Question about 1991 Cadillac DeVille

2 Answers

1991 cadillac deville 4.9 fuel trouble

I have replace fuel filter,fuelpump,egr,all injectors,coil pack,plugs,wires,cts and this car still will not idle right,engine surges up and down.At times it is getting to much gas other times it acts like it isnt getting enough gas.Also just replaced fuel pressure regulator.Can not get to the bottom of the proublem.Any suggestions?I am at wits end.

Posted by on

  • Equipman Jun 26, 2013

    Sounds like possibly the Idle speed control motor is causing a problem. There is a switch in the motor assy that tells the pcm the throttle is closed and it should take over the idle. If the switch which is nothing more than a set of points is dirty or not making good contact the pcm will order the motor to send the plunger out to accept it\'s return like the old dashpot used to on carb engines. Then pcm recognizes that throttle is actually closed and retracts. If you shift from park or reverse into gear when this is happening it will retard the timing to slow the engine down so it doesn\'t slam into gear. This continual hunting and surging and timing variation causes an erratic idle. If you are handy enough you can take the ISC apart, clean it up, re-grease with a silicone type lube and put it back into service. Otherwise, buy a new one.

×

Ad

2 Answers

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that got 5 achievements.

    Novelist:

    An expert who has written 50 answers of more than 400 characters.

    Governor:

    An expert whose answer got voted for 20 times.

  • Expert
  • 117 Answers

You just need to go through a simple Idle Relearn Process.

The Idle Speed Control motor will cause the accelerator pedal to tap and the car will surge back and forth, actually acting like there is a lack of power during intial startup.


Whenever a battery is changed, went dead or the ECM computer is replaced.

In order to make the engine run normal again, you need to take the car through a relearn process. Otherwise the idle could be very slow or have a 30mph idle.

To enable it to relearn, here's what to do.

1) Disconnect the battery cable for 15 minutes, before hooking it back up.

2) (KOEO) Turn the Key On with Engine Off, just so the electronics are on, but without starting the engine and turn the climate control panel to off.

3) Push the off and warmer buttons on the climate control panel at the same time and hold for up to 5 seconds for the computer to go into diagnostics.

On the fuel panel screen it will display 888 then E52 and then 70.

When it gets to 7.0 shut off the key for 1 minute.

4) Repeat step 3, two more times.

5) Start the engine without pushing on the accelerator pedal and let it run for 18 minutes with the climate control panel off.

6) After 18 minutes put your foot on the brake and shift into drive and wait 1 minute.

7) Then turn on the a/c by pushing the auto button. It needs to be warmer than 60 degrees F so the compressor can engage. Wait 1 more minute.

8) Put the shifter back in park and turn the key off.

9) Wait 1 minute

10) Idle relearn is now complete and the engine should start and run correctly.


Posted on Sep 16, 2009

  • Jack McCann
    Jack McCann Sep 16, 2009

    In order to make the engine run normal again, you need to take the car through a relearn process. Otherwise the idle could be very slow or have a 30mph idle.



    To enable it to relearn, here's what to do.



    1) Disconnect the battery cable for 15 minutes, before hooking it back up.



    2) (KOEO) Turn the Key On with Engine Off, just so the electronics are on, but without starting the engine and turn the climate control panel to off.



    3) Push the off and warmer buttons on the climate control panel at the same time and hold for up to 5 seconds for the computer to go into diagnostics.



    On the fuel panel screen it will display 888 then E52 and then 70.



    When it gets to 7.0 shut off the key for 1 minute.



    4) Repeat step 3, two more times.



    5) Start the engine without pushing on the accelerator pedal and let it run for 18 minutes with the climate control panel off.



    6) After 18 minutes put your foot on the brake and shift into drive and wait 1 minute.



    7) Then turn on the a/c by pushing the auto button. It needs to be warmer than 60 degrees F so the compressor can engage. Wait 1 more minute.



    8) Put the shifter back in park and turn the key off.



    9) Wait 1 minute



    10) Idle relearn is now complete and the engine should start and run correctly.



×

Ad
  • Level 1:

    An expert who has achieved level 1.

    Mayor:

    An expert whose answer got voted for 2 times.

  • Contributor
  • 1 Answer

My be the transmission discs are not changing proprerly. may need new transmission>

Posted on Sep 10, 2009

Ad

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of.(from cars to computers, handyman, and even drones)
click here to download the app (for users in the US for now) and get all the help you need.
Goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

How to check coil packs and spark plugs wire with a multimeter. ..having random/ multiple misfire P0300...need to know their spec? 97 Cadillac Deville, 4.6 engine/Northstar


I don't think you really understand what this fault code means, it means that likely all the engine cylinders are misfiring at random no set pattern, not any particular cylinder. I would start with checking for engine vacuum leaks like the intake manifold gasket. that is all I can say since you provided no make, model or year and engine type and size information.

Sep 21, 2016 | 1997 Cadillac DeVille

1 Answer

What is causing misfire on cylinders 2, 4, and 6?


Could be injectors, but I would focus on the spark plugs and coils. I'm not sure if you have a coil pack on your car, or individual coils on each spark plug. If the plugs and coils are ok, then check the injection. All your codes are the same bank, so it could possibly be your fuel rail is not getting correct pressure.

