I just recently replaced my 305 tpi with a 350 using almost all of the same parts from the 305 including injectors, and we installed headers. Now the SES light will randomly popl on and the shop siad the code it was putting off was the MAF sensor. We have sense replaced the MAF and the three relays, the shop says the only thing left is the computer, but i think it could be something else. Even though i have no idea what. Once again the problem is that everynow and then the SES light pops on and the car will hesitate while i am on the brake even though i am not pressing the gas. It tries to go without me. I would love to have some help. Let me know please.

 

i dont know if this will help but its possible that with the more flow of the engine that maf sensor things there is a leak such as vaccum leak which will cause a high idle or a lean condition it is possible that you would need to reprogram the ecm not sure though

 

Find out what the error code number is. You can do this yourself actually. Do a search to find this method.
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BTW: You need an Eprom for the 350 and use 22#/hr injectors.

 

the error code said it was the MAF sensor i believe it was a 34. i dont remember for sure. is it probably just running really lean b/c of the 305 injectors and the MAF is sensing that its running lean and thats whats sending the error code

 

That is most likely your problem. you either need to swap it for a 350 computer and change the injectors to #22's or change the injector constants in the chip so it knows its running #19's.

 

it is the old computer from my 305 and the old injectors so it should know that it is runnin 19's but is it possible that its just that the injectors need to be switched to like 22's and then fixed in the comp or do u think im gonna have to get a new computer

 

sorry im kind of car illeterate not super bad but im pretty new thanks for helping me with this stuff guys

 

The MAF is the same for both engines. The injectors are different. You do not need to change the ECM for the larger engine. You may eventually need to change the PROM programming, but it should run in closed loop mode with the current parts without setting a '34' error code.

Running lean due to small injectors will NOT set a '34' code. If it is in fact a '34' the MAF is not reporting air flow to the ECM. This is usually due to leaks in the intake air ductwork, improperly connected PCV/CCV hoses, a leaking EGR, leaking power brake booster, TPS set too high, or a contaminated/dirty MAF hot wire. The MAF is NOT the problem, and the ECM is NOT the problem. Insist that the shop not charge you for a MAF, or install your old one. That's $400 you didn't need to spend. If they replace the ECM without your approval, insist that they install the old one. Parts changing is usually not a proper method of diagnosis, and you don't need to pay for their ignorance.

 

I am pretty sure its running a 34 code but i know for sure the code is saying its the MAF sensor or thats what the mechanic (one i trust) told me. what is the first thing I should do. I planned on having them reprogram the ecm and replace the injectors, which i would most likely replace any. But yah where should i start