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Removed Cat 2.5l now having issues by Burly1
Started on: 06-04-2015 01:10 AM
Replies: 24 (297 views)
Last post by: thesameguy on 06-04-2015 05:53 PM
Burly1
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Report this Post06-04-2015 01:10 AM Click Here to See the Profile for Burly1Send a Private Message to Burly1Edit/Delete MessageReply w/QuoteDirect Link to This Post
I just had my catalytic converter removed and replaced with a straight pipe on my 88 4 cyl. The car now has problems starting and doesn't like to idle. After running for awhile the car died all on its own at a stoplight. It likes to backfire now and runs hot. Anyone have any ideas as to what it could be?
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jaskispyder
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Report this Post06-04-2015 07:20 AM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
What else was touched when this was done? O2 sensor? Check engine light on?
Why did you remove cat?
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Report this Post06-04-2015 08:35 AM Click Here to See the Profile for JetroGTSend a Private Message to JetroGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
Less back pressure could change things up a bit.

This is the best explanation that I could find.

http://www.mustangevolution.../forum/f312/t296628/

[This message has been edited by JetroGT (edited 06-04-2015).]

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Report this Post06-04-2015 09:11 AM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
It should run fine without a cat. I didn't have one on three different 2.5l Fieros. Something else was touched, or it is a coincidence that something went bad at the same time. I had a fuel injector go bad after working on something else.... just odd timing.
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2.5
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Report this Post06-04-2015 09:18 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
How much has it been driven since the removal? Wondering if there is a learning period for the car.
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jaskispyder
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Report this Post06-04-2015 09:22 AM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 2.5:

How much has it been driven since the removal? Wondering if there is a learning period for the car.


Shouldn't be, never had any issues with replacing good cat with straight pipe.

UNLESS the exhaust is plugged (and that is why they removed the cat., thinking it was the issue). We need more information to help this person.

[This message has been edited by jaskispyder (edited 06-04-2015).]

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Report this Post06-04-2015 09:40 AM Click Here to See the Profile for jmbishopClick Here to Email jmbishopSend a Private Message to jmbishopEdit/Delete MessageReply w/QuoteDirect Link to This Post
Sometimes with a clogged cat you can overheat the car causing problems, I've had it kill spark plugs.
Check your cooling system, check or add a ground. replace o2, replace plugs and wires, check fuel pressure, clean the injector. If you don't know the last time these things were done, you're probably overdue anyway. The injector shouldn't be a problem but I've seen more and more problems with TBI especially if they sit with our ethanol gas mixture.

[This message has been edited by jmbishop (edited 06-04-2015).]

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Report this Post06-04-2015 09:47 AM Click Here to See the Profile for jmbishopClick Here to Email jmbishopSend a Private Message to jmbishopEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by JetroGT:

Less back pressure could change things up a bit.

This is the best explanation that I could find.

http://www.mustangevolution.../forum/f312/t296628/


Back pressure is a problem on carburated vehicles. The jetting needs to be changed when you change things that increase or decrease air flow/mixture including altitude changes. Fuel injected vehicles use the o2 sensors to adjust the fuel air ratio so opening up the exhaust is not a problem.

[This message has been edited by jmbishop (edited 06-04-2015).]

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Burly1
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Report this Post06-04-2015 11:04 AM Click Here to See the Profile for Burly1Send a Private Message to Burly1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks guys. I had just replaced the spark plugs within the last 500 miles or so. Also it has been driven at least 400 miles since the removal of the cat so if there was a learning period i would assume it is well beyond that, especially since the car ran fine for awhile after a short period of having these same issues but not as bad and then the problems came back more extreme.
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jaskispyder
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Report this Post06-04-2015 11:09 AM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Check engine light on?

Check your plug wires to make sure they are seated properly.

Why did you remove the cat.

Who removed the cat.?
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Burly1
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Report this Post06-04-2015 11:27 AM Click Here to See the Profile for Burly1Send a Private Message to Burly1Edit/Delete MessageReply w/QuoteDirect Link to This Post
The Service Engine Soon light comes on intermittently. Removed cat because it was bad and I had it done at an exhaust shop in my town. My mechanic drove the car today and he had no issues at all, but yesterday it was constantly having problems.
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Report this Post06-04-2015 11:33 AM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Does it act up when it is wet outside? Could have a bad coil (cracked).

See if you can pull a code from the computer: http://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

Hmm, why would a shop not put a new cat on (legally i thought they couldn't remove a cat)? Did they verify that the rest of the exhaust is good as you could have a bad muffler, where it is blocking the exhaust (sometimes... a piece moves around in the muffler).

[This message has been edited by jaskispyder (edited 06-04-2015).]

