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Plugged Catalytic? by thecage
Started on: 06-24-2020 09:07 PM
Replies: 11 (188 views)
Last post by: thecage on 06-26-2020 12:30 PM
thecage
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Report this Post06-24-2020 09:07 PM Click Here to See the Profile for thecageClick Here to Email thecageSend a Private Message to thecageEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ok here is my situation.

1984 2.5 Auto - 69,000 miles

Car will start up cold but will die after 1-2 minutes and not restart unless sitting for approximately 30-60min.

It will crank over but will not start.

It has spark and good fuel pressure (tested with guage & inline spark tester)

For giggles this morning I started the car with air filter lid off to observe if injector was indeed spraying fuel and sure enough no problem nice even cone.

Car idle ran a bit high at first for awhile until warm enough and eventually idled normally with a slight hiccup (hunting) for a sec but leveled out. WTF never shut off however. So while running I installed the air filter lid and sure enough a minute or two later car dies.

Is my assumption the catalytic converter is plugged/clogged?

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wftb
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Report this Post06-24-2020 09:51 PM Click Here to See the Profile for wftbClick Here to Email wftbSend a Private Message to wftbEdit/Delete MessageReply w/QuoteDirect Link to This Post
Sounds like the normal airflow in to the throttle body has an obstruction. Is there a heater tube flap on that motor? Been a long time since I had a 2.5. But I would think a plugged cat would behave the same air cleaner off or on.

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thecage
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Report this Post06-24-2020 10:16 PM Click Here to See the Profile for thecageClick Here to Email thecageSend a Private Message to thecageEdit/Delete MessageReply w/QuoteDirect Link to This Post
First time owning a 2.5 myself. Has a heater tube from exhaust up to air intake. Not sure about this flap but looks like something on top of the air intake that may be a flap.

Is this the flap? Is this accessible or repairable?

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sourmash
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Report this Post06-25-2020 09:09 AM Click Here to See the Profile for sourmashClick Here to Email sourmashSend a Private Message to sourmashEdit/Delete MessageReply w/QuoteDirect Link to This Post
My cat plugged so I pulled the O2 sensor and that proved that it was the Cat or muffler causing the problem. Engine ran good enough to drive to the shop for a replacement.
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fierofool
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Report this Post06-25-2020 10:20 AM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
Look inside the filter housing and see if that thermac flap is capable of closing off the intake. I think it probably isn't. The valve opens to pull heated air off the exhaust down-pipe when first starting in cold weather so the throttle body doesn't ice then it gradually opens to allow air to be pulled in through the side intake of the car as the engine warms and closes off the heated air from the down-pipe. But it's open to air flow in all positions.

The blockage is likely in the main air inlet from the side of the car.
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fierosound
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Report this Post06-25-2020 11:57 AM Click Here to See the Profile for fierosoundClick Here to visit fierosound's HomePageClick Here to Email fierosoundSend a Private Message to fierosoundEdit/Delete MessageReply w/QuoteDirect Link to This Post
Definitely sounds like air not getting through to engine from air system.
How new is the air filter element? Take filter out, put lid back on.

This is from Haynes Manual to check for thermac valve operation.



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[This message has been edited by fierosound (edited 06-25-2020).]

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Dennis LaGrua
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Report this Post06-25-2020 01:28 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
 
quote
Originally posted by sourmash:

My cat plugged so I pulled the O2 sensor and that proved that it was the Cat or muffler causing the problem. Engine ran good enough to drive to the shop for a replacement.


I've experienced this on my 85GT quite a few years back. I replaced it with a straight pipe ( for off road use of course!) and wow what a difference. Gas mileage went up 25%.

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theogre
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Report this Post06-25-2020 01:50 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by thecage:
Ok here is my situation.

1984 2.5 Auto - 69,000 miles

Car will start up cold but will die after 1-2 minutes and not restart unless sitting for approximately 30-60min.

It will crank over but will not start.

It has spark and good fuel pressure (tested with guage & inline spark tester)...
Likely is electrical getting hot and wait until cool again.

Pull the console, and tap ECM w/ fingers might show ECM problems.
or change time to run because ECM Case is also Heatsink and has a lot of airflow now.
Helps then get replace ECM, Move PROM to replacement ECM, See my Cave, ECM Heat

Exact what spark tester? Many time set wrong etc and seem to "pass" but ignition still have problems.
Pull tach filter and leave it, See my Cave, HE Ignition and Ground "Myth" notes

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ltlfrari
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Report this Post06-25-2020 03:03 PM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Bad eggs smell is an indication of a cat getting clogged.
Clogging is caused by car running rich so car goes into overdrive converting the extra fuel i the exhaust, gets too hot and melts.

Had that problem, car would drive ok at first then slowly loose power until it choked to death and died. Leave it a while and it would fire back up but even that got worse and worse as time went by.
Suspect I have same problem again. Think I am just going to straight pipe it next time (no emissions here for pre 96 cars), or build me another and swap it in. Too much going on right now though for any of that!

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thecage
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Report this Post06-25-2020 07:33 PM Click Here to See the Profile for thecageClick Here to Email thecageSend a Private Message to thecageEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thank you all for the replies.

I'm back to square one. This time it died idling even with air filter cover off.

Checked and cleaned entire air intake no issues there, thermac system is operational.

I did pull the O2 sensor and let it hang but car still died at idle after a couple of minutes. So i guess not a cat issue.

FYI what I have replaced with new last few weeks:
Distributor with ICM & Pick Coil
Dist Cap, Rotor, Plugs, Ignition Coil
Set timing to 8deg with AB jumped
IAC, TPS, MAP, EGR

I'm leaning now more towards ECM

Funny however that if I jump AB car will run and not shut off, doesn't idle as smooth but not terrible either. So shut car off, plug jumper AB and car restarted and did not shut off even after 10-15 min.

I'm going to leave car tonight and restart in the AM and see what happens.
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ltlfrari
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Report this Post06-26-2020 08:36 AM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Does it still have good fuel pressure when it dies?
If not, fuel filter or pump maybe?
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thecage
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Report this Post06-26-2020 12:30 PM Click Here to See the Profile for thecageClick Here to Email thecageSend a Private Message to thecageEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yes good fuel pressure when it dies, new fuel filter as well.
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