QuestionQUESTION: Hello, I have been experiencing rather odd problems as of late... When I turn the key over to start, my car acts as if its choked off, or flooded... And it immediately dies... Usually after the 3rd try it'll fire up, but runs rough until I drive it 40-50 yds... It also sounds like someone's tapping, or knocking behind the dash (under the hood) when I turn it off... On occasion it will idle, and rev. Hard a couple times... I just had the TPS, and the ISC motor replaced, my exhaust sealed up, and an 02 sensor put on... The codes it is throwing now are 30, E39, E47, E48, F31, F32, and F48... I was told after replacing the ISC motor, if problems still continued with the throttle reving hard (previous problem) that the computer module was the next suspect... I already purchased the comp. Module due to the fact that everyonce in awhile my digital read out goes crazy, and starts flashing, along with the svs, ses lights... Have any insight to why this is happening? Thanks...
ANSWER: Hello,
The first problem is you are guessing at repairs which can run you broke quick!
There are far too many components in the system to guess. Now you change the computer and you still have problems then what.
One sensor can set out other sensors and other issues.
I highly recommend as I have been lately if you want to save money and fix the car yourself great, but you need a factory service manual. Without it, you are working in the blind!
That is the only way we fixed those cars back then. It wasn't like now where you just plug in a scanner and it tells you what is wrong.
Back then I used the manual frequently for the diagnostic flow charts. Don't get over the counter manuals. Get the factory service manual for your car. You should be able to scare one up on Craigs or Ebay. It is a mandatory tool!
Good luck!
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---------- FOLLOW-UP ----------
QUESTION: I have a relative idea of what's wrong... It has a built in on board diagnostic system... That's why I stated the codes... Just by the symptoms stated, do u have any ideas?
AnswerHello,
No sir, I don't.
This was the old computer system known as OBD !. In 1994 the international standard was OBD II. I realize that you can get the codes from the dash on this old system, however the codes are general in that system and should not be considered an accurate way of diagnoses.
An example would be a general GM code for that era on an Olds was 13. 13 is O2 sensor. The O2 sensor can set off a code 34 which is a map sensor, which may generate a code of 55 an internal ECM issue.
In the case of the old system which you have, you could have a cascading of codes. Which came first the chicken or the egg?
As for the exact meaning of the codes on a 1992 Cadillac, I don't remember the codes anymore and I got rid of my reference material for this year make model 15 years ago.
When I suggested you obtain a manual, that is in my opinion the only way you will get this car to run right.
I have been working on your style computer system since it came out in the half year of 1980 and Cadillac actually came out a little earlier. I have tried to chase codes as you are oing and as I said, the manual kept me from wasting lots of time and the customer's money.
The OBD II which is still used today is a much easier system to isolate the exact problem with a manual.
I am not here to argue with you. Just to give suggestions to find out exactly the problem is and how to fix it.
If you are dead set on fixing this car by the trouble codes, I wish you luck and I can't do anything else to assist you. I am sorry.
