounds more hardware related than anything.

Please list all of the specifics of your setup: turbo, size, wg, mani manufacturer etc...

Also, a local customer had a similar problem and it he brought it to us. After 2 mins of investigation I discovered it was a VAC line that had melted and partially collapsed due to where it was routed causing irregular boost response.

 

sounds to me like you sucked on of these in through your intake:



and now its ____ed off in your engine.

i had three.. yes (3) customers who had this same issue.

 

Did you run a pressure test to see if you have any vacuum leaks? Doesn't sound like a WG issue.

 

everything iv got is in my profile but ill try and list everything

tt simple kit

Garett t3/t4b stage 5 wheel .60A/R compressor housing .82A/R turbin housing
Tial 38mm wastgate
550cc deachwerk injectors
TT log manifold
PWR couplings
PWR fmic
HKS ssqv bov
Turbosmart single stage boost controller
TT vac block
stock engine and stock fuel pump

all screw in fittings wher teflon taped carefully not to have little pieces sucked in. all couplings wher checked a couple of monthes ago for tightness. havnt really checked the tightness of bolts on the turbo to mani but havnt seen any evidence (black carbon buildup) on the flange. no evidence of leaks at the wastgate to mani flange. no evidence of leaks of any sort on the manifold.

 

haven't done that as of yet, but have visually checked the vacuum connections. i may go out and try and tighten some of the clamps.

 

crush, you didnt address my post which i feel is a strong possibility in your case. just a heads up

-java09

 

haha kitten bumble bee hybrid!

 

^^becoming a real threat nation wide to the turbo community.

 

yeah i think kitten james is in my engine........ill have to flush him out with some kitty chow and kitty litter. hahaha

 

i feel as though thats a good starting point in your diagnosis and solution to your issues.

while something else might be wrong, it is my professional opinion that this is your issue.

 

posted again for reference:



Please be on the look out for these nusences.

 

great pic btw....lol