Upgraded 7 turned into downgrade
03-26-12, 01:55 PM
#1
Upgraded 7 turned into downgrade
Hello all, Instead of hi-jacking others threads, I will start my own. Before upgrading, my 7 ran flawless. It is 1988 10th AE 64000 miles. It has down pipe, greddy bov, wb, high flow cat, rb cat back, rtek 2.1 untunned, mbc set to 10psi, water injection, and air to water intercooler. No issues with this set-up.
Last dec. I took the turbo out to get the BNR stage 3, I also got the upper and lower intake mani's powder coated. I installed all new 720cc, new injector air bleeds/defusers, new turbo to mani gasket, new lim to block gasket, new lim o-rings, new uim to lim gasket, new TB to greddy elbow o-ring, and all new vac lines and fuel lines. Removed all emissions, PD, and FPR. I installed new fpr, kept the BAC. Did not touch the TB, still stock. I added new grounds and removed rats nest, I did keep the twin scroll intact. I set the rtek to all 720's.
The 7 started first try, idle was normal 1200rpm untill it warmed up and dropped to 600rpm. I turned up the FPR to about 38psi and it now idles at 750rpm. It drives and idles great. It is a little on the rich side, about 13.5 AFR at idle. It also has low vac at idle about 13inhg.
So, I decided to try to boost it and it got to about 5-6psi and thats all the turbo would put out all the way to redline. I checked for boost leaks with a smoke tester and the only leak I could find was the mazda hidden metered leak behind the fast idle cam/thermal wax thing on the firewall side of the TB.
Ive checked for vac/boost leaks, wastegate psi, twin scroll systems.
Any input on this would be good, Im out of ideas.
Last dec. I took the turbo out to get the BNR stage 3, I also got the upper and lower intake mani's powder coated. I installed all new 720cc, new injector air bleeds/defusers, new turbo to mani gasket, new lim to block gasket, new lim o-rings, new uim to lim gasket, new TB to greddy elbow o-ring, and all new vac lines and fuel lines. Removed all emissions, PD, and FPR. I installed new fpr, kept the BAC. Did not touch the TB, still stock. I added new grounds and removed rats nest, I did keep the twin scroll intact. I set the rtek to all 720's.
The 7 started first try, idle was normal 1200rpm untill it warmed up and dropped to 600rpm. I turned up the FPR to about 38psi and it now idles at 750rpm. It drives and idles great. It is a little on the rich side, about 13.5 AFR at idle. It also has low vac at idle about 13inhg.
So, I decided to try to boost it and it got to about 5-6psi and thats all the turbo would put out all the way to redline. I checked for boost leaks with a smoke tester and the only leak I could find was the mazda hidden metered leak behind the fast idle cam/thermal wax thing on the firewall side of the TB.
Ive checked for vac/boost leaks, wastegate psi, twin scroll systems.
Any input on this would be good, Im out of ideas.
Last edited by 10thaniv; 03-26-12 at 01:57 PM. Reason: typo/pic
03-26-12, 02:00 PM
#2
03-26-12, 02:58 PM
#5
I will check that again. When I first got the turbo back from BNR, I did find that when I opened the wastegate by hand it would stick. I had to put my finger in the turbo and push on the flapper and it would snap closed. I called BNR and he told me it did that due to me holding the turbo sideways instead of upright in its normal position, so I tested it a couple of times in it correct position and it didnt stick. Maybe with thermal expansion it sticks. Hmmmm. Would a sticking wastegate also cause low vacuum?
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03-26-12, 07:51 PM
#8
I will check that again. When I first got the turbo back from BNR, I did find that when I opened the wastegate by hand it would stick. I had to put my finger in the turbo and push on the flapper and it would snap closed. I called BNR and he told me it did that due to me holding the turbo sideways instead of upright in its normal position, so I tested it a couple of times in it correct position and it didnt stick. Maybe with thermal expansion it sticks. Hmmmm. Would a sticking wastegate also cause low vacuum?
03-26-12, 10:28 PM
#9
That's some bullshit. The orientation doesn't matter. If it's sticking, the pressure will be inconsistent. You might have to modify the actuator flange or linkage so the flapper shaft is held in a certain position. I've found that it's not good if the actuator linkage is pulling the flapper arm away from the turbo exhaust housing.
03-27-12, 09:14 AM
#11
Update: I pulled the hose off the waste gate and took the 7 for a spin and it boosted fine, I had to watch the boost gauge so I didnt overboost so I let off the gas as the boost got up to 10psi. I will reattach the hose and adjust the wastegate arm to give it more pressure and retest. I think the wastegate was set too soft so it would only boost to 6psi. I still have a vac leak that I will work on this weekend. Correction AFR at idle is 11.2. I think when I find the vac leak I can then pull some fuel with the FPR.
Hozz: I let my USTA membership expire this year, I havnt played in some time. Thanks Allan
Hozz: I let my USTA membership expire this year, I havnt played in some time. Thanks Allan
03-28-12, 12:31 PM
#13
Well, the stock wastegate spring is 5.5psi and your exhaust sounds very restrictive so it is possible you are actually NOT getting boost creep.
Everyone else running that turbo probably has at least 3" turbo back with no cats and the higher boost numbers they have are due to boost creep.
On my BNR it won't even achieve full boost on 2.5" downpipe to 3.5" midpipe/cat back (no cats), will get full boost @ 4,000rpm on full 3" turbo back and full boost @ 3,500rpm on 3.5" down pipe to 3" RB rear section or the full 3.5" turbo back.
