Supercharger Question for my Nice Friends on Oppo

"Firewrx234" (firewrx234) 10/08/2013 at 15:49 • Filed to: Car Problem

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I've got a '99 GTP (Supercharged with an Eaton M90 stock everything) and yesterday while waiting to get gas I heard my engine start ticking or knocking while at a stop but in Drive. When in Park or Neutral, no sound. Anyway after I revved it the sound went away. I filled up on Premium (thinking this could have been the issue). No more knock. Success...I thought.

While driving home I noticed something else odd. My car no longer produces the full boost. It appears as thought the ticking might have corresponded to something else rather than the fuel. After lots of searching today I finally found out a couple of things about the superchargers and what makes them work (or not work) and one of the potential things that I found was the Boost Bypass Valve. So I quickly found this and tested to see if it moves freely, it does. It also moves correctly according to acceleration (I think...).

So now I'm left with a big question. Why no boost? Why did it tick? Why isn't it ticking now? And finally just to make sure, which way means the BBV is open vs closed?

I know that's a lot of gibberish but I'm hoping someone's random weird comments will spark some sort of enlightenment and make the solution appear.

Thanks guys and I look forward to some help!

Casper > Firewrx234 10/08/2013 at 15:55

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I would try to isolate the ticking. I would also try to see if the boost level is steady and low or if it's indicative of a leak by wavering/fluctuating. Does the ticking match revs? Does it change in volume? At idle, if you take stethoscope (or the more redneck approved a long screw driver to the ear) and touch parts does it sound like it's in the blower, head, or accessories?

Firewrx234 > Casper 10/08/2013 at 16:00

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Unfortunately, for the sake of learning things, the ticking stopped all together after only ticking for about 3-4 minutes. Now it won't tick and have no way of figuring out what it was.

The ticking did match the revs and I don't think volume changed though

Casper > Firewrx234 10/08/2013 at 16:09

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Sounds like the ticking may have indeed been in the valve train. If you were getting detonation/ping the ECU would pull timing to compensate to a point, so something could have happened there. Have you checked codes? I think those engines were timing belt, so it shouldn't have been tensioner noise or anything like you would get from a chain.

I would focus on the boost issue. Go out and try doing a pull and watching the gauge. See if it looks like it's uneven or if it's building pressure smoothly. Then I would pull codes. Those cars do some weird stuff if they don't get good premium fuel sometimes, but I think this maybe related to the boost system. How many miles are on the blower?

Firewrx234 > Casper 10/08/2013 at 16:13

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The boost meter appears to build like it always has but it will only build to about 1/4 or 1/2. I can't tell why it goes to 1/4 or 1/2 but it definitely won't go further than that. And when driving, it honestly feels like I'm getting no boost. It truly feels NA.

Firewrx234 > Casper 10/08/2013 at 16:14

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Oh and to answer the first question, I haven't pulled codes yet and no CEL popped up.

Demon-Xanth knows how to operate a street. > Firewrx234 10/08/2013 at 16:15

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You might look into an intake gasket leak, that would let a little coolant into the lifter valley and keep one from pumping up. I know there was a problem with it on one year, but I don't remember which, so do a search on it before running down that rabbit hole.

04sneaky - Boxers. Blowers. Bikes. And bitches. > Firewrx234 10/08/2013 at 16:16

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Boost bypass valve opens to allow air from the bottom of the supercharger (ie. where it would begin to enter the motor) to be recirculated and go back into the top of the supercharger (ie. where the air initially gets sucked in). What this does is de-pressurize the air after the supercharger, therefor preventing "boost" (which is just pressure in the intake manifold) from building because it's effectively "leaking" back into the top of the supercharger instead of building pressure.

So when you got WOT the valve should be staying closed and therefore not moving. If you drive it like normal it should be opening and therefor moving. The valve is always closed, so if it moves that means its opening.

Can you "unhook" you bypass valve from the controller? Or pull the vacuum line that runs to it's controller? That should make it always stay shut so you can see if it builds boost then.

And when you get on it does it sound like the supercharger is actually spinning? Does it make the actual "whine" but just not show boost?

Casper > Firewrx234 10/08/2013 at 16:17

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It almost sounds like either your ECU pulled back on you or your blower went out. How does the oil look for the super charger? I know I have heard of them burning up with oil issues, but I have also heard of people having their ECUs limp on them or partially go bad as well. The fact you heard pinging/possible detonation before it did makes me think it may have just pulled back on you.... but not about the boost issue. I don't know how it could change what a pulley driven blower is pushing at the ECU level. I would assume the boost is read right at the blower making the system pretty simple and easy to trouble shoot.

