86 SVO overboosting

[scenario]

When I floor it I am overboosting and the yellow oil light and buzzer sound mementarily. I even had a backfire a couple of times. What could cause this. I replaced the vacuum hoses that go from solenoid to turbo. There were 3 hoses I replaced.

The part number on the solenoid is E5ZE-9K378-AB. I was thinking of replacing it but can not seem to find one. I dont know if it is bad or not.

I did some research but am still a bit confused on how all this works. Not really sure what the solenoid does or does not do.???? Problem could be elsewhere.

[65ShelbyClone]

Does it overboost on the "regular" fuel setting?

The boost control solenoid opens a passage to the wastegate circuit. When the solenoid is open, it releases pressure through a metering orifice in the t-fitting on the compressor housing. It then takes 14-15psi to open the wastegate instead of 10 because of the "leak."

[scenario]

Yes it is overboosting on the "Regular" setting.

[Patrick]

The latest similar complaint ended up being a bad wastegate actuator diaphram. Pump a wee bit of air (~10PSI) into the actuator with a mityvac and see if it leaks.

[SVOTim]

If you have a extra vac/air port on the turbo compressor housing blocked off with a rubber cap, check it. Could be cracked. That was the cause of my overboost issue, moons ago.

[scenario]

Ok here is the update.

I pulled the actuator rod off the WG arm and tested with air. Actuator works as it should.

The wastegate is stuck and I can not turn the arm. This is a problem with the wastegate itself. I can not get it to move at all by hand, not even a bit. I am going to try to put visegrips on it and then try to move it and hopefully I can work it free.

Anyone have any suggestions???

I am starting to think I may have to pull the unit off which I REALLY do NOT want to do. Should I try spraying with PB or something????

[scenario]

After some real convincing with PB Blaster and some hard raps with a hammer and long chisel, I worked it free constantly going back and forth. I may have slightly bent the WG handle that the actuator rod attaches to. There was nothing I could do. It was either all or nothing bc it was not moving.

I do not know how much the WG travels from closed to open. I would say the handle is moving 45 degrees atleast. I soaked it with more PB Blaster when I was finishing up and will reattach it all tomorrow. I will also play with it a little more to see if it gets even more loose. It is turning by hand pretty good though.

I am hoping it just locked up from sitting for 15 years and now that it is free and will be driven often it may stay that way.

[oneowner88lx]

Glad you found the problem. That waste gate arm does not move a whole lot. The flapper inside the elbow housing, when it opens, hits the back of the inside of the elbow fairly quickly restricting its movement. As long as the waste gate is held shut nice and tight with the actuator hooked up you should be good to go.

[65ShelbyClone]

Something that might help is getting some graphite powder worked in there between the wastegate shaft and housing. A 2000°F anti-seize compound may also be an option provided it won't affect the O2 sensor.

[MikeFleming]

Take the two nuts and flange off the downpipe. Unplug the O2 sensor connector. Carefully loosen and remove the five 13mm hex bolts that hold the outlet elbow to the turbine housing (Note these are NOT normal hardware store bolts!). Clean all the surfaces of rust especially the dump hole in the turbine housing. Clean everything up (180/220 grit paper) and run a tap through the bolt holes (8x1.25mm). Then re-assy the outlet elbow and bolts using a high-temp graphite/moly lube on the bolts. Bolts go to 164 INCH-LBS - less than 15 Ft-Lbs. Re-connect the downpipe flange and nuts.

Do this every 30K miles.

You can attempt to add some lube to the wastegate flapper shaft hole, but nothing will last very long (like minutes to maybe a few hours max).

[oneowner88lx]

I would be afraid those bolts would snap off inside that hot side housing if he tried to take that elbow off.

[MikeFleming]

^ DOH! Take them out when they're cold!

It's always a good idea to have spares.

[scenario]

Problem solved. Here are a few short video clips of boosting without any lights or buzzers going off!!!! YAY!!!!!!!



http://www.youtube.com/watch?v=iM_9Hn2wpvA&feature=autoplay&list=UUexAWtvAky89fxkWY RGzygQ&playnext=1


http://www.youtube.com/watch?v=Zg2C4DkVa5M&list=UUexAWtvAky89fxkWYRGzygQ&index=1&fe ature=plcp

[65ShelbyClone]

Problem solved. Here are a few short video clips of boosting without any lights or buzzers going off!!!! YAY!!!!!!!


http://www.youtube.com/watch?v=iM_9Hn2wpvA&feature=autoplay&list=UUexAWtvAky89fxkWY RGzygQ&playnext=1


That pretty well dispels any myths about turbo lag, huh?

