Suddenly no boost
#1
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Suddenly no boost
After racing a 911 Carrera last night (which I spanked ) I'm getting just about 0 boost all the way through the rev range. If the car is decently cool I'll get 1 or 2 psi, but nothing above that. Because this happened so suddenly, and right after I brought my car out of storage from the winter, I assumed it'd be an IC coupling, or one of the hoses. I can hear a nice whooshing sound as soon as I should be seeing some boost, so I know the turbos are spinning away just fine. The engine idles solidly, makes great vacuum, and normal rotary N/A power, so I know the engine is fine.
So I took a look through my intake track this afternoon. Working from the intake elbow back, the hose that goes into the top of the IC was fine, and attached quite well. The hose that comes out of the bottom of the IC and up to the coupling with the crossover pipe was fine. The coupling between the IC hose and the crossover pipe looked good, and the crossover pipe itself looked fine.
The coupling between the crossover pipe and the y-pipe looked ok. And heres where my question is. How is the y-pipe attached to the turbos? Are there 2 more couplings? I didn't have enough time to keep digging this afternoon, so I didn't get to check that.
I also took a look at the BOV, and it's functioning fine, holding pressure until vacuum is applied.
And if anyone thinks my issue could be something other than a coupling or pipe, feel free to chime in.
Thanks for any help.
So I took a look through my intake track this afternoon. Working from the intake elbow back, the hose that goes into the top of the IC was fine, and attached quite well. The hose that comes out of the bottom of the IC and up to the coupling with the crossover pipe was fine. The coupling between the IC hose and the crossover pipe looked good, and the crossover pipe itself looked fine.
The coupling between the crossover pipe and the y-pipe looked ok. And heres where my question is. How is the y-pipe attached to the turbos? Are there 2 more couplings? I didn't have enough time to keep digging this afternoon, so I didn't get to check that.
I also took a look at the BOV, and it's functioning fine, holding pressure until vacuum is applied.
And if anyone thinks my issue could be something other than a coupling or pipe, feel free to chime in.
Thanks for any help.
#2
don't race, don't need to
The Y-pipe (stock) is actually a two piece affair. There is an "elbow" that attaches to the output of the primary turbo via a metal to metal bolted interface, with a metal gasket. This elbow also contains the combined output connection (Y-pipe to crossover) and the blow off valve connection. BTW, did you remove the coupler for the Y-pipe to crossover and fold it inside out? Or just visual? Splits in this coupler can be difficult to see.
Anyway, the other half of the Y-pipe is an elbow that mounts to the output of the secindary turbo, again with a gasketed metal to metal bolted interface. the rear elbow has the connection for the charge releif hose. Since you have no primery boost, I wouldn't suspect a torn CRV connection.
The two elbows meet on the secondary side of the combined output, but before the carge control valve. You can see where the one pipe is larger than the other (I forget which). They mate together with a simple O-ring. If the O-ring is blown, this could also be a culprit. You will need to pull the y-pipe to check this out.
Anyway, the other half of the Y-pipe is an elbow that mounts to the output of the secindary turbo, again with a gasketed metal to metal bolted interface. the rear elbow has the connection for the charge releif hose. Since you have no primery boost, I wouldn't suspect a torn CRV connection.
The two elbows meet on the secondary side of the combined output, but before the carge control valve. You can see where the one pipe is larger than the other (I forget which). They mate together with a simple O-ring. If the O-ring is blown, this could also be a culprit. You will need to pull the y-pipe to check this out.
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Originally posted by spurvo
BTW, did you remove the coupler for the Y-pipe to crossover and fold it inside out? Or just visual? Splits in this coupler can be difficult to see.
BTW, did you remove the coupler for the Y-pipe to crossover and fold it inside out? Or just visual? Splits in this coupler can be difficult to see.
Originally posted by spurvo
Anyway, the other half of the Y-pipe is an elbow that mounts to the output of the secindary turbo, again with a gasketed metal to metal bolted interface. the rear elbow has the connection for the charge releif hose. Since you have no primery boost, I wouldn't suspect a torn CRV connection.
Anyway, the other half of the Y-pipe is an elbow that mounts to the output of the secindary turbo, again with a gasketed metal to metal bolted interface. the rear elbow has the connection for the charge releif hose. Since you have no primery boost, I wouldn't suspect a torn CRV connection.
Originally posted by spurvo
You will need to pull the y-pipe to check this out.
You will need to pull the y-pipe to check this out.
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The other day I was spiritedly driving with some friends and all the sudden I had no boost and had all the same symptoms you have. My problem was a split in the IC piping coming off the bottom. It was really hard to see but once I found it it was pretty large and easy to see.
Double check the IC piping before you start taking other things apart.
Double check the IC piping before you start taking other things apart.
#6
the REAL deal
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Originally posted by Azaka
The other day I was spiritedly driving with some friends and all the sudden I had no boost and had all the same symptoms you have. My problem was a split in the IC piping coming off the bottom. It was really hard to see but once I found it it was pretty large and easy to see.
