My Rear Turbo Mount Build

[cmtapanes]

Well.. now the car when I hit the gas the cars stalls is like is asking or missing gas for the amount of air going to the intake. Chris, that was your issue with the G3 spark plugs? Because I still have the G3.

I'm getting an LS1 MAF so I can tune the car with that MAF.

[AaronGTR]

My fuel pressure at idle with stock injectors and FPR was 48psi. I do believe the '99 cars where slightly lower. I always recommend getting an adjustable regulator anyway when you are changing injectors and adding boost. That way you can adjust the pressure as needed and get a true 1:1 rising rate under boost, which the stock FPR does not do. 36lb GTP injectors would be a good choice for you Carlos, since your car is a '99 and you won't need to change the injector harness plugs to use them. They do require slight modification to work with the injector retainer clips on the grand am fuel rail though, and yes they absolutely require PCM tuning. I can help you out with both those things if you want.

I would definitely recommend making sure there is absolutely nothing else wrong with the car before switching injectors and pressure regulators though. That way if anything goes wrong you know it's due to those things, and you're not chasing symptoms caused by other problems. If you are running low boost you can actually run on the stock injectors for a while if you're not beating on it. I know you said the sound you heard was being made by a leaking exhaust gasket so I guess that's fixed now. Did you ever find out if that misfire problem went away?

[cmtapanes]

Well.. I can't tell you if the spark plug issue went away because I don't have a way to scan the PCM. I think it may have because that plug wasn't all the way in. I think the problem was a leak issue; the only problem I have right now is that when I floor the gas the car stalls... don't now if is a spark problem or the car neediing some tunning. I start having the problem right after I fix the leak by changing the clamps with some t-bolt clamps.

Are you busy this weekend to play with the pcm?

Originally Posted by AaronGTR

My fuel pressure at idle with stock injectors and FPR was 48psi. I do believe the '99 cars where slightly lower. I always recommend getting an adjustable regulator anyway when you are changing injectors and adding boost. That way you can adjust the pressure as needed and get a true 1:1 rising rate under boost, which the stock FPR does not do. 36lb GTP injectors would be a good choice for you Carlos, since your car is a '99 and you won't need to change the injector harness plugs to use them. They do require slight modification to work with the injector retainer clips on the grand am fuel rail though, and yes they absolutely require PCM tuning. I can help you out with both those things if you want.

I would definitely recommend making sure there is absolutely nothing else wrong with the car before switching injectors and pressure regulators though. That way if anything goes wrong you know it's due to those things, and you're not chasing symptoms caused by other problems. If you are running low boost you can actually run on the stock injectors for a while if you're not beating on it. I know you said the sound you heard was being made by a leaking exhaust gasket so I guess that's fixed now. Did you ever find out if that misfire problem went away?

[AaronGTR]

Originally Posted by cmtapanes

Well.. I can't tell you if the spark plug issue went away because I don't have a way to scan the PCM. I think it may have because that plug wasn't all the way in. I think the problem was a leak issue; the only problem I have right now is that when I floor the gas the car stalls... don't now if is a spark problem or the car neediing some tunning. I start having the problem right after I fix the leak by changing the clamps with some t-bolt clamps.

Are you busy this weekend to play with the pcm?

Hmm, that sounds kinda strange. Yeah, I could probably work on it a couple hours this weekend. Do some scanning and see what it's doing.

[cmtapanes]

ok Aaron, I'll give you a call on Friday to confirm.

[cmtapanes]

Ok.. I have a question for all the boosted people. What do you guys really do with this tube (mark on the below picture)? Don't know what's call but the tube connects to the rear valve cover. Do you guys eliminate that pipe or can I route the tube from the valve cover (rear) to my oil catch can? The reason I ask is because I'm afraid I'm loosing boost thru that tube.



Thanks

[cmtapanes]

anyone?

[AleroB888]

Cap it off and run the tube from the rear valve cover to the () air cleaner housing box.

[cmtapanes]

air cleaner housing box? filter?
Don't have the filter on the engine bay... I have the turbo on the back (rear mounted) and the filter is behind the rear bumper.

Originally Posted by AleroB888

Cap it off and run the tube from the rear valve cover to the () air cleaner housing box.

[3800SII]

Originally Posted by cmtapanes

air cleaner housing box? filter?
Don't have the filter on the engine bay... I have the turbo on the back (rear mounted) and the filter is behind the rear bumper.

Carlos, I capped mine and added a breather filter to my oil fill cap. I was wondering the same thing as you for a while.

BTW, It rained like a MOFO last night. I spent 30 minutes today flushing water out of my charge pipe and MAF sensor . This is the third time this has happened because I did not use the airfilter shield...

Can you guess what's gonna happen to my rear bumper and crash support this weekend?

[AaronGTR]

That is the PCV intake tube. In order for the PCV system to still function, it has to be attached to the intake somewhere between the MAF and TB, and the PCV valve side on the front valve cover needs to be attached to the intake manifold (behind the TB) so that is has vacuum. It needs vacuum to draw the blow by gasses out of the crank case. I personally think you should not eliminate the system. It's been discussed at length here Remove the PCV system for performance?

