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93 Caddilac Deville 4.9

  
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93 Caddilac Deville 4.9

 
PizzaboyMike PizzaboyMike
New User | Posts: 25 | Joined: 11/11
Posted: 12/09/11
11:56 AM

My dad has one, He loves the car, but I never have thought it runs quite right Confused , when you put your foot in it, it'll leave black marks! But at idle it dies once and awhile. He took this car to his favorite mechanic, they forwarded the car to the Caddy dealer..had it for six months...blah blah..Never really found or fixed anything. I thought --maybe there is a way to just put a carb on it and a differnt distributer? Kinda by-pass the computer outfit. Has anyone fooled around with this Idea? I'd love to make the car run great for him. It gets him around, but he would'nt take it anywhere...Know whata mean?!  Gosh and it has a beautiful body and Chassis. Laugh  
Pontiac Power!

pepsi1 pepsi1
Enthusiast | Posts: 301 | Joined: 10/11
Posted: 12/09/11
05:13 PM

Hi pizzaboumike:

That still has OBD-1. So take this as ba basic clean -up. If none of this works then we'll get into the other stuff.

A. Is the check engine light on?
B. Do you have any codes in the computer?

1. Go to the EGR. Disconnect the vacuum hose from it and for now plug the line from the engine side. So when your done thr EGR is just sitting there.

2. TBI.  remove the assembly. Just mark anything you remove so it  will put back together correctly. Clean the IAC (idle air control),with a cleaner made for that. Once your done with all the cleaning.
3. Replace the spark plug wiress
4. Replace the spark plugs
4.A Replace distributor cap and rotor.
5. clean all the battery connections.
6. Put it back together and let us know how its doing.
7. Just make sure the CAT isn't plugged from all the rich running.

Don't remove any parts without marking their oriantation! Grin  Cool  

waynep7122 waynep7122
Enthusiast | Posts: 594 | Joined: 08/09
Posted: 12/09/11
09:12 PM

turn the key on...     with your first and forth finger.. push the OFF and warmer buttons on the ac panel.. do not have your foot on the brake when doing this...

one of the displays.. perhaps the one to the left off the steering column might start displaying trouble codes..

write them down..    it will stop at 7.0       if you missed one.. turn off the key and start again...

these models have a built in scan tool right at your fingers...

please post any codes...

i have worked on dozens of these...

i would suspect the throttle body throttle shaft bore for wear if the car has over 80,000 miles..    engine off.. grab the throttle lever.. open it slightly.. see if it wiggles around in the bore..   it should NOT..    the TPS voltage needs to come back to the exact position each time you take your foot off the gas..  if it varies..  you will have intermittent stalling..


idle air control motors have failed..  idle air control valves have failed...  when the external idle speed control motors fail.. the NOSE switch may hang up.. the motor may retract.. and not extend.. leaving the throttle body too far closed..  engine stalls..    i have one 92 that the guy keeps calling me on why his car runs rough..  but the nose switch is not in contact with the throttle lever so the ECM thinks the throttle is open..  preventing it from reverting to idle fuel trim..  idle fuel trim will have the fuel injector pulse width of 1.3 or 1.4MS... and you can see that with a proper push of the button..

the guy with the 92 just does not want to pay me to pull the glove compartment and ohm the harness to the idle speed control motor.. i can see it work sometimes.. other times it retracts and won't extend..   i was going to resolder his ecm also...

i have found the black and yellow twisted pair for the coolant temp sensor with the insulation broken away.. this will usually set a coolant temp sensor voltage high code..

i will have more info in a little while

if you can.. can you take a picture off the ac control panel.. there are several versions..  i just want to make sure that i post the right picture/diagram..  

PizzaboyMike PizzaboyMike
New User | Posts: 25 | Joined: 11/11
Posted: 12/09/11
09:17 PM

Pepsi,

Thanks for the list, This one will take me awhile, but we have awhile, the car has been like this for at least 8 years I bet...But he loves it and I'd love to help the ole man out. But I'll get the car from him one of these days and tackle these steps, it doesn't sound too bad, and I have a couple friends who the computers to read codes..

And I bet the cat is clogged, I can remember him revving it up and black smoke rolling out...Not real bad black, but blacker than normal. I was reading on other forums on this site too, Do you think it could be a ground problem at the starter? Some guy wrote to drop the starter and clean up the ground real good. But I doubt its that.