Edit: Also, check the boost solenoid if possible. That maybe letting boost out early or be stuck/dead.

04sneaky - Boxers. Blowers. Bikes. And bitches. > 04sneaky - Boxers. Blowers. Bikes. And bitches. 10/08/2013 at 16:25

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Belt slip could also affect the "boost" portion. So you may try double-checking your tensioner and inspecting the belt to see if it's worn or might need to be replaced.

Firewrx234 > Demon-Xanth knows how to operate a street. 10/08/2013 at 16:25

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I can almost guarantee I have a slight intake gasket leak because when starting the car up, it lopes (and in my estimates is burning off the built up coolant).

FireSpittingV12 > Firewrx234 10/08/2013 at 16:28

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Check the pulley and belt. There could be some slippage. Or the boost valve could be malfunctioning.

Squid > Firewrx234 10/08/2013 at 16:29

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If you weren't running premium fuel all the time, your motor may be unhappy with you. The ticking most likely was due to low octane fuel if that is what was in the car at the time. If you had any low octane fuel in the tank and filled it up with premium you will still have lower than the recomended 91 in the tank. Try putting an octane booster in to get the octane rating back up to prevent further detonation.

I guess with regards to the boost, I would check to make sure that your blower rotates freely and without noise then verify your boost with another gauge if possible. Checking for codes to see if any are pending or thrown would also be advisable. If you have access to a scan tool than can monitor PIDs while driving may also give insight to your boost issue.

Is your bypass valve solenoid actuated? If so have you tried powering and depowering it to check for correct movement? Or is it vacuum operated? If it is vacuum operated you may need to check for vacuum leaks and check the function of the valve with a hand pump.

Aside from that, I got nothing. I am also not a boost expert, just someone who can try to troubleshoot problems, so what I have said may be inaccurate regarding the S/C but the octane rating of fuel needs to be at 91 or above to prevent detonation on a force induction motor.

Firewrx234 > 04sneaky - Boxers. Blowers. Bikes. And bitches. 10/08/2013 at 16:30

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When I was on the road, I didn't hear the whine when I got into it. It definitely isn't supplying what it normally does.

Also, any idea on how to pull the vacuum line or disconnect the valve from the controller because at the moment, I'm a little hesitant to break things.

Firewrx234 > Casper 10/08/2013 at 16:31

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It was just odd because normally knock would occur under pressure or when it wouldve been driven hard. And at the time I was stopped and waiting to pull into a gas pump. Just seemed really odd to me.

Firewrx234 > FireSpittingV12 10/08/2013 at 16:33

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Pulley and belt seem to be ok. The belt probably wouldn't be bad to replace in the future but seems fine for the moment and the pulley doesn't seem to have play.

At this point it could be the boost valve (which I'm not really sure how to check if it's operating correctly) or some other unknown issue.

Casper > Firewrx234 10/08/2013 at 16:34

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That's what made me start to wonder about something like the solenoid. It may have been it having problems, getting damaged/stuck, or who knows. It would also explain why your pressure is too low possibly.

FireSpittingV12 > Firewrx234 10/08/2013 at 16:34

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Definitely sounds like a boost valve then. It could be something else but I would start with the valve.

04sneaky - Boxers. Blowers. Bikes. And bitches. > Casper 10/08/2013 at 16:34

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Boost is mechanical. The ECU doesn't control anything related to boost in a roots-blower car.

The issue is likely vacuum, belt, or something with the eaton itself.

But if not, the absolute worst alternative is an issue with the valvetrain or lower intake manifold. Causing pressure to be lost in the manifold, thereby reducing "boost" because the manifold is not properly being pressurized. This could also cause detonation if too much air or even not enough air is reaching the cylinders.

Casper > 04sneaky - Boxers. Blowers. Bikes. And bitches. 10/08/2013 at 16:35

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That's why I said it wouldn't make sense for it to be the same issue. The old cars did have a solenoid that caused problem that I remember and could cause boost to be low though. That or the entire supercharger noise unit has a problem of some kind. It's really hard to say without knowing what the blowers oil looks like. The M90 being a self contained unit makes me think it's a larger problem.

Firewrx234 > Squid 10/08/2013 at 16:37

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The fuel problem seemed like a non-issue because it wasn't a problem until I was sitting in the gas station lot waiting to pull up to the pump. It had never knocked before and wasn't knocking when being pushed. I'm just perplexed by that in general.