[MikeFleming]

Those vids reminded me of some dyno dash shots a few years back. Thought I'd share.

[oneowner88lx]

Nice job getting that problem solved.

[scenario]

Thanks to all. NOW this is the car I remember!!!!!!!!!


When I bought this car there was no such thing as the internet. There were no kids car seats (if there were I never saw them....LOL). My children until last month (thats when I resurrected the SVO) never saw a lap belt before. Every car they have been in has had 3 point seat belts in the rear. They think the lap belts in the rear seats are the COOLEST thing they ever saw and they think its like a ride at the amusement park.


I love this car. It just wants to GO! and GO FAST!!! Handles great, nothing better than that turbo spooling up......

[MikeFleming]

And another SVO back on the road!

Congrats on getting it running properly again!

[Larry_S]

My car is overboosting. I have the boost lines capped off at the T fittings and only have a line running directly to the wastegate. I also connected wastegate directly to the vacuum tree to try that. The gauge approaches 18 psi with full throttle applied. The wasegate arm moves roughly .2" - .25" with 10psi applied. Full scale on the psi side of the gauge is 10psi. Note the vacuum line is not connected in pic the intent of pic is to show the capped off t fittings. When tested I connected the wastegate to the t fitting and also tried connecting to the vacuum tree.

28202821

http://mc2.gotdns.com/photo/photo_thumb.php?dir=73766f2f38345f31452f656e67696e652f626f6f 73745f6973737565

[MikeFleming]

From the video you posted earlier, some of the bolts mounting the turbo outlet elbow are falling out. Fix that first.

On another note the wastegate diaphragm spring is weak and opening too far under 10 PSIG (spec is 0.015") but that will cause a lower boost setting, not a higher one.

[Larry_S]

The bolt has been fixed. It was loose as I was between swapping a turbo outlet housing just to eliminate that and that bolt was the hardest to get to. So with two housings swapped in I am having same issue.

[Stinger]

There are only a few things that can cause an overboost condition. Cracked/old lines running to the boost control solenoid or wastegate actuator, bad actuator diaphragm, stuck or sticking wastegate arm/flapper, or in cases of a well modded car, insufficient wastegate flow. Working through these issues one by one, you should be able to find the problem.

[Larry_S]

There are only a few things that can cause an overboost condition. Cracked/old lines running to the boost control solenoid or wastegate actuator, bad actuator diaphragm, stuck or sticking wastegate arm/flapper, or in cases of a well modded car, insufficient wastegate flow. Working through these issues one by one, you should be able to find the problem.

I tried new vacuum lines and rerouted from the tree as well. The actuator seemed to work ok and hold pressure with 10 pounds applied using hand pump. I picked up a wastegate actuator from Merkur Depot to try that. I am curious about insufficient flow though. Not sure if my engine would be considered well modded: stock turbo, ATR header, 3 inch down pipe, intake and exhaust valves max size, esslinger roller drivetrain, esslinger cam, head not ported other than for larger valves, 2.5 liter, Wiseco custom pistons 8:1, 5.5" connecting rods. The exhaust is not ideal, It is 3" downpipe to dual flowmaster chambered muffles which I know are not ideal for turbo flow.

[MikeFleming]

How far did the actuator rod move out of the actuator body with 10 PSIG applied?

Was the pressure applied constantly or was it clamped off from the air source ot see if it held?

Did it hold that position, and pressure, for 10+ seconds while being clamped off?

[Larry_S]

The test rig was admittedly not the best. But two actuators I had moved about the same distance: .2" - .25" with 10psi applied and seemed to hold pressure. The rig was a bicycle pump teed off to a gauge and the actuator. I think I'll try again and clamp off as you suggest to see the results.


How far did the actuator rod move out of the actuator body with 10 PSIG applied?

Was the pressure applied constantly or was it clamped off from the air source ot see if it held?

Did it hold that position, and pressure, for 10+ seconds while being clamped off?

[MikeFleming]

The movement is good (a bit more than ideal, but since it's overboosting that's not a concern just now).

Next test the actual flapper arm movement with the wastegate thingie attached to the turbo. Let's make sure the flapper moves.

[Larry_S]

With the wastegate actuator not attached the door moved very easy by hand. However I even swapped out a different turbo outlet elbow for kicks but no change. Video link shows door movement with 10psi applied.

http://mc2.gotdns.com/photo/photo_one.php?name=50313032303238312e4d5034&dir=73766f2f38345f31452f656e67696e652f626f6f73745f6973737565

[Stinger]

I wouldn't consider your mods list to cause a "too little wg flow" condition.