With the peculiarity of your rear mount turbo system, that might make it hard to keep that system working properly, since all the intake tubing in your engine bay will see boost at various times. The purpose of the PCV valve on the front is to stop gas reversion and it opens when there is a vacuum on the engine side, but I don't know if it seals well enough to stop boost pressure from leaking by. It's very possible that under boost you could be pressurizing the crank case from the tubes on both sides, as well as the extra pressure from the blow by gases. I don't know what effect this would have on how the engine runs, but it's definitely not optimal. It's not possible to put check valves in both lines because the air wouldn't go in the intake tube under boost OR vacuum, so the system wouldn't work. You could put a breather on the rear, and leave the front hooked up with an extra check valve to keep boost out. That would give you a vacuum source under low throttle, but it would also mean you are pulling in un-metered air and it will throw your fueling off a little. It would make it very hard to dial in your fuel trims.

The only other option would be eliminating both tubes and using breathers. Only problem is, the crank case would only ventilate under full throttle when pressure builds up inside. During low throttle (the majority of your driving in a daily driven car) you have no vacuum to pull contaminates out unless you install some kind of vacuum pump with an oil catch can after it. That would work. Otherwise that stuff is going to sit in your crank case and dilute your oil over time. You could do it... but I'd make sure I was using premium oil and changing it every 3000 miles instead of waiting for 5-6k like normal with synthetic. Obviously that is not the best setup. Also by venting those things into the air instead of into the engine where they get burned, you are adding pollutants to the atmosphere.

[Shock24Z]

Run breathers. It'll be fine.

[3800SII]

Originally Posted by AaronGTR

That is the PCV intake tube. In order for the PCV system to still function, it has to be attached to the intake somewhere between the MAF and TB, and the PCV valve side on the front valve cover needs to be attached to the intake manifold (behind the TB) so that is has vacuum. It needs vacuum to draw the blow by gasses out of the crank case. I personally think you should not eliminate the system. It's been discussed at length here Remove the PCV system for performance?

With the peculiarity of your rear mount turbo system, that might make it hard to keep that system working properly, since all the intake tubing in your engine bay will see boost at various times. The purpose of the PCV valve on the front is to stop gas reversion and it opens when there is a vacuum on the engine side, but I don't know if it seals well enough to stop boost pressure from leaking by. It's very possible that under boost you could be pressurizing the crank case from the tubes on both sides, as well as the extra pressure from the blow by gases. I don't know what effect this would have on how the engine runs, but it's definitely not optimal. It's not possible to put check valves in both lines because the air wouldn't go in the intake tube under boost OR vacuum, so the system wouldn't work. You could put a breather on the rear, and leave the front hooked up with an extra check valve to keep boost out. That would give you a vacuum source under low throttle, but it would also mean you are pulling in un-metered air and it will throw your fueling off a little. It would make it very hard to dial in your fuel trims.

The only other option would be eliminating both tubes and using breathers. Only problem is, the crank case would only ventilate under full throttle when pressure builds up inside. During low throttle (the majority of your driving in a daily driven car) you have no vacuum to pull contaminates out unless you install some kind of vacuum pump with an oil catch can after it. That would work. Otherwise that stuff is going to sit in your crank case and dilute your oil over time. You could do it... but I'd make sure I was using premium oil and changing it every 3000 miles instead of waiting for 5-6k like normal with synthetic. Obviously that is not the best setup. Also by venting those things into the air instead of into the engine where they get burned, you are adding pollutants to the atmosphere.

Damn Aaron... I think you just owned me and Carlos on this one
I broke my PCV hose during the initial install so it can't be helped for me anyhow.
I have had no problems so far with just one breather. Thanks for the input.

[RPO3]

Like I said before
Aaron is the man

[GA2000GTSpeed]

how bad is it on the engine to not have the rear pcv line on right now. cause the gromit is missing i need to go get it

[AaronGTR]

Originally Posted by GA2000GTSpeed

how bad is it on the engine to not have the rear pcv line on right now. cause the gromit is missing i need to go get it

Not real bad but it will affect your fuel trims a little. If the front PCV is connected, but the rear is open to atmosphere, that means that when there is vacuum the engine is pulling in air thru the rear vent. That is air that is un-metered by the MAF sensor, so it's going to throw your fueling off a little bit and the O2 sensor will have to compensate. It's just like having a vacuum leak.

I've seen this first hand. I ran for a while with a breather filter on the rear cover. After doing some studying and finding out how the PCV system worked, I made a fitting for my CAI and ran a hose to the back valve cover. It only made a small difference in my LTFT's, but it was immediately noticable how the LTFT's weren't as erratic anymore.

Originally Posted by Shock24Z

Run breathers. It'll be fine.

Prove it. That might be your opinion, but a lot of people would disagree with you.

[AleroB888]

Originally Posted by AaronGTR

Not real bad but it will affect your fuel trims a little. If the front PCV is connected, but the rear is open to atmosphere, that means that when there is vacuum the engine is pulling in air thru the rear vent. That is air that is un-metered by the MAF sensor, so it's going to throw your fueling off a little bit and the O2 sensor will have to compensate. It's just like having a vacuum leak.

