pressurizing to test for leaks...?

sen2two · 08-15-2009, 06:32 PM

Well, i been trying for about a month now to get my idle to stop bouncing. I thought i fixed it numerous times. heres whats been done.

Replaced throttle body
Replaced and adjusted TPS
Put new gaskets upper and lower minifolds
New air bleeds under secondary injectors
pressure tested and theres no air leaks that i can find with soapy water.
tried different MAP, AFM, and ECU

still the thing bounces kinda from 1000-1500. sometimes it will bounce, sometimes it will raise up, hold there. then flutter around a few 100rpm. hold again. bounce a little more from, 1000-1500. kinda wierd idle. dont know really how to explain it.

One thing that had me thinking its still a vacuum leak is, no matter how much i bleed the brakes. I still get no brakes pressure when the car is on. So i capped off the brake booster line, and that did nothing.

OK, so i the way i pressureize it is, i bought a cap at home depot for 2.5" piping and tapped it with a fitting for air tools. i put in on pre-turbo (i remove the MAF and put it on the intake) I then lower my compressor down to about 5psi and fill it with some air. i remove it after a few second becuase i dont want to damage the motor by forcing to much air in there. i cap it with my finger so air dosnt back out. I can hear the air running through the motor. but cant tell if that air passing through the manifold or excaping some where underneath the manifolds. all the air escapes in about 7-10 seconds. so im just thinking thats the air passing through the motor and coming out the exhaust...

so is there a way to have the air pressure stay inside to see if it leak that way?

RotaryDiagnostics · 08-16-2009, 03:31 PM

Pressurize the intake system to a steady pressure (less than 10 psi) and see if you hear air rushing out anywhere. You don't need to remove the air hose. If there is a leak, you will hear air rushing out and can easily find the leak. If the intake system is sealed, you will not hear air rushing out, but the adapter may pop out so be careful.

Also, you can run the car at idle (warmed up) and spray engine starter sparingly around the engine compartment--primarily around the intake piping-BAC valve area. If the engine smooths out, you will have isolated the air/vacuum leak. Then carefully inspect all hoses/pipes in that area.

sen2two · 08-16-2009, 07:11 PM

yeah i tryed spraying for leaks. found nothing. I even ran a hose over the engine and nothing...

misterstyx69 · 08-20-2009, 09:37 PM

www.fighters-garage.com Take a look at the Fighters Products.they have a pressure tester..Copy it..simple thing..I used a POOL gauge and a Tire valve on a PVC Cap(2 inch).I put it on a end piece so it would be longer and you could get a clamp on it.
Fill the system with air and watch the gauge.Look/feel for leaks.It allows you to actually walk around the engine IF the air isn't leaking out as fast as you put it in!

sen2two · 08-25-2009, 03:36 AM

raised the pressure some on the compressor so the leaks would be more noticable...

found 2 leaks on the throttlebody. and a MAJOR leak at the primary injectors. ordered new grommets. the originals were pretty worn. we'll see if that fixes it...

sen2two · 08-27-2009, 06:30 PM

put the new grommets in. fixed the leaks there, and no more leaks on the throttlebody either. so i thought all was good. But there is still a major leak somewhere underneath the manifold...

I cannot see or feel anywhere under there. I was lucky enough to see the primary injector leak the 1st time. So, i removed the upper manifold for about the 30th time in about 3-4 weeks (not exagerating). i checked every single place air could escape. One oil injector was semi-loose. but i think it was still tight enough to seal. So, i have no idea where the air is escaping...

anyone have any ideas to check for leaks with the upper manifold off? I been adding the pressurized air at the throttle body. so with it removed, i will not be able to do that.

sen2two · 08-27-2009, 09:47 PM

i made a little flange that bolts to the lower intake manifold. im going to tap that with a air hose fitting and put air in there. this will allow me easily find the leaks with the upper manifold being removed...

where to get the tap for it though? i went to the local stores and couldnt find it. i also needed a -12AN tap for something else. anyone know where to buy taps online for a good price?