You actually don't even need a pump to test the wastegate actuator. Just blow into the hose with your mouth. If you can blow through it, it's bad. It sounds like your actuator and wastegate arm/flapper are fine.

What happens when you just run a hose from the compressor outlet to the actuator, bypassing the BCS altogether?

[Larry_S]

I wouldn't consider your mods list to cause a "too little wg flow" condition.

You actually don't even need a pump to test the wastegate actuator. Just blow into the hose with your mouth. If you can blow through it, it's bad. It sounds like your actuator and wastegate arm/flapper are fine.

What happens when you just run a hose from the compressor outlet to the actuator, bypassing the BCS altogether?

I have 3 stock actuators around and one of the actuators I tried would not hold pressure and failed as you mentioned so when i pumped air in I could hear it escaping and the gauge would not hold pressure. The other two seemed to hold pressure and move ~.25 inch with 10 psi applied. During troubleshooting I have removed the BCS system and connected a line from the compressor outlet to the actuator directly and the boost approached 18-19. Also connected a line from the tree to the actuator with the BCS bypassed and same thing boost approached 18-19 psi. The pressure was the same on the stock gauge and an autometer pressure which was connected in parallel approaching 18-19.

[Stinger]

What happens if you unhook the actuator from the wastegate arm and then wire the arm all the way open? If you still get too much boost, that would mean you have a wastegate flow issue.

[Larry_S]

Aah great idea. I'll try that when we get good weather here again on a weekend.

[Stinger]

You shouldn't see any boost below 4000 rpm and maybe 2psi or so at redline with the gate wired open.

[Larry_S]

You shouldn't see any boost below 4000 rpm and maybe 2psi or so at redline with the gate wired open. With the wastegate wide open the boost is spooling practicaly like you would normally expect and the boost buzzer is going off at ~18psi. Is there any chance the dual flowmasters that were installed could have caused this? I do not recall an issue previously and since then I changed the turbo and the exhaust. The exhaust before was 3 inch down to a chambered muffler with a turn down before the rear axle. Now it is a 3" downpipe to dual 2.5 I think and into two flowmasters and then tail pipes. The turbo in both cases are stock water-cooled I think.

[MikeFleming]

If boost is normal, then the wastegate is NOT open.

[Larry_S]

If boost is normal, then the wastegate is NOT open. It seems to boost normal and goes to 18 psi or so before I back out of throttle. The wastegate is zip tied wide open. So what in the heck is going on?

[MikeFleming]

I do not recall an issue previously and since then I changed the turbo and the exhaust. Tell me more about the new turbo.

Got any pics of the turbine housing outlet side without the outlet elbow attached?

[Larry_S]

Tell me more about the new turbo.

Got any pics of the turbine housing outlet side without the outlet elbow attached?

I do not but as far as I know it is a stock water cooled SVO turbo. I will look into this next. Thanks

[Larry_S]

The turbo that came on the car has a .48 exhaust housing part number on turbine is E5ZZ-9G438-D Compressor has M11 stamping
Latest turbo on the car overboosting has a .48 exhaust housing part number on turbine is E5ZZ-9G438-B Compressor has A/R 60 stamping

Turbo once again off the car. argh........
3881

Original turbo:
38823883

overboosting turbo pics:
388438853886

The car did not overboost before and the parts that have been changed since then are the turbo and exhaust.

[MikeFleming]

Original turbo:
3884
3885

You should be able to stick an index finger into the round waste gate dump hole in the first pic and have it come out the rectangular hole in the second pic. Verify there is no restriction in that area (looks clear in the pics).

Then verify there are no obstructions in the outlet elbow in the same area (snap a pic also). And there should be no gasket between the turbine housing outlet and the outlet elbow.

I'll mix up a batch of Crocodile Tongues. just in case.

[Larry_S]

There are no obstructions nor gasket material. Elbow is clear. I am considering putting the original turbo back on and perhaps opening wastegate opening in the turbine until the flapper doors just makes contact. Looks like it can be opened 5mm or so. Does that seem reasonable at this point?

[MikeFleming]

Opening the dump hole can help if that's the actual restriction - at very high airflow rates.

Radius the inlet (turbine inlet side) and keep the exit a sharp edge (where the flapper covers it). Iirc some folks used to make outlet elbows with a larger flapper plate, !~1.125". iirc). Couldn't tell you where to look for such a thing though.

While we're in picture mode, snap some pics of the compressor wheel & housing between the two turbos after taking off the inlet elbow (to show the wheel and housing sizing).

Doesn't seem to me that you should be having this issue with your current mods and a stock size turbo. But I guess there's a first time for almost everything. Except perhaps skiing through a revolving door.

