Hi guys I need your help and expert advise on my recent swap. Mine does not seem to be typical so i need help!!!! 1992 Firebird 305 TBI. Main bearing went out and replaced it with a remanufactured 350 long block from Advance Auto Parts. It is for 1992 year. It is a chevy 350. Professionally installed. Still has original 305 computer chip (prom?) I kept all origianl external components off the 305 tbi with exception of a few sensors of which i replaced new and new ignition system as well. I Re-installed the original 305 manifold and original throttle body off the 305. New parts: 1. throttle position sensor 2. EGR valve 3. O2 sensor 4. Idle air control valve 5. Coolant temp sensor 6. Air temp sensor (in air cleaner) 7. K&N air filter element 8. Tornado insert for TBI 9. New Carter fuel pump 10. V Force muffler Ignition: (original distributor) 1. Accel 8.8 mm wires 2. Mallory external Coil 3. NGK iridium plugs 4. Blue Streak cap and rotor So, all that out of the way, lol. here are the issues at hand: 1. Excessive fuel consumption. Used to get 21 mpg now i get 10 to 12 max (not due to burn outs either, lol). 2. Hesitation at all temps with a rough idle in park and at stop light. Drives well at higher speeds with no hesitation. Able to punch it from a dead stop and light the tires up without hesitation or bogging down. 3. Car periodically will die out. No rhyme or reason. Happens at any temp. 4. Surging during idle and at constant speeds. Manifold vacuum is 20 psi and constant/strong. Fuel pressure is a steady 13 psi at the throttle body. Timing is set to 0. HELP!!!! Do i need to replace the 305 computer chip with a 350? If so, which do i go with? No 350 in those years came with a throttle body with exception of a few pick up trucks and the chips seem to be determined by tire size, etc. Anything else to look at? Any help would be great!!!

You probably should ditch the tornado thing as I'm sure its restricting the extra flow you'll need out of a larger block. I don't see anywhere that you switched over to a 350 knock sensor. You need tuning making the switch as the computer isn't used to adding the extra fuel and you probably need one anyways since I'm sure the cam is different. There is some info floating around on this, quite a bit of it actually... if you didn't pull up anything in the search you were probably adding too many words in there or something. Try "305 to 350 swap" search in TBI section only.

TierAngst thanks for the info. I will upgrade the knock sensor today. I assume you when are saying "tuning" that you are refering to a new chip that is designed for my car. Is that right? Thanks again for your help. Are there chips out there already set for this swap? This swap must be typical but for some reason i cant find hardly anyone out there that has done this exact swap. Kinda strange.

Thanks again!!!

All of your problems are caused by running the stock chip. You need to burn your own chips or find someone locally that can do it for you. Since no two cars will require the same chip you won't find one that you can buy. Each application is specific to that engines needs. Likewise, mail order chips will not suffice. It is best to bite the bullet and learn how to do it yourself.

You also need to add a few parts to your new combo. You need 350 injectors, knock sensor (as stated above) and ESC module.

How do i get the right 350 injectors? Also, what are we looking at cost wise to burn this chip?

There is more than one 350 injector that you can choose from. Each of which have a different advertised flow rate. You will have to choose which one will work for your combo. Seeing how your combo seems basic you can get away with any of the 350 TBI injectors. When you brun your own chips you will dial in the injectors (you will all injector parameters). You can make any TBI injector work provided you know what the flow rating is and what fuel pressure your system is capable of.

The chip burning stuff will run you from $150 to $200.

I live in central Illinois near Springfield. I have called around and nobody seems to do the burning of the chip. So, would love to find out how to get this done.

Thanks. Also, can i just buy a set of injectors that i think will be best and have someone work around that? Also, we have the following parts stores here in town.

Advance Auto Parts
Auto Zone
O'Rileys
Car Quest
Napa

What is the best place to buy the injectors, etc???

http://www.1fastcar.com/sa/p/KEM_-_F..._TBI_28262.htm

That is the cheapest I've found the injectors. They're supposedly the 350 cop injectors which are rated at 65pph.

