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.

dctrumpet

iTrader: (10)

I see alot of viewing of my post. Any ideas?

Fast355

iTrader: (2)

Check engine light status?

Does the timing advance when you reconnect the connector?

Poorly calibrated prom chip comes to mind as well. What ECM do you have? The 8746? If so I will send a modified 350 cop car .BIN for a stock 350 with exhaust.

Make sure that you BPWC is set properly to reflect your injector size and engine size, rough out your timing table, get your BLMs into line, then tweak on the spark some. Now your VEs will probably need to be revisited. Then back to the spark.

dctrumpet

iTrader: (10)

No check engine light at all. (only when est is disconnected)

Timing does not advance when i connect the EST back.

Craig Moates burned chip for me. I sent him a reman 8746 ECM and he burned and installed it for me. He sent me the bin file for it. If you give me your email i will send it to you. Please check it out for me.

The 350 long block is reman to factory specs other than being bored to .040. Exhaust is stock except for muffler.

He said he set the .bin file for 55# injectors, 350 tbi, automatic, etc.

Fast355

iTrader: (2)

Sounds like an EST or Module fault. Perhaps the ECM is not commanding any extra timing advance?

Stock 350 injectors are 61 lb/hr. 305 injectors are 55 lb/hr, this is probably adding to the high fuel consumption.

dctrumpet

iTrader: (10)

Ignition module? Is that what you mean? The following table is what i went by for the injectors. I got my injectors from Advance Auto and they told me they were 55# injectors for a 350 TBI caprice. Do i need to upgrade to 61#?

GM Tbi Flow Rates Measured at 13psi

Application Color Code Flow Rate lbs/hr at 13psi

5.0L Green/White 40

5.7L Orange/Black 55

5.7L Police package Yellow/Brown 68

*7.4L Blue/Black 75

*7.4L Dark Red/ Dark Blue 85

Fast355

iTrader: (2)

That table is around 10+ years old and it has been updated over the years. At one point in time, it was not even known that the color codes meant anything. If they are equivalent to the orange/black code 350 injectors they are 61 lb/hr, no need to upgrade.

The size on the 305 injectors is horribly off. A stock 4.3 uses 45 lb/hr injectors.

http://www.turbocity.com/default.php?cPath=16_30

dctrumpet

iTrader: (10)

My injectors are GP Sorensen 800-1807N. These are for a 1995 GMC Pickup with a 350 tbi.

OE number that matches this GP Sorensen are OE #17112493; Throttle Body Injection. So, i believe that i have the correct injectos, but are these 55# or 61# or....?

Fast355

iTrader: (2)

OE spec should be the 61 lb/hr for that application.

dctrumpet

iTrader: (10)

So, I am sure that he burned the chip for 55# and not 61# injectors. So, I have 61# injectors installed and an ECM that is set to 55#. Can this cause my issues with rough idle? I had this same rough idle, poor fuel economy, etc with my stock 305 chip and stock injectors. Hmmmmm!

Fast355

iTrader: (2)

IF it is setup that way, you are overfueling your engine. It is more or less the equivalent of putting 350 injectors in a 305.

dctrumpet

iTrader: (10)

Where in TunerPro RT or the .bin file do i look to see how he programmed the chip for the injectors?

dctrumpet

iTrader: (10)

Prior to this chip and new injectors i had the opposite problem right? 305 injectors and 305 ECM trying to fuel a 350. I had the same rough idle, poor fuel mileage, etc.