vacuum readings are these normal?
01-17-10, 08:00 PM
#1
vacuum readings are these normal?
I just installed a VDO boost/vac gauge this weekend.
At idle I'm at 20mm of mercury on the vac side.
At easy accelleration I'm at 10mm of Hg.
Under boost I'm maxing at 6psi.
When I turn the car off the gauge returns to slightly below 0 psi.
The only hitch is that my AEM H20/Alc. injector controller is on the same line as the boost gauge.
I don't know if having the boost line "teed" and running about 12" of vac hose over to the injector controller would effect it so I thought I'd ask.
Next step will be diagnosing the seq. turbos.
At idle I'm at 20mm of mercury on the vac side.
At easy accelleration I'm at 10mm of Hg.
Under boost I'm maxing at 6psi.
When I turn the car off the gauge returns to slightly below 0 psi.
The only hitch is that my AEM H20/Alc. injector controller is on the same line as the boost gauge.
I don't know if having the boost line "teed" and running about 12" of vac hose over to the injector controller would effect it so I thought I'd ask.
Next step will be diagnosing the seq. turbos.
01-17-10, 10:22 PM
#4
how is 20mm Hg of manifold vacuum (relative not absolute) normal?? Something's gotta be messed up with your gauge or with your car.. 20mm is less than one inch Hg of vacuum. 25.4mm per inch.
even if it was 200mm it would still be low unless you had a bridgeport. vacuum readings can vary a lot, but I can say that you're looking for a minimum of 250mm for a street ported engine--that's about 10 inches.
even if it was 200mm it would still be low unless you had a bridgeport. vacuum readings can vary a lot, but I can say that you're looking for a minimum of 250mm for a street ported engine--that's about 10 inches.
01-17-10, 10:29 PM
#5
how is 20mm Hg of manifold vacuum (relative not absolute) normal?? Something's gotta be messed up with your gauge or with your car.. 20mm is less than one inch Hg of vacuum. 25.4mm per inch.
even if it was 200mm it would still be low unless you had a bridgeport. vacuum readings can vary a lot, but I can say that you're looking for a minimum of 250mm for a street ported engine--that's about 10 inches.
even if it was 200mm it would still be low unless you had a bridgeport. vacuum readings can vary a lot, but I can say that you're looking for a minimum of 250mm for a street ported engine--that's about 10 inches.
Stock engine, runs great otherwise, 40k miles.
01-17-10, 10:43 PM
#7
Now I just have to figure out why I'm only getting 6psi on primary. I think that is keeping secondary from coming on at all. Doing a lot of reading on vac hose replacement and turbo troubleshooting. Leaning towards the y-pipe coupler right now.
I can hear a rushing air noise when I boost. I first noticed it after I installed the HKS downpipe. Not sure if this could have anything to do with it but on my first drive since the DP and ever since I hear this noise once the boost builds. I asked the forum about the noise and everybody said it's normal to hear the turbos more without the precat but I think I'm hearing pressurized air leak as well.
I can hear a rushing air noise when I boost. I first noticed it after I installed the HKS downpipe. Not sure if this could have anything to do with it but on my first drive since the DP and ever since I hear this noise once the boost builds. I asked the forum about the noise and everybody said it's normal to hear the turbos more without the precat but I think I'm hearing pressurized air leak as well.
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01-17-10, 10:47 PM
#8
boost leak tester for twins: http://www.fighters-garage.com/rx7.html scroll to the bottom
01-18-10, 12:10 AM
#9
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I have pretty much the same problem as adamrs. idles at 15mm, can roughly boost to 4 - 5lbs, but feels like very little power, just did block off plates and checked my vac lines, everything looked ok. Eliminated acv unit, split air pipes, double throttle, Isc, and aws tube. Helped with pressure a little but still runs the same when boost builds, can now boost to roughly 6-8 lbs but still very little power.Sounds like turbos are getting overworked. Here the same rushing air sound as well.
Mods are, dp exhaust with resonators, intake intercooler. How does the boost leak tester work?
Mods are, dp exhaust with resonators, intake intercooler. How does the boost leak tester work?
01-18-10, 07:14 AM
#11
I did a full block off plate job and vac job along with daleclark check valves. Now I'm gonna chang my stock spipe out Last time I try spraying brake cleaner. On it while at idle. After spraying the brake cleaner the idle whould idle like **** for a few second. So I'm aiming to that. For
boost leak.
boost leak.
01-18-10, 11:34 PM
#17
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how do you test the solenoids? And do you need a compressor to the boost leak tester? Could a faulty bov be part of the problem as well? I have a knock off one right now.
01-19-10, 12:26 AM
#18
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I'm pretty sure you'd need a compressor for the boost leak tester. It'll shoot air into the system then you try to figure out where it's leaking by listening or spraying carb cleaner.
you can try to access the leak visually without one but the stock vacuum stuff on these cars looks like a nightmare to me.
you can try to access the leak visually without one but the stock vacuum stuff on these cars looks like a nightmare to me.
01-19-10, 06:49 AM
#20
I'm pretty sure you'd need a compressor for the boost leak tester. It'll shoot air into the system then you try to figure out where it's leaking by listening or spraying carb cleaner.
you can try to access the leak visually without one but the stock vacuum stuff on these cars looks like a nightmare to me.
you can try to access the leak visually without one but the stock vacuum stuff on these cars looks like a nightmare to me.
01-19-10, 08:56 PM
#21
back in business
The coupler from the y-pipe into the plastic intercooler entrance pipe was totally loose. The plastic pipe had popped off the coupler. I knew the air leaking noise was coming from somewhere. Now I'm getting 10-8-10. Sweetness again
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