BOOOOOOOOst
Re: BOOOOOOOOst
This whole thing sounds like a problem one would have with a German car.
Re: BOOOOOOOOst
It actually does. Matt Farrah drove an E39 M5 on his one take recently. The owner was like, yeah I got this 2 years ago, 127k, but it's been a great car. Then during the test drive, it goes into limp mode for no apparent reason. Matt pulls over and shuts it off then restarts it. Fine for the rest of the video. Nothing sketchy about that...
Re: BOOOOOOOOst
That all sounds legit, but why doesn't it set a check engine light (an ignition or knock detection issue issue that cuts boost by design) to send you in the right direction instead of guessing?Fast_Ed wrote:OK, so I finally got the Bypass Valve into the car last night. It did the 'boost thing' again on the way home, so I took the five minutes to do it that night.
This morning I tried some more 5th gear boosting, and it did it again. Under boost, a sudden loss of power like a fuel cut. No boost after that. A couple boost free miles later, I pulled over and turned the car off. Counted to five and turned it back on again. Boost returned immediately. Boosted the rest of the way to work.
I was gentle with it on the way home, but it boosted when I asked it to.
I actually think it's plugs. I was still running the old ones from 2011... I found out today I can run copper ones for $2 apiece vice the $13 each for platinums.
I had both of my turbo SAABs do this when they needed plugs. I replaced with copper NGK's on the second one and it boosted like crazy all of a sudden! I remember hitting fuel cut on my return trip over the newport bridge. Someone had messed with the APC (Automatic Pressure Controller) screws. I turned it back down just enough and that car was pretty fun.
Re: BOOOOOOOOst
That occurred to me as well.. It should detect something. Could be that the plugs are so bad that it doesn't show up as knock?
I did get a P1549 the other day right after a 'no boost', which was a saab-specific boost control issue of some sort. So this may not fix it. New copper NGK's couldn't hurt anyways.
I did get a P1549 the other day right after a 'no boost', which was a saab-specific boost control issue of some sort. So this may not fix it. New copper NGK's couldn't hurt anyways.
Re: BOOOOOOOOst
The spark plugs, they do nothing!
Well, they didn't solve my boost issue anyways. Time to do what I should have done in the first place: Check Base Boost. The actuator still takes some pretty good effort to move, so it's possible that the spring has lost preload over the years. The rod on the actuator is threaded to allow adjustment of base boost. There are at least four or five full threads left to tighten, so I have adjustment left. It is pretty rusty, so I'm going to pull it off, clean up the threads, and free up the locknut/arm. I have a true boost gauge that I can temporarily plumb to check the current boost. It may just be a matter of tightening this up to get the correct 6psi of base boost. There is some ratio of number of turns per psi of base boost.
Well, they didn't solve my boost issue anyways. Time to do what I should have done in the first place: Check Base Boost. The actuator still takes some pretty good effort to move, so it's possible that the spring has lost preload over the years. The rod on the actuator is threaded to allow adjustment of base boost. There are at least four or five full threads left to tighten, so I have adjustment left. It is pretty rusty, so I'm going to pull it off, clean up the threads, and free up the locknut/arm. I have a true boost gauge that I can temporarily plumb to check the current boost. It may just be a matter of tightening this up to get the correct 6psi of base boost. There is some ratio of number of turns per psi of base boost.
Re: BOOOOOOOOst
So, this is where the story gets slightly embarassing... If that's possible.
When I completed installing my fan resistor, I decided to move on to addressing my boost issue. I recently decided that the problem is likely my wastegate actuator, blowing open when the pressure on the wastegate door gets too high. I discovered that some SAAB enthusiasts have used something called a 'Helper spring' on their wastegate actuators, to assist a weak spring in holding a higher base boost pressure.
As SAAB turbo people will know, saabs have, since 1983 or so, used an electronically controlled valve to interrupt the boost signal to the wastegate actuator and run a higher boost pressure under ideal conditions. A normal wastegate actuator will simply be exposed to boost pressure. When this pressure exceeds, say, 6psi, the spring in the actuator is overcome. The wastegate is opened, exhaust bypasses the turbine wheel, and boost is limited. Interrupting this 'signal' with a valve allows my Viggen to attain between 16 and 20psi of full boost, depending on what the ECU determines is needed to obtain the requested torque.
