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Old 09-30-2013, 08:42 PM   #1
911/M5
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Need help: Boost/power problem on 2002 E46 M3 AA Gen VI/Stage II

Hey guys,
I'm having a problem with my 2002 E46 M3, Gen VI, Stage II. My mechanic and I deduced it could only be a few things causing it and he suggested I run this by the boards first to see if anyone could help. AA is 600 miles away and there just aren't many supercharging shops in Nashville.

Here are the symptoms:
1) Car is bogging down at about a 60-70% reduction of power at full throttle. It feels like a car using bad gas or a car that has a clogged exhaust system.
2) If you lightly press the throttle, you actually have about 70% power. but if you push pedal about 40% down the bogging starts.
3) The further you push down the gas pedal, the more it shrugs, chokes out and misses. Almost impossible to get over 6-7,000 rpms.
4) The car has been perfect for the 4+ years I have owned it, except for replacing the coils which have less than 1,000 miles on them. We went with the updated factory coils as they supposedly won't fail anymore.
5) The engine, outside of the supercharger system seems to be running fine. There is a drag from the S/C system however, so full power is not normal.
6) No lights, no warnings, no error codes in the OBD II scanner.
7) The S/C belts is fine. The filter is dirty, but not enough to choke an engine out.
8) The fuel pump appears to be running normally. AA installs a gauge in the engine compartment and it appears to be consistent with normal operating range.

So based on all of that, we deduced it is probably an air intake, vacuum or supercharger problem. I wanted to ask the board what their thoughts are on trying to diagnose this loss of power and bogging down. Here are our questions:

1) How can you tell if the S/C has failed? It only has about 7,000 miles on it, but maybe that is the problem.
2) If this is something as simple as a vacuum line come loose, that is great. My problem is knowing where to look for the most likely ones that have come loose. Everything attached to the S/C is secure, so where else do I look and how many are there?
3) Blow-off valve? My system has two...how do I know if one of them has gone bad? At least one is clearly working as you can hear it plain as day when you let off the gas.
4) Based on the symptoms, is there something that we are completely missing?

Thanks for any help anyone can give...this car has been a joy to own but I knew going into buying a high HP custom S/C E46 M3 there would be days like this where you have to figure it out.

Best regards,

Robert Collins
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Old 09-30-2013, 09:10 PM   #2
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Need help: Boost/power problem on 2002 E46 M3 AA Gen VI/Stage II

Sounds like a serious boost leak. Check the piping and clamps all throughout. Even check throttle body area.


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Old 09-30-2013, 09:14 PM   #3
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Do you have a boost gauge currently installed? There are two blow off valves as you mentioned: one in front, and one on the bottom. They are both tee'ed to the nipple that is at the end of the fuel rail near the firewall. Inspect the vacuum hoses that are connected to both blow off valves as well as the hose that connects to the nipple. I've had the rubber diaphram in the purple blow off on the bottom develop a hole and I was loosing boost/vacuum this way. Also, check the silicone connectors that connect all the piping, as that may have gotten loose.

What has changed on your car recently? Have any hoses or clamps been changed or adjusted?

Also inspect the silicone hose/connector on the last throttle body (closest to the firewall). See if it has not loosened.

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Old 09-30-2013, 09:34 PM   #4
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Thanks guys. Answers to your questions:

1) Nothing has changed on the car recently. Nothing at all. Running fine one minute (literally), then pop...limited power. At first I thought, oh no a cylinder, but then the engine itself kept running fine under light load or at idle with no missing. That's when we figured it wasn't inside the engine, but something affecting it from the outside.
2) I'm heading to the garage to check on all of these hoses and connections as you have both recommended. Thanks for the ideas...I'll report back!
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Old 09-30-2013, 10:09 PM   #5
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OOPS...sorry, missed a question...

Yes I have a boost gauge along with two others. The boost gauge showed 4-5 pounds of boost at full throttle. Of course it was bogging down so it's not really full throttle. Hope that helps.
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Old 10-01-2013, 07:56 PM   #6
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4-5 psi at full throttle?? You definitely have a boost leak. What is it showing at idle...should be 18-20 in/Hg or so. Anything below that and a vacuum leak is very likely.

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OOPS...sorry, missed a question...

