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1997 deville no power and stalling


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1997 Deville 4.6 112,000 miles

It has no power in the accelerator.At 55mph it is going about 20 at the top of the next hill.Rolling on a flat I have to feather the accelerator to get it up to speed.Ocasionall complete stall.

Current codes

PCM

P0151

P0171

P0174

Last two codes I understand is "Fuel trim lean both banks"

The car operates like this at cold start and at normal operating tempurator.

I have checked as many sensor connections that I can find.They looked good.I removed the plenum cover and looked for vacume leaks.I cannot find one.Can someone please help.Thank you.Kurt.

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The loss of power that you describe sounds like a classic case of Catalytic Converter failure.

I had one clog up and that's exactly how it acted.

P0151 - Heated Oxygen Sensor (HO2S) Circuit Low Voltage Bank 2 Sensor 1

The p0171 and P0174, indicate a vacuum leak...probably on the rubber plenum between the throttle body and the intake.

Probably cracked on the bottom where you can't see it.

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Which bank is which?

Clogged converter causing o2 sensor to overheat?Is it ruined(02 sensor)?

Where will be the best deal on a converter?I do not mean to say least expensive.

The car ran great.The next time I started the car I experienced all of this.Actually it would not even start up for about a week.Then it was in my way and it started then ran poorly since.

Edited by kurt123
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If this is a 97, there is no rubber plenum between the TB and the intake on this year. But, you do have a vacuum leak or a lack of fuel that affects both banks causing a lean condition. I used to think of a LEAN code as a vacuum leak allowing unmetered air, but have seen these LEAN codes set when not enough fuel is delivered due to a bad fuel pump pressure or clogged filter.

I would look for a vacuum leak, its going to be quite large check the line to the brake booster, and I would put a fuel pressure gage on and check fuel pressure, it should be around 40 to 42 psi.

Here is the O2 Sensor Location Key:

Bank 1 Sensor 1 - right bank (rear) manifold

Bank 1 Sensor 2 - pre-cat

Bank 1 Sensor 3 - aft-cat

Bank 2 Sensor 1 - left bank (front) manifold

If you change an O2 sensor, warm the engine up first, it helps the sensor to come out

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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2 important things to check is fuel pressure at the rail, and your fuel pressure regulator vacumn line for gas. It sounds like possibly a weak fuel pump, clogged fuel filter, or bad pressure regulator

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I appreciate all suggestions.There is a gizzmo just off of the beauty cover.Drivers side and close to the firewall.I believe that sensor has two vacume ports.One is hooked up.The one nearest my right foot has a vacume line going forward .The other one has 90 degrees rubber connection that is not hooked up to anything.Part ?

How do I hook onto the fuel rail?I see the connection.I use it to see if fuel is there with fingernail.I have some guages(retired mech)I'm told this is high presssure.Question .....how do I get on the rail?TY

The description that I have mentioned does fluxuate.

I'm new to this or any Caddy site.

My 91 2500 Chevy P/U W/O O.D. gets bad mpg.

I, love to get my Deville out again.

As always.Thank everyone for all suggestions......Kurt

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ok. on the solenoid toward the firewall, if you see a rubber elbow that swivels, and has nothing attached, that is normal.

To check fuel pressure you hook a FUEL pressure tester up to the schraeder valve on the fuel rail. I believe running should be 37-43. But might not be quite accurate.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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All of these suggestions and facts are great.I will put them to use asap.My car problem really has had me thinking that it is running out of fuel.With your help here on this site I look forward to staying in my deville.

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All of these suggestions and facts are great.I will put them to use asap.My car problem really has had me thinking that it is running out of fuel.With your help here on this site I look forward to staying in my deville.

Without this board, I could not have owned my 96 Deville, the help and information here is invaluable toward owning these great cars.

If you keep your Deville, please consider becoming a supporting member to help maintain this site, for the small annual fee you spend you will save hundreds and up your enjoyment greatly. I didnt appreciate my Deville when I owned it, I wanted an STS, now I miss my Deville, the Monte Carlo and Hyundai Santa Fee just don't get me excited! You just can't beat the ride.

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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All of these suggestions and facts are great.I will put them to use asap.My car problem really has had me thinking that it is running out of fuel.With your help here on this site I look forward to staying in my deville.

Without this board, I could not have owned my 96 Deville, the help and information here is invaluable toward owning these great cars.

If you keep your Deville, please consider becoming a supporting member to help maintain this site, for the small annual fee you spend you will save hundreds and up your enjoyment greatly. I didnt appreciate my Deville when I owned it, I wanted an STS, now I miss my Deville, the Monte Carlo and Hyundai Santa Fee just don't get me excited! You just can't beat the ride.

Took a little 250 mile trip in mine today...

Did a lot of it on backroads instead of the interstates.

That gave me plenty of opportunities for WOT when passing on the little two lane roads.

It killed my fuel mileage, but it was worth it... :) :)

I love my Cadillac.. :)

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I installed a fuel pressure guage to the shrader valve on the fuel rail.

I taped the guage to the windshield.Took an extigiusher along.

It ran 20 to thirty psi.

I think that I will rule out the Cat.Car will run fine at 6000 rpm.

I can be driveing normal(45) ask for a little bit of throttle and still feel it failing in my foot and hind side.

I'll check the pressure regulator for fuel in vacume line but I do not expect to see any.

What is the fuel line pressure excactly supposed to be?

How many cc,s per how many seconds at idle should the flow be?

Thank you.Kurt.