I believe my spring has weakened, giving me a 'base boost' of approximately 1psi. My electronic valve is sparing my wastegate actuator from being exposed to a boost signal. However, the wastegate door is not held shut very well by the weakened spring. It is directly affected by boost pressure. When the boost gets high, it is overcome, causing an extremely sudden drop in boost. This freaks out the ECU, and it drops to base boost. This exposes the wastegate actuator to boost pressure. Base boost is basically zero, so I observe a 'no boost' situation until I turn the car off and back on again.
So I bought a turnbuckle, and used a repurposed a B-body drum brake spring to assist my wastegate. It was terrible, bloody job, but I learned something. Essentially, the lesson was 'Don't do that!' Should have taken a picture. Damn.
Anyways, I put this spring on, attached in parallel with my wastegate actuator. I had cranked it up to full turnbuckle tightness after about a half mile. Base boost was still very low, but I had a resistor to test as well (see my oil temperature thread). So I plugged my electronic turbo valve back in, and headed back to the highway. I had always been able to duplicate the boost problem on the highway, during fifth gear boosting. Maybe the additional spring tension would at least hold my wastegate door closed better.
I merged onto the highway somewhat gently. I took a couple of opportunities to explore higher and higher boost, approaching full boost. When I finally went for full boost, the boost gauge shot up into the red, I heard a pop and had a sudden power loss. Nearly immediately, the smell of hot oil started to come through the vents. The check engine light began to blink, the battery light came on, and I was coasting for the side of the highway. Great, I freaking killed it. Am I about to spend the afternoon waiting for a tow?
When I completed installing my fan resistor, I decided to move on to addressing my boost issue. I recently decided that the problem is likely my wastegate actuator, blowing open when the pressure on the wastegate door gets too high. I discovered that some SAAB enthusiasts have used something called a 'Helper spring' on their wastegate actuators, to assist a weak spring in holding a higher base boost pressure.
As SAAB turbo people will know, saabs have, since 1983 or so, used an electronically controlled valve to interrupt the boost signal to the wastegate actuator and run a higher boost pressure under ideal conditions. A normal wastegate actuator will simply be exposed to boost pressure. When this pressure exceeds, say, 6psi, the spring in the actuator is overcome. The wastegate is opened, exhaust bypasses the turbine wheel, and boost is limited. Interrupting this 'signal' with a valve allows my Viggen to attain between 16 and 20psi of full boost, depending on what the ECU determines is needed to obtain the requested torque.
I believe my spring has weakened, giving me a 'base boost' of approximately 1psi. My electronic valve is sparing my wastegate actuator from being exposed to a boost signal. However, the wastegate door is not held shut very well by the weakened spring. It is directly affected by boost pressure. When the boost gets high, it is overcome, causing an extremely sudden drop in boost. This freaks out the ECU, and it drops to base boost. This exposes the wastegate actuator to boost pressure. Base boost is basically zero, so I observe a 'no boost' situation until I turn the car off and back on again.
So I bought a turnbuckle, and used a repurposed a B-body drum brake spring to assist my wastegate. It was terrible, bloody job, but I learned something. Essentially, the lesson was 'Don't do that!' Should have taken a picture. Damn.
Anyways, I put this spring on, attached in parallel with my wastegate actuator. I had cranked it up to full turnbuckle tightness after about a half mile. Base boost was still very low, but I had a resistor to test as well (see my oil temperature thread). So I plugged my electronic turbo valve back in, and headed back to the highway. I had always been able to duplicate the boost problem on the highway, during fifth gear boosting. Maybe the additional spring tension would at least hold my wastegate door closed better.
I merged onto the highway somewhat gently. I took a couple of opportunities to explore higher and higher boost, approaching full boost. When I finally went for full boost, the boost gauge shot up into the red, I heard a pop and had a sudden power loss. Nearly immediately, the smell of hot oil started to come through the vents. The check engine light began to blink, the battery light came on, and I was coasting for the side of the highway. Great, I freaking killed it. Am I about to spend the afternoon waiting for a tow?
Re: BOOOOOOOOst
For those of you that don't know, a blinking check engine light means "ENGINE DAMAGE IS BEING DONE NOW. PULL OVER IMMEDIATELY AS SOON AS IT IS SAFE." Remember that SAFE part. It's more important to keep your family safe than your engine.
