1990 Seville enginemiss

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds

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 3 of 3
HT4100 4.1, 4.5, 4.9 Discussion, 1990 Seville enginemiss in Cadillac Engine Discussion; I have a 90 model seville with the 4.5 engine. While stopped in traffic I noticed the engine was misotice ...
  1. #1
    robbie109 is offline Cadillac Owners Member
    Automobile(s): seville
    Join Date
    Nov 2009

    1990 Seville enginemiss

    I have a 90 model seville with the 4.5 engine. While stopped in traffic I noticed the engine was misotice at highway sing. It misses at idle and low speeds. Do not notice at highway speeds. I have replaced the plugs and wires, added fuel additives, cleaned the os sensors, dist cap. But the miss is still there. All the injectors seem to be working according to the mechanic. However he said it was getting to much fuel. The new plugs are already sooted up as is the o2 sensors. The converter is also getting red hot. I am almost broke and cannot afford to do anymore process of elimination repairs. The only code I am getting is a 0048 or it may have been 0049. I still have the car @ the shop and cant check it. Any help would be great, thanks!!!

  2. Remove Advertisements

  3. #2
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
    Automobile(s): 69 Thunderbird | 90 Seville | 89 Marquis | 72 Torino
    Join Date
    Oct 2008
    Palm Bay, FL

    Re: 1990 Seville enginemiss

    Quote Originally Posted by robbie109 View Post
    misotice at highway sing.

    It's obviously running rich. The most common cause seems to be leaking injectors but it's hard to check them without pulling the fuel rail with the injectors attached and running the fuel pump, watching for drips. Other causes can be a bad fuel pressure regulator, failed O2 sensors, a restricted catalytic converter, or a very dirty air filter.

    E048 (EGR fault) and E049 (A.I.R. system fault) are two separate systems. Verify which of those codes you are getting and note whether they are current or history.

    What are you having done at the shop?

  4. #3
    carnut is offline Cadillac Owners Master
    Automobile(s): 1999 BMW 740 Il. 2005 Jag XK8, 1988 Mercedes Benz 300 SE
    Join Date
    Feb 2003

    Re: 1990 Seville enginemiss

    If the A. I. R system is not diverting air back to the air cleaner once the engine temp is up to normal, that air will super heat the cat. converter. The smog pump supplies air to the cat when cold to shorten the time it takes to reach cat. temperature. Once in closed loop 80 % of that air is diverted to the air cleaner. So have him ck that 1st. The smog pump air acts like a bellows applied to a fireplace fire. More air bigger the fire becomes. That car can be monitored thru on board diagnostics to read the fuel trim values in regards to left bank vs. right bank. If the fuel trim is higher on one side then , most likey, thats where a dripping injector is. If the fuel trim is even left vs. right then probably not an injector problem. The fuel pressure regulator diaphram can rupture causing unregulated fuel into the injector rail. Simply remove the vacuum hose to it just after shutting off the engine. There should be NO fuel dripping from that hose. If there is, replace the regulator and fuel saturated spark plugs.

  5. Remove Advertisements
    Cadillac Forums

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

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

Please enter a valid email address for yourself.

What Cadillac(s) do you own? (Or type NONE)

Please select your insurance company (Optional)


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.


Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts