slow, low boost. Stumped!

[vr3.9]

Car was great a few days ago. (20psi as soon as you moved the gas peddle down. Finally faster than I needed it) Turned boost controller off for a few days. Turned it back on and now.

Will boost to 12 maybe 14 psi if you wait long enough. Boost comes on very slow and car lacks power.

Car doesn't smoke at all.
Pulled waistegate hoses no difference.
Checked boost leaks. all good.
no shaft play and turbo's spin freely.
check front waistegate actuates normal.
Did not check rear hard to get too so I thought I would see if anyone can think of anything else that might cause this.




oh and this happened before I picked up another VR4 today so I know the cars not just pouting.

[OhioSpyderman]

Turned boost controller off for a few days. Turned it back on and now.

Just have to ask, what controller?

Turned off or momentarily disconnected?

I know you know you're shit, but I am just trying to help...

Bob. :)

[vr3.9]

greddy profec b
yea at first I just thought oh well, the controllers gone. turned it up to 73 from 60 made no difference. Disconnecting the waistegates, unfortunately proved it's some other problem. Should have hit 25psi before I could get my foot of the gas.

[wraith]

You need to pressure test her. I had a boost leak that I could not locate for the life of me and it sounded like it was internal. Ended up being one of the two check valves. You should be able to pressurize her up and not hear a peep anywhere.

[OhioSpyderman]

"Disconnecting the wastegates, unfortunately proved it's some other problem."

So, with the wastegates disconnected you had LOTS of boost? (sorry, its late and I did a whirl wind trip to Toledo today for a college visit for my youngest boy...the other two boys are already there..)

If so, it may not be the controller, but instead the valve...might want to check the lines to the VALVE....

Bob.

[vr3.9]

Pressure tested, it was fine. held 20 psi with the real slow drop just like always.

The car seems to run just fine but weak.

If the timing belt jumped and it's out of time could that cause such a problem.
If I hold down the peddle instead of the boost just jumping on and the car getting scary it goes to about 8 then will crawl to 12 or 14 if I hold it long enough. Not much fun...:( Lets just say the seat doesn't hardly know my butt's in it.

[DuTTch]

hows yur ecu?

[vr3.9]

So, with the wastegates disconnected you had LOTS of boost?

leaving the waistgate line open makes no difference on boost.


hows yur ecu?

Should be fine. rebuilt I will swap it out with another one and try but don't really think that's it.

Remaining possiblities.

a. Ecu
b. timing somewhere is off
Don't really see how it's either one of these. I will check tming belt timing and swap ecu. If those are ok I'm really stumped.

I would think if something was so bad with the motor that it couldn't spool turbos it would smoke.

[JasonY]

Are you running water/meth? I was eating up ebc solenoids back in the day since my pressure source was after my water/meth nozzle and it was getting into the solenoid and messing it up.

Jason

[OhioSpyderman]

Do you have an FPR and gauge? (perhaps the fuel pump took a dump or is running slowly...have you measured the voltage at the pump?)

*trying to help*

Bob. :(

^^^^ is a sad face, not a MAD face :)

[vr3.9]

Are you running water/meth? I was eating up ebc solenoids back in the day since my pressure source was after my water/meth nozzle and it was getting into the solenoid and messing it up.

Jason

no water meth. running the same with lines to waistegate off.


Do you have an FPR and gauge? (perhaps the fuel pump took a dump or is running slowly...have you measured the voltage at the pump?)

*trying to help*

Bob. :(


^^^^ is a sad face, not a MAD face :)

this is something I was just thinking about. I recently started running a blend of E85 and turned my fuel pressure up to 58psi. The car doens't miss or cough spit or give any signs of anything being wrong other than taking for ever to build up boost. If fuel pump is not providing enough fuel would it still run smooth but just not build more power or would it jerk and buck.

Unfortunately the gauge is in the engine bay and kinda hard to see when driving.
I do notice that wideband isn't dropping into the 12 like normal but I would think that's due to lack of enough boost.

I like this possibility any ideas on how to confirm it?

[a2j]

could wastegates be stuck open? or how would you check for that without taking the turbo out? would like to know myself.

[OhioSpyderman]

Take cover off of fuel pump area in trunk and with a voltmeter measure the pump voltage with the car running in neutral, it should be around 12 volts. (do you have any "hotwire" of the pump?)

According to the manual, the blue wire at the pump should be the positive (+) and the negative (-) is black (or you could just put the black lead of the meter to a clean body ground)

Bob.

[R/T93]

I dont know if the Greddy has it but my Blitz has a "Learning" mode. If you choose automatic and change ANY setting, you have to do like three full 3rd gear pulls in order for it to figure itself out. It boosts REALLY slow and takes FOREVER to boost.

Your controller may have the learning mode on or something.

I was getting super pissed cuz the car was only seeing 6-8 psi and I didnt know of the learning function, I switched to manual control and just limit the boost spikes from cold weather with the warning limiter, it works quite well actually.

[vr3.9]

I dont know if the Greddy has it but my Blitz has a "Learning" mode. If you choose automatic and change ANY setting, you have to do like three full 3rd gear pulls in order for it to figure itself out. It boosts REALLY slow and takes FOREVER to boost.

Your controller may have the learning mode on or something.

I was getting super pissed cuz the car was only seeing 6-8 psi and I didnt know of the learning function, I switched to manual control and just limit the boost spikes from cold weather with the warning limiter, it works quite well actually.

running open waistegates makes not difference, so not the controller.
Swapped ECU's runs the same.
at 10psi AFR's are 12.8 it's tuned 11.8 WOT. Not sure that's abnormal since it's not getting full boost.

If the rear waistegate arm came off how would it act?
It's hot now and not sure I can get back there, but that's about the only logical thing left.

[vr3.9]

Wooo hooo!!!! problem found.

Rear wastegate arm is off the flipper arm. Tooooo hot to try and put it back on but did get my hand down there and it flopping loose. Slight burn to the palm, but feeling so much better.

thanks guys.

[OhioSpyderman]

Glad you found it :)

(sorry about your pain)

*also sorry I wasn't more help.....

Bob.

[DuTTch]

could wastegates be stuck open? or how would you check for that without taking the turbo out? would like to know myself.

One turbo can still boost 16psi on demand, it would be highly unlikeley that both waste gates would be stuck open.

[vr3.9]

One turbo can still boost 16psi on demand, it would be highly unlikeley that both waste gates would be stuck open.

Maybe one of yours...... mine got to about 14 but that was foot on the floor, 3rd gear, wait for it, wait for it, wait for it... maybe, wait. ok

At least now I know the ECU from the new one is good. :)

[vr3.9]

right foot down.... grin plastered on face, ears touch behind the head, sounds of giggling school girl are heard.

Yes! we have boost.