The other day I was spiritedly driving with some friends and all the sudden I had no boost and had all the same symptoms you have. My problem was a split in the IC piping coming off the bottom. It was really hard to see but once I found it it was pretty large and easy to see.
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Check the lines going to the BOV and CRV. The CRV should not be functioning if you're running NS.
In a sequential setup the CRV enables the secondary turbo to prespool, by providing an alternate path for the turbo's output, when the turbo's main output pipe is blocked by the Charge Control Valve
When the system switches from primary only to primary/secondary mode the CRV closes and the door between the two sections of the Y-pipe opens. The secondary turbo's output is diverted from the CRV valve to the Intercooler.
If you still had the CRV hooked up to the solenoid you would get no boost below the turbo transition point. However if the valve is still physically attached to the Y-pipe, but stuck closed then it should be fine.
The CRV connects to the section of the Y-pipe closest to the firewall. The BOV connects at the center of the pipe. Regardless of what is attached to them, I would check both connections. However, if you're getting ZERO boost I tend to think the cause of your problem is more than a loose hose.
I agree with Rynberg re the AWS hose.
In a sequential setup the CRV enables the secondary turbo to prespool, by providing an alternate path for the turbo's output, when the turbo's main output pipe is blocked by the Charge Control Valve
When the system switches from primary only to primary/secondary mode the CRV closes and the door between the two sections of the Y-pipe opens. The secondary turbo's output is diverted from the CRV valve to the Intercooler.
If you still had the CRV hooked up to the solenoid you would get no boost below the turbo transition point. However if the valve is still physically attached to the Y-pipe, but stuck closed then it should be fine.
The CRV connects to the section of the Y-pipe closest to the firewall. The BOV connects at the center of the pipe. Regardless of what is attached to them, I would check both connections. However, if you're getting ZERO boost I tend to think the cause of your problem is more than a loose hose.
I agree with Rynberg re the AWS hose.
Last edited by CCarlisi; 04-22-04 at 09:35 PM.
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#8
Tony Stewart Killer.
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bro where have you been this has been discussed so many times
stick to what azaka said. you either blew the coupler holding the crossoverpipe onto the y pipe, the lower intercooler pipe, or the upper intercooler hose. Simple, its there 100%. great idea on the AWS hose as well thats the only other place I forgot.
stick to what azaka said. you either blew the coupler holding the crossoverpipe onto the y pipe, the lower intercooler pipe, or the upper intercooler hose. Simple, its there 100%. great idea on the AWS hose as well thats the only other place I forgot.
Last edited by Snook; 04-22-04 at 09:50 PM.
#9
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Originally posted by rynberg
Also check to make sure your AWS hose is still firmly connected to intake elbow.
Also check to make sure your AWS hose is still firmly connected to intake elbow.
Originally posted by Azaka
The other day I was spiritedly driving with some friends and all the sudden I had no boost and had all the same symptoms you have. My problem was a split in the IC piping coming off the bottom. It was really hard to see but once I found it it was pretty large and easy to see.
The other day I was spiritedly driving with some friends and all the sudden I had no boost and had all the same symptoms you have. My problem was a split in the IC piping coming off the bottom. It was really hard to see but once I found it it was pretty large and easy to see.
Originally posted by CCarlisi
Check the lines going to the BOV and CRV. The CRV should not be functioning if you're running NS.
Check the lines going to the BOV and CRV. The CRV should not be functioning if you're running NS.
#10
Tony Stewart Killer.
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the crv closes a tad bit later than the bov does so it will let out a very small amount of air that could be going to the engine. you are non seq on twins. you only need one bov cap the crv run a line from the bov to manifold and be done with it. yur the one who wants simplicity why would you keep something you totally dont need
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Originally posted by SurgeMonster
the crv closes a tad bit later than the bov does so it will let out a very small amount of air that could be going to the engine. you are non seq on twins. you only need one bov cap the crv run a line from the bov to manifold and be done with it. yur the one who wants simplicity why would you keep something you totally dont need
the crv closes a tad bit later than the bov does so it will let out a very small amount of air that could be going to the engine. you are non seq on twins. you only need one bov cap the crv run a line from the bov to manifold and be done with it. yur the one who wants simplicity why would you keep something you totally dont need
#12
Tony Stewart Killer.
