I have a 87 firebird with the L69 305 and it runs perfect ........sometimes. There is no rhyme or reason when it happens. Hot,cold,slow,fast,etc... It is like a bucking when I am on the gas but if I let off it stops but when I get back in the gas it starts bucking again......sometimes! Some days it runs perfect and other days it wont hardly run at all, rain or shine. Its been doing this for about a year and I cant figure out what is going on. No codes at all. Can someone help me? BTW car is bone stock except flowmaster catback and K&N filter.

 

If it's an '87, it's not a bone stock L69. If it's a bone stock L69, it's not an '87.

Unless somebody swapped a bone stock L69 into your '87.

Most likely you've got an ignition component going south. Candidates include coil and ignition module. Could also be cap, rotor, wires, or plugs.

 

MY mistake its a LG4. Anyway I have a new module , cap ,rotor, plugs and wires. Any other suggestions?

 

I replaced the coil and it does the same thing! Whats next? BTW the carb has been rebuilt also, Professionally. The fuel pump is out of the equation as I replaced it too.How about the ECM? Could it be bad without a code coming up?

 

Could it be the Oxygen sensor? It does smell like it is running rich sometimes. Usually when it starts bogging. But wouldnt I get a code if it was running rich? Does anyone know what is going on here? Thanks for all replies!

 

Have you checked the wires going to the distributor ignition module. Sometimes they get corroded and will intermittently act up. Try running the car and wiggling those wires to see if it will act up. If it does, you've found your culprit. Either way, chasing down your gremlin will require more info that can only be obtained by you doing further investigation. Ground wires should also be suspect. Since the computer isn't throwing any codes at you, the problem must be either mechanical or electrical in nature. I would be loathe to claim the ecm as your problem, since it doesn't happen all the time. The same thing goes for the mechanical side. Other than electrical, the only intermittent problem I've ever run accross was a fuel pressure regulator with a diaphram that was only weak at w.o.t., but that was only intermittent for a short time before it yelled "hey, it's me!" If you're smelling gas and the computer isn't throwing any codes, I'd say you either have a leaky fuel line or your carb or t.b.i. needs to be rebuilt.

 

I had the carb rebuilt and I did have a leak at the rubber fuel hose but I fixed that. I will check the grounds and wiring to the distributor as you suggested. Thank you. If I find the problem I will report back.

 

Well I looked at the connectors on the coil and noticed that both of them had the locking tab broken off. I took the connectors off and clean the terminals and put them back on. Took it for a drive and it performed flawlessly. But It has done that before, run great then the next day not. So I will drive it for a while this week and see what happens. Do you think the coil connectors could be losing contact and causeing the problem?

 

Anythings possible. Sometimes the easiest fixes are the most elusive. Keep driving it around and post again if the problem rears it's ugly head again. I hope it's fixed though. Take care my man.

 

Thanks buddy and I will post if it comes back or if I know it is gone for good!

 

I'll keep an eye out.