i installed a 350 into my 85 iroc. the only sencor i changed was the knock. the car runs strong but it has iradic idle? engine light somes on and i get codes 24,34,42 and 44. before the swap i never had the light come on? the engine is from a 84 vette cfi .040 over. PLEASE HELP!

 

Im having the same problems with my Formula, just put a new 350 in. Im pretty sure what the problem is the TPS, throttle posistion sensor. Im going to check mine tomorrow and change it need be, you mgiht need to adjust it. There is a step by step on TPS here, I judt did a search for "TPS" on the message board and found alot of info. But anyways this seems like the symptons we are both having...

 

i disconected the maf, and it wont run without me giving it throttle?

 

come on guys?

 

the 305 and 350 has ALOT of difference in the sensors, you need to change the ESC module, you need to change your CHIP/PROM beacuase that will be alot difference, you need to change the injectors (not good running 19lbs injectors on 350engine, will shorten the life of the injectors..)
And if you got EGR and using the stock 305 egr on a 350 = not good..

Why youre running lean is prolly if you using 19lbs injectors and stock 305 prom... you gotta get that fixed.. if this is the case or does you have an new prom ?

Whats your TPS volt, vacuum ? fuelpressure..?!

 

what chip can i use for a 85? it was a "one off" year and only came with a 305? egr's carry the same part #. i will try a 350 esc.im working on getting injectors.shouldnt my car run with the maf unhooked? it just dies. thank you.

 

The car wouldnt run good without the MAF.. it should run, but not good..
Is it working temp when you unplig it ?

In that case you have to take an prom from an newer car, example ARAP bin with lower spark advance (araps is pretty agressive..)

An Custom prom for your ride would be the best. and some new injectors atleast 22lbs/hr injectors

egr is adapted to engine size, in 1989 it is for sure, gotta check how it was 84..

 

the car was up to temp when i unpluged the maf, and it died imediatly? where could i get a custome chip burned? i have a JET chip would that be good enough?

 

If the Jet chip is for an 305 it would not help you out.

Cusom prom could be bought from tpiparts.net or you buy the stuff yourself and start learning moates.net (sells burners, proms, adapters and more.)

There are tons of info about how to do it yourself on this forum, If you thinking of doing it yourself you need an laptop and an ALDL cable so you can scan the car off and see how it feels and runs.. Its bad that you arent in Sweden orelse I could have helped you out with an prom and scanning..

 

well, i got to looking for vacume leaks...i got to the egr system, looked at it real closely and noticed that i had the vacume lines crossed . that cleared up most of my "rough"idle! now the only codes present are 44 o2 lean? and 24 vss? i didnt know my car had a vss. its a 85 iroc w/ a manual 4 speed.origanlly a 700r4.

 

You might try getting a hold of parts from an 85 vette, that would be a TPI 350.

 

would #19 injectors directry cause a lean o2 code in a 305 .040 over?

 

No, .040 is nowhere near enough difference to affect the A/F ratio. A vacuum leak could cause it though, does the car idle really high? Also, I'm pretty sure the EGR is the same between the 305 and 350. It's controlled by the computer, so it can be adjusted for whatever engine it's on, that's the whole point of an ECM tune, and different chips for different engines. I would also be willing to bet the MAF sensors are the same - again, the 350 computer would expect more airflow from a 350 than a 305, using the same MAF.

 

opps...i meant 350 .040 over

 

The 19lbs injectors will make it lean on some places because they will have a hard time to keep up. Because they have to work at a high pulse width all the time... The MAF sensors are the same from 305 to 350.. again, You using a 305 prom and you gotta get a 350 prom thats one of the reasons for it running lean.
The MAF tables are alot diffrent in a 305 than a 350.. So you gotta get it fixed, the prom..