And I remember his mechanic, whom I know too, was saying somthing about how they have a goofey distributor they only made for a couple of years? It only has a 100,000 on it, Which is alot, but I know they should probably get twice that if not more.

Like I said, I'll print and save your list, and run through your suggestions. thanks again..but this may take a little while. I let you know what I find.

-Mike Smile  
Pontiac Power!

PizzaboyMike PizzaboyMike
New User | Posts: 25 | Joined: 11/11
Posted: 12/09/11
09:24 PM

Hey Wayne,

Must of posted while I writing to pepsi, Okay guys stay tuned, but give me awhile, I might rally a couple of true mechanic soldiers to help tackle this one. It sounds pretty straight forward from both of you, but I know guys that know alittle more than me, especially when it come to electrics.  But thanks for writing and sharing knowledge, maybe we can get this beauty running like it should. And I will take pics! Thanks,

Mike  
Pontiac Power!

waynep7122 waynep7122
Enthusiast | Posts: 594 | Joined: 08/09
Posted: 12/09/11
10:11 PM

this is one set... i don't know if its the exact one for your car.. but how its done does NOT change...

86 89Cadillaccodeaccess


lets go through this again..   key on.. engine off.. or running..  foot off the brake pedal...

two fingers.. push the OFF and the WARMER buttons at the same time for 5 or 6 seconds.. all the dash segments will turn on. let go...    look for the other display or the one below it to display codes...  write them down..    you can turn the key off..  start over till you have verified the codes have been written down properly...

you should now be at 7.0...

then push the LO button...

86 89Cadillacdiag1

this takes you to ECM data...    it should start flashing P.0.1   then a number.. then back to P.0.1... work the throttle.. you are looking at degrees of the throttle..  it should return the same number it started with..  you still need to do the hands on shaft bore test.. got any wiggle..

you should be able to push the LO button again.. to get to P.0.2.. the MAP sensor.. should be close to 100...
when you start the motor.. this P.0.2 should drop to around 40 to 50..  as you slowly accelerate the engine.. the numbers should NOT get larger.. that would indicate a blocked exhaust system...

push the low button again.. P.0.3.. should be really close to the same 100  depending on weather conditions..

push the lo button again.. p.0.4   coolant temp sensor..   should match the engine temp as tested with an infrared temp thermometer..

push the LO button again.. P.0.5   manifold air temp sensor..   engine cold.. should really match the coolant temp sensor..

push the LO button again.. P.0.6...  this is the fuel injector pulse width..  with the engine running.. up to temp.. around 95C to 100 C on the P.0.4 range..    you should get 1.3. or 1.4 at idle...



this is the business end of the idle air control motor..    see the threaded opening.. there is a screw that fits in that ..  it should be touching the throttle lever when the engine is idling..   when you bring the RPMs up.. the shaft should extend..  as you release the throttle.. the lever should come into contact with the head of the screw. and the shaft retract slightly..   always maintaining.. contact at idle...  never retracting all the way ..



oh.. these are the trouble codes for the ECM on the 4.9 motors

0900C1528025ed53  

waynep7122 waynep7122
Enthusiast | Posts: 594 | Joined: 08/09
Posted: 12/09/11
10:39 PM

screw #3 is accessed through the hole in the bracket #9

0900C1528025edcc

i sometimes find it easier to bend the TAB on the throttle lever slightly to change the base idle speed other than trying to get a T15 into the screw.. if the tamper proof plug has not been removed..

there is a base idle speed adjustment.. but it requires a switch to plug into only two of the wires from the idle air motor and back it off totally ..   its a REAL pain to get the idle speed control motor unplugged.. i normally have to use a pair of LONG nose pliers and a screw driver to gently lift the latch just enough to NOT break it off..  

pepsi1 pepsi1
Enthusiast | Posts: 301 | Joined: 10/11
Posted: 12/09/11
10:54 PM

Wayne your my savior and I'm not making fun.BUD... Thanks Grin  Cool
Bob  

PizzaboyMike PizzaboyMike
New User | Posts: 25 | Joined: 11/11
Posted: 12/09/11
10:58 PM

Wow! Awesome !!! Great pics.....or Diagrams Rather! I will get back to you guys, but give me some time. Thanks a bunch!

Mike  
Pontiac Power!