91' Deville, 78k miles, running/accelerating rough, Need some help! No codes
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 6 of 6
HT4100 4.1, 4.5, 4.9 Discussion, 91' Deville, 78k miles, running/accelerating rough, Need some help! No codes in Cadillac Engine Technical Discussion; Hey fellow Cadillac people. I drove a minivan for the last 10 years, it wasn't fun but it happened. The ...
  1. #1
    dvaughndeville is offline Cadillac Owners Member
    Automobile(s): 91' Deville
    Join Date
    Jan 2014
    Age
    29
    Posts
    2

    91' Deville, 78k miles, running/accelerating rough, Need some help! No codes

    Hey fellow Cadillac people.

    I drove a minivan for the last 10 years, it wasn't fun but it happened. The van finally died and I picked up a 91' white deville (sedan) pretty cheap. The guy that sold it to me told me it skipped a little and probably needed a good tune up. The thing is really clean inside and out and I didn't even feel what he was talking about right off the bat, but now that's my main issue.

    So this is my deal: I'm no mechanic but I'm not afraid to get my hands dirty and can follow directions to a T. I didn't really take great care of my past vehicles but if I can get this car running nicely I want it to be the one that lasts a long time and am willing to put the time and effort in to get that done.

    The problem: I don't think this car was driven much recently and may have sat for some time (not sure). When accelerating, It feels quite rough, I can feel a pulsing through the gas pedal and wheel and can see the hood vibrating with the pulse too, it just feels shaky. I feel it more in the lower portion of each gear and especially when it gets into overdrive around 45mph. I don't think it's alignment because if I take my foot off the pedal it coasts like a stick of butter on a hot pan. When idling it sounds the same way and will occasionally "surge"? sounds like someone hits the gas pedal for a quick second. And the exhaust makes a "put put put put" sound. Also when I park the car and get out the exhaust has kind of a strong smell, not like eggs but just strong exhaust (sorry I don't know how to describe it). None of the lights are on either and no codes

    Here's what I've done so far:
    I picked up a Haynes manual for the car and did the tune up, got all the parts from rockauto, I changed the plugs, wires, distributor cap and rotor, air filter, fuel filter, ran 2 bottles of fuel injector cleaner (techron) in two tanks of 93 octane gas. Also replaced the battery. When I took the plugs out they seemed ok also the distributor cap and rotor looked fine but I had already got the parts so I changed them anyway. It was the first tune up I had done by myself so I felt good when the car started again hah, but the problem remained. I took it to a local shop owned by my buddies father, he took it for a spin said he could feel it skipping, he took a closer look and I guess tested the ignition system and said it was fine (which made me feel good about the work I did) He said he thought it might be a fuel injector sticking, and told me to run more of the same stuff (techron) through and to come back if nothing changed. I don't think it will and just want to know what the problem might be and how to deduce what is going on with it without slowly doling out money to some guy I don't know.

    I really appreciate any help/ideas!

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    drewsdeville is offline Cadillac Owners Master
    Automobile(s): 2011 Crown Vic LX
    Join Date
    Oct 2004
    Location
    Oak Creek, WI
    Posts
    5,310

    Re: 91' Deville, 78k miles, running/accelerating rough, Need some help! No codes

    You can find the misfiring cylinder the old fashioned way - pull ignition wires one at a time until you find one that doesn't change how the engine runs. That will be the cylinder you focus on.

    Once you find the misfiring cylinder, check resistance through it's fuel injector coil with a multimeter. This can be done at the harness connector (follow the wires) - no need to remove the injectors just to check them. It should return 12-18 ohms (cant remember spec, but that's the typical range). If you want, compare it to the others. They should all match each other closely. Those that don't match the majority need to be replaced.

  4. #3
    dvaughndeville is offline Cadillac Owners Member
    Automobile(s): 91' Deville
    Join Date
    Jan 2014
    Age
    29
    Posts
    2

    Re: 91' Deville, 78k miles, running/accelerating rough, Need some help! No codes

    will do this very soon (once it goes above 12 degrees outside), and report back, thanks for the quick response drewsdeville!

  5. #4
    Ranger's Avatar
    Ranger is online now Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Location
    Woodstock Ill.
    Age
    66
    Posts
    73,020

    Re: 91' Deville, 78k miles, running/accelerating rough, Need some help! No codes

    Return the Haynes manual or use it to sop up oil, coolant or trans fluid. Get a real FSM by Helm Inc. Ebay is your friend.

    Did you check the two EGR tubes down in the TB to see if they are carboned closed?

    Have you checked for vacuum leaks?

  6. #5
    drewsdeville is offline Cadillac Owners Master
    Automobile(s): 2011 Crown Vic LX
    Join Date
    Oct 2004
    Location
    Oak Creek, WI
    Posts
    5,310

    Re: 91' Deville, 78k miles, running/accelerating rough, Need some help! No codes

    ^^^also worth looking into - after the dead miss is resolved.

  7. #6
    charco68 is offline Cadillac Owners Member
    Automobile(s): 1990 Cadillac Deville
    Join Date
    May 2013
    Posts
    6

    Re: 91' Deville, 78k miles, running/accelerating rough, Need some help! No codes

    Hey dvaughndeville-

    Sounds exactly what I went through with my '90 DV, that had 47k on the clock. Beautiful car that rode like a dream, but chugged along like a cylinder was missing. It was really bad in OD, it practically shook the dashboard. I ended up replacing all 8 fuel injectors, and that did the trick. I couldn't believe it the difference. The originals were still in there, and weren't doing their job well thanks to 23 years/2k miles a year of driving. I did have the EGR valves cleaned out (sooty) the spark plugs and O2 sensor replaced *just* in case, but look into those injectors, IMO. Let sus know what happens!

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting