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Discussion Starter #1
I'm not a complete stranger to the no/low boost struggle but I've gotten nowhere this time around.
Lost almost all boost last summer in my 89 lebaron.
Drove it 500+ miles a week w/o issue (for the most part lol)
Had recently added a big FMIC, stage v cal, 3" sv housing
Was running 20# w/ a rebuilt stock Garrett T03.

Noticed a lack of power under load leaving for work one day.
Gave it WOT and boost seemed almost hesitant, then came back in like nothing had happened.
Tried again to confirm it was back to normal and- it hasn't built over 3psi since.
Does make a high pitch whistle right at 0 on boost/vac gauge.
Very noticeable even over loud 3" side exit exhaust (flow thru cat not the problem)
Just now needing to get to the bottom of it.

The turbo:
spins freely, no in/out or side to side play
wheels look normal and spin in tandem so shaft isn't broken
doesn't smoke or leak oil
w/ support bracket removed, I can't move it or any part of it

Going from 2.5 to 3" SV housing it may have been missing the bottom inside bolt or it sheared off in the housing.
Didn't have issues either time.
I'd have to recheck.
Removing the 3" for inspection originally I sheared off the next closest bolt nearer to the firewall.
I had stuck a bright light in the housing to check for gaps though I'm sure its not the same.

I've checked:
PCV valve
SV flapper action/sealing
Actuator rod and clip, pulled the line to actuator too
A few other things

Also made a "J" charge pipe to try and rule out boost leaks.

Warped mating surface, loose housing, bad seal somewhere? Anyone?
 

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I dont know squat about your system, but the first thing that came to mind for me was jumping to 20#s of boost, I would think you needed to go to a 3 bar MAP. If you stayed with a 2 Bar MAP, I dont know if putting too much boost into the 2 Bar MAP can make it go bad.

Also to me the whistle is a tell tale of a vacuum/boost leak.

As for chasing boost leaks, on a different supercharged car I owned, I disconnected the boos pipe coming off the supercharger (Procharger) and installed a plumbing closet adapter with cap installed (the plastic base that a toilet mounts to) and in the cap I drill it to install an air chuck adapter. Once installed into the boost pipe (clamp it down!) I applied air pressure from my air compressor and that pressurized the entire boost side of my system. From there I could check for IC leaks, hose leaks, warped flanges etc just you mentioned.

Sorry I cannot be of more help and hope someone with the right knowledge can chime in.
 

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A lack of boost (assuming the turbo itself is OK) is going to be caused by...
1)Wastegate stuck open
2)Wastegate rod disconnected
3)Boost leak in the charge piping (turbo to intercooler, intercooler to throttle body) or the intercooler itself.
 

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Are you running a BOV, either aftermarket or a stock one inside the air box assembly??

Thanks
Randy
 

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1987 Shelby GLHS #0958
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The BOV in my IROC RT was the reason I couldn't build boost. Having a quiet car is nice for checking for a boost leak. Just throw it in 5th gear at about 45 and floor it. You can hear it plain as day without a loud exhaust.
 

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Discussion Starter #6
Thx for the feedback yall!

GLHS0815 I made the jump to 3 bar & 40 injectors when the cal came. Tried that same boost leak test but couldnt come to any conclusions.

Naj The turbo seems perfectly fine but I'm fairly confident I can rule all 3 of those out. I didn't wire the SV shut like I've seen others mention before, but it had plenty of tension and nothing seemed off with the way it opened and closed. I tried a few different actuators. Even shortened the adjustable one I had been using that was set at 10.

GLHS60 Was running aftermarket BOV right before throttle. Thought that was the culprit unitl I removed it and same thing.
I use a cut open stock box ran right up to where a stock intercooler would normally sit.

INSATANSSEAT I'm over loud exhaust in general. Hopefully soon I'll have 2 of my 3 TDs back on the road and I can start to look into making them as quiet as possible.

