3 mechanics can't diagnose this.... anybody???
07-27-2004, 02:10 PM
#1
Guest
Posts: n/a
3 mechanics can't diagnose this.... anybody???
Cats - burned thru 5 of them. Running now on front only. Back one burns out first. Some of them burned up in as fast as a week.
Borla header - cracked it all over the place. Replaced.
MAF sensor - completely blows when near redline under load. Car is DEAD until MAF is replaced. Happened twice now.
Check engine is light on permanently. Code reads O2 sensor problem (if memory serves me).
Not racing the car.
Apparently if I drive it somewhat lightly, no problems. No cats lost or MAF pops in a few months, but something is clearly wrong. Afraid to run it hard, plus I've got emissions before long.
3 different mechanics have not been able to diagnose: aircraft mechanic friend, subaru race tuner, and local dealership subaru mechanic.
The theory is a rich/lean condition is burning up cats; but sniffer says normal at idle. Have not tested under load.
Exhaust place says it's my motor problem and will not replace any more cats.
Subaru says it's the aftermarket work, because they could find NO PROBLEM with the motor whatsoever. Full diagnostic.
What has been checked: mass air sensor (recall), fuel pressure regulator, O2 sensors, etc.
What was done: (99 impreza L wagon) new intake, borla header, larger exhaust, standard muffler. That's it.
The only immediate repeatable symptom is to blow the MAF. Spendy.
NOBODY has got this yet. And all my guys are completely stumped. Completely. Car is working for now, but what other damage is being done?
Anybody??? Anybody even heard of anything like this? Love the car and paid in full, want to keep it.
Thanks in advance....
Borla header - cracked it all over the place. Replaced.
MAF sensor - completely blows when near redline under load. Car is DEAD until MAF is replaced. Happened twice now.
Check engine is light on permanently. Code reads O2 sensor problem (if memory serves me).
Not racing the car.
Apparently if I drive it somewhat lightly, no problems. No cats lost or MAF pops in a few months, but something is clearly wrong. Afraid to run it hard, plus I've got emissions before long.
3 different mechanics have not been able to diagnose: aircraft mechanic friend, subaru race tuner, and local dealership subaru mechanic.
The theory is a rich/lean condition is burning up cats; but sniffer says normal at idle. Have not tested under load.
Exhaust place says it's my motor problem and will not replace any more cats.
Subaru says it's the aftermarket work, because they could find NO PROBLEM with the motor whatsoever. Full diagnostic.
What has been checked: mass air sensor (recall), fuel pressure regulator, O2 sensors, etc.
What was done: (99 impreza L wagon) new intake, borla header, larger exhaust, standard muffler. That's it.
The only immediate repeatable symptom is to blow the MAF. Spendy.
NOBODY has got this yet. And all my guys are completely stumped. Completely. Car is working for now, but what other damage is being done?
Anybody??? Anybody even heard of anything like this? Love the car and paid in full, want to keep it.
Thanks in advance....
07-27-2004, 04:17 PM
#2
NASIOC Slut
iTrader: (2)
Join Date: Nov 2002
Location: Roseville, CA
Posts: 4,723
Car Info: 1995 Subaru Impreza 1.8 L
1. Replace the 99RS MAF with a non-paper MAF. That year MAF has serious problems.
2. Borla headers make the car run rich, that could blow out the cats (remove the borla, or get a high flow cat section ala Random Tech [CARB aproved] rather than a stock-like cat)
3. Borlas also make the CEL come on with an 02 error. Either remove the Borla, or get a CEL eliminator.
These are all problems I have heard about before.
2. Borla headers make the car run rich, that could blow out the cats (remove the borla, or get a high flow cat section ala Random Tech [CARB aproved] rather than a stock-like cat)
3. Borlas also make the CEL come on with an 02 error. Either remove the Borla, or get a CEL eliminator.
These are all problems I have heard about before.
