1990 Left pre-cat pipe glowing red!
Thread Starter
Le Mans Master
Joined: Mar 2001
Posts: 9,740
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From: A Pretty Part of MO
1990 Left pre-cat pipe glowing red!
Hey, all...
My 90 l98 coupe still isn't running right. I'm starting it up each day to burn out the old gas that's in the tank. I'm down below half a tank now. I noticed today that after maybe 15 minutes of running, I was getting white smoke from under the car. I pulled the car back in the garage and took a look underneath. The exhaust pipe in front of the driver's side pre-cat was glowing red, while the passenger side pipe was not. Any thoughts on what would cause this?
The car idles rough, and stumbles. It will run for a few minutes, and then bog out and almost die. Then it will clear up and run for another few minutes.
I have a front y-pipe that eliminates the pre-cats. How tough is it to swap that out? IIRC, I bought it from Mid-America. Is it doable for 1 guy, or will I need some help?
thanks,
Chris
My 90 l98 coupe still isn't running right. I'm starting it up each day to burn out the old gas that's in the tank. I'm down below half a tank now. I noticed today that after maybe 15 minutes of running, I was getting white smoke from under the car. I pulled the car back in the garage and took a look underneath. The exhaust pipe in front of the driver's side pre-cat was glowing red, while the passenger side pipe was not. Any thoughts on what would cause this?
The car idles rough, and stumbles. It will run for a few minutes, and then bog out and almost die. Then it will clear up and run for another few minutes.
I have a front y-pipe that eliminates the pre-cats. How tough is it to swap that out? IIRC, I bought it from Mid-America. Is it doable for 1 guy, or will I need some help?
thanks,
Chris
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
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The left pre-cat glowing would make me think that it's running rich on that side and the pre-cat is clogged. The white smoke would indicate coolant being burned though it is possible that it's just oil on the exhaust system. Can you determine the source of that smoke; does it smell like burned oil or coolant?
First off pull all the spark plugs in the left bank and a copla plugs from the right bank for comparison.
Jumper ALDL pins A&B (upper right) and start the engine to put the ECM into Field Service mode. After a few minutes the SES flashes should slow from 2Hz to 1Hz and the on/off segments should be of equal duration. This will tell you if it's going closed loop and if it's running too rich.
The hard parts of installing the front Y will be in getting the header bolts out without breaking (use lots of PB Blaster) and getting the main cat off the OEM front Y. Here you may need to cut off the old Y and slot the end still in the front of the cat.
First off pull all the spark plugs in the left bank and a copla plugs from the right bank for comparison.
Jumper ALDL pins A&B (upper right) and start the engine to put the ECM into Field Service mode. After a few minutes the SES flashes should slow from 2Hz to 1Hz and the on/off segments should be of equal duration. This will tell you if it's going closed loop and if it's running too rich.
The hard parts of installing the front Y will be in getting the header bolts out without breaking (use lots of PB Blaster) and getting the main cat off the OEM front Y. Here you may need to cut off the old Y and slot the end still in the front of the cat.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Originally Posted by 90qzrblu
Hey, all...
My 90 l98 coupe still isn't running right. I'm starting it up each day to burn out the old gas that's in the tank. I'm down below half a tank now. I noticed today that after maybe 15 minutes of running, I was getting white smoke from under the car. I pulled the car back in the garage and took a look underneath. The exhaust pipe in front of the driver's side pre-cat was glowing red, while the passenger side pipe was not. Any thoughts on what would cause this?
The car idles rough, and stumbles. It will run for a few minutes, and then bog out and almost die. Then it will clear up and run for another few minutes.
I have a front y-pipe that eliminates the pre-cats. How tough is it to swap that out? IIRC, I bought it from Mid-America. Is it doable for 1 guy, or will I need some help?
thanks,
Chris
My 90 l98 coupe still isn't running right. I'm starting it up each day to burn out the old gas that's in the tank. I'm down below half a tank now. I noticed today that after maybe 15 minutes of running, I was getting white smoke from under the car. I pulled the car back in the garage and took a look underneath. The exhaust pipe in front of the driver's side pre-cat was glowing red, while the passenger side pipe was not. Any thoughts on what would cause this?
The car idles rough, and stumbles. It will run for a few minutes, and then bog out and almost die. Then it will clear up and run for another few minutes.