Yes I have a boost gauge along with two others. The boost gauge showed 4-5 pounds of boost at full throttle. Of course it was bogging down so it's not really full throttle. Hope that helps.
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Old 10-02-2013, 12:42 AM   #7
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I'll check in the morning. Don't want to wake the neighbors. ;-)
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Old 10-02-2013, 09:06 AM   #8
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Hello Robert,

I would recommend changing out the fuel filter just to rule out that issue of possible clogged fuel filter or bad gas. Just to ensure that the fuel system is operating properly the vehicle at idle,the fuel pressure regulator should be reading at 40 lbs. Once you pull the vacuum hose the fuel pressure should shoot up to 52 lbs if not your regulator could be faulty. If the Supercharger has failed you would not be building boost and the vehicle would run really rich.I would recommend performing a smoke test to help identify any possible leaks. Also I would recommend vacuum testing the BOV just to ensure they hold pressure and there is no leaks in the diaphram and the valve is stuck open. If you still have issues please feel free to contact me directly at 305-233-9300 Ext: 232.

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Old 10-02-2013, 10:56 PM   #9
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Thanks Viral. We are planning on getting to most of it Saturday, but I did test the fuel pressure gauge tonight and it was at 46 at cold idle. Let me know if this is an issue.
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Old 10-03-2013, 08:52 AM   #10
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Thanks Viral. We are planning on getting to most of it Saturday, but I did test the fuel pressure gauge tonight and it was at 46 at cold idle. Let me know if this is an issue.
Glad to hear the car is going to get worked on soon. As for fuel pressure regulator at cold idle 46 seems to be alright but pull the vacuum line and see what the regulator goes up to at idle. Also check to see if there is any fuel in that line if so then your fuel regulator diaphram might need replacing.
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Old 10-03-2013, 12:56 PM   #11
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Are you making full boost? Does boost suddenly drop to 0 when it starts to bog down?
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Old 03-24-2014, 10:41 PM   #12
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Hey guys, this has been a circus since September and we are just now getting to the root of all of the issues. In hindsight, we now know what the issue was, but the new problems created opened up a massive can of worms that I'm not sure all of you want to hear but it will be good to share in case this ever happens to anyone else. More importantly, I hope I can save someone else from this. Here goes...

Everything listed above from previous posts was due to ONE single solitary problem...the catalytic converter. I bought the car in Miami from an individual who had AA assemble and test the car, so I know the install was first class and top notch. One problem for me was that it had no cats. Living in Tennessee, however, we have cat converter laws and I had to have one. Not knowing the ways of the world where you can have a hollowed out cat with bypass sensors to fool the system, and also wanting to add a rasp reducer due to the very Japanese sound of the car when I bought it, I had someone custom manufacture a set of 100 cell cats along with the rasp eliminators. After the install 2-3 years ago, I was fully legal in Tennessee and the car sounded badass, with a very deep booming exhaust note.

Initially, upon the car bogging down we checked everything, and I mean EVERYTHING. Unfortunately, we had little if anything to go on. My mechanic, who is very smart and very good at deductive reasoning, ran through every system the car had, from fuel system to air intake to electrical to the supercharging system itself, etc...and came up with nothing. Unbeknownst to us at the time, several monitors were turned off on the car due to the AA Supercharging system. And rightfully so, they had to turn them off so the car won't light up like a Christmas tree every other stop light. Nonetheless, we had no monitors to flag the fact that there was trouble, so we had to try to figure this out one deductive step at a time.

After going through every system we could, we probably should have taken the exhaust apart for inspection. However, my mechanic knew that one of the techs at BMW of Nashville was familiar with the car and Viral had suggested a smoke test to see if that could help us diagnose the problem. So I agreed to have the car sent to BMW of Nashville for further diagnostic testing. They had the car for three days, ran several tests and put about 17 miles on it. They told my mechanic that it was more than likely the cats being clogged.

When my mechanic went to pick the car up (I was out of town) he noticed it was smoking wildly out of every orifice in the engine bay. It wasn't doing this when he dropped it off. Someone in the parking lot stopped him and said, "Man your car is smoking ALOT! Are you sure you want to drive it out of here?" He mentioned they did the smoke test on it and therefore thought it was okay to drive home as it would probably wear off. Not knowing any better, he drove it home. Whatever they did there, the damage was done, and we are just now getting to the bottom of it this week. I think there is probably some liability on their part for the fact they were the ones that inflicted the actual damage, but I'm not sure how to ever prove it.