And with the BBV it appears to be vacuum operated. When the car is off, the BBV lever is all the way down on the stop. When the engine is on it goes all the way up unless I gas it in which it will move back toward the stop.

Firewrx234 > FireSpittingV12 10/08/2013 at 16:40

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Got any suggestions on how to check one of those? It seems to move how I (untrained eye) would expect it to move. When off -> Down at stop, When started -> All the way up, When accelerating -> Moves downward.

Not sure if that's correct but that's how it moves

Firewrx234 > Casper 10/08/2013 at 16:41

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Any suggestions on how to check the solenoid?

04sneaky - Boxers. Blowers. Bikes. And bitches. > Firewrx234 10/08/2013 at 16:41

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Here is a short guide. http://www.zzperformance.com/blog/boost-byp…

Also believe you can just unhook the top vacuum tube from the bypass valve and it will stay closed. I would try that first before following my link. So, start the car, and then unhook that vacuum line on top of the valve and see if it shuts.

However, DO NOT LEAVE IT THIS WAY AFTERWARDS! The boost bypass valve prevents the car from building boost while under normal driving, therefor not trying to force air into the motor when it doesn't need it. It won't hurt anything to do it, just to quickly see if it makes full boost without it. But leaving it like this, and thereby always closed will make the car drive differently.

FireSpittingV12 > Firewrx234 10/08/2013 at 16:43

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Sounds right. Maybe it's a gasket letting boost escape? I'm not entirely familiar with one of those superchargers.

Squid > Firewrx234 10/08/2013 at 16:49

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Running 87 octane on a boosted motor will cause detonation and knocking and will cause the ECU to retard timing to prevent engine damage. You will also notice less power. In general 91 is the minimum safe rating for boosted cars but they prefer much higher octane than 91.

Try to get a vacuum gauge to measure your vacuum pressure through out the car or just go around the motor and do light sprays of brake cleaner or such and see if anything increases your idle. That is the oldschool way of finding a vacuum leak if you have one.

You may want to check the condition of your belt and pulleys. they may be slipping or have incorrect tension causing boost to be low or fluctuating.

Firewrx234 > Squid 10/08/2013 at 16:54

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Yeah I know the car wants 91+ but I don't think that was the source of the tick. The car wasn't ticking before stopped, when driving and hasn't since.

I'll check the vacuum as best I can without a gauge.

Belts seem ok. Could be replaced in the future but fine at the moment.

Casper > Firewrx234 10/08/2013 at 16:54

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Not sure on that car. I am going to pull manufacturer diagrams up if I have a sec. Hopefully it's not something built into the blower on that model. See the M90 is more or less self contained where as other cars had external solenoids. If they ended up using an integrated system in the M90 (which I don't remember because I never work on them) it maybe a problem inside the blower nose.

Edit: Take a look at this and see if any of the info is helpful. I'm being bothered by people who need domain help...

http://www.w-body.com/showthread.php…

Firewrx234 > 04sneaky - Boxers. Blowers. Bikes. And bitches. 10/08/2013 at 16:55

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Tried to unhook the vacuum tube but appears to be stuck on pretty good. Going to wait until the car cools down in hopes that the rubber will unstick and be less glue-y.

Firewrx234 > Casper 10/08/2013 at 16:57

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I appreciate it.

Also, I tried to check the fluid but the hex bolt is jammed in their really tight...So tight that it broke one of my hex keys and stripped the other one...fun fun

Squid > Firewrx234 10/08/2013 at 16:57

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If it was a sort of tapping knocking noise deep in the motor it most definitely was the low octane causing knock and that could really be the source of your whole problem.

When it comes down to it the price for premium v. regular is about $2 for 10 gallons. It really isn't worth it to go that route to save money, all you are doing is potentially harming your motor which will cost you a whole lot more than $2 to fix.

Casper > Firewrx234 10/08/2013 at 16:58

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You may not have one accessible if it's just a bypass system (which you said you checked) but these guys are talking about how to tell if it's open and where to go from there:

http://gtpworld.net/viewtopic.php?…

Firewrx234 > Squid 10/08/2013 at 17:00

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Honestly, I have no idea the location of the knock. It could've been the motor but it bothered me that the noise went away in park and in neutral but remained when in drive.

I honestly do use Premium more often than not. I just was forced into cheaper stuff on my last gas station visit due to some decreased funds and looming bills.

