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1990 Coupe w/142K intermittant stalling problem


ptt

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Ive been having an intermittant stalling problem lately.  Usually restarts but sometimes stalls again after trying restarting a few times. Its been about 1K miles since coils and ICU were replaced. This problem has happened a few times now and theres no definate pattern to it happening.  Pulling codes on this car is not very easy as the LED  function is spotty and unreadable.  Its died on me at stop lights and stop signs and has always restarted but usually powerless and then catches and will run until coming to another stop sign or stop light then maybe it will want to stall again.  Ocassionally it will run fine for awhile afterwards stalling.  Maybe I should clean the IAC or spray the MAF with electrical contact spray?  Thoughts?

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Is there something that makes the display for codes unreadable and has it been this way even when it ran properly? It certainly makes it more difficult to diagnose if basic readings like tps, maf, iac and others aren't accessible. By the way, what number is good fuel pressure?

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38-50 psi

"display for codes unreadable" if able to get into diiagnostics then it should start with ECM codes. It may say "No ECM Codes" which means there aren't any.

Does it just shut off like a switch or does it sputter a bit ?

Does the tach just go to zero ? MPH continue to read ?

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On 2/1/2021 at 9:24 AM, padgett said:

38-50 psi

"display for codes unreadable" if able to get into diiagnostics then it should start with ECM codes. It may say "No ECM Codes" which means there aren't any.

Does it just shut off like a switch or does it sputter a bit ?

Does the tach just go to zero ? MPH continue to read ?

It seems to sputter with tach going to zero.  I havent noticed if the speedometer does anything but go on reading zero because Im always at a full stop.  It never stops running while under way...yet.  Sometimes it will restart right off...other times it takes a few tries before it will catch and start.  There must be some codes stored as it doesnt show "No ECM Codes".  Would a fuel filter issue be a possibility?  It isnt an issue thats consistant but seems to happen after warmed to operating temperature.

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How old is the Oxygen Sensor ? Does it only stall once warmed up ? If so unplug OX sensor and see if it still stalls. This will put it into open loop when warmed up.  OX sensor works with MAF to adjust fuel load based on sensor readings. 

I had a stalling issue when it went into closed loop. It was the OX sensor on my car causing the issue.

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"died on me at stop lights and stop signs" Last time I had something like that it was an intermittant TPS going open (zero) ED01. Wild thought: marginal fuel pump dieing when voltage drops at idle. Instrumentation including fuel rail pressure monitor is in order.

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34 minutes ago, Dashmaster said:

How old is the Oxygen Sensor ? Does it only stall once warmed up ? If so unplug OX sensor and see if it still stalls. This will put it into open loop when warmed up.  OX sensor works with MAF to adjust fuel load based on sensor readings. 

I had a stalling issue when it went into closed loop. It was the OX sensor on my car causing the issue.

Since I've have had this 1990 coupe I've never replaced the O-sensor.  Going on 13 years now owning it.  Its surely about time to either replace or clean just about every one of the sensors.  I'd be doing whats considered "SHOTGUNNING" it with new parts but its probably time to as I used it as a Winter time daily driver.  I will be checking its performance as each sensor is replaced to see which one improves performance.  I have misplaced or lost my only OBD-1 scan tool and cant seem to find a replacement online  thats priced close to reasonable.  I do have an AUTOSCAN OBD-2 SCANNER but it only works on 1995-2002 OBD-2 systems. 

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13 minutes ago, padgett said:

"died on me at stop lights and stop signs" Last time I had something like that it was an intermittant TPS going open (zero) ED01. Wild thought: marginal fuel pump dieing when voltage drops at idle. Instrumentation including fuel rail pressure monitor is in order.

I dont think its ever had this issue while idling.  Im going to hook the 

fp gauge back up this afternoon and let it idle and see if I can reproduce the sputtering and dieing.

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13 minutes ago, ptt said:

I have misplaced or lost my only OBD-1 scan tool and cant seem to find a replacement online  thats priced close to reasonable.

 

On 1/31/2021 at 11:57 AM, ptt said:

Pulling codes on this car is not very easy as the LED  function is spotty and unreadable.

The Reatta's onboard diagnostics is about the best scan tool you can get for troubleshooting a Reatta. Why can't you read it? If the Instrument panel is the problem you would be better off replacing it than buying an obsolete OBD-1 scan tool.

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6 hours ago, handmedownreatta said:

center of the firewall behind the engine.three relays.at least on an 89.i temperarely swapped it with one of the others.

My 1990 coupe only has two relays on the firewall.  

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  • 2 weeks later...

I finally saw some sunlight this morning so I put the recharged battery back in the Coupe and started replacing the oldest sensors beginning with the MAF.  That was the culprit.  First I unplugged it and it started right up.  Plugged it back in  and the engine died.  Tried to clean the old MAF with MAF SENSOR SPRAY CLEANER and let it dry for a half hour inside while I went in to warm up.  No dice.  Engine would catch but I had to pump the pedal to keep it running.  It wouldnt idle at all.  Put new MAF in and it started right up immeadiately.  I checked my records and the Ignition Module and Magnovox Coils are less than 500 miles old.  I let the engine run up to operating temp and took a short drive.  All appears to be back to normal.  Thanks to all for your replies!

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On 2/3/2021 at 8:51 AM, Ronnie said:

 

The Reatta's onboard diagnostics is about the best scan tool you can get for troubleshooting a Reatta. Why can't you read it? If the Instrument panel is the problem you would be better off replacing it than buying an obsolete OBD-1 scan tool.

Almost everything I own is OBD1.....I think I loaned it out and it didnt find its way home....

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Fuel pressure good?

I had one Reatta that would act like PTTs. Checked the fuel pressure and was 39 PSI. You would think that was enough but changed the fuel pump and no more troubles. I think off hand the book calls for 43 PSI.

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  • Ronnie changed the title to 1990 Coupe w/142K intermittant stalling problem

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