Feb 14, 2016 | 2007 Cadillac CTS 3.6L

1 Answer

What are codes p1401 p0302 p0305 p1409 p0301


P1401 Differential Press Feedback EGR Circuit High Input
Your EGR port is plugged. Replace your EGR valve, and clean the ports
A code P0302 may mean that one or more of the following has happened:
  • Faulty spark plug or wire
  • Faulty coil (pack)
  • Faulty oxygen sensor(s)
  • Faulty fuel injector
  • Burned exhaust valve
  • Faulty catalytic converter(s)
  • Running out of fuel
  • Poor compression
  • Defective computer
  • A code P0305 may mean that one or more of the following has happened:
    • Faulty spark plug or wire
    • Faulty coil (pack)
    • Faulty oxygen sensor(s)
    • Faulty fuel injector
    • Burned exhaust valve
    • Faulty catalytic converter(s)
    • Running out of fuel
    • Poor compression
    • Defective computer
    • A code P0301 may mean that one or more of the following has happened:
      • Faulty spark plug or wire
      • Faulty coil (pack)
      • Faulty oxygen sensor(s)
      • Faulty fuel injector
      • Burned exhaust valve
      • Faulty catalytic converter(s)
      • Running out of fuel
      • Poor compression
      • Defective computer
      • A code P0302 may mean that one or more of the following has happened:
        • Faulty spark plug or wire
        • Faulty coil (pack)
        • Faulty oxygen sensor(s)
        • Faulty fuel injector
        • Burned exhaust valve
        • Faulty catalytic converter(s)
        • Running out of fuel
        • Poor compression
        • Defective computer
        • p1409
        • EGR Vacuum System Leak - Read Our Article on EGR Valve Codes For Help With This Oldsmobile Check Engine Light Code

Sep 25, 2014 | Cars & Trucks

2 Answers

2008 Cadillac CTS returning P0303 after replacing spark plug and coil pack


Error Code: P0303
Description:
Cylinder 3 - Misfire Detected
Possible Cause:
Wiring harness, igniter and fuel injector connectors.
Ignition system. (Spark plugs gaps)
Fuel injector No. 3.
Fuel pressure.
Running out of fuel.
EVAP canister purge valve.
Evaporative emission system.
Low compression, cylinder No.3. (check valve clearance and throttle plate for excessive wear)
Engine control module (ECM).

Feb 27, 2014 | 2008 Cadillac Cts

1 Answer

2005CADILLAC CTS INTERMITANTLY SHUTS OFF WHEN STOPPED


many things cause intermittently stalling if you see check engine flashing on code scan for faulty mass air flow sensor.faulty idle air control valve or egr solenoid.could have bad spark plugs and wires faulty fuel injector. contaminated fuel restricted fuel filter or fuel pump failing. faulty TCC solenoid .

Aug 14, 2013 | 2005 Cadillac CTS

1 Answer

I have a 1991 Cadillac Deville with a V8. It won't pass smog. Has high co. I replaced the egr valve, charcoal canister, spark plugs, spark plug wires, cap and rotor, catalytic converter, oxygen sen


Hello! when you say you checked the MAP sensor what do you mean? Did you take voltage readings at idle ? A vacuum leak is the likely culprit, especially to the MAP...The minor shake at idle being the major clue...Send a comment...guru..saailer

Dec 24, 2011 | 1991 Cadillac DeVille

2 Answers

1991 cadillac deville fwd 4.9 engine shudders hard under slight acceleration. replaced plugs,wires,cap,rotor button,ignition module,egr valve, cleaned throttle body, still have same problem


I have a 1991 Cadillac Fleetwood 4.9 120000 miles, I have the same problem. replaced plugs,wires,cleaned throttle body, and O2 sensor and have same problem. Taking it to a GM shop on 02/24/10.

Feb 13, 2010 | 1991 Cadillac DeVille

1 Answer

1990 cadillac deville 4.5l runs rough and missfires. Checked fuel pressure and for vac. leaks, both ok. have replaced plugs, wires, cap, rotor, performed injection service. no results. Hooked to scope and...


Had a computer on my 1990 Cadillac Deville bad, after changing plugs, wires, cap, fuel injectors, egr valve, etc.

The computer was not firing an injector and i had a miss and rough running mostly at 35 mph on the roads. It bucked like a bull.in a rodeo.

Aug 02, 2009 | 1990 Cadillac Deville

1 Answer

Car has very ruff idle in park and drive&cuts out while driving


I had a similar problem in my grand prix i did some research and found out a couple different things that it could be... it could either be a bad fuel pump, a bad resitor, or a bad connection in the wires on the fuse box. My problem was solved simply by taking out the fuse box and checking the wire that came from the fuel system. It turned ot that it was just a bad connection. 

Apr 09, 2009 | 1991 Cadillac DeVille

Not finding what you are looking for?
1991 Cadillac DeVille Logo

1,964 people viewed this question

Ask a Question

Usually answered in minutes!

Top Cadillac Experts

yadayada
yadayada

Level 3 Expert

76691 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22219 Answers

Jeffrey Turcotte
Jeffrey Turcotte

Level 3 Expert

8531 Answers

Are you a Cadillac Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...