Boosting Past 10PSI...car faulters

[bangedUpGSX]

Hello,

I've got a problem, my mechanic installed a boost controller this week and I'm absolutely sure something he did was wrong. Before he installed it the factory setting was reached at 10psi. Now he has installed and once it reaches 10psi the car shudders (much like it has a vacuum leak, but I'm pretty darn sure it isn't).

Here is what he did as I looked at it this afternoon. The turbo outlet hose goes into the boost controller....then the outlet of the boost controller goes right back into the turbo. I'm thinking the factor boost controller has not been accounted for, and I'm wondering how the car knows when the to open the wastegate if there is no hose going from the boost controller to the car.

I don't know much technically, but it seems like the boost controller short circuits the wastegate until the set level of boost is reached at which point the car computer is notified the desired level of boost (at factor it would be 10psi) has been reached and the wastegate should be activated.

Am I way off here? Can someone give me or direct me to a 2G boost controller install for dummies...my mechanic is and I'm trying to fix it.

Thanks all.

R

 

[oldman]

(much like it has a vacuum leak, but I'm pretty darn sure it isn't).

How are you so sure?

Here is what he did as I looked at it this afternoon. The turbo outlet hose goes into the boost controller....then the outlet of the boost controller goes right back into the turbo. I'm thinking the factor boost controller has not been accounted for, and I'm wondering how the car knows when the to open the

If by "goes right back into the turbo" you mean back to the actuator under the turbo then he has it right. You're not suppose to reconnect the the factory bcs. MBC blocks off (or bleed off depending on which mbc) pressure until setting is reached, sends pressure to the actuator under the turbo which then opens the wastgate.

I don't know much technically, but it seems like the boost controller short circuits the wastegate until the set level of boost is reached at which point the car computer is notified the desired level of boost (at factor it would be 10psi) has been reached and the wastegate should be activated.

The wastegate is a mechanical device, nothing to do with the ecu.

Am I way off here?

No comment.

 

[Gary 420A RS]

maybe you need a new bov. cause the stock 2g one doesnt do well after i think 12? also i wouldnt be assuming shorting or anything like that cause seriously? but maybe like i said check with the bov.

 

[bangedUpGSX]

I already have a 1g bov.

 

[bangedUpGSX]

oldman,

because when the turbo was replaced the vacuum tube that attached under the air filter attachment wasn't re-attached and everytime the turbo kicked on the car faltered. Its a bit different now, the boost goes to 10PSI like I said, then the car immediately falters.

For some more information - the EGTs only go to 1400 degrees so I'm pretty sure its not lean and retarding the timing.

Is there a scenario where the boost controller wants to go past 10PSI, but the car is still limiting the boost somehow?

Basically the boost controller is either improperly installed or something is not detached right on the car and it is still trying to remain at stock boost levels.

thanks for the help, I'm going to try to get it on a lift this afternoon, any nice descriptive articles on boost controller installs for turboXS (besides the manufacturer instructions)

R

 

[oldman]

because when the turbo was replaced the vacuum tube that attached under the air filter attachment wasn't re-attached and everytime the turbo kicked on the car faltered.

Make sure you cap that off.

nice descriptive articles on boost controller installs for turboXS (besides the manufacturer instructions)

No, but it's very simple. The pressure source (the compressor nipple) goes into the T nipple on the mbc, the nipple inline and opposit to the adjustment knob goes to the actuator. Is the mbc brand new? There seems to be mix reviews on the TurboXS contoller, people either love it or they have problems with it.

Basically the boost controller is either improperly installed or something is not detached right on the car and it is still trying to remain at stock boost levels.

This is what you do after you verify that the mbc is hooked up correctly.

1. Remove the hose between the mbc and the actuator under the turbo then cap off the nipple on the mbc but leave the actuator nipple open. What you are doing here is disabling the wastegate so that it would never open, this will result in all out boost (boost shooting straight up to whatever the turbo can handle) so watch the boost gauge carefully and let off the throttle at about 15psi. If in fact you get all out boost, the mbc is either defective or it's installed incorrectly. If problem persists go to step 2.

2. Perform a boost leak test like this. http://www.vfaq.com/mods/ICtester.html I suspect you probably have some leaks either way because you have done work to the intake trac, a leak test should always follow. If problem persists after you fixes all leaks and the able to pressurize the intake to 20 psi, I suspect your turbo is in question.

Have fun.

 

[bangedUpGSX]

ok, I took it out for a drive a little while earlier today after checking the installation (which was hooked up correctly after all). The BCS hose was cut and capped with a screw and the MBC was hooked correctly.

This is what the car is doing:

Boost spools up to between 7 and 13 depending on how I throttle and then the car shudders and then the power drops. From what I've read of other people's problem, this sounds like timing retardation. The turbo has almost no mileage on it (its a ball-bearing "16g Killer") and the car has been sitting for almost a year.

Now why might the timing be retarded? Last time I drove it the boost would hit 10psi (per the BCS) and stay there (no timing problem or hesitation). Perhaps the knock sensor?

I'm going to take it to a tuner shop so they can put a logger on it, but I just wanted to make sure it wasn't something simple I could fix.

Any suggestions? Any good tuner shops in Boston area?

 

[bangedUpGSX]

forgot to mention....mechanic tried installing Walbro 255lph pump, car wouldn't run, put the old pump back in....could this be a fuel pump problem? EGTs are not excessive.