Fast forward 5 months later, and we now know that the cats had basically melted over 2-3 years of heat cycles. This car was never tracked or really run hard other than 0-100 runs on the open road and things like that. The melted cat material finally broke loose while I was driving the car with my kids. I limped it home and that's when all these tests started. Unfortunately, when the car was at BMW of Nashville, whatever tests they performed caused metal shrapnel from the catalytic converter to be sucked back into the engine itself. This caused damage to piston #2 which literally had a chunk of it break off and drop into the bottom of the engine. Pistons 1 and 5 also showed signs of scoring, etc...that basically meant the entire block had to be sent off to VAC for porting, polishing and fitment for new pistons. The engine gets there this week and we will assess the condition of the crank, block, pistons, rods, etc...but I can tell you the pistons will be replaced and the block is almost a certainty to have to be machined.

The funny thing is we started from the top down in our research for some reason, and we basically decided to rebuild the head completely with porting, polishing, etc... due to marginal results from testing the head. We rebuilt it with new hardened bolts, new stiffer springs, new lifters, new shims, some new valves, etc...so the top end of the engine is basically brand new and built for a supercharged engine. We are probably also going to rebuild the vanos to brand new with a rebuilt vanos just to make sure everything is top notch.

So at this point, we are sitting on a car with a brand new head built for the AA system, and a rebuilt VANOS on the way. The cylinders in the block will more than likely have to be bored out and fitted with new, slightly larger pistons from VAC. The rod bearings and other wearable parts will be replaced. We think we will likely be able to salvage the crank and the rods based on their condition.

All in all, I am looking at a bill between $10-12,000 for something that could have been completely avoided had we checked the catalytic converter early on, or never installed the damn thing in the first place. I never would have imagined that a silly little emissions reducing component could cause so much damage to an engine. I have learned my lesson about trying to satisfy the bureaucratic emissions system. The ghost in this machine has taken us 5 months to track down, all because of a bullshit part that I never should have installed in the first place. I can blame those that had their hands on the car when it detonated, but ultimately I wish I had never put the damn cat on it in the first place.

The only great news that comes out of this scenario is that many people believe that if you increase the HP in a car like this from 333hp to roughly 620 hp, you should start from the source and build it from the inside out to really last. Despite my intentions of simply enjoying this car as a weekend toy, it looks like I'm going to get my chance to do this after all.

I hope this helps anyone who has cats on their car already or possibly considers adding them to a car that doesn't have them. Through many conversations, my mechanic has learned that the BMW factory cat is the only, REAL option for a cat if you must have one. They don't disintegrate near as easily and are up to the task. Yes, they have much more restriction, but that is the price you pay for having a cat on your car in the first place. Everything else, especially the 100/200 cell cats are designed for flow. I'm not an engineer, but since mine was a 100 cell cat that literally disintegrated into engine, I can guess they are designed for flow, not durability and true resistance to high heat.

I'll keep the updates flowing as we finish this project and happy to post pics if anyone is interested.
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Old 03-25-2014, 10:05 AM   #13
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Wow so sorry. From reading the first post again, you had nailed the symptom and almost knew it all along and mystically underlined the car and the problem it had. I always though failed catalytic converters made rattle sounds, but I will keep this in mind as I have stock cats with boost.



I am trying to guess how the shrapnel got sucked back in and none got spit out into other sections of the pipes to make any sounds.
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Old 03-25-2014, 10:42 AM   #14
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Need help: Boost/power problem on 2002 E46 M3 AA Gen VI/Stage II

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Wow so sorry. From reading the first post again, you had nailed the symptom and almost knew it all along and mystically underlined the car and the problem it had. I always though failed catalytic converters made rattle sounds, but I will keep this in mind as I have stock cats with boost.



I am trying to guess how the shrapnel got sucked back in and none got spit out into other sections of the pipes to make any sounds.

Deceleration creates vacuum in exhaust.... Some stock cars with cats close to ports r known for the same problem when cats break apart and get sucked into cylinders... I hate to see when that happens...
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Old 03-25-2014, 11:06 AM   #15
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the best cats are the vibrant race cats. They are meant for the higher EGTs found in FI cars. They flow well also. If you need cats, you need these
http://vibrantperformance.com/catalo...1022_1063_1326
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Old 03-25-2014, 11:45 AM   #16
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HJS cats are the only way to go on a FI car. They are expensive... Supersprint use them in their $3k section 1's. In 8000 supercharged miles, I've had no issues. Talk to Jack @ ************************ to build you a section 1.