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Fuel pressure is very low, I believe that is your stalling problem, and I am shocked that you can run the engine at 6000 rpm with that pressure.

If you can feel problems at 45, how are you getting 6000 rpm?

Fuel pressure checking procedure according to the manual:

  1. Install the J 34730-1A fuel pressure gage.
  2. Place the bleed hose of the fuel pressure gauge into an approved gasoline container.
  3. Turn the ignition ON.
  4. Bleed the air out of the fuel pressure gage into an approved gasoline container.
  5. Turn the ignition OFF for 10 seconds.
  6. Turn the ignition ON

According to the manual the fuel pressure should be 48-55 psi

However, to me 48 to 55 appears high, I am not sure that any of us has gotten those numbers, hopefully others will report their experience, I think I used to get 42, but then, I never bleeded the gage as they suggest above, so many that is why! Maybe if I bled the air out, I would have gotten the range reported in the manual.

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 use rule of thumb 37-42 being acceptable. have never seen on over 48 psi.

By chancce hav you checked your fuel filter?

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I checked the fuel pressure guage this morning.No fuel in vacume line.Tried to see any indication of fuel on the top half of valve.None found.

Usually I can tell the car is running poorly.Sometimes it feels fine hence starting the car in drive at dead stop like last night and W.O.T in first and second gear to 6K.Iturned to home ,ran it normal and proble reoccured.Almost stalled at 1100rpm when I turned the last corner.Pressure showed under 15psi right then.At 6000rpm pressure aproxamently 30.psi.Never more.I checked pressure with an old A/C low side guage with an adapter on it.Whatever is the problem changes.It has been always changing since I first encounterd this.

I'm a retired mechanic from the 80's.I used to take pride in diagnosing instead of replacing parts untill the problem goes away.I live out in the country a ways.60 miles gets me to an Oreilly with pimpled faced kids and their vast knowledge of anything.Im not flaming.There are 2 "mechanics" in town.1 GM dealer.None will work on any Cadillac except to change oil.I live on the side of a rock hill with no slab or shop.Not complainig.Just wanted to describe that simple things can be not simple here.With your patience I'm sure we can get thru this.Even with all of the gadgets on this car bottom line is it is still a simple gas internal combustion engine.

I'm leaving to drive 95 mile to go purchase a new fuel pressure guage for diagnoses and grab a fuel filterwhile I,m there.

Thanks for the pressure and flow numbers that you gave me.

I promise to keep further post a lot shorter.Thank you.Kurt.

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This definately seems to be low fuel pressure, that would also cause the LEAN codes.

The only reservation I had was your gage, and you are going to get a fuel pressure gage, good for you.

Hang in there, we can help you, it will be no problem with your mechanical experience. We have all levels of experience here, and there is nothing that can go wrong that we have not covered Ad nauseam. Yes this engine is different and it has sensors, but its all very logical. Don't get frustrated.

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 just changed a fuel pump in a mustang that would rev to red line and run great for 10-20 minutes. After the pump had a chance to work a while it could not maintain fuel pressure. The engine would gradually lose power and many times if you shut it of for a very short time (3-4 min) it would rev to red line again. I doubted the pump since it would run to red line fine. Replaced and running fine now. Fuel pressure was just as you describe, actually 55 psi at start up, then gradually lower.

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I did a completely different guage set up and I found the exact same readings as my first.Took it to town and paid a"mechanic" to put his guage on.Never got above 30psi usually not up to 30psi.Since he has a lift I had him install my new hastings fuel filter.Checked pressure again(Mechanics guage)Same results as all before.Did not think I could limp home.Then it started running up to 80mph in 2nd again.

I hope that there is a access panel in the trunk to replace the pump.If not there will be.This last Mustang post makes me a believer.

I reckon the bright spot of this episode is that my fuel guage quit working about 70K ago.May that'll go away too.

For now.....Thanks guyyyyys!

I'll be back...

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Sounds promising

Yep the fuel level sensor is part of the fuel pump, hopefully that will solve your gage problem,

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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Yes the fuel guage on mine did not work either, added benefit, fixed both at once. I also installed a gauge before the filter to rule out blockage from filter etc...I hope you havent just filled your tank like I did, the filler neck had some thing that stopped a siphon hose from reaching the gas::wipetears

so that added a little fun. I will tell you a trick I used though. I removed the pad from the end of my floor jack and used a piece of 2x10 approx 2 ft long with a hole bored in the center and a deep well socket (very tight fit) poked through it and into the jack to help steady the tank on the way down.

Edited by airmike
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Yes the fuel guage on mine did not work either, added benefit, fixed both at once. I also installed a gauge before the filter to rule out blockage from filter etc...I hope you havent just filled your tank like I did, the filler neck had some thing that stopped a siphon hose from reaching the gas::wipetears

so that added a little fun. I will tell you a trick I used though.

I removed the pad from the end of my floor jack and used a piece of 2x10 approx 2 ft long with a hole bored in the center and a deep well socket (very tight fit) poked through it and into the jack to help steady the tank on the way down.

Same thing I did when I dropped the tank on my 84 Fleetwood Brougham... :)

The floor jack really made a difference on getting it down "AND" putting it back in place..

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It helps to have the tank almost empty before starting the job. The job is not all that bad - the worst part is dislodging the short lengths of rubber hose that connect the fuel filler pipe & vent to the tank. After several years, they are really stuck.

I would buy some new strap nuts in case the old ones strip out when removing the strap bolts. It make sense to have new strap bolts on hand as well.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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