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1995 caddy chugs until warm


steve6

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just looking for best suggestions on this, fuel pump/pressure ruled out and fuel filter changed.. 1995 deville, 4.9 and no ODB II codes, can you get more detailed info through the dash controls?

Starts up and seems fine, once you start driving it, rough idle, chugs until fully warm.. not sure where to start.

I don't know these engines, just wondering if anyone who has one has seen similiar issue, or best place to start.

Edited by steve6
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just looking for best suggestions on this, fuel pump/pressure ruled out and fuel filter changed.. 1995 deville, 4.9 and no ODB II codes, can you get more detailed info through the dash controls?

Starts up and seems fine, once you start driving it, rough idle, chugs until fully warm.. not sure where to start.

I don't know these engines, just wondering if anyone who has one has seen similiar issue, or best place to start.

Turn ignition ON. Depress WARMER and OFF simultaneously for a few seconds until codes show up on the driver info center. Write them down and post here. Turn ignition OFF. Most likely dirty throttle body and EGR passages, but can be many other things too.

The saddest thing in life is wasted talent

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Sounds like an open loop problem before the engine gets warmed up.

You say NO CODES, good that you changed the fuel filter. Do you have black exhaust when this is happening? Do you smell fuel?

In open loop before the O2 sensors take over, the engine is designed to run rich, like in the old days when the CHOKE was on till it warmed up. Whatever is happening is slight because the O2 sensors are able to stabilize the engine once its warmed up, so its not outside their range of affect

It sounds like she is either starving for fuel or running very rich till it warms up, that is why I asked about the exhaust color.

How is the air filter? Have you replaced these items recently (ISC motor, TPS)? Have you checked for vacuum leaks? Have you cleaned your EGR valve? Have you checked your FPR for fuel at the vacuum nipple (not likely the problem but check it anyway). What kind of spark plugs are you using, are they the correct heat range? When did this start?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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not sure the old man wrote these all down right, car history is a little unknown, but passed etest with flying colors....

p012 history

p023 history

p030 history

1027 history

1039 current

1052 history

no ACP codes

no SIR codes

T061 current

PCM ?

if the issue continues, i think ill tell him to check the egr and throttle body

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  • 3 months later...

Just a small update, still happening, my dad took it in to have it looked at, they diagnosed it as 'computer', paid about $300 to have it replaced. Still doing it.. wouldn't start last weekend for him, he hasn't tried starting it since.

I looked it over, I think EVERY sensor on the engine has been changed... I've never seen so many new parts before... but still has issues until warm.

It runs SUPER rich until warm...

Edited by steve6
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Are these codes still valid?

p012 history P012 (E012) .................................................. No Distributor Signal

p023 history P023 (E023) ..................... Electronic Spark Timing (EST) Signal problem [EGR]

p030 history P030 (E030) ................................................... ISC RPM out of range

1027 history I027 ........................................................ PRND321 switch failure

1039 current I039 .......................................... Loss of Road Sensing Suspension Data

1052 history I052 ....................................................... Keep Alive Memory Error

T061 current T061 ...................................................... Motor Pump Circuit Fault

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I would start by studying all the ECM Data parameter values (post them here?). All temperature readings should be close to ambient after the car has been parked overnight. Once the system enters closed-loop operation, pay particular attention to the B/L (Block Learn) and Int (Integrator) values to see how the ECM is adjusting the fueling in response to oxygen sensor voltages.

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  • 3 months later...

Are these codes still valid?

p012 history P012 (E012) .................................................. No Distributor Signal

p023 history P023 (E023) ..................... Electronic Spark Timing (EST) Signal problem [EGR]

p030 history P030 (E030) ................................................... ISC RPM out of range

1027 history I027 ........................................................ PRND321 switch failure

1039 current I039 .......................................... Loss of Road Sensing Suspension Data

1052 history I052 ....................................................... Keep Alive Memory Error

T061 current T061 ...................................................... Motor Pump Circuit Fault

I will have him check them again, he had taken it to a mechanic for the last two months to see if they could fix it, they couldn't figure out what is wrong, he has the car back now.

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Dude get your money back on the computer replacement. Obviously that was not the cause of your problem.

however, make sure the eprom (memcal) inside the computer is installed correctly and locked in place. That being loose can cause probs.

hope they gave you your old computer back...

thre is a while befor all planets align up to warm up where the "stoiciometrics" of the fuel management gets into line.

My car sometimes is a bit rough until it gets warm. The service manual attests to that.

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