Boost hits zero and thats it

[1cln91]

Ok put a manual boost controler on my car (91 tsi, all stock) and ran it at about 14-15 psi?, it was a lot faster of course but then i came to a stop light, took off hit 7grand shifted to second got up to about 5 and then started acting funny so i let off and shifted to third, it had no power and i looked at my boost gauge and it would go to zero and the stop boosting, took off the mbc and still did it, tested the wastegate, operted normaly, tested the wastegate selonoid, perfect, havn't done a boost leak test yet, but could it be boost leak, last time i had a boost leak it would hit 4-5 grand and pop and fall on it's face but its not doing that it just doesnt make any boost, what could be the problem, any help would be greatly appriciated.

 

[1cln91]

ok but once i get that boost leak, (leaks), fixed should that fix my fuel cut? If it will my ass is saved.

 

[dsm-onster]

Fuel cut is designed to guard against runaway boost due to a defective wastegate, what triggers fuel cut is not fuel starvation, it's a sudden drastic increase in air flow count that exceeds the pre-programed factory setting. The reason boost leak and fuel cut are often spoken in the same sentence is because boost leaks accounts for most fuel cuts by inflating the air flow count therefore triggering fuel cut even though you're running pig rich.

. . .

 

[1cln91]

Ok that is what i wanted to know, has any one ever had a boost leak at their air idle control screw and if so how do you fix it.

 

[1cln91]

also i need to know what im doing wrong, when im doing the boost leak test my boost gauge doesnt read anything ive tried it with the key on and off, i do have a stock boost gauge i don't know if that will make a differencen or not, also i need to know if a 16g is supposed to spool up slow than the stock 14b if not i think my stock boost gauge is messed up

 

[oldman]

The stock boost gauge doesn't measure real pressure, it estimates pressure based mainly on air flow reading, it will not move unless the engine is on. Install a real boost gauge and continue your boost leak test.

 

[1cln91]

Ok thats what i thought but i wasn't 100% sure, but what about the spool up time on the turbo

 

[oldman]

I wonder how much boost you're really running, I suspect much higher than 14-15psi, probably the reason why your first turbo died and why you're hitting fuel cut now. Bypass your mbc to run stock pressure until you install the boost gauge.

 

[1cln91]

i took the boost control off the night i blew the turbo

 

[1cln91]

Does anyone wana buy a talon,

 

[oldman]

Patience... You can't really blame the car on this one, it didn't make the decision to install a 16G, well known for boost creep, without having the most basic mod, boost gauge, you can be boosting 20+psi even without the mbc. Who knows?

Take a deep breath and start over, order yourself a dependable boost gauge, I like this one. Until then, stay off boost.

 

[MrBoxx]

i took the boost control off the night i blew the turbo

Did you take the boost controller off and happen to leave it off? If so, you may have been running in infinite boost mode.

 

[1cln91]

i know, i've just put put so much money into this car and i haven't recived any of the benifits, i'm having to put off going to college because it wont stay running good enough to even drive for more than two weeks, the only reason i went with the 16g is because i got an extemly good deal on it and what i read told me that all i needed was the 190lph fuel pump (which i did do) and i would be set to go, im about down to the point im going to take off the mainfold, replace the gasget with, permatex right stuff (which has work wonders on all my other part) do the same with the TB, and just replace the injector o rings to be safe, cause i cant find the other leaks, i can hear them but i just cant find them, at least if i do that i know 100% that it wont be leaking there

 

[1cln91]

no i hooked the vacum lines back up to the factory routing, sorry i didnt see your post

 

[oldman]

i know, i've just put put so much money into this car and i haven't recived any of the benifits, i'm having to put off going to college because it wont stay running good enough to even drive for more than two weeks, the only reason i went with the 16g is because i got an extemly good deal on it and what i read told me that all i needed was the 190lph fuel pump (which i did do) and i would be set to go, im about down to the point im going to take off the mainfold, replace the gasget with, permatex right stuff (which has work wonders on all my other part) do the same with the TB, and just replace the injector o rings to be safe, cause i cant find the other leaks, i can hear them but i just cant find them, at least if i do that i know 100% that it wont be leaking there

Do not lose your focus.

1. Order a boost gauge, sell your blinking light A/F gauge if need be.

2. Repeat your boost leak test following this list.

1. Disable your mbc.

2. Turn your motor to 30* ATDC to avoid valve overlap.

3. Start your test at the TB elbow and focus on area behind the TB first.

4. Spray soapy water at TB gasket, BISS, TB shaft on both sides, IM gasket, injector insulators, brake booster, afpr and all vacuum lines/connections.

5. Open your oil cap and listen for leaks. (PCV, valve seals/guide, rings)

5. Listen to your tailpipe for leaks. (EGR, valve overlap, jumped timing, bent/unseated valves)

6. Once all leaks are fixed, move the tester back to the turbo inlet.

7. Spray down the compressor cover (known leak), BOV return/flange (DO NOT TAP YOUR BOV LINE FOR YOUR MBC!!!), IC end tank/fins and all connections. Re- test.

8. Note that you will leak air into the crankcase through the turbo seal but do not panic, this is normal during a static pressure test as long as there are no shaft play.

The desired test result from the begining of the LICP (bypassing turbo) is around 20psi (on boost gauge) with the compressor set at 30psi, while taking no less than 30 seconds to bleed down to 0.

As a reference, my last test on my 500 mile new engine, I was able to pressurize the system to 25psi, bled down to about 16psi (my 1G bov) in about 30seconds, then took about 3 mins to 6psi and just kinda lingered there for a while. It's not easy to do but the point is it's possible. My next goal is 30psi After motor break in and Dodge modding my BOV. A boost leak test is one of most pita but important regular maintenace task, the key is patience and endurance, have fun.

3. After the leak test, test run without the MBC and report back your actual boost level.

 

[1cln91]

Ok i'll be able to do that this weekend, now that i acctually have a really good step by step procedure it's not as bad as i thought, thank you so much for this information you've given me, if all goes well i should be able to let you know what hapens sunday night, again thank you so much

 

[oldman]

No problem, good luck.

 

[1cln91]

ok got a real boost gauge, running around 15psi, couldnt set the timing, should be able to this week tho, started at the tb and have found and fixed quit a few small leaks, the injector isolators are leaking gona get some tomorrow (as long as their in stock)and thats pretty much all of theme as far as i know as of this monent. wont know for sure till i get the inlector leak stoped, is 15 psi to much boost with my setup (just the 190lph walbro fuel pump and the 16g)

 

[oldman]

15 psi should be fine, just don't go over that. Continue with your leak test, remember, every little leak counts.

 

[1cln91]

i thought i heared air in the valve cover, i dought its the valve guides cause the head is new would a cylinder leak down test tell me if it was something other than the pvc and how do you test that