I just bought a 86 firebird with a 2.8 awesome car with only 130,000 miles on it so it still has some like left in her.
I have been having some problems with the idle upon cold start up and siting at stop lights. With the cold start u have to hold the gas pedal down a bit to keep it from dieing if you let go or don't do it at all it fires right up then dies. After holding the gas pedal down a bit it will idle fine but still seems like it has sudden drops in rpms but go's right back up.
When driving its perfect but when you come to a stop light it idles fine for a bit but then it has its sudden drop in rpms and sometimes dies.

Did a fuel pressure test and it reads 40 psi and thats good also did a vacuum test in my shop with a smoke machine and there was no leaks so I'm lost at what it could be right now any help!!!

 

I would complete the full Tune up described in the first thread of FAQ's and see how things are after that.

https://www.thirdgen.org/forums/v6/6...or-tuneup.html

 

Thanks THE GAFFER i cleaned the IAC sensor and she runs perfect still gonna do a tune up tho because its been sitting for like 2 years

 

also check your MAP sensor on the left firewall( looking from the front back) sometimes that small hard vacuum line melts near the EGR and will not get the correct signal and you wont have a vacuum cause its melted closed. and it runs under the upper plenum.
make sure your previous owner did not mess with the idle screw

 

ok will check on that today. Also did have oil pressure problem. when i first start the car it sits at 40 or above that once the engine is warmed up it goes down to 20 at idle and only 25-30 well driving is this a bad thing or am i ok on this???

 

as long there is no knocking. what grade oil do you have in it and how long since last oil change. I would run 10w-40 or 15w-40 also you need an oil with a zinc additive because new oils today don't have it in there and you have a flat tappit (hydraulic lifters) all newer engines are roller cams or over head cam so its zinc is not needed.

 

Ugh. I don't know how many times I've said THERE IS NO MAP SENSOR ON A 2.8 EXCEPT 1982-1984 CARBURETED CARS.

Those symptoms posted above are, if not resolved by fixing vacuum leaks and cleaning the IAC, the results of a bad MAF sensor in the air duct.

 

I still need to do the oil change as I'm still tuning her up just got plugs and wires as this were bad. Ill do my oil change soon and do they sell the oils with zinc in it at auto stores or is it something i have to get special. And checked the MAF sensor does need to be changed but well looking there is another sensor in the round air box what is that if i may ask???

Thanks for all your help guys!!!

 

Rotella diesel oil is one oil with zddp in it. You can also run whatever oil you want, and pick up a zddp additive as well at virtually any auto parts store.

That would most likely be your air temp sensor.

Also, welcome to the forum.

 

ok thanks for all your replays it has helped out so much

 

a carb does not require a map sensor , manifold absolute pressure is not a requirement for running a carb. if there is an ECM involved there's a Map or MAF

 

Technically there is a MAP sensor on the 82-84 2.8 carb car. No it is not REQUIRED, but GM put it there anyway.

But here is the kicker; the MAP sensor is the same as the Barometric sensor, but on the 82-84 cars its not used as a MAP sensor, its only used to sense atmospheric pressure.

You are right, its not required, but that doesn't change the fact that its there. Seen it with my own two eyes in the jy.

 

I saw a Firebird converted into a Batmobile in the junkyard once.

 

tightened the belts and that fixed the oil pressure problem i guess the belts where skipping over the oil pump pulley. after cleaning the cap and rotor still having a bad idle when stopped at a light but it won't stall any more.

 

The oil pump dont have a pulley, i think you meant the water pump,but sounds like you just needed very badly needed tune up.glad its running better i hate to hear about f bodys running poorly

 

just found out today that i needed a new radiator cap went through 2 gal of coolant in the past 3 days so a new cap fixed the problem. Also well changing the plugs a few days ago there was a hole in the EGR line from the EGR to the intake. gonna have to go to the local junkyard because none of the shops in town sell it and can't find one on ebay so this in the next quest wish me luck