TierAngst

Thanks for your help. Will these exact injectors work in my car? Part number that you have in the link? Is this what you would do if it were your verhicle? Also, can i install these and the knock sensor now and then in a few days/week get teh chip done? Or do i have to do it all at the same time?

Thanks

Yes thats the right part number, and yes they'll work in your car. The knock sensor I think you can do now, the injectors I would definitely wait on doing until you get a chip.

TierAngst

THanks so much. May i have a number to speak with you in person? My email is rondeauchiropractic@mchsi.com if you want to send it there as so no one else will see your phone number.

Talked to Advance Auto just now. They cant cross reference the KEM numbers but they have in stock the injectors for a 1992 Buick Roadmaster and they will price match them for me. Part number of the injectors is GP Sorenson 800-1807N.

350 injectors are 350 injextors right? not much difference in cars? All 350 TBI ones?

Is the ESC module the same as the Ignition Control Unit? Advance did not have a listing for an ESC module.

Also, the igntion control unit is the same part number for 305 TBI and 350 TBI;

The 92 RM injectors are 55pph and aren't the same as the ones I listed, however these are still 350 injectors and will work just fine as long as you don't have any future plans for big mods like heads/cam. If thats the case by all means let them price match those injectors and don't mention the fact that they're different Or... you can have them look up a 93 caprice 350 and have them look for the part that says police on it. Parts america (advance's distributor) lists it as PN 8001827N for GP Sorsen. Which are just a different brand of the injectors I listed. Either will work with your setup.

Awesome. Getting the GP Sorenson that you told me about.

The ESC the same as the ignition control unit?

ESC = Electronic Spark Control module
They have them.

I looked it up under my car and it comes up as a LXE6



They look like this.

And the GM part number should be 16128261

Ok. SPent a few hours tracking down parts. Here is what i got:

1. Fuel Injectors GP Sorensen 800-1807N
2. Knock Sensor GP sorensen KS7

Now, all the other parts that i installed are for 305 tbi not 350. Will that be a problem? here is what i have put on:

1. EGR valve for 305 tbi
2. Throttle Pos. Sensor for 305 TBI
3. O2 Sensor for 305 TBI
4. Idle air control valve for 305 TBI
5. Ignition coil, plugs, wires, cap and rotor, etc all for 305 TBI

Also the ESC module that i ordered is a GP Sorensen EL607 (old part number) and new part number is EL605. Is this ok for my vehicle????? They call is a camshaft interupter ESC module.

Thanks so much for your help. Anyway that i can speak with you in person? Via phone?

I've never heard of a camshaft interupter but the part number you listed for the ESC Module is correct. Everthing you listed under #5 is fine for any SBC TBI, don't have a clue on the rest. You can always check the part numbers under both size engines and see what you come up with that matches.

I'm about out of useful comments now so no need for phones (I avoid them as much as I can) If you ever need me though I'm usually on AIM as "A Fool To Trust"

Thanks so much for your help. I guess my question is do i need all of the sensors for a 350?? Or are the ones i have already changed sufficient? They are for a 305 with the exception of the ESC module, Injectors and the Knock Sensor.

Also, what car would be good for me to get parts from? Since no firebird has a 350 tbi??????? should i always use the buick roadmaster? 1992?

where do i get the chip and programmer? Everything i have looked at is $500-600

moates.net for everything you need to burn your own chips.

I don't know why everyone switches the ESC module. I have 3 laying around in my garage, all 3 have the same GM part number and lettering on them. One was from a 1988 cadillac with a carbed 307, the other was from a 1992 G20 Van 350, the other was from a 305 TBI caprice. All three function the same exact way, no noticeable difference to any. Knock sensors are a different story though.

Good to know, I didn't think an ESC was a must change item but I only know what I read on here so I helped him find the right part number for that motor.

Thanks guys!!! So, i need to make sure the knock sensor and injectors are for a 350 correct? All other sensors etc can be for a 305 correct? Things such as IAC, TPS, EGR valve, O2 Sensor, etc?

i bought all the stuff from moates to burn my own chip. Anything else that i need?

The throttle body is from my 305. Everything is from my 305 EXCEPT knock sensor and injectors which are for a 350. Have not installed either yet. Waiting for the chip.