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Old 03-25-2014, 11:35 PM   #17
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Sorry to say, but Jack at custom performance is who built my race cats and my rasp eliminators...the ones that detonated my engine. I may not have received the proper cats, but I did tell him exactly what my car was, so I would have hoped he would have steered me in the right direction. The rasp eliminator and the cats were around $1,200 IIRC.

Live and learn. If your engine ever bogs down, turn it off and take the cats off for inspection.

BTW, We did see shrapnel going both ways...there were metal parts all the way down to the mufflers. We saw nothing going towards the engine until we took it apart. I assume that means anything that close was sucked straight into it.
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Old 03-25-2014, 11:40 PM   #18
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Quote:
Originally Posted by MachRc View Post
Wow so sorry. From reading the first post again, you had nailed the symptom and almost knew it all along and mystically underlined the car and the problem it had. I always though failed catalytic converters made rattle sounds, but I will keep this in mind as I have stock cats with boost.



I am trying to guess how the shrapnel got sucked back in and none got spit out into other sections of the pipes to make any sounds.
Yes, I am literally kicking myself for not just stopping and ripping the damn cats off from day one. I had a 1983 BMW 320is that I put leaded fuel in on accident and it melted the cats. So I Knew EXACTLY what a clogged. melted cat felt like, but due to the non-factory supercharged setup, I did not rely on my instincts and chose to let the inspection of all systems play out. It didn't end well.
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Old 03-26-2014, 09:23 AM   #19
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Originally Posted by 911/M5 View Post
Sorry to say, but Jack at custom performance is who built my race cats and my rasp eliminators...the ones that detonated my engine. I may not have received the proper cats, but I did tell him exactly what my car was, so I would have hoped he would have steered me in the right direction. The rasp eliminator and the cats were around $1,200 IIRC.

Live and learn. If your engine ever bogs down, turn it off and take the cats off for inspection.

BTW, We did see shrapnel going both ways...there were metal parts all the way down to the mufflers. We saw nothing going towards the engine until we took it apart. I assume that means anything that close was sucked straight into it.
Strange, he recommended the HJS cats to me since I told him it was a FI application. Sorry to hear about your issues.

HJS lists the maximum horsepower per cat. I have a Y-pipe on my other supercharged car, and I chose to go with two smaller cats over one large one due to the horsepower ratings. On my FI ///M, I have dual piping all the way back to an X-pipe, so I went with two cats again.

If you find a way to pass both visual and OBD II inspection in TN, please let me know. I haven't tried to pass yet


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Old 03-26-2014, 09:27 AM   #20
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Quote:
Originally Posted by 911/M5 View Post
Hey guys, this has been a circus since September and we are just now getting to the root of all of the issues. In hindsight, we now know what the issue was, but the new problems created opened up a massive can of worms that I'm not sure all of you want to hear but it will be good to share in case this ever happens to anyone else. More importantly, I hope I can save someone else from this. Here goes...

Everything listed above from previous posts was due to ONE single solitary problem...the catalytic converter. I bought the car in Miami from an individual who had AA assemble and test the car, so I know the install was first class and top notch. One problem for me was that it had no cats. Living in Tennessee, however, we have cat converter laws and I had to have one. Not knowing the ways of the world where you can have a hollowed out cat with bypass sensors to fool the system, and also wanting to add a rasp reducer due to the very Japanese sound of the car when I bought it, I had someone custom manufacture a set of 100 cell cats along with the rasp eliminators. After the install 2-3 years ago, I was fully legal in Tennessee and the car sounded badass, with a very deep booming exhaust note.

Initially, upon the car bogging down we checked everything, and I mean EVERYTHING. Unfortunately, we had little if anything to go on. My mechanic, who is very smart and very good at deductive reasoning, ran through every system the car had, from fuel system to air intake to electrical to the supercharging system itself, etc...and came up with nothing. Unbeknownst to us at the time, several monitors were turned off on the car due to the AA Supercharging system. And rightfully so, they had to turn them off so the car won't light up like a Christmas tree every other stop light. Nonetheless, we had no monitors to flag the fact that there was trouble, so we had to try to figure this out one deductive step at a time.

After going through every system we could, we probably should have taken the exhaust apart for inspection. However, my mechanic knew that one of the techs at BMW of Nashville was familiar with the car and Viral had suggested a smoke test to see if that could help us diagnose the problem. So I agreed to have the car sent to BMW of Nashville for further diagnostic testing. They had the car for three days, ran several tests and put about 17 miles on it. They told my mechanic that it was more than likely the cats being clogged.

When my mechanic went to pick the car up (I was out of town) he noticed it was smoking wildly out of every orifice in the engine bay. It wasn't doing this when he dropped it off. Someone in the parking lot stopped him and said, "Man your car is smoking ALOT! Are you sure you want to drive it out of here?" He mentioned they did the smoke test on it and therefore thought it was okay to drive home as it would probably wear off. Not knowing any better, he drove it home. Whatever they did there, the damage was done, and we are just now getting to the bottom of it this week. I think there is probably some liability on their part for the fact they were the ones that inflicted the actual damage, but I'm not sure how to ever prove it.

Fast forward 5 months later, and we now know that the cats had basically melted over 2-3 years of heat cycles. This car was never tracked or really run hard other than 0-100 runs on the open road and things like that. The melted cat material finally broke loose while I was driving the car with my kids. I limped it home and that's when all these tests started. Unfortunately, when the car was at BMW of Nashville, whatever tests they performed caused metal shrapnel from the catalytic converter to be sucked back into the engine itself. This caused damage to piston #2 which literally had a chunk of it break off and drop into the bottom of the engine. Pistons 1 and 5 also showed signs of scoring, etc...that basically meant the entire block had to be sent off to VAC for porting, polishing and fitment for new pistons. The engine gets there this week and we will assess the condition of the crank, block, pistons, rods, etc...but I can tell you the pistons will be replaced and the block is almost a certainty to have to be machined.

The funny thing is we started from the top down in our research for some reason, and we basically decided to rebuild the head completely with porting, polishing, etc... due to marginal results from testing the head. We rebuilt it with new hardened bolts, new stiffer springs, new lifters, new shims, some new valves, etc...so the top end of the engine is basically brand new and built for a supercharged engine. We are probably also going to rebuild the vanos to brand new with a rebuilt vanos just to make sure everything is top notch.

So at this point, we are sitting on a car with a brand new head built for the AA system, and a rebuilt VANOS on the way. The cylinders in the block will more than likely have to be bored out and fitted with new, slightly larger pistons from VAC. The rod bearings and other wearable parts will be replaced. We think we will likely be able to salvage the crank and the rods based on their condition.

All in all, I am looking at a bill between $10-12,000 for something that could have been completely avoided had we checked the catalytic converter early on, or never installed the damn thing in the first place. I never would have imagined that a silly little emissions reducing component could cause so much damage to an engine. I have learned my lesson about trying to satisfy the bureaucratic emissions system. The ghost in this machine has taken us 5 months to track down, all because of a bullshit part that I never should have installed in the first place. I can blame those that had their hands on the car when it detonated, but ultimately I wish I had never put the damn cat on it in the first place.

The only great news that comes out of this scenario is that many people believe that if you increase the HP in a car like this from 333hp to roughly 620 hp, you should start from the source and build it from the inside out to really last. Despite my intentions of simply enjoying this car as a weekend toy, it looks like I'm going to get my chance to do this after all.

I hope this helps anyone who has cats on their car already or possibly considers adding them to a car that doesn't have them. Through many conversations, my mechanic has learned that the BMW factory cat is the only, REAL option for a cat if you must have one. They don't disintegrate near as easily and are up to the task. Yes, they have much more restriction, but that is the price you pay for having a cat on your car in the first place. Everything else, especially the 100/200 cell cats are designed for flow. I'm not an engineer, but since mine was a 100 cell cat that literally disintegrated into engine, I can guess they are designed for flow, not durability and true resistance to high heat.

I'll keep the updates flowing as we finish this project and happy to post pics if anyone is interested.
Wow I am reading this and I can feel your pain . Headers play a big role especially if you go F/I. Shoot me a PM or E-mail if you need any help.
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Viral Vahia
Active Autowerke | 9940 SW 168 Terrace Miami, Florida 33157
www.activeautowerke.com | viral@activeautowerke.com
Phone: 305.233.9300 Ext. 232 | Fax: 305-253-8921
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