Casper > Firewrx234 10/08/2013 at 17:00

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When was the last time it was serviced? I think it is recommended to be changed every 50k miles.

Firewrx234 > Casper 10/08/2013 at 17:00

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Thanks, I appreciate it.

04sneaky - Boxers. Blowers. Bikes. And bitches. > Firewrx234 10/08/2013 at 17:01

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If its never been unplugged it'll probably take a bit of work. I've had to use some pliers with a rag or something around the hose to keep the pliers from damaging the rubber a few times.

I forgot to mention I hate those boost bypass valves. And eaton really seems to know that it's an issue with almost all their factory products, yet they keep making them the same cheap plastic that either cracks or leaks or fails in some way eventually.

Firewrx234 > Casper 10/08/2013 at 17:07

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To be honest, not entirely sure. I got the car in August of '12 and the guy told me he had personally replaced the coupler in the s/c and replaced the s/c oil. So not sure whether that was a good or a bad thing lol.

Squid > Firewrx234 10/08/2013 at 17:07

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It makes sense for it to go away in neutral as there is no load on the motor. In drive there is a load and when an engine is under load you have a greater chance of seeing detonation. Just put some octane booster in the tank and see if it helps, if any left over 87 was in the tank when you pu 91+ in the octane rating will still be low which will have an effect on the ECU pulling timing and limiting power. It really could just be your ECU pulling boost to help prevent detonation.

It may also take a bit for the ECU to realize that there is better quality fuel for it to burn, and will take a little bit to give you full power.

My armchair QB diagnosis is that. Hopefully it is just poor fuel and the cars sense of self preservation that is hampering your boost filled fun.

Firewrx234 > Squid 10/08/2013 at 17:10

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If i just unplug the battery for 30 minutes will that fix the ECU issue?

Casper > Firewrx234 10/08/2013 at 17:11

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Interesting. Well hopefully you can get at it and maybe just do an oil change so that you know for sure it has been done. Then walk down the check list.

Squid > Firewrx234 10/08/2013 at 17:31

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Yes, but make sure you get some octane booster fully mixed in the tank and have it run through for a few minutes at idle so when you reset the ECU you have the proper octane flowing into the engine.

Also, the battery should remain disconnected for 10 minutes so that all residual power in the capacitors discharge and there is no chance of them staying in the KAM.

SteyrTMP > Squid 10/08/2013 at 18:01

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Meh, those octane boosters are a load of crap. They don't do shit... >1 octane for a can/bottle of that shit. (typically around . 2 to .3 octane). Use toluene if you need to raise octane and can't get 100 race gas around you. (Toluene is a lot cheaper, as well)

http://vanilla47.com/PDFs/Toluene/B…

SteyrTMP > SteyrTMP 10/08/2013 at 18:18

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http://www.gnttype.org/techarea/misc/…

Squid > SteyrTMP 10/08/2013 at 18:35

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Yeah, you are correct on that. But this test That HotRod did shows that the 104+ helps relieve the detonation problem even if mildly so. I don't think FireWRX234 needs to go on a hunt to find pure, reagent grade toluene to shove in his tank. For his purposes the 104+ or Lucas product will work to stave off detonation due to 87 being in there. While I do agree with you in the fact that looking for power in a bottle is fruitless and you'd be better off getting pure 100 octane race gas, but just trying to get detonation to stop occurring on a street car with bad gas the octane booster should do the trick for this tank of fuel.

SteyrTMP > Squid 10/08/2013 at 18:44

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Yeah, when I had my Mini, there was a Speedway by the shore of Lake Erie that sold 100 unleaded race gas... I put it in the Mini a few times, and the difference was noticeable. It ran better. I didn't notice power increase as much as the fact that it sounded happier.

On the other hand, there's a place not that far from me that sells 100 leaded race... I've been tempted to fill up the Seven with that. Oh well. I don't want to see the price. I'd be better off trying toluene and 2-stroke oil. I have a hunch it's going to run considerably better with higher octane. On the negative side, it'll probably be even pickier when cold.

Squid > SteyrTMP 10/08/2013 at 18:58

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You got the turbo BP in that right? I think the leaded would just cause issues, and foul a cat if you are running one. You really shouldn't see any benefit other than a happier detonation free engine unless it was tuned for the 100+ gas. The tuning with the higher octanes is where the power comes from.

SteyrTMP > Squid 10/08/2013 at 19:04

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Yeah. No cat, just a 12-14" long downpipe/side exhaust. I don't think I should try anything until I can get better injectors. The Megasquirt III will work well with high octanes.