I am by myself, but it's still important to be safe. I pull over as quickly and safely as possible, giving myself room to get out of the car without stepping into traffic. None of these things are new to me in the saab. I've had the blinking check engine light in this car as many as three other times. All for good reason, of course. I open the hood and immediately want to look at my helper spring, under the plate that says "HOT!" I learn that it is, indeed, hot, and take a deep breath.
I check to see if the pipe leading into the throttle body is loose. This was the source of one of those blinking check engine lights before. It is not. Nothing seems obviously out of place, and nothing is spewing from anywhere. It appears to still contain both coolant AND oil. No check engine light and the reader (already plugged in for coolant temp monitoring) says no stored or pending codes.
I decide to try to start it. It starts and idles normally. For about fifteen seconds. Then the boost gauge shoots up to the red, the idle flares slightly and then drops to a stall. F#@@.
I remember my MAF lesson from Kevin. If I can't find the boost leak, I'll just unplug the MAF and drive home using the MAP sensor. So I unplugged the MAF, put the connector behind the airbox, and started it. It ran and idled normally. No check engine light, still. After a minute or so of idling, I decide I should start driving home. Luckliy, traffic is only moving at 55mph or so. I limp along, and it keeps going. Coolant temps look good at least.
It's not like the old 'no boost' situation. There's nothing. Boost is not 'almost one psi.' It's the old type of no-boost, with a wall at 0psi. I've felt that before. The turbo was seized.
After a couple of miles, I get brave and open the window to hear if there is any turbo noise at all. I have hope when I hear some turbo-type sound out there.
I got home and idled it in the driveway to check the fan. This checks out good. I look around the engine bay while it idles. The hose between the intercooler and the throttle body piping is completely disconnected and lodged up against the engine block. It is oily because the intercooler is oily from pre-turbo-rebuild times. I turn off the car and reconnect this piping tightly. Restore the MAF to functionality. Start it back up. Drive it around and get normal boost, being careful to limit boost with my foot rather than the wastegate.
Conclusion:
The "helper spring" lodged the wastegate door completely shut. I'm not sure if the fuel cut or the hose blowing off is what limited the boost. Fuel cut is a crappy thing to to use. But it definately works and saves your ass when your BPC (Boost pressure Controller) valve fails completely. I've had that happen too. But the hose blowing off is the reason for the check engine light.
Kevin, I finally sealed my wastegate door shut like you had requested. This is what happened! To be fair, at least it was interesting.
Forward path:
Ebay has a wastegate actuator for approx 60 bucks that has a replaceable spring. So I'll never need another one again. And the stupid helper spring has been completely removed. Never doing that again either.
I am by myself, but it's still important to be safe. I pull over as quickly and safely as possible, giving myself room to get out of the car without stepping into traffic. None of these things are new to me in the saab. I've had the blinking check engine light in this car as many as three other times. All for good reason, of course. I open the hood and immediately want to look at my helper spring, under the plate that says "HOT!" I learn that it is, indeed, hot, and take a deep breath.
I check to see if the pipe leading into the throttle body is loose. This was the source of one of those blinking check engine lights before. It is not. Nothing seems obviously out of place, and nothing is spewing from anywhere. It appears to still contain both coolant AND oil. No check engine light and the reader (already plugged in for coolant temp monitoring) says no stored or pending codes.
I decide to try to start it. It starts and idles normally. For about fifteen seconds. Then the boost gauge shoots up to the red, the idle flares slightly and then drops to a stall. F#@@.
I remember my MAF lesson from Kevin. If I can't find the boost leak, I'll just unplug the MAF and drive home using the MAP sensor. So I unplugged the MAF, put the connector behind the airbox, and started it. It ran and idled normally. No check engine light, still. After a minute or so of idling, I decide I should start driving home. Luckliy, traffic is only moving at 55mph or so. I limp along, and it keeps going. Coolant temps look good at least.
It's not like the old 'no boost' situation. There's nothing. Boost is not 'almost one psi.' It's the old type of no-boost, with a wall at 0psi. I've felt that before. The turbo was seized.
After a couple of miles, I get brave and open the window to hear if there is any turbo noise at all. I have hope when I hear some turbo-type sound out there.
I got home and idled it in the driveway to check the fan. This checks out good. I look around the engine bay while it idles. The hose between the intercooler and the throttle body piping is completely disconnected and lodged up against the engine block. It is oily because the intercooler is oily from pre-turbo-rebuild times. I turn off the car and reconnect this piping tightly. Restore the MAF to functionality. Start it back up. Drive it around and get normal boost, being careful to limit boost with my foot rather than the wastegate.
