I installed a fresh 355 in my 85 iroc. it is a TPI MAF. iI dont know if this is normal but it takes about 10-15 sec of cranking or pushing the throttle to crank. also,it idles around (950-1000rpms/750-800 in gear)when I put it in gear and put it back in park or neutral, it idles up to 1200-1500rpms. the car makes excellent power, i just would like to fix the annoying hard starts and high idle.
Do I have a vacuum leak? i sprayed wd40 at all the hose connections, it never idles up or down.
Any Help Would be GREATLY appreciated!!!

 

Hot starts? Cold Starts? Both? What?

Have you tried resetting the ECM and driving "normally" to let it "learn" ?

( Easy way pull the fuse for awhile then put it back in )


Have you set the idle? Checked the TPS? The IAC?

 

its always hard to start, and i have replaced all of the sensors, including the MAF. it has a new ECM, and both chips are new. i bought the prom for the 85 vette to help on the new engine. i have checked all of the vacuum lines, the only place i could possibly see there being a leak is somewhere around or in the vacuum canister to the left of the engine. i think it only idles up to build enough vacuum to keep the computer happy. its usually around 9-10 psi of vacuum at the plenum. is there any way to adjust the IAC? i was once told before replacing the ecm that my iac reading was off the map, the SES light shows no codes and it confirms CLSD loop operation. am i just missing something?

 

i have the idle screw backed out so far its not touching the throttle blade!!!

 

A MAF setup doesn't know how much vacuum your engine is pulling, so it's not idling up to keep the vacuum in a normal range. I have a cammed up 1969 327 with a MAF tpi conversion. I idle around 10" vacuum (vac. is usually rated in inches of mercury by the way, not psi) and I have no problem maintaining my commanded 750 rpm idle (custom chip). I agree that you will need to drive the car to let it learn. My setup would hold a 750 rpm idle until the engine got into closed loop. Once this happened, the idle would start approaching 1500 rpms. It took 15 miles of driving for the idle to become normal in closed loop, I have no idea why. Yes you can set your IAC, do a search for "minimum airflow" on the board. If you haven't set your minimum airflow and TPS accordingly, there is no hope of the idle speed being correct with a modified engine. You can't just crank your idle screw all the way out. As you do this, the IAC will open to maintain whatever minimum airflow idle speed your components are set for.