I have a front y-pipe that eliminates the pre-cats. How tough is it to swap that out? IIRC, I bought it from Mid-America. Is it doable for 1 guy, or will I need some help?
thanks,
Chris
more then likely, gunk in the old gas has damaged some of the injectors, causing raw fuel to dump into the exhaust, killing the cat.
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Originally Posted by bogus
stop trying to burn that old gas... drain it out and dispose of in a lawn mower. All it will do is mess up a good engine.
more then likely, gunk in the old gas has damaged some of the injectors, causing raw fuel to dump into the exhaust, killing the cat.
more then likely, gunk in the old gas has damaged some of the injectors, causing raw fuel to dump into the exhaust, killing the cat.
If running the engne to get rid of the old gas is such a good idea, just drive the car 200 miles and all the old gas will be gone lot quicker! I am being facetious!After you get rid of the old gas, I would suggest (maybe someone already has), change the fuel filter, add a bottle of drugstore variety Isopropyl alcohol 93% to your new tank of gas and also use AMZOIL PI as directed to clean out the injectors and the system.
Hopefully you haven't created any "terminal" problems with the injectors, pump or pressure regulator. If the exhaust condition continues, you may have bigger problems
Jack
Burning Brakes
Joined: Aug 2001
Posts: 1,238
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From: walled lake MI
agree with the cat theory.
i would pull that pre-cat and check it out ASAP. a clogged cat will trap heat, cat temps rise, high temp melts the monolith, clogs it some more, and so on.
good luck...
i would pull that pre-cat and check it out ASAP. a clogged cat will trap heat, cat temps rise, high temp melts the monolith, clogs it some more, and so on.
good luck...
Pro
Joined: Sep 2002
Posts: 609
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From: Buford Georgia
My 89 was making strange noises and was taking it to the local dealership thinking I had a water pump bearing going out. Car went into shut down mode but I limped into the shop. Precats were glowing red. Found that both precats were clogged.
Got lucky and didn't hurt anything else. But decided to put the precat eliminator pipe in and put a high flow main cat on. Runs great and passes the sniffer test in Ohio.
Good luck.
Got lucky and didn't hurt anything else. But decided to put the precat eliminator pipe in and put a high flow main cat on. Runs great and passes the sniffer test in Ohio.
Good luck.
Thread Starter
Le Mans Master
Joined: Mar 2001
Posts: 9,740
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From: A Pretty Part of MO
Update....
I took it up to a shop today, and they changed the front Y-pipe to the pre-cat eliminator pipe, and I also had them put on the muffler eliminator kit that I bought nearly 2 years ago. The gas gage went from just under a half tank when I took it out this morning to the last 2 little bars and the reserve light when I picked it up. So, I filled it up with fresh 92 octane on the way home. It still stumbled a bit, but was much smoother overall. It's still running rich on me, so I'm going to take it to another shop next week to have them look at that.
The exaust sounds wonderful, though...no precats and no mufflers. Pure music when it revs, nice and rumbly when it idles.
I took it up to a shop today, and they changed the front Y-pipe to the pre-cat eliminator pipe, and I also had them put on the muffler eliminator kit that I bought nearly 2 years ago. The gas gage went from just under a half tank when I took it out this morning to the last 2 little bars and the reserve light when I picked it up. So, I filled it up with fresh 92 octane on the way home. It still stumbled a bit, but was much smoother overall. It's still running rich on me, so I'm going to take it to another shop next week to have them look at that.
The exaust sounds wonderful, though...no precats and no mufflers. Pure music when it revs, nice and rumbly when it idles.
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Racer
Joined: Oct 2001
Posts: 311
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From: Roseburg OR
I'm with cash's 90, I had the same problem, same year. checked on getting them reconditioned, but was told they are not worth it, get new ones.
The only problem I had with the exhaust was where there was a slip fit that was tight, I also did it by myself, with Rhino ramps. I was even looking at the same y-pipe but went with the Flowmaster force 2 for an LT-1, and had the downpipes made to adapt it, I like them.
The only problem I had with the exhaust was where there was a slip fit that was tight, I also did it by myself, with Rhino ramps. I was even looking at the same y-pipe but went with the Flowmaster force 2 for an LT-1, and had the downpipes made to adapt it, I like them.
