Leak at the back of the intake?
06-29-2010, 10:38 PM
#1
Leak at the back of the intake? I'm in the final steps of swapping an L33 into my Miata and am having issues with the car. HPTuners is saying its at 70kpa at idle (should be 45-50 even with this 226/236 111 LSA ASA cam). That is equal to about 8 inches of vacuum, where it should be ATLEAST 12-15 inches.
Now my question- I noticed the LS6 intake I installed would let me kind of spin the back piece where the booster and map are. I pressure tested the intake and am hearing hissing back there, but the booster hose is tight, and removing the MAP sensor and putting my finger over the hole. I also pulled the hose out and put my finger in its place to seal it off with no difference.
Ideas? Is there a seal in the back of the intake? If I can't replace it, should I seal it with RTV? I'm really at a loss.
Thanks!
Now my question- I noticed the LS6 intake I installed would let me kind of spin the back piece where the booster and map are. I pressure tested the intake and am hearing hissing back there, but the booster hose is tight, and removing the MAP sensor and putting my finger over the hole. I also pulled the hose out and put my finger in its place to seal it off with no difference.
Ideas? Is there a seal in the back of the intake? If I can't replace it, should I seal it with RTV? I'm really at a loss.
Thanks!
06-30-2010, 12:11 AM
#3
None right now while diagnosing this issue. I have the two vacuum ports blocked off at the front of the intake, the small one at the back blocked, and the intake is torqued to spec. In the 7-8 years I've been playing with these cars extensively, I've never run into this. It's also making the engine run peg rich I assume. White smoke, soot on the tailpipes and the wideband is reading 10.0 afr's the entire time. Propane does not effect the rpm at all, even sprayed into the throttle body.
06-30-2010, 07:11 AM
#5
Mike,
some things i can think of off the top of my head
1. make sure all your injector o-rings are seated properly, none pinched
2. check your intake to head o-rings for the same problem.
3. check the brake booster line for cracks, splits and other ****.
4. what i would do, is pull the intake off and block all the ports you can and fill it with water and see where it leaks from. (just be sure to dry it out good before installing it again).
call me if you cant figure it out, ill think about it the next day or so and see if i cant come up with anything else.
some things i can think of off the top of my head
1. make sure all your injector o-rings are seated properly, none pinched
2. check your intake to head o-rings for the same problem.
3. check the brake booster line for cracks, splits and other ****.
4. what i would do, is pull the intake off and block all the ports you can and fill it with water and see where it leaks from. (just be sure to dry it out good before installing it again).
call me if you cant figure it out, ill think about it the next day or so and see if i cant come up with anything else.
06-30-2010, 10:56 AM
#6
TECH Senior Member
There's a an o-ring that seals it to the manifold... I'm not sure how to remove it from the manifold, there seems to be 3 lock tabs on the inside (don't want to break them).
06-30-2010, 11:56 AM
#7
You also need to run a PCV or breather system of some kind. You're begging to destroy your rings blocking it off completely like that. I'd be willing to bet that could be contributing to your problems seeing as how your motor has absolutely no way to vent crankcase pressures.
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06-30-2010, 12:12 PM
#8
Good idea!
I'll check around the injector area. I put a cap on the throttle body to pressurize the intake and its hissing at the back of the intake. Like the F-bodies, its a real PITA to get to the booster port.
That is the seal I wonder about! I'm tempted to squirt some RTV around it to help try to seal it off.
Right now the crankcase is open atmosphere, but once the vacuum situation is sorted out, I'll have the PCV hooked back up to it. Right now I just have the ports on the intake blocked off to eliminate one more possible issue while diagnosing.
Mike,
some things i can think of off the top of my head
1. make sure all your injector o-rings are seated properly, none pinched
2. check your intake to head o-rings for the same problem.
3. check the brake booster line for cracks, splits and other ****.
4. what i would do, is pull the intake off and block all the ports you can and fill it with water and see where it leaks from. (just be sure to dry it out good before installing it again).
call me if you cant figure it out, ill think about it the next day or so and see if i cant come up with anything else.
some things i can think of off the top of my head
1. make sure all your injector o-rings are seated properly, none pinched
2. check your intake to head o-rings for the same problem.
3. check the brake booster line for cracks, splits and other ****.
4. what i would do, is pull the intake off and block all the ports you can and fill it with water and see where it leaks from. (just be sure to dry it out good before installing it again).
call me if you cant figure it out, ill think about it the next day or so and see if i cant come up with anything else.
You also need to run a PCV or breather system of some kind. You're begging to destroy your rings blocking it off completely like that. I'd be willing to bet that could be contributing to your problems seeing as how your motor has absolutely no way to vent crankcase pressures.
06-30-2010, 09:51 PM
#9
Pressure tested the intake today. Two injector O-rings are leaking and the booster line leaked at 10psi. I fixed the booster line and will be running to O'Reilly for the seals tomorrow. Is 8-10 inches of vacuum normal for this 226/236 110lsa cam in a 5.3? I don't see how the small CI will effect the vacuum readings, but then again, I've never looked in depth at how CI's effect vacuum readings when it comes to amounts of overlap.
