I have several questions...I guess I'm a newbie when it comes to electronic/computer stuff.

I have an '87 Camaro in which I replaced the 305 TPI with the 350 TPI--and I replaced only the block. Everything else remained stock. It ran OK--the power dropped off at around 2000RPM.

Recently, the stock MAF died and I replaced it with the adjustable Granatelli MAF which is pre-set for the stock engine. Since then my SES light has been on and there is no response from the ECM/PROM giving me codes using a scan device nor using the ground method (connecting the 2 ports with a wire). I replaced both the MAF burnoff and power relays and there has still been no change.

The car runs normal and the light does not come on until several minutes after I start driving it (seems fine at initial idle). Then while driving it it seems to hesitate slightly and 10 sec. later the SES light comes on and the car runs roughly.

Do I need to replace the ECM or PROM to get this to work and retrieve the code--does the ECM or PROM need to be replaced anyways due to the engine swap?

Also, I bought .26lb injectors from Accel to replace the 305 .19lb injectors. Upon switching the injectors will I need a custom ECM/PROM to accomodate the injectors?

 

You should reprogram the prom.
There are several differences between the 305 and 350 programming. Injector size and engine volume to name a couple.
Your ECM is thinking that you have 19 pound injectors in there when in reality you have 26 pounders. The 350 ecm can't even compensate for the 26's without programming.
Your code may be an O2 code. Those typically come on after a few miles of driving.
Regarding your ECM, it does kinda sound like it may have taken a dump. Regardless of what engine you put it on it should still give you the codes.

 

Did you replace the knock sensor? The knock sensor is calibrated to bore size primarily. The 305 knock sensor in a 350 block will tell the ecm that the engine is knocking and pull timing killing power above 2000 rpm. The stock injectors for a 350 are 22 lb/hr, 26 lb/hr injectors are way too big unless you have done something to improve the breathing ability of the engine beyond putting a 350 block under a set of stock 305 heads with a stock cam, stock intake manifold and stock exhaust manifolds. If you have more mods to your engine to require the 26 lb injectors, you need to post them. So far the information you have given indicates that you could get by better with the stock 19 lb injectors than the 26 lb injectors although 22 lb injectors would be ideal. The ecm thinks you have 19lb injectors in a 305, but you actually have 26 lb injectors in a 350. That is enough to throw the ecm into confusion because it makes changes based on what the programming it has says to do and it isn't even close. Are you sure your old maf is dead? Do you still have the old maf? I have read of people having problems with quality control issues with the Granatelli mafs. I'm running 19 lb injectors in a 350 with a custom speed density chip without problems. I don't race the car, so I haven't tried to run it for sustained power at wot on the drag strip where the 19 lb injectors would probably not give enough fuel. Put your old injectors in and your old maf on it, change your knock sensor, and then see what it does.

 

Okay, the 26lb injectors will be history, then. Is the PROM or ECM going to be different for the 305 vs. 350? I compared the part numbers for an ECM and they seem to be the same (through partsamerica.com), but if I were to put in 22lb injectors to stick with the original 350 set up I'd need a different ECM, correct? Or would I just need a new PROM instead of an ECM?

I was able to retrieve codes & I got code 36 & code 33. Bad burn off relay and too many volts going to the MAF--would the new Granatelli be a cause of this? It didn't happen until after I installed it--the old MAF sensor, when hooked up, would choke out the car and it could barely hold an idle and would die once given a little gas.

I'm def. gonna try the knock sensor.

Sorry about the q. overload, I'm just getting really frustrated with this and am about ready to send my car to the junk pile. (joking)

 

Don't worry about question overload, the biggest problem I find on boards is people asking questions without giving enough information to allow anyone to come up with an answer. The 305 and the 350 tpi cars use the same ecm, the chip for the two engines may be different. Logic tells me that a 305 with 19 lb injectors would probably operate very close to a 350 with 22 lb injectors. The ecm sends a signal to the injectors telling them how long to stay open. The longer they are open, the more fuel flows. I suspect that if the 19 lb injectors stay open the right length of time to properly feed a 305, 22 lb injectors staying open the same length of time will probably be pretty close to what is needed for a 350. Try one thing at a time. Put in the knock sensor and the 22 lb injectors with the Granatelli maf and see if that straightens it out before you change the maf again. The maf is telling the ecm how much air is flowing into the engine, and the O2 sensor is telling the ecm how rich or lean the exhaust is. The ecm adjusts pulse width and timing to try to balance things out. If you have 26lb injectors in the engine and the ecm is programed to think they are 19lb injectors, it just won't lower the pulse width enough to run the engine correctly.

 

Okay, thanks a lot, I really appreciate your help. That makes a lot of sense. I'll give it a shot and see what I can come up with.