QuestionQUESTION: My car is a 95 Cadillac Fleetwood which has the LT-1 which is stock with 75000 miles, recently my car has been running extremely rough in all weather, it has been happening for a while but recently it has be getting exponentially worse. The car still runs, but at lower rpm especially in higher gears the car runs so rough that the entire car shakes in drive from 55- about 70 however shaking less as I travel at higher speeds and dissipates as I accelerate. Thinking that it was maybe the injectors I started putting in fuel injector cleaner which had no noticeable effect. And even more recently there has been a dramatic drop in my fuel efficiency, I was getting about 24-25 MPG when it was all normal then it slowly lessened to about 20-22 MPG, but within a month and about 300 miles it now gets about 14-15 MPG(note all these are highway fuel efficiency observations). The amount of gas that is used during city driving has lowered from 17 MPG to 14-15 MPG. I have taken it to a couple paces and each say it might be something else one says the injectors, another the oxygen sensors, and another said that it might be the EGR since that the diagnostic system says that sometimes that it is not operating properly, but this has not happened for a while and the car has been getting much worse over a short period of time. About 5000 miles ago I replaced the Opti-spark, the plugs and wires, coil, and water pump due to it not starting in wet weather. Hopefully you may be able help me, I would really like to do a road trip for spring break but if the car keeps acting like this I may have to rent one.
Thank You for your time and your help
ANSWER: IS or HAS the check engine light ever illuminated on the dash and if it HAS, What codes are you getting ?.
---------- FOLLOW-UP ----------
QUESTION: There are currently non showing but i did use the On-Board Diagnostics system when it traveled home for Christmas and had them written down on paper, but i remember that a egr code did pop up at random times i think it was
(PCM) Codes
00-32 .......... EGR open command did not change fuel mixture during off idle operation.
but could the EGR cause the car to actually shake when driving highway speeds
These are the codes that i wrote down when checked it during Christmas break
(PCM) Codes
00-44 ....................... Left oxygen sensor under voltages (closed loop operation)
and
(HVAC) Codes
02-26 .................................. Serial Data Communication error (shorted/open)
Thank you
AnswerThe FIRST thing you want to do is to CLEAR ALL the codes from the computer using the climate control panel and then seeing which codes return as CURRENT or HISTORY codes and letting me know what you get.
NOTE: Disconnecting the battery will NOT CLEAR the codes.