07-27-2004, 09:14 PM
#4
NASIOC Slut
iTrader: (2)
Join Date: Nov 2002
Location: Roseville, CA
Posts: 4,723
Car Info: 1995 Subaru Impreza 1.8 L
The newer model cars (WRX, etc.) use them, and the 93-98's used the wire based MAF too. I dont know if the wiring is compatible, but either type of MAF is much more durable than the 98 version.
07-27-2004, 10:32 PM
#5
Registered User
Join Date: Feb 2004
Location: The Hunted Forest
Posts: 720
Car Info: Mazda Protege '02 (Wishing protege has AWD and a H6 twin turbo)
I would definitely assume that the car is running very rich.
I would like to know what the code is exactly. Then fix it and clear the codes on the car.
Possibly a bad cel fix installed becuase of the headers. I could assume its removing the o2 sensor on the headers before the cat and a faulty cel fix would make it run too rich or lean given rpms and load. I could also assume alot but who knows atm
I would like to know what the code is exactly. Then fix it and clear the codes on the car.
Possibly a bad cel fix installed becuase of the headers. I could assume its removing the o2 sensor on the headers before the cat and a faulty cel fix would make it run too rich or lean given rpms and load. I could also assume alot but who knows atm
07-28-2004, 12:52 AM
#7
Registered User
Join Date: Feb 2004
Location: The Hunted Forest
Posts: 720
Car Info: Mazda Protege '02 (Wishing protege has AWD and a H6 twin turbo)
Originally Posted by Ken Berg
That has been a big theory of ours, we're just not able to prove it via measurements. The sniffer at idle showed everthing at normal.
Also, there is almost no soot at the muffler. Which I thought was a lean condition.
So what exactly is a cel fix?
Also, there is almost no soot at the muffler. Which I thought was a lean condition.
So what exactly is a cel fix?
It can be caused by anything but most notibly the EGT and o2 sensors
The fix is a piece of electronics that fool the ECU into thinking the sensor isn't reading faulty becuase something is either missing or changed in the system.
like the 2.2k resister mod for example.
Last edited by RoadSpike; 07-28-2004 at 12:54 AM.
08-01-2004, 08:11 PM
#8
Old School
iTrader: (6)
Join Date: Jan 2001
Location: Union City
Posts: 14,983
Car Info: '99 RBP GM6
he cant use the resistor mod for this N/A engine block..
This is what you NEED TO DO:
1. Go back to 100% stock. Period. Try this first. then put the mods back one ONE at a time.
2. Next time the maf blows, don't buy the $350 maf. Just get the $50 sensor. Part number is 22794AA000. Your local dealership may have to order it, and that could take a day or two. Using good pliers, you can install it yourself in less than 10 minutes. refer to www.scoobymods.com for more information on changing the maf sensor.
3. You need to keep track of the CEL codes you get. This way, you can post them and we can help you figure the issues.
Going back to stock is essential. I wouldn't run the intake, 95% chance that it will blow your maf. It's very hard to find one that wont. Make sure that the headers you are running are sealed using fresh gaskets. Make sure all contact points in your exhaust are using good gaskets. (ie, not blown ones)
I wouldn't run a big exhaust pipe and then into a stock muffler, that's constrictive, and that could further agrivate your exhaust issues. Go full out and use a nice cat back with a free flowing muffler, or keep it stock.
My bet is your headers are blowing the cats, but i know personally that once the maf goes, many other systems have issues. You should really return to stock and start from there.
This is what you NEED TO DO:
1. Go back to 100% stock. Period. Try this first. then put the mods back one ONE at a time.
2. Next time the maf blows, don't buy the $350 maf. Just get the $50 sensor. Part number is 22794AA000. Your local dealership may have to order it, and that could take a day or two. Using good pliers, you can install it yourself in less than 10 minutes. refer to www.scoobymods.com for more information on changing the maf sensor.
3. You need to keep track of the CEL codes you get. This way, you can post them and we can help you figure the issues.
Going back to stock is essential. I wouldn't run the intake, 95% chance that it will blow your maf. It's very hard to find one that wont. Make sure that the headers you are running are sealed using fresh gaskets. Make sure all contact points in your exhaust are using good gaskets. (ie, not blown ones)
I wouldn't run a big exhaust pipe and then into a stock muffler, that's constrictive, and that could further agrivate your exhaust issues. Go full out and use a nice cat back with a free flowing muffler, or keep it stock.
My bet is your headers are blowing the cats, but i know personally that once the maf goes, many other systems have issues. You should really return to stock and start from there.
08-02-2004, 08:53 AM
#9
Guest
Posts: n/a
I had a similair problem in a jeep with repeated burnt cats and a cracked (stock) exahust manifold. It was the Air sensor (I can't recall if it was a MAF or ?). As each new one failed it sent erroneous data to the computer causing the engine to run rich (and lean) and then other symptoms (like cats and cracked manifold) occurred as the air sensor died. I suspected that the problem was that somehow contamination was destroying the sensor, but could never figure out how. It ceased when I replaced the air inlet tube from the front grill with a new, less worn tube. The engine was a stock 4 cylinder with 80,000 hard miles on it.
08-04-2004, 09:40 PM
#10
Registered User
Join Date: Nov 2002
Posts: 56
Hey Ken,
You don't need to be a rocket scientist or racecar mechanic to figure this out. Here's how to approach your problem.
You have two problems: Blown maf and Cats going bad.
There's a reason your maf is going bad. Get rid of that intake and change it back to stock. Replacing your maf sensor can be as cheap as $50 for a new one.
http://www.scoobymods.com/forums/showthread.php?t=414
What's that? That sensor doesn't apply to your car?!? Well, you can shop at
car-part.com. I have gotten many air flow meters from there, from those salvage yards. I get them for around $25 and up...used. I simply spray electronic cleaner through it and install them. Never had a problem with them.
That should take care of your Maf. As for your exhaust, don't touch anything. If you have a good cat on it now, leave it alone. I don't think the problem is your exhaust but with your maf and your engine. Here is the most important thing you can do............
Pull your spark plugs and read them. I'm shocked none of your mechanics did this. It WILL tell the tale as to what is going on inside your engine and why your cats keep melting. You don't need a mechanic to do this. You can do it yourself. Don't know how?
http://www.strappe.com/plugs.html
http://www.nightrider.com/biketech/spkplghnbook.htm#We
http://www.eric-gorr.com/techarticles/sparkplugs.html
A 2 second search pulled that up and those sites are just the beginning. I'm no mechanic but I hope this helps.
You don't need to be a rocket scientist or racecar mechanic to figure this out. Here's how to approach your problem.
You have two problems: Blown maf and Cats going bad.
There's a reason your maf is going bad. Get rid of that intake and change it back to stock. Replacing your maf sensor can be as cheap as $50 for a new one.
http://www.scoobymods.com/forums/showthread.php?t=414
What's that? That sensor doesn't apply to your car?!? Well, you can shop at
car-part.com. I have gotten many air flow meters from there, from those salvage yards. I get them for around $25 and up...used. I simply spray electronic cleaner through it and install them. Never had a problem with them.
That should take care of your Maf. As for your exhaust, don't touch anything. If you have a good cat on it now, leave it alone. I don't think the problem is your exhaust but with your maf and your engine. Here is the most important thing you can do............
Pull your spark plugs and read them. I'm shocked none of your mechanics did this. It WILL tell the tale as to what is going on inside your engine and why your cats keep melting. You don't need a mechanic to do this. You can do it yourself. Don't know how?
http://www.strappe.com/plugs.html
http://www.nightrider.com/biketech/spkplghnbook.htm#We
http://www.eric-gorr.com/techarticles/sparkplugs.html
A 2 second search pulled that up and those sites are just the beginning. I'm no mechanic but I hope this helps.
Last edited by Myxalplyx; 08-04-2004 at 09:42 PM.
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