In the original Magnuson kit, of course, the tube from the rear cover went back to their own OEM looking filter box. But nobody ever keeps those in use for long

I know it doesn't pull nearly as much vacuum there as at the upper IM, but I will try to do some tests with and without it hooked up. I never thought to look closely at the fuel trims as affected by that source.

[AaronGTR]

Originally Posted by AleroB888

In the original Magnuson kit, of course, the tube from the rear cover went back to their own OEM looking filter box. But nobody ever keeps those in use for long

I know it doesn't pull nearly as much vacuum there as at the upper IM, but I will try to do some tests with and without it hooked up. I never thought to look closely at the fuel trims as affected by that source.

Yeah, I always thought that was a weird place to have it as well, and it turns out it's not really the right place for it to be hooked as it would be pulling un-metered air. That tube is just the intake though so it doesn't really matter where it's hook in regards to how much vacuum it gets. It gets all it's suction from the vacuum provided to the PCV line on the front valve cover.

I looked at the setup on Carlos' car today. It's basically all hooked up the way it would be on a stock NA car right now. That means when he isn't in boost and has vacuum behind the TB, it's working just like stock, but when he hits boost it will send pressure down both PCV tubes and pressurize the crank case. Not really sure how bad this is. I'm thinking it could possibly cause some ring flutter or some other adverse effect? The other bad thing of course is that they are just plastic hoses pushed into rubber grommets. As soon as he hits enough boost they are going to get blown out.

His other option is to just put breather filters on both valve covers as was mentioned, and plug both holes in the UIM and the intake tube. That would get rid of any pressurizing of the crank case, but it would also mean no crank case evacuation during normal driving (no vacuum). It would only push the contaminants out at WOT when the blow by creates pressure in the crank case. This would also vent those pollutants to the air instead of injecting them back into the UIM to get burned.

Obviously neither of these setups is optimal. It's just a question of which one is worse. The only way I can see to make a setup that will work with his turbo setup, is if he disconnected the PCV lines from the UIM and the intake and plugged the holes, put a breather filter on the rear valve cover, and put an electric vacuum pump on the line coming from the front valve cover (post catch can of course). That way he would have crank case ventilation 100% of the time, but still venting to the atmosphere. They couldn't be injected into the intake without throwing off the fuel trims by adding un-metered air unless they were plumbed in front of the MAF, which might get the MAF sensor wires dirty, and he'd still need a check valve in that line since his intake sees boost there.

[2000 GT Coupe]

Originally Posted by AaronGTR

Yeah, I always thought that was a weird place to have it as well, and it turns out it's not really the right place for it to be hooked as it would be pulling un-metered air. That tube is just the intake though so it doesn't really matter where it's hook in regards to how much vacuum it gets. It gets all it's suction from the vacuum provided to the PCV line on the front valve cover.

I looked at the setup on Carlos' car today. It's basically all hooked up the way it would be on a stock NA car right now. That means when he isn't in boost and has vacuum behind the TB, it's working just like stock, but when he hits boost it will send pressure down both PCV tubes and pressurize the crank case. Not really sure how bad this is. I'm thinking it could possibly cause some ring flutter or some other adverse effect? The other bad thing of course is that they are just plastic hoses pushed into rubber grommets. As soon as he hits enough boost they are going to get blown out.

His other option is to just put breather filters on both valve covers as was mentioned, and plug both holes in the UIM and the intake tube. That would get rid of any pressurizing of the crank case, but it would also mean no crank case evacuation during normal driving (no vacuum). It would only push the contaminants out at WOT when the blow by creates pressure in the crank case. This would also vent those pollutants to the air instead of injecting them back into the UIM to get burned.

Obviously neither of these setups is optimal. It's just a question of which one is worse. The only way I can see to make a setup that will work with his turbo setup, is if he disconnected the PCV lines from the UIM and the intake and plugged the holes, put a breather filter on the rear valve cover, and put an electric vacuum pump on the line coming from the front valve cover (post catch can of course). That way he would have crank case ventilation 100% of the time, but still venting to the atmosphere. They couldn't be injected into the intake without throwing off the fuel trims by adding un-metered air unless they were plumbed in front of the MAF, which might get the MAF sensor wires dirty, and he'd still need a check valve in that line since his intake sees boost there.

I like this idea, it is what I was thinking, keep the stock setup but instead of plumbing into the intake as stock would go into a catch can with a vacuum pump if the catch can had some sort of filter it should catch most of the bad stuff so you would not be polluting enough to worry about.

[Shock24Z]

Originally Posted by AaronGTR

Prove it. That might be your opinion, but a lot of people would disagree with you.

Prove to me otherwise.

Angrysk8r's car has been this way for almost 2 years with no signs of anything wrong and it's probably seen more abuse than any 3400 on this board.

If nothing has gone wrong thus far, do you think it ever will?

I don't.

If you've had first hand experience with differing results let us know.