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Report this Post06-04-2015 11:44 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
Intermittent SES for me has mostly been EGR.
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Burly1
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Report this Post06-04-2015 11:46 AM Click Here to See the Profile for Burly1Send a Private Message to Burly1Edit/Delete MessageReply w/QuoteDirect Link to This Post
The car did act up when it was both dry and wet conditions. I was surprised that the shop let me just have a straight pipe welded in, they did it without hesitation. I guess they just assume nothing will happen to them if they do it.
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Report this Post06-04-2015 11:52 AM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 2.5:

Intermittent SES for me has mostly been EGR.


2.5L doesn't have a solenoid, just dumb valve. So it shouldn't be a code for EGR. Now, I would check the EGR valve anyway, but no code should appear.

"Code 32 - Exhaust Gas Recirculation system (V6 only)
The EGR solenoid should not be energized and vacuum should not pass to the EGR valve. The diagnostic switch should close at about 2 inches of vacuum. With vacuum applied, the switch should close. Check the EGR vacuum lines for leaks. Replace the EGR solenoid. Replace the EGR valve. "

[This message has been edited by jaskispyder (edited 06-04-2015).]

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Report this Post06-04-2015 12:52 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Burly1:

The car did act up when it was both dry and wet conditions. I was surprised that the shop let me just have a straight pipe welded in, they did it without hesitation. I guess they just assume nothing will happen to them if they do it.


The shop is not liable for registering the vehicle and keeping it road legal. If you pay them to do something that is only legal for off-road vehicles, then it's up to you to only use the vehicle off-road.

That said, if you removed the cat and other problems are apparent that were not before, your car almost certainly has other issues. If the straight pipe was welded or clamped in, and done so poorly, the exhaust could suck in air from outside the system, which could cause the O2 sensor to have incorrect readings, which would normally result in the car running more rich. It would rarely be enough to cause the symptoms you described, however. If a large crack developed upstream of the cat position, in the manifold, it could cause such behavior, though. Most likely you have an issue with a major exhaust leak, or a bad EGR valve or such.

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Report this Post06-04-2015 01:06 PM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jaskispyder:


2.5L doesn't have a solenoid, just dumb valve. So it shouldn't be a code for EGR. Now, I would check the EGR valve anyway, but no code should appear.

"Code 32 - Exhaust Gas Recirculation system (V6 only)
The EGR solenoid should not be energized and vacuum should not pass to the EGR valve. The diagnostic switch should close at about 2 inches of vacuum. With vacuum applied, the switch should close. Check the EGR vacuum lines for leaks. Replace the EGR solenoid. Replace the EGR valve. "



Couldnt the EGR cause it though, by its malfunctioning triggering another item which does set an SES? I seem to have solved SES lights before in this manner. But did so without checking the code, just basing the EGR cleaning or replacement on a hunch based on symptoms.
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Report this Post06-04-2015 01:14 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
What kind of spark plugs did you get?
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jaskispyder
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Report this Post06-04-2015 01:23 PM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Gall757:

What kind of spark plugs did you get?


Yup, AC Delco OEM plugs are the best....
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jaskispyder
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Report this Post06-04-2015 01:36 PM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 2.5:


Couldnt the EGR cause it though, by its malfunctioning triggering another item which does set an SES? I seem to have solved SES lights before in this manner. But did so without checking the code, just basing the EGR cleaning or replacement on a hunch based on symptoms.


Yes, in theory. There is a manual test of the EGR valve that would verify it is working. I suspect something else though.

I am guessing it is an ignition issue, or a plugged exhaust. With that being said, we really don't have enough information at this point.

[This message has been edited by jaskispyder (edited 06-04-2015).]

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Burly1
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Report this Post06-04-2015 02:43 PM Click Here to See the Profile for Burly1Send a Private Message to Burly1Edit/Delete MessageReply w/QuoteDirect Link to This Post
I did use AC Delco replacement plugs.
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Report this Post06-04-2015 03:28 PM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
See if you can pull a code from the ECM to help us figure out what is going on.
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Burly1
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Report this Post06-04-2015 04:49 PM Click Here to See the Profile for Burly1Send a Private Message to Burly1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Car is currently at my mechanics, I will let you know if he gets a code.
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Report this Post06-04-2015 05:25 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Removing the catalytic converter should not cause starting, idle or driving problems. The O2 sensor will signal the ECM to compensate for any change in mixture caused by the free flowing exhaust. Something else must have let go. The car is 27 years old and things can happen.

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Report this Post06-04-2015 05:53 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
The cat can't have anything to do with anything. The last sensor in the system is the O2 sensor and THEN the cat. The fuel injection system doesn't know that the cat even exists on pre-OBDII cars. Maybe the shop damaged the O2 sensor when cutting the cat out, or maybe they did a bad weld job and air is somehow circulating around the sensor and causing bad readings. More likely, I'd say, is that something is wrong with the engine and that's what fouled the cat in the first place necessitating its removal. Maybe you're just seeing an evolution of a pre-existing problem.
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