My boost is lost... have you seen it??

[kane]

:confused5:
Around half a year ago... everything was ok. I had peak 0.7bar and WOT 0.5bar with stock chip and after replacing EM chip, peak was 1.0 and WOT 0.8bar...
Now I can't figure out what changed...? I get only 0.5-0.7 at WOT and the turbo meter needle does small up/down WOT. If I close wastegate manually... same boost. Nothing more at all... Even with stock chip I get 0.4 WOT... no 0.7 peak...

I've checked intake, no leaks at all, fuel pump ok and pressure seems ok, HO injectors been 1 year, if I understand right... it won't spool enough if there's not enough fuel??
Turbo seems good, no bearing "freeplay" and it does rotate manually very nice. No signs of "wings" touching to base.
Air intake, exhaust's been "open" all the time. Before intercooler it was same, no difference.
Still wondering fuel supply, could it be or is it IP... TDCO is close to -1.6x

There's no black smoke more than before...Sub runs very good but I just wonder why boost has changed.
I have TDScan sw and fuel rate seems the same ~80mm3 WOT what PCM tells.

BR, kane

 

[ghitch75]

has it gottin' any louder?....might have hole in crossover pipe?...my 93 dropped boost 1 day and the 1/8" tube to gauge was full of oil...tuna can went bad....unhooked line from gauge end and blew it out and all was good...

 

[kane]

Hi!

I have new crossover now... was the same before. Intake is nice clean, light oily but looks very nice. I tested another boost gauge what shows the same reading.
Can the wastegate itself have a leak? Injector(s)? :crazy:

br.kane

 

[kojo]

Maybe i stealed your boost when you looked something else :devil:

I Think you are not getting enough fuel, stock pump delivers only 1 quarter in minute, if you calculate how much 80mm3 makes at 3000rpm you will notice injection pump tries inject more fuel than your lift pump could deliver... :smash:

Should i make custom chip for you with smaller fuel delivery so you could use all what computer gives? :rofl:

 

[Turbine Doc]

If wiring shut does not improve boost, and compressor inspection isn't showing any problems, then it is time to remove the turbo and check the WG, for binding, looseness in the shaft or carbon not allowing it to seat closed properly, it does not take much opening at all for it to dump boost.

 

[kane]

kojo, I thought you did something last time... :driving:

Doc, that't what I wondered if... well, I will check turbo cause I'm lost otherwise... Thanks!

br.kane

 

[kane]

I haven't checked turbo yet (later next week), but... with kojo, we tested another lift pump, no luck. At Idle is fuel pressure is 4psi and WOT it drops to -1psi both pumps...
I believe stock 6.5td (f) would boost over 1.3 bar (wastegate closed manually)... or does someone have readings (experience) how much it's able to boost?
Compared with kojo's suburban, we have same setup and his turbo spool is really faster than mine. My Sub feels about the same what comes to power but it's spooling with slow response... and when I release pedal... there's no strong turbo release sound like before...

Have to take it off for inspection... :idea:

 

[Turbine Doc]

get the turbo off, it's only way to know, also sinc you recently replaced x over double check it is still bolted up solid, an exhaust leak would impar spoolin

 

[kane]

yes, I will take it off tomorrow. We already checked one old turbo (GM4) how it looks from exhaust side...
I need to check both manifolds and crossover are tight.

 

[kane]

Turbo looks good, no bad signs... So, it has to be something else.
I need to check exhaust carefully.

 

[kane]

 

[Schwind]

Just a thought but have you checked your boost fooler to see if it might have moved.

 

[kane]

:smile5: You're a mindreader...
Today I'll continue, I take fooler out and will check carefully manifolds and x over. I did tighten intake before. Also I need to test it without intercooler.
Even it was same before IC, I need to go back step by step.

 

[kane]

Good news! I did put all parts back and boost was like before. I "locked" wastegate good and hoblaa.... there's my lost boost back.

So, I did not test it right when I thought wastegate was closed.

Next is to find out if it's wastegate bell or vac pump faulty because vacuum is 26Hg" (idle at the wg bell).

 

[kane]

Wastegate actuator is the guilty one. I replaced it (friend had a used one) and boost is back. It's not leaking, diaphragm must be stretched?!
There might be a need to change MAP (boost) sensor later. Boost reading has a bit "nervous" movement, I put fooler back and it did change it good way more calm...
Heh :thumbsup: it was a bit tricky to follow boost meter, vacuum meter and tdscan (laptop) same time when test driving!