dctrumpet

iTrader: (10)

Thanks again for all your help on my 305 tbi to 350 tbi swap. You guys have been great.

I have another issue to deal with and i will give all the tech info that i have at this point and try to be very specific. I think giving a complete history of what has been done will be best then i will give the symptoms. lol!!!

So, if anyone has any ideas i would greatly appreciate your help.

Let me begin with a detailed history of my recent swap.

HISTORY:
I recently installed a reman. 350 long block from Advance Auto into my 92 firebird. Originally a L03 305 tbi. I transfered the throttle body, intake, etc over to the new 350. I installed the following items on the new engine:

New Parts:
1. Knock sensor & ESC module for a 350
2. 350 Injectors
3. IAC, TPS, Coolant temp sensor, Temp send unit, fuel pump &
filter.
4. Mallory coil, Accel 8.8mm wires, Blue streak cap/rotor,
NGK iridium plugs
5. Adjustable fuel pressure regulator
6. All new vacuum hoses, etc
7. A/C Delco EGR valve and O2 sensor
8. New ECU with a Moates chip he burned for me (i have all equipment to burn new chip and datalog.

SYMPTOMS:
1. Very rough idle in park/neutral (smooths out some when in drive or reverse).
2. Extremely poor gas mileage (11 mpg. Used to get 21 mpg with old 305 engine).
3. Some hesitation while engine is cold and slightly improves at full operating temp.
4. surging while driving
5. somewhat of a raw fuel smell
6. engine/car seems to be rough while accelerating.
7. overall the power does not seem to be there. My 305 did better even with a main bearing going out, LOL!

TECH STUFF:
1. Base timing 0 with EST disconnected
2. Manifold vacuum 20 in/Hg and strong/steady
3. Fuel pressure 13 psi at the throttle body and 28 on pinch test
4. Traced all vacuum lines/wires, etc and all is 100%

HELP!!! I am going to run datalogging today on this to see what things are doing. What do i need to look for specifically? BLM? O2? etc??? What should i do from here?

Does it sound like i need to tune the chip more or does it sound like a valve issue or SOMEHTING ELSE???? LOL

Thanks so much for everything.

gapimpin

it sounds like eigther your timing is off or your flooding the engine check the timing first then check the f/a ratio with that raw gas smell you may wanna be carefull not to leave it running too long or you may wash the cylinder wall and im sure you know what a b**** that will be

redbird_400

Ok maybe I've just been reading to much on EGRs and emissions but I swear these symptoms were listed under a failing EGR or other emission components almost everywhere. Though with that check I'd still wonder why your a/f mixture seems rich.

oh, got any error codes?

dctrumpet

iTrader: (10)

Base timing is set to 0. No codes at all at this point.

iroc89123445

well i think u should trade it in for a honda cas there junk

ljnowell

I can agree with that!

z28maro

id agree with the others you sound like youre running rich. before you spend to much time playing with that though id check to make sure youre sparking, ie fouled plugs, melted wires, ec

crapper_mekanic

Isn't average base timing, disconnected from ECM, 6 degrees BTDC? Unless there are some special conditions I'm not aware of...

dctrumpet

iTrader: (10)

I am not sure what the timing should be. I have been told that with the EST disconnected it should be 0, but do you think that 6 BTDC is correct for a 350 TBI??????

crapper_mekanic

The term "top dead center" refers to the furthest point the piston travels in the cylinder at the end of the compression stroke. If your timing is set at 0 degrees, the plug emits spark to ignite the fuel right at the beginning of the combustion stroke. I don't believe that is enough time for the fuel to burn completely in the cylinder. It doesn't explode, when fuel explodes in the cylinder, that is when you get "pinging". From what I know, you want the fuel to ignite BEFORE the end of the compression stroke. That way the fuel burning and expanding is what drives the piston to the end of the combustion stroke.

crapper_mekanic

The ECM performs the function of the vaccuum advance, which is what used to be used for spark advance. You always set base timing with the vaccuum disconnected, and the same principle applies to the ECM disconnected as well. When you put the hose on the vaccuum advance after setting the base timing before OBD-1, it advanced the spark as soon as it was hooked up.

ShiftyCapone

iTrader: (7)

Your car is running rough because your stock chip thinks it is running a stock LO3 with 12psi of fuel pressure with 45lb injectors making 170hp. Your car is horribly out of tune. The solution is chip work. If you need an imediate/temporary solution you can run a caprice 350 TBI chip in your f-bodies ECM. A truck chip will not work.

What heads do you have on your motor? If you have swirl ports than 0° is a good place to start. Swirl port heads are fast burn heads and do not need a lot of timing. Guys like Fast355 and Dewey316 only run a max of 28° total with their 300+ hp TBI set-ups. That is all that is required for peak power and it is a positive trait of that head design.

If you are running non SP heads than you can dial in some initial advance. However, this is a bandaid solution until you do chip work. The chip will add timing to whatever your base is set at. So, when you get into the chip you will have full control of timing, fuel and spark requirements.

Also, gas doesn't explode, it burns . Pinging or knock is pre detonation and occurs when the fuel prematurly burns and sends pressue waves that travel through the combustion gases.

dctrumpet

iTrader: (10)

HI Shifty. The chip was done by craig moates. I found out the my harmonic balancer was bad. Just replaced it today. I have standard/stock heads on it.

If i set base timing with EST disconnected and then reconnect the EST the car dies and runs like poop. If i set base timing and leave the est disconnected the car runs great.

Hmmm!!! what to do?

ShiftyCapone

iTrader: (7)

How did the car run when Craig was tuning it? Did the car run fine at one point after your swap? This wasn't a mail order chip was it?