I just built my GSR for boost. Its a fully built motor just installed it 2 weeks ago. I'm using a GM 3 bar map sensor and 880cc injectors. I have skunk2 pro manifold with 70mm TB portmatched. Motor starts right up, then starts to surge from about 1k to 1,500k rpm. I've checked for vaccum leaks, cleaned the IACV.
Also When you hit the gas fast like if your going to rev it to 3k rpm... it boggs for an instant before revving.

Could the surging be caused by a Basemap not being tuned?
I have not set the Timing either.

If anyone has had experience with this problem please shed some light. Thanks.

 

try adjusting your tps sensor.

 

I did that last night. Set it to .5 closed and 4.5 WOT

I am also using Silcone on my Throttlebody instead of a gasket because I didn't have a 70mm gasket at the time of install. I heard if the map sensor port doesn't seal properly I could have idle issues,, but the thing is I'm using an external GM 3 bar mapsensor so the factory one isn't even hooked up.

 

"Could the surging be caused by a Basemap not being tuned?
I have not set the Timing either."

Ummm get it tuned! And sure as **** dont hit boost till its tuned.

 

where do you have your map sensor hooked up? I take it you have a pretty close base map for your setup.

 

O wuzzup man i didnt even really you wur the guy i got some parts from a month ago. I just started a thread with my setup. I got it tuned yesterday.

 

I just want to make sure that it could be a tuning issue before I actually take it somewhere. I'd hate to find problems when I make an appointment and take other people's time up.

I am definently not going to boost on it.

 

I have my GM 3 bar map sensor hooked up straight to my I.M.
Well I had phearable.net make me a base map for my setup. I'm sure it could be a tuning issue but its just hard to tell because of the surging and boggy rev.

 

more than likely needs to be tuned cuz i had a base from them a while ago and due to the difference in altitude in florida and here in abq mine was a lil bouncy it would idle right at 900 drop for a sec and bounce to 1500 or so and do it all over again. Also with that huge intercooler i hope you got a nice rad fan to keep things cool. the stock one wont cut it with that intercooler hogging all the cool air from the radiator.

 

You know what that sounds like thats what it just is. I have a dual core radiator on the way with 2 slim fans. Should do the job. I'm also going to heat wrap the manifold.

By the way. I saw your dyno sheet. Good numbers at 10psi. I'm going for 20psi+. I hope I come out alive lol.

 

Thx. we couldnt go any higher. i only got 440cc injectors. Do you have a date set for the dyno yet. Also i dunno if this is your first build or not. This was my first turbo build. When i went to the dyno i brought a bunch of extra stuff like oil, spark plugs, vacuum lines, zip ties and a bunch of other tools/stuff but it came in handy.

 

No this is not my first turbo build. But its my first ground up build with the motor being built and all. I'll definently bring supplies. I plan on getting it tuned very soon.

 

is the basemap scaled for a 3bar map sensor?

 

I was thinking the same thing. So I emailed John at Phearable.net and he said it was. I just think it needs some teaking on the dyno.

I've got someone that has a good name over here for street tuning... Anyone really suggest that over dyno tuning, for a quick and safe fix?

I mean I would really like to know my numbers and make sure that the tune is safe.

 

?

 

you need a vacuum gauge and should be at -21 inches of vacuum on the gauge at idle (kragen autozone etc should have one for cheap)...this will tell you if it has a vacuum leak...i would not try to street tune something like this...doing 3rd gear pulls on the street in a turbo car is not safe.

oh another trick while im thinking of it.....take some starting fluid or some brake cleaner (something flammable that will evaporate) and spray around the intake manifold gasket, throttle body, injectors etc etc and if there is a leak when you spray the rpm's will shoot up.

 

vac leak test is easy.. weld a air hose fitting or drill a hole in a 2.5 circle of metal (get it from a using a hole saw. Then weld that on a 3" long 2.5" tube and use a 2.5 coupler and 2 clamps mount that on the throttle body and set your air compressor to like 10-20psi and hook the hose up. That way you can hear the leak... its really easy, if you need those parts to test i can send you the setup for a few bucks pm me

 

I have a boost gauge and it reads -20 vac. So that means I have no leaks right?

 

not necessarily. a small leak might not show up all that well on the gauge. that being said -20 vac is pretty solid for our engines.

 

Yeah this is way too much work to find a leak lol
If your still looking for a leak here's what u do. Take off all your piping or just your pipe at the throttle body. Cover the throttle body if your car turns off you have no leaks there. Then put the next pipe on do the same cover it if your car turns off your good. If the car stays on at all you will be able to hear the leak really loud then you fix the problem. You can do the same with the intercooler too just cover the end if the car doesn't die you found your leak. It sounds like a lot of work but its Not and works everytime trying to find a leak.
Or just cover your turbo to find the leak.
And I don't know if -20 vac is good cause my digital blitz gauge reads -67 but my regular one reads -20