Pulled the head earlier. Tired of my lack of progress. Putting an identical head/turbo back on it. We'll see if it boosts then. I wanted the manifolds from that head in the Omni anyway. Considering looking into a belt sander like the guy uses in this video at 6:50
DSM turbo swap and exhaust leak fix tutorial. Seeing how I still dk whats going on I'm concerned about exhaust leaks. Think I need to buy a longer straight edge and find either set of my feeler gauges.
 

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A lack of boost (assuming the turbo itself is OK) is going to be caused by...
1)Wastegate stuck open
2)Wastegate rod disconnected
3)Boost leak in the charge piping (turbo to intercooler, intercooler to throttle body) or the intercooler itself.
Well...It has to be one of those three (Wastegate Issue, Boost Leak, Faulty Turbo)

Keep us posted.
 

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Sounds like a clogged cat or kinked exhaust pipe.

Thanks
Randy
 

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When I was at SDAC-7 with GLHS #0956, I had been having the same problems with boost and overall power to the wheels.
It felt like a N.A. Charger.
There was a local shop that was doing Dyno testing for the SDAC while we were at the convention.
I decided to get the car on the Dyno and it was only making around 100 HP.
Everyone said to check the same things NAJ said, which I did.

Since I also had #0325 in the garage that was known to be Ok, we swapped out the quad solenoid pack and guess what.
It was a bad solenoid.

They can go bad from age, or they can get fouled with dirt or water contamination.
I'll bet you have a stuck or bad solenoid.
 

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Discussion Starter #10
I wish. Last tested it w/o the downpipe. Ive had a cat clog on me in a TD b4. Luckily I coasted to my exit lol.
 

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Discussion Starter #12
Gonna try to get it back together in the next 24hrs. I cant remember if I tried swapping out the wastegate solenoid or not, I have a few that are good afaik. I did try a manual ball/spring valve. Im under the impression if the line to the actuator is removed and still no pressure is created solenoids and controllers are ruled out.
 

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Gonna try to get it back together in the next 24hrs. I cant remember if I tried swapping out the wastegate solenoid or not, I have a few that are good afaik. I did try a manual ball/spring valve. Im under the impression if the line to the actuator is removed and still no pressure is created solenoids and controllers are ruled out.
And that is true.
The purpose of the solenoid is to control boost by allowing pressure to the wastegate.
Without pressure to the wastegate it will not open and the result would be an overboost condition.
The only way the solenoid could create a lack of boost issue is if it is not bleeding off pressure and the trapped pressure is keeping the wastegate open.
 

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I always test for solenoid issue by just unhooking the vacuum line at the actuator. I still have to completely go through our '89 Shadow ES boost control vac circuits. It will peak at 8 the immediately drop to 4 PSI. Initially it was only boosting at 4 at all times, so we went through it. Made it identical to the underhood vac diagram. Maybe the check valve has failed. Wrong size orifice? The car does peg OBS with the actuator disconnected. Plenty o' spoolins from that stock mitsu.
 

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Discussion Starter #15
Just got the head back on last night. Havent "buttoned" everything back up yet but I think I found the issue. The far left exhaust nut was just tight enough that I couldnt loosen it by hand. The next closest one was missing entirely. Probably would have heard it if the exhaust was more muffled. Gonna run the same turbo on a different head. Gave me a chance to clean after driving too many miles with a leaking dip stick tube.
What are the chances I can replace the missing nut and not have to replace the gasket? I'll probably try it anyways unless I hear strong opinions otherwise lol between this and the mostly complete omni project ive had my fill for the moment.
 

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You mean the exhaust manifold to head has a missing nut? If you're that far in I'd replace the gasket as the gasket can get burned by not being properly torqued.
 

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I've replaced missing nuts in the past with no issues.

If it's actually leaking then that's another story.

Thanks
Randy
 

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Re-reading this reminds me of another guy with a no boost issue.

He had an exhaust leak pre-turbo that was costing him his boost.

Turbo Engines tend to be quieter than N/A with no muffler/ pipes.

Manifold exhaust leaks tend to snap and crackle annoyingly.

The exhaust has to go through the Turbo to build boost!!

Thanks
Randy
 
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