idle problems and vacumm low

[99boostedgst]

okay i just replaced the motor in my 95 gst with a 97 gst motor from a local dsmer that totaled his car.

the problem i am having is it idles fine then starts sounding like its cammed then straightens back out then does it again. everything is hooked up and also the cam sensors are completly differnt if that has anything to do with it. 95 motor has the cam sensor under cam gear and the 97 is on the left side of the cams.

and what is the normal idle vacumm on these? im at 11-14 depending on day i dont hear any vacumm leaks besides when i hit the trottle... could my exhuast leak at the o2 housing cause this low vacumm?

no it is not tuned yet i am doing it this coming friday.

build includes 1050cc injectors(last owner put on),57trim garrett turbo,megan manifold,thrown together short ram air intake(stock maf) dsm link v2, stock fuel rail but have a magnus fuel rail that may go on before tune along with fr,arp head bolts, and a catless turbo back exhuast unknown name...

please help
thanks dustin

 

[92AWDHX40]

Read this, did you do a BOOST Leak Test?

 

[BurrowZ]

Low vac with idle problems can point to mechanical timing being off.

As stated above too, boost leak tests. I had a similar problem that turned out to be two pinholes in my vac line to my boost gauge.

 

[99boostedgst]

well i have a exhaust leak at he o2 housing so i didn't know if that would be a problem or not, to the boost leak test no... i havent done one how would i go about doing that(boost leak test), i wanna get this all squard away before i tune of course.. and when this engine was in my buddys 97 it idled fine and all, could it of jumped timing when the impact hit? it was a front end crash.

 

[BurrowZ]

2G Turbo DSM Boost Leaks -How to test and fix

Fix your exhaust leak too. That is a big deal as it throws off your o2 sensor.

 

[99boostedgst]

okay thank you sir, i appricate the advice and help. will keep you updated

 

[MHuddy1213]

boost leak test deffinatly but vacume levels are affected by the altitude above sea level i just forgot if it lower to sea level the higher or lower the vacume will be but i do know it will be affected and it will be a decent amount too but it does sound like you have a pretty good boost leak alot of people make them but you can buy them off ebay for i think 20 dollars and they work fine and have a gauge

if you dont find any boost leaks it may all be in the tune or the TPS could be off and are you running an adjustable fuel regulator with those injectors and what fuel pump are you running?

 

[99boostedgst]

I don't know what fuel pump I'm running yet ill have to look through my folder of receipts and yes it is adjustable but it's not on yet due to being spliced inline with the magnus fuel rail(braded lines).... I also found out that it's perfectly reving up until 3200-3400rpms. At a stop could that be 2 step with the Dsm link v2 that I have?

Thanks again for all the help guys!!