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NviouSS
May 24th, 2006, 02:41 AM
my car is misfiring and i don't know why. all the plugs are connected. it was running fine all day yesterday until i was heading home from the gf's place. when i try to start it it acts like it wants to die. rpms dip to about 500 then go up to 900. the car shakes a little too.

i logged some data from it and saw that my LTFT's cell count was really high. like 400+ in one cell and 200 in another
joecar
May 24th, 2006, 12:28 PM
What are your LTFT's...? If you have a log chart, post a pic of it.

Do you smell gas from your exhaust tips...?

Check that you get good spark on all plugs (there are various ways to do this, it's a little hard to do in F-body engine bay);
are any plugs not firing: engine running, remove one plug wire at a time, stumble means that one was firing.

Check that you get 58 psi constant (+/- 2 or 3 psi maybe) at the fuel rail with engine running;
are any injectors not firing: get a cheap stethoscope from Sears and listen to each injector;
you'll be able to hear each one above the sounds made by the others, listen carefully;
if you can't hear one, or it pulse at an irregular rate, then it's either not firing or sticking.

Watch out for hands, feet, hair in pulleys/belts and hot engine/exhaust.

Basically you have to determine is the problem spark or fuel.
joecar
May 24th, 2006, 12:38 PM
Also check your O2 sensors/connections/wiring, and your ECT sensor/connection/wiring.
joecar
May 24th, 2006, 03:27 PM
Pull your IAC valve out and clean it.
caver
May 27th, 2006, 09:16 PM
Use the biderectional controls and do a cyl balance test.
If one or more cylinders are dead you will hear no idle speed difference when it is cut out.
If you pick that up then direct your attention to those cylinders.
Check plugs, leads etc
Tre-Cool
June 3rd, 2006, 03:17 AM
Had a mis-fire on mine the other day, took all the spark plugs out and found one of them had cracked the porcelain area in half.

new set of plugs and all is well again.
joecar
June 3rd, 2006, 05:18 AM
Had a mis-fire on mine the other day, took all the spark plugs out and found one of them had cracked the porcelain area in half.

new set of plugs and all is well again.Any ideas what may have caused it to crack...?