[Mike S]

If you connect directly to the waste gate from compressor housing and it still over boost, there are only two things I can think of to cause over boost conditions:
1 - the fitting on the compressor housing is plugged.
2 - there is a boost leak in that connection causing the pressure to bleed off of the WG actuator.

[MikeFleming]

^
Mike - If i understand correctly, he's been running with the wastegate flapper arm in the outlet elbow blocked open - without any diaphragm involved at all.

[Larry_S]

^
Mike - If i understand correctly, he's been running with the wastegate flapper arm in the outlet elbow blocked open - without any diaphragm involved at all.

Yea started with eliminating BCS by running line directly from compressor to wastegate. Then removed compressor t-fitting and was able to blow air through it. Replaced the t-fitting for the heck of it. The latest was to tye wrap the flapper arm wide open to a downpipe bolt and with wastegate wide open the car continues to overboost. Now turbo is removed and thinking of porting wastegate opening on exhaust housing.

[Mike S]

What turbo do you have?

[MikeFleming]

He's posted some pics of the turbine side above. It's a 0.48 AR husing with a stock (stage 0) turbine wheel.

I've asked for pics of the compressor side and he's not posted them yet. Info above says the compressor housing is a 0.60 AP, but no data on what wheel it has.

Overboosting problem continued after the "new" turbo was installed - with the wastegate flapper arm fully opened. Tirc. the previous over-boosting was due to a ruptured wastegate diaphragm. So it may have a larger comp wheel installed.

Need pics.

[Larry_S]

He's posted some pics of the turbine side above. It's a 0.48 AR husing with a stock (stage 0) turbine wheel.

I've asked for pics of the compressor side and he's not posted them yet. Info above says the compressor housing is a 0.60 AP, but no data on what wheel it has.


Overboosting problem continued after the "new" turbo was installed - with the wastegate flapper arm fully opened. Tirc. the previous over-boosting was due to a ruptured wastegate diaphragm. So it may have a larger comp wheel installed. Need pics. This is not entirely accurate. Overboosting is a new phenomenon after a number of parts were changed for different reasons. I do not recall it occurring previously with original turbo that came on car when I purchased. I replaced that turbo with a stock 86 SVO one, changed the exhaust, removed an ETS MAF and chip extender and I now have this overboosting issue. So I am thinking of putting original turbo back on and having wastegate hole opened up and reinstalling. I am not sure why it is overboosting but I do know currently it is overboosting with the wastegate flapper door open and the turbo which I think is a regular 86 SVO turbo.

current turbo on car:
3888

original turbo on car when I purchased:
3889

[in2fords]

I'm no expert by any stretch of anyone's imagination but in my mind if you are over boosting your waste gate is not open. I have a hard time seeing any turbo reach full boost with the gate open, if so that's a mean turbo I would like to get my hands on!
If you don't see a obstruction in the elbow blocking the gate then either the arm is slipping on the shaft or you might have wired it in the closed position some how.

[Stinger]

I agree, I can't fathom any way it overboosts (and at a reasonable rpm) with a stock type turbo and the gate wired open. You must have wired it shut rather than open. You need to push the wastegate flapper towards the rear of the car to be "open".

[Larry_S]

I agree, I can't fathom any way it overboosts (and at a reasonable rpm) with a stock type turbo and the gate wired open. You must have wired it shut rather than open. You need to push the wastegate flapper towards the rear of the car to be "open".

I installed another stock turbo and have the exhaust not attached tied to k-member so the exhaust is exiting the elbow. Flapper door is zip tied open and car makes 18psi at roughly 5200 rpm. Seems to start making power at ~4500.

http://mc2.gotdns.com/photo/photo_one.php?name=4453435f313534322e4d4f56&dir=73766f2f38345f31452f656e67696e652f626f6f73745f6973737565

stock turbo, ATR header, intake and exhaust valves max size, intake gutted, esslinger roller drivetrain, esslinger cam, head not ported other than for larger valves, 2.5 liter, Wiseco custom pistons 8:1, 5.5" connecting rods.

[Larry_S]

stock turbo: .48 exhaust turbine housing, compressor housing has A/R 60 stamped on it.
ATR header
SVO gutted lower intake / ported upper
Wiseco: .030 8-1 pistons 5.5"
Esslinger: roller rockers / studs, dual valve springs, mouse trap springs, cam, bronze valve guides.
Manley 1.89, 1.59 valves
Multi-angle valve work including comp style bowl blending, block squared and o-ringed, head trued
Racer Walsh: 2300 windage tray, 2.3 bearing inserts, 2.5 stroker crankshaft, 2.3 connecting rods sportsman 2.5

[Stinger]

That's a weird one. Certainly won't hurt to port the WG hole and smooth the entrance side significantly to force exhaust through the hole, though it doesn't look like a setup that should "need" this, or should make that much boost with the WG wide open. I had a ~400hp setup that ran on a stock T3 for a short time (hybrid blew up and took a few weeks to rebuild it) and that much higher flowing engine only made about 6psi with the WG open...and it was closer to 7000rpm before it got there.