Just an example so you can see how sensitive these set ups can be to exhaust back pressure.
You could connect the wastegate line again but disconnect the cat so you are running open down pipe and take a spin to see what the boost pattern is.
Do you have the MBC on the new set up with the BNR?
Everyone else running that turbo probably has at least 3" turbo back with no cats and the higher boost numbers they have are due to boost creep.
On my BNR it won't even achieve full boost on 2.5" downpipe to 3.5" midpipe/cat back (no cats), will get full boost @ 4,000rpm on full 3" turbo back and full boost @ 3,500rpm on 3.5" down pipe to 3" RB rear section or the full 3.5" turbo back.
Just an example so you can see how sensitive these set ups can be to exhaust back pressure.
You could connect the wastegate line again but disconnect the cat so you are running open down pipe and take a spin to see what the boost pattern is.
Do you have the MBC on the new set up with the BNR?
03-28-12, 04:59 PM
#14
The waste gate is not stock, its the adjustable one from BNR. It was supposed to be set to 12psi. I will adjust the actuator arm to give it more pressure. I hit 10psi with the wastegate hose off at 3800rpm's, not that restrictive and it was climbing fast. Since I deleted the smog crap, I ordered a cat replacement pipe a week ago and I came in today. I will install pipe and retest boost and adj wastegate if needed. Once I find the small vac leak, I will install my boost controller and set it to 12psi or so. I will update in a couple days. Thanks
03-28-12, 07:55 PM
#15
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I was going to say, boost controller should fix everything.
When I upgraded the stock turbo wastegate flapper with a much larger washer and massive porting I could not get boost to climb over 4 psi. before I would always hit fuel cut.
I ended up putting on my 3574 kit and never looked back. Thinking about it I never did try twisting up the boost controller. So my conclusion is the opening rate of the stock wastegate was amplified by the HUGE flapper so it was basically opening too fast
If you wire the wastegate shut and get boost then you know for sure it is in the wastegate control
When I upgraded the stock turbo wastegate flapper with a much larger washer and massive porting I could not get boost to climb over 4 psi. before I would always hit fuel cut.
I ended up putting on my 3574 kit and never looked back. Thinking about it I never did try twisting up the boost controller. So my conclusion is the opening rate of the stock wastegate was amplified by the HUGE flapper so it was basically opening too fast
If you wire the wastegate shut and get boost then you know for sure it is in the wastegate control
04-02-12, 01:54 PM
#16
I installed the cat replacement and took her for a spin. She boosted quicker than before but only to 8psi. I was about to install the boost controller and found a very small coolant leak coming from the LIM. I have to take her back down to the block and I will be installing freeze plugs in the block for the coolant passages to the LIM. I will then use the coolant line from the rear iron to feed the turbo with coolant. Im also going to get the powder coatings removed from the mating surfaces on the lim and uim witch I think the vacuum leaks are coming from. I will update in 2 weeks. Thanks All
04-02-12, 04:06 PM
#18
We couldnt get more than 9.9 psi out of our Stage 1 and Brian said that even with the adjustable WG actuator (which turns out he forgot to put on ours) you can only add one or two PSI. He told us to add a helper spring.
I used a 4" 9.55 lb spring from HD and while it took some tweeking of the spring length we are now happily boosting to 12psi at 50% on the EBC and it holds nicely up the revs.
Might be worth trying.
I used a 4" 9.55 lb spring from HD and while it took some tweeking of the spring length we are now happily boosting to 12psi at 50% on the EBC and it holds nicely up the revs.
Might be worth trying.
05-17-12, 06:57 PM
#20
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Did you ever get this done? I am considering using freeze plugs on my block before I even put it in just to avoid this issue in the future. Is there any downside?
Hope the cars running for ya!
Hope the cars running for ya!
I installed the cat replacement and took her for a spin. She boosted quicker than before but only to 8psi. I was about to install the boost controller and found a very small coolant leak coming from the LIM. I have to take her back down to the block and I will be installing freeze plugs in the block for the coolant passages to the LIM. I will then use the coolant line from the rear iron to feed the turbo with coolant. Im also going to get the powder coatings removed from the mating surfaces on the lim and uim witch I think the vacuum leaks are coming from. I will update in 2 weeks. Thanks All
05-17-12, 07:16 PM
#21
There are mechanical aspects to a wastegate. The preload in the arm is one of them: the size of diaphragm and springrate are another. Exhaust backpressure plays a big role.
And then there is the way you have your boost controller set up. An MBC has less precision than an EBC for adjustment.
What this really requires is careful adjustment of the boost curve by using the datalogging capability of the Rtek.
And then there is the way you have your boost controller set up. An MBC has less precision than an EBC for adjustment.
What this really requires is careful adjustment of the boost curve by using the datalogging capability of the Rtek.
05-17-12, 10:09 PM
#22
I have not taken her back apart but installing the boost controller solved my boost problem, she runs great. Holds at 11 psi all the way to redline. I still have the coolant leak and have all the parts to fix it, but just dont have the time to do it right now. I have a vacation in july, so I will do it then. Thanks
05-18-12, 05:53 AM
#23
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Good to hear! Is there any reason not to do the freeze plug deal? I'd rather take that extra precaution and make sure I don't end up with the same problem down the road unless there is a reason not to.
05-18-12, 04:58 PM
#24
Put the freeze plugs in. Search the forum for 20mm freeze plug and you will find good info. I bought 3 from the auto parts store for less than $2. I would of done it while I had the LIM off, but I didnt know about the freeze plugs until I had issues with the stock orings not sealing good.