hey everyone my 1991 pontiac firebird is having some problems.it runs but does not have enough power to move.it backfires and misfires like crazy .the spark plugs blacken up after a while of running but are not wet with fuel and it has a little bit of blue smoke comming out.i already repplaced the injectors and map sensor and many other parts on it.it has a 3.1L V6 as an engine.....any ideas???

 

I would check your timing first and make sure you are in the 6-10 degree range.

https://www.thirdgen.org/settingtiming

 

i just had the timing done in june though

 

Any codes? Do you have a scanner? (to read data from various sensors...)

 

If you think your timing is set correctly and it is misfiring from all cylinders and not just one the next thing you should probably check is the ignition system. Also try disconnect the est wire (used to set timing) and see if it helps clear up the misfires.

this too!

 

i dont have a scanner at home but i do have one at the shop.ill try these ideas.thanks

 

oh also does anyone know where i can get a bigger engine for my car really cheap???these 3.1L's suck

 

How much bigger would you like to go? (and how much money ya got?)

Going from the six, to a v8, will require changing the trans as well, as the bellhousing bolt pattern is different from the six, to the eight.

 

oh honestly i dont care bout the work i just wanted a v8.and ill spend around 300-400

 

ouch. I would recommend saving your money for a while, until you have enough to do the swap right. 3 to 4 hundred is only going to get you a VERY used engine/trans (if that...)..... and you will probably be installing more problems than you can shake a forest at.

 

Did this problem just start?

 

no i rode it all summer with the plugs getting black problem but all i kept doin was replacing them so it wasnt bad.it all of a sudden just happened

 

Need to have a look and see what the temp guage the computer uses thinks coolant temp is at. (separate sensor from the gauge)

 

i think i know wats wrong. for some reason the owner before me never put a fuel filter on the car.

 

Your symptoms don't match with your fuel filter diagnosis. My first thought is that you are running too rich. That will result in black fluffy deposits on your plugs. Another possible cause is weak spark, which may mean that your ignition coil is slowly dying. That fits your symptoms pretty well, especially if you are not getting any computer codes.

 

i know im running to rich but i dont know how to stop it

 

Well, as with all problems, the best approach is troubleshooting. Because I suspect a weak ignition coil, I would do a spark check:

Pull one spark plug wire, insert a philips screwdriver into the boot, and secure it so that the shaft of the screwdriver is positioned about a quarter inch from a good ground (DO NOT DO THIS IF YOU HAVE ANY KIND OF A FUEL LEAK). Have an assistant crank your engine over, and observe the spark. If it is blue, your spark is OK. If it is yellow, it's probably not strong enough, and you should try swapping in a new coil.

If you are uncertain about how to do the test, or about your results, a standard replacement coil is about $20, so it isn't a huge risk to replace it. You can also opt for a higher performance coil, such as an ACCEL, but its about $50.

Again, this is all assuming that you don't have a "CHECK ENGINE" light or any error codes. The temp sensor theory mentioned earlier also seems valid, but then I would expect you to have an error code. Also, it would probably run OK until it warmed up.

The temp sensor can be checked by putting an ohmmeter across the terminals. If the resistance remains the same regardless of temperature, it's bad. You may want to invest in a Haynes or Clymer manual for your car to help you with more scientific diagnosis of your sensors.

I hope this helps.

 

I accept with information:Pull one spark plug wire, insert a philips screwdriver into the boot, and secure it so that the shaft of the screwdriver is positioned about a quarter inch from a good ground

 

ignition coil was already replaced right before i bought the car

 

You might want to try an oxygen sensor. They're fairly cheap and a bad one will cause your car to run rich.

 

That begs a couple of more questions:

• Why was the coil originally replaced? For this problem, or some other reason? What were the results? Did the PO tell you that the car had a problem that he couldn't solve? I ask because if he replaced the coil for some other reason, it may be that this coil is defective, and actually introduced the problem.
• I notice you said that you drove it all summer by replacing the plugs every so often... which tells me that the problem has been getting steadily worse. Has this problem been with the car for the entire time that you have owned it?
• Are you getting any trouble codes (CHECK ENGINE light)? If your oxygen sensor is not right, you should be getting an error code.

 

already found out it is my computer thats bad

 

OK, well, I think that is a bit uncommon, but it explains why you were getting no trouble codes.

Are you up and running now? Merry Christmas to you!

 

Glad to hear this was finally solved! Been following this thread for awhile

 

im in the proccess of getting a computer now. thanks for all the help. happy new year=]