 

[rowlex]

as oldman said, pull the line that hooks to your wastegate to see if there are other problems, then try this: hook the boost source vaccuum line straight up to your wastegate, see what happens. This will tell you if your MBC is causing a problem. (it should boost to 12 psi and stop, tell us after you do this if your car still shudders)

Sounds like you recently did a turbo upgrade, did you install new intercooler pipes? If so, do a real boost leak check, find your leaks.

Here is what has been happening to my car, and from your description it does NOT sound like timing retardation. Timing retardation is a very slight powerloss. Ive upgraded to a 16g, and a FMIC. My J-pipe had a pretty bad leak, I would get on it, hit 13-14lbs and the car shuttered, bucked a little and fell on its face. Huge boost leak was killing it.

Here is info on how a wastegate is controlled. a "spring" inside it is pushed by the actual boost pressure that your turbo creates, opening the wastegate to control the boost at the setting you want it to. What your MBC is doing, is it bleeds off pressure so your wastegate does not see the *actual* pressure your are running thus allowing you to increase your boost.

P.S. (offtopic) oldman, it seems we now unfortunently have a lot of experience in boost leaks and creep. . Anyway for an update on my setup, I think ive finally fixed my boost leak at my j-pipe, im gonna pressure test tomorrow. And my car still creeps real bad, hitting 1.6 bar by 6100 rpm. Car still feels slow, maybe I still have boost leaks. ugh. Im going to send my exhaust manifold to SBR and have them weld a 38mm flange on it for my Tial external gate. DONE with creep...

 

[oldman]

P.S. (offtopic) oldman, it seems we now unfortunently have a lot of experience in boost leaks and creep. . Anyway for an update on my setup, I think ive finally fixed my boost leak at my j-pipe, im gonna pressure test tomorrow. And my car still creeps real bad, hitting 1.6 bar by 6100 rpm. Car still feels slow, maybe I still have boost leaks. ugh. Im going to send my exhaust manifold to SBR and have them weld a 38mm flange on it for my Tial external gate. DONE with creep...

Yes, we all live and learn.... Luda should implement a mandatory boost leak test for all new membership so total number of new thread could be cut in half.

So you're finally giving up and going external. If memory serves me right (I find myself saying that more as I get older ), you didn't really give it a full port job. Send me your turbine and o2 housing and give me one week and I will port them for you, make sure you send your carbide burr, I'm not wasting mine on your housings.

 

[rowlex]

Yes, we all live and learn.... Luda should implement a mandatory boost leak test for all new membership so total number of new thread could be cut in half.

! I like it!

So you're finally giving up and going external. If memory serves me right (I find myself saying that more as I get older ), you didn't really give it a full port job. Send me your turbine and o2 housing and give me one week and I will port them for you, make sure you send your carbide burr, I'm not wasting mine on your housings.

Its right I did not do a full port job, I only ported the path on the exhaust side inlet, as my o2 housing is a full 1.5" dump tube. I know i should have ported the hole on the wastegate and the area around the flapper when it opens, but that would require taking the turbo off and I HATE taking it off. I got a good deal on a tial 38mm and its no trouble pulling the manifold off. I'd send it all to ya(of coarse if I got this far I could probably do it myself), but i cannot have any downtime, the car is my DD until I get the ESI on the road, thanks tho

 

[oldman]

but i cannot have any downtime, the car is my DD until I get the ESI on the road, thanks tho

You're welcome, was hoping you would say that anyway. Let me know how the external worked out for you.

 

[bangedUpGSX]

Well, I haven't driven the car before the other day in about nine months. When it was put away it didn't seem to have boost leak (went perfectly up the BCS 10PSI).

However, given that I just drove it from ME to Boston, I'm pretty sure you're right...when you just give a quick shot of gas, the turbo spools up to say 4-6psi and the car seems to react somewhat ok, the more PSI, the more it falters until I (?) could hear slight backfiring as it tried to spool up to 10 and above. I guess this is the car trying to add gas to what it thinks is the correct ratio...only to over richen the gas mix because of the escaped air?

I'll try looking into this, but unfortunately I'm going to have to postpone work as I won't have time to fiddle with it.

One add-on question, where the BOV tube goes back into the hose that connects back to just behind the air box the angle of the BOV outlet doesn't match well with the hose. I guess this would be a good place to start looking for boost leaks? I'm trying for the easy fix until I can make a boost leak kit.

Thanks guys for all your help. You'll have another converted person if it is indeed a boost leak....live and learn...I'm trying!

R

 

[oldman]

One add-on question, where the BOV tube goes back into the hose that connects back to just behind the air box the angle of the BOV outlet doesn't match well with the hose. I guess this would be a good place to start looking for boost leaks? I'm trying for the easy fix until I can make a boost leak kit.

Take your car to an auto parts store and ask them to help you find a 1" ID molded radiator hose with the best fit. Don't bother checking for leaks without a home depot leak tester (they're are a lot easier to make than it seems once you get started) and an air compressor, there are simply no pressure air to leak during idle.

Even if you find nothing, you'll be able to rule intake out and focus on ignition and compression.

 

[bangedUpGSX]

the leak test link said I can use a tire pump...is this true....air compressors are expensive...

Forgive the stupidity...what is ID in the above..?

 

[oldman]

the leak test link said I can use a tire pump...is this true....air compressors are expensive....

If you can only boost 10psi and the cause is boost leak, you have a pretty big leak or a lot of leaks and bike pump will not do you any good. I bought a 2 gallon compressor from Walmart for $60, it was a good investment for me. At least pick up a tank and fill it up at the gas station but expect to make a lot of runs.

what is ID in the above..?

Inner Diameter

 

[bangedUpGSX]

Well, I didn't hammer on it to get it to go over 10PSI, (the car felt pretty bad doing this).

Hmmm...