firebirdkid26

Alright so I have an 86 T.A. that I purchased dead and brought back to life with a 305 in it. I finally got it running and registered and drove around for a couple days happy as can be. I then developed an antifreeze leak and had to replace a couple hoses and thermostat. Now my idles a little rough, and when decelerating the car backfires. The engine is mostly stock but I have headers, a transgo shiftkit, and I cut off my exhaust from the cat back and I did a full tune up when I got the car. Any help is appreciated I just want to get this thing back on the street!

gta_knight

Have you got the orange SES light on the dash ?

It could be a few different things, dirty plugs, bad TPS etc

firebirdkid26

My snapon scanner was giving me code #34 which was saying I have carbon buildup in my throttle body, so i bought tb cleaner and cleaned it out and it started running a little better but didn't fix the backfiring on deceleration problem. I don't have any other codes but the scanner does say I'm running lean, I tested all my injectors and they passed every test I through at them so I dont think i'm lacking fuel which means I must be getting too much air, I thought perhaps the EGR was stuck open so I plugged it to see if it would run better but no dice. I'm stumped

firebirdkid26

I think I may have the problem the scanner is saying I'm running 20 degrees advanced... I believe thats high, what should I be running with a stock 305 tpi?

gta_knight

stock setting is 6 degrees mate.

i know some people advance to 8 or even 10, it just depends if your car likes it or not, mine is set at 6, but im thinking of advancing it a bit to try and get rid of my low down misfire ive got

firebirdkid26

timing didn't change much, my scanner was just reading it differently then you would with a timing light. I changed the o2 sensor in hope of at least getting it to run in closed loop. Now it idles in open loop but when i give it gas it changes to closed, and then when i let off its back to open. I believe this is normal, but i'm running out of ideas without just throwing parts at it! thank you for the help!

firebirdkid26

So heres an update, yesterday I decided to check all the voltage on my plug wires, they were all over the place reading below 5 at some points and above 20 at others. I ordered a new ignition module, accel distributor coil, and accel wires. Hooked it all up today and it started idling really good, I got excited went to go take it for a test drive and what do you know, it still backfires when I deccelerate -__-

now i suspect the timing. When I busted out the timing light the timing mark was unable to be seen. I turned the distributor to where the engine ran best and turned off the car, I looked to see if the timing mark was appearing and with the engine off I saw it sitting at 8 degrees. This must of been a coincidence because I ran the car again, couldnt see the mark still, and then turned it off and the mark was gone. What could cause the mark to be completley unseen? when the car turns off does the mark stop randomly? I need help ! thanks in advance

gta_knight

Did you unplug the connector at the firewall before you done the timing ? otherwise this exact thing happens, the timing mark is off the scale when running the car with it plugged in.

once unplugged thats it ready to set the base timing, when i checked mine a few months ago it was just over 4 degrees so i moved it back up to 6

PhoenixFirebird

iTrader: (2)

Like gta_knight said, make sure you unplug the EST to set base timing or when reading timing. It's a single tan wire with a disconnect right on top of your A/C box towards the passenger side firewall. Disconnecting it disables the computer from advancing the timing, for you to read your base timing. Keep in mind that with it plugged in, your timing mark might shift around a bit because most spark advance tables are tuned to different advances at different loads and rpms.

firebirdkid26

yeah unfortunatley I had it unplugged already so thats not the issue, this car has got me stumped, I changed the TPS just for fun yesterday but still nothing. I'm assuming timing isn't my main issue here, but i'm really out of ideas or parts to change. getting frustrated with this car now!!

firebirdkid26

I forgot to update, but for whatever reason my 2 week old NGK spark plugs were all ****ed up so I replaced them with AC Delcos and now she runs like a beaut!

nomader68

well what happened i have the same problem been searching old forums for a answer. trying to get my timing set did everything that you have...disconnected the tan wire and my timing light says 55 degrees . had it running good but the hei connector is tight up to the firewall... moved the distributor over one tooth both ways and she miss fires. set it back on tdc replaced distributor to hit number 1 cylinder fired her up and again showing 55 degrees of timing i had to move all the wires one post over to get it to run without the cap hitting the firewall. still at 55 degrees of timing

hoytjr

I am having the same problem. Exactly. Any one have a clue?