Conclusion:
The "helper spring" lodged the wastegate door completely shut. I'm not sure if the fuel cut or the hose blowing off is what limited the boost. Fuel cut is a crappy thing to to use. But it definately works and saves your ass when your BPC (Boost pressure Controller) valve fails completely. I've had that happen too. But the hose blowing off is the reason for the check engine light.
Kevin, I finally sealed my wastegate door shut like you had requested. This is what happened! To be fair, at least it was interesting.
Forward path:
Ebay has a wastegate actuator for approx 60 bucks that has a replaceable spring. So I'll never need another one again. And the stupid helper spring has been completely removed. Never doing that again either.
Re: BOOOOOOOOst
What I actually said was:Fast_Ed wrote: Kevin, I finally sealed my wastegate door shut like you had requested. This is what happened! To be fair, at least it was interesting.
Forward path:
Ebay has a wastegate actuator for approx 60 bucks that has a replaceable spring. So I'll never need another one again. And the stupid helper spring has been completely removed. Never doing that again either.
By keeping rpms low you limit maximum boost. I don't know what rpms you used but I figured it was a good bet that your stock turbo/engine can't make over 20psi under 2500 rpm (or 2000 or 1500, your choice based on your understanding of your engine, the "or whatever" part). I wasn't there but I get the feeling you were over those rpms and tried using the throttle to modulate boost.I'd give the waste gate linkage/stuff a closer look.
Can you force it closed for testing purposes? You could free rev and listen for the turbo. Or drive with it and not exceed some RPM where it would be clear if it was working or not, but not so high that you'd be over boosting. Maybe 2500 rpm (or whatever the soonest RPM is that you think the waste gate would normally begin to open).
All that said, I guess I was in the ballpark when I said it sounded like a wastegate linkage-type issue. Yay?
Also I liked the "yay, my name appeared in the story!" part. Then I was like "oh."
Re: BOOOOOOOOst
This is a solid explanation for the symptoms.Fast_Ed wrote:I believe my spring has weakened, giving me a 'base boost' of approximately 1psi. My electronic valve is sparing my wastegate actuator from being exposed to a boost signal. However, the wastegate door is not held shut very well by the weakened spring. It is directly affected by boost pressure. When the boost gets high, it is overcome, causing an extremely sudden drop in boost. This freaks out the ECU, and it drops to base boost. This exposes the wastegate actuator to boost pressure. Base boost is basically zero, so I observe a 'no boost' situation until I turn the car off and back on again.
Re: BOOOOOOOOst
Yeah, all in good fun, of course. Any repair I do on my car is at my own risk. Rule of common sense?kevm14 wrote:What I actually said was:Fast_Ed wrote: Kevin, I finally sealed my wastegate door shut like you had requested. This is what happened! To be fair, at least it was interesting.
Forward path:
Ebay has a wastegate actuator for approx 60 bucks that has a replaceable spring. So I'll never need another one again. And the stupid helper spring has been completely removed. Never doing that again either.By keeping rpms low you limit maximum boost. I don't know what rpms you used but I figured it was a good bet that your stock turbo/engine can't make over 20psi under 2500 rpm (or 2000 or 1500, your choice based on your understanding of your engine, the "or whatever" part). I wasn't there but I get the feeling you were over those rpms and tried using the throttle to modulate boost.I'd give the waste gate linkage/stuff a closer look.
Can you force it closed for testing purposes? You could free rev and listen for the turbo. Or drive with it and not exceed some RPM where it would be clear if it was working or not, but not so high that you'd be over boosting. Maybe 2500 rpm (or whatever the soonest RPM is that you think the waste gate would normally begin to open).
All that said, I guess I was in the ballpark when I said it sounded like a wastegate linkage-type issue. Yay?
Also I liked the "yay, my name appeared in the story!" part. Then I was like "oh."
As to the rpm thing, I needed to approach max boost to determine if it was limiting correctly. The specs on this car indicate that full torque is available from 1800 rpm on. I knew it had a failsafe in the boost fuel cut through experience with a failed BPC that would never open the wastegate. However, I never thought I could reliably tension the door closed. Luck did that for me!
SAAB luck.