08-15-2009, 06:32 PM	#1
sen2two KTEC Join Date: Jan 2009 iTrader: (2) Posts: 642 Rep Power: 0	pressurizing to test for leaks...? Well, i been trying for about a month now to get my idle to stop bouncing. I thought i fixed it numerous times. heres whats been done. Replaced throttle body Replaced and adjusted TPS Put new gaskets upper and lower minifolds New air bleeds under secondary injectors pressure tested and theres no air leaks that i can find with soapy water. tried different MAP, AFM, and ECU still the thing bounces kinda from 1000-1500. sometimes it will bounce, sometimes it will raise up, hold there. then flutter around a few 100rpm. hold again. bounce a little more from, 1000-1500. kinda wierd idle. dont know really how to explain it. One thing that had me thinking its still a vacuum leak is, no matter how much i bleed the brakes. I still get no brakes pressure when the car is on. So i capped off the brake booster line, and that did nothing. OK, so i the way i pressureize it is, i bought a cap at home depot for 2.5" piping and tapped it with a fitting for air tools. i put in on pre-turbo (i remove the MAF and put it on the intake) I then lower my compressor down to about 5psi and fill it with some air. i remove it after a few second becuase i dont want to damage the motor by forcing to much air in there. i cap it with my finger so air dosnt back out. I can hear the air running through the motor. but cant tell if that air passing through the manifold or excaping some where underneath the manifolds. all the air escapes in about 7-10 seconds. so im just thinking thats the air passing through the motor and coming out the exhaust... so is there a way to have the air pressure stay inside to see if it leak that way? __________________ what I have: 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2

08-16-2009, 07:11 PM	#3
sen2two KTEC Join Date: Jan 2009 iTrader: (2) Posts: 642 Rep Power: 0	yeah i tryed spraying for leaks. found nothing. I even ran a hose over the engine and nothing... __________________ what I have: 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2

08-25-2009, 03:36 AM	#5
sen2two KTEC Join Date: Jan 2009 iTrader: (2) Posts: 642 Rep Power: 0	raised the pressure some on the compressor so the leaks would be more noticable... found 2 leaks on the throttlebody. and a MAJOR leak at the primary injectors. ordered new grommets. the originals were pretty worn. we'll see if that fixes it... __________________ what I have: 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2

08-27-2009, 06:30 PM	#6
sen2two KTEC Join Date: Jan 2009 iTrader: (2) Posts: 642 Rep Power: 0	put the new grommets in. fixed the leaks there, and no more leaks on the throttlebody either. so i thought all was good. But there is still a major leak somewhere underneath the manifold... I cannot see or feel anywhere under there. I was lucky enough to see the primary injector leak the 1st time. So, i removed the upper manifold for about the 30th time in about 3-4 weeks (not exagerating). i checked every single place air could escape. One oil injector was semi-loose. but i think it was still tight enough to seal. So, i have no idea where the air is escaping... anyone have any ideas to check for leaks with the upper manifold off? I been adding the pressurized air at the throttle body. so with it removed, i will not be able to do that. __________________ what I have: 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2

08-27-2009, 09:47 PM	#7
sen2two KTEC Join Date: Jan 2009 iTrader: (2) Posts: 642 Rep Power: 0	i made a little flange that bolts to the lower intake manifold. im going to tap that with a air hose fitting and put air in there. this will allow me easily find the leaks with the upper manifold being removed... where to get the tap for it though? i went to the local stores and couldnt find it. i also needed a -12AN tap for something else. anyone know where to buy taps online for a good price? __________________ what I have: 1985 Gs:12a All motor Drag car - 1973 Rx2: Play car What I had: 93 Touring: TRADED - 91 Coupe: TRADED - 90 GTU: RHD - 88 10AE: SOLD - 87 Base: SOLD - 86 Base: SOLD - 1985 GSLSE - 85 Gsl: SOLD - 80 Gs: TRADED - 1972 Rx2

08-16-2009, 03:31 PM	#2
RotaryDiagnostics Compression Tester Man Join Date: Feb 2009 Location: Mont Alto, PA iTrader: (1) Posts: 137 Rep Power: 16	Pressurize the intake system to a steady pressure (less than 10 psi) and see if you hear air rushing out anywhere. You don't need to remove the air hose. If there is a leak, you will hear air rushing out and can easily find the leak. If the intake system is sealed, you will not hear air rushing out, but the adapter may pop out so be careful. Also, you can run the car at idle (warmed up) and spray engine starter sparingly around the engine compartment--primarily around the intake piping-BAC valve area. If the engine smooths out, you will have isolated the air/vacuum leak. Then carefully inspect all hoses/pipes in that area.

08-20-2009, 09:37 PM	#4
misterstyx69 .drives like MrMagoo! Join Date: Feb 2008 Location: Smiths Falls,Ontario iTrader: (5) Posts: 198 Rep Power: 17	www.fighters-garage.com Take a look at the Fighters Products.they have a pressure tester..Copy it..simple thing..I used a POOL gauge and a Tire valve on a PVC Cap(2 inch).I put it on a end piece so it would be longer and you could get a clamp on it. Fill the system with air and watch the gauge.Look/feel for leaks.It allows you to actually walk around the engine IF the air isn't leaking out as fast as you put it in!