As a side note, try not to run WOT under boost when the engine isn't warmed up. It tends to break distributor gear pins, shear the distributor gear, etc.

[Larry_S]

That's a weird one. Certainly won't hurt to port the WG hole and smooth the entrance side significantly to force exhaust through the hole, though it doesn't look like a setup that should "need" this, or should make that much boost with the WG wide open. I had a ~400hp setup that ran on a stock T3 for a short time (hybrid blew up and took a few weeks to rebuild it) and that much higher flowing engine only made about 6psi with the WG open...and it was closer to 7000rpm before it got there. If I leave flapper as is 28mm I figure I can open up port to ~26mm and it is currently ~22.5 so that would be roughly 34% increase in area. Does that seem like it would be enough to help or should I take the additional time to put 32mm flapper valve which would also require removing some material from housing and then I could open port to 29mm or so?


As a side note, try not to run WOT under boost when the engine isn't warmed up. It tends to break distributor gear pins, shear the distributor gear, etc. Yea I thought I might get some flak in hindsight but for the record I did not just start engine and take off. The engine had been running for 5 minutes or so I just had tuned off for a minute or so while getting camera ready. But it was not quite up to operating temperature so point taken thanks.

Valve train pics

3892

[Stinger]

34%, plus an additional 10-20% more flow from the short side radius into the port and it will certainly help at minimum, or even fix it.

[Larry_S]

I think I am going to have wastegate hole enlarged to 26mm or so. Based on my engine mods should I keep the .48 turbine or change to a .62 that I have?

PE computer
36lb injectors
190lph fuel pump
4:10 rear end
trans (not sure)
86 intake
stock VAM (stock air box removed with k@n type filter attached)
86 SVO water cooled turbo: .48 exhaust turbine housing, compressor housing has A/R 60 stamped on it.
ATR header
SVO gutted lower intake / ported upper
Wiseco: .030 8-1 pistons 5.5"
Esslinger: roller rockers / studs, dual valve springs, mouse trap springs, cam, bronze valve guides.
Manley 1.89, 1.59 valves
Multi-angle valve work including comp style bowl blending, block squared and o-ringed, head trued
Racer Walsh: 2300 windage tray, 2.3 bearing inserts, 2.5 stroker crankshaft, 2.3 connecting rods sportsman 2.5

[MikeFleming]

The 0.63 exhaust side will let it breathe more on the upper end and will loose 300-600 RPM on start of boost on the lower end. So it kinda depends on gearing and your driving style.

Personally I'd go with the 0.63 and downshift if needed.

[Larry_S]

I am not sure of trans I am thinking it is 86 SVO but not positive. rear end is 4:11 and cam probably pulls to 7500 or so I am guessing if rev limiter was removed.

[Stinger]

If you're flowing enough air to have wastegate flow issues, I think it would be foolish to use a .48 housing as it will leave a lot of power on the table, especially with a high rpm cam.

[Larry_S]

If you're flowing enough air to have wastegate flow issues, I think it would be foolish to use a .48 housing as it will leave a lot of power on the table, especially with a high rpm cam. That makes sense. Thanks for the help!

[65ShelbyClone]

+1 for a 0.63 housing. I never found myself unexpectedly waiting for boost with one on a stock engine and you have a lot more than a stock engine.

[Larry_S]

I adjusted cam timing by moving a tooth to the left, installed a .63 turbine housing, opened wastegate port a bit, installed gillis valve. Power comes on quite a bit earlier now and does not pull as hard in upper rpm range, boost spikes to 22psi then controlled at 20 psi. Perhaps have to live with 2 psi spike and as for the power earlier that is likely due to cam being retarded a bit. I need to order an esslinger adjustable pulley so I can zero cam but at least boost is under control now.

[65ShelbyClone]

as for the power earlier that is likely due to cam being retarded a bit.

That would move your power band higher up. Advancing the cam brings it down in the RPM range. Advanced = earlier, retarded = later.

[Larry_S]

That would move your power band higher up. Advancing the cam brings it down in the RPM range. Advanced = earlier, retarded = later. yea your correct cam is advanced now.