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im not trying to be an *** you just seem like you are avoiding learning some easy things because someone else did the work. Id sure hope they could figure it out being a 3d gen shop but most are still pathetic.
heres a diagram I made for dummies like myself who finally learned
http://plaza.ufl.edu/yanni25/mynonseqsetup.jpg
heres a diagram I made for dummies like myself who finally learned
http://plaza.ufl.edu/yanni25/mynonseqsetup.jpg
#13
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Originally posted by SurgeMonster
im not trying to be an *** you just seem like you are avoiding learning some easy things because someone else did the work. Id sure hope they could figure it out being a 3d gen shop but most are still pathetic.
heres a diagram I made for dummies like myself who finally learned
http://plaza.ufl.edu/yanni25/mynonseqsetup.jpg
im not trying to be an *** you just seem like you are avoiding learning some easy things because someone else did the work. Id sure hope they could figure it out being a 3d gen shop but most are still pathetic.
heres a diagram I made for dummies like myself who finally learned
http://plaza.ufl.edu/yanni25/mynonseqsetup.jpg
#14
Cheap Bastard
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I'm not too familiar with non-seq setups, so this may not be helpfull. I had a similar problem last year, and it was just a hose that had popped off under the black pressure tank in front of the UIM. If you are still using this part of the vacuum system, its an easy spot to check. Just remove the pressure tank and take a look around.
It does not sound like a bad intake hose to me.
It does not sound like a bad intake hose to me.
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How are you holding the 2 flappers? Did you weld them ? The two under the turbo area. If both (or even one maybe) got loose then that is your problem. I forgot to hold them open and I finished the non-seq and with the wastegate closed I could only get 3 psi pushing it 5! So just imagine Im pretty sure that could be your problem.
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Originally posted by Azaka
The other day I was spiritedly driving with some friends and all the sudden I had no boost and had all the same symptoms you have. My problem was a split in the IC piping coming off the bottom. It was really hard to see but once I found it it was pretty large and easy to see.
Double check the IC piping before you start taking other things apart.
The other day I was spiritedly driving with some friends and all the sudden I had no boost and had all the same symptoms you have. My problem was a split in the IC piping coming off the bottom. It was really hard to see but once I found it it was pretty large and easy to see.
Double check the IC piping before you start taking other things apart.
joel
#17
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Originally posted by adam c
I'm not too familiar with non-seq setups, so this may not be helpfull. I had a similar problem last year, and it was just a hose that had popped off under the black pressure tank in front of the UIM. If you are still using this part of the vacuum system, its an easy spot to check. Just remove the pressure tank and take a look around.
It does not sound like a bad intake hose to me.
I'm not too familiar with non-seq setups, so this may not be helpfull. I had a similar problem last year, and it was just a hose that had popped off under the black pressure tank in front of the UIM. If you are still using this part of the vacuum system, its an easy spot to check. Just remove the pressure tank and take a look around.
It does not sound like a bad intake hose to me.
Originally posted by Fatman0203
How are you holding the 2 flappers? Did you weld them ? The two under the turbo area. If both (or even one maybe) got loose then that is your problem. I forgot to hold them open and I finished the non-seq and with the wastegate closed I could only get 3 psi pushing it 5! So just imagine Im pretty sure that could be your problem.
How are you holding the 2 flappers? Did you weld them ? The two under the turbo area. If both (or even one maybe) got loose then that is your problem. I forgot to hold them open and I finished the non-seq and with the wastegate closed I could only get 3 psi pushing it 5! So just imagine Im pretty sure that could be your problem.
Originally posted by bigmack000
thats rigthwhere mine was but 2 times the size. got maybe 5 psi then it would be 0 when it got hot under the hood.
joel
thats rigthwhere mine was but 2 times the size. got maybe 5 psi then it would be 0 when it got hot under the hood.
joel
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Originally posted by 911GT2
But then again, I also talked to Dave about street-porting the motor before he put it in, which he conveniently forgot...
But then again, I also talked to Dave about street-porting the motor before he put it in, which he conveniently forgot...
#19
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Originally posted by CCarlisi
LOL. That is so so sad. I wonder if they actually rebuilt your motor or just middle manned a Malloy reman.
LOL. That is so so sad. I wonder if they actually rebuilt your motor or just middle manned a Malloy reman.
#20
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911GT2
Check the flappers, this IS your problem if he wired them shut or even if he did a bad job on the weld. All you have to do is get under where the turbo area is and just take a look and the flappers try to move them. If they open and close with your hand then their lose and will close under exhaust pressure.
Check the flappers, this IS your problem if he wired them shut or even if he did a bad job on the weld. All you have to do is get under where the turbo area is and just take a look and the flappers try to move them. If they open and close with your hand then their lose and will close under exhaust pressure.
#21
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Leak Fixed!
I found the cause of my boost leak this afternoon. I decided to do a quick check to see if rynberg and others were right with the AWS hose, but unfortunately it was still firmly connected.
I took one more look at the y-pipe and bingo, the 3/4" nipple previously used for the CRV had only the remains of a vacuum cap on it. Over heat cycling I guess the cap cracked, and the first good long in boost run to redline I had this spring blew it right off. So I stuck a new cap on, and viola! No more boost leak
Thanks to all for the help as usual.
I took one more look at the y-pipe and bingo, the 3/4" nipple previously used for the CRV had only the remains of a vacuum cap on it. Over heat cycling I guess the cap cracked, and the first good long in boost run to redline I had this spring blew it right off. So I stuck a new cap on, and viola! No more boost leak
Thanks to all for the help as usual.
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