throwing the code for high map low vaccum. using c.a.t.s. its shows the map being at 85-90 kpa at idle. just checked vaccum and its inconsistant from 0-5. the motor is a forged 383 splayed to 4bolt, le3 heads, comp cam 468 242/248 113 lsa .584/.579 at 050, 1.6 roller rockers, 44lb injectors, walbro 255, fuel regulator set at 43lbs, 2400 stall, 58mm t/b, lt's, 3" o/r y/p, march underdrive pulley. im lost on what to do cant find a vaccum leak. it back fires majorly and has no power. what is strange is i can set the injectors to 38 and it runs rich but has a ton of power. yes they are 44 lb injectors on it says on the sides of them.

 

If the rockers are too tight, it will kill the vacuum.

 

i set them at zero lash and then 1/8 th turn you can with just a little pressure twist the pushrods.

 

i have 5v from gray to black running and with the key on engine off.
i have 4.7v roughly green to blck key on/engine off and 4.1 running.

tried a map off another car and it read 85-90kpa like mine did. i dont know what to do next i cant fine a vaccum leak and have no emmissions equipment (all is blocked off)

 

Check the rubber seal on the MAP sensor.

 

we did and we tried another sensor. no change.

 

also i didnt have this code until i changed the iac which itsd reading wide open at idle.

 

im at a loss

 

Did you do an IAC reset when you changed it? Look on my site for a how to.

 

but that wouldnt cause the map to be high would it?

 

I had high map thrown and TONS of backfire when I blew a header gasket. It would idle alright but any type of throttle under load and it would pop like gunfire out of the exhaust. Its worth a check to make sure your header bolts are all tight and the gasket is good.

Made the o2's go crazy and the car run rich as hell, with stumbling idle. When the idle drops very low you can get the MAP high code thrown.

 

well if i set the pcm for 38 injectors the map it still high but it runs right little or no backfire and runs like a bat out of hell. which is wierd since i have 44 lb injectors. also according to the readings my o2's are bad and not working. they have no readings or if they its single diggit readings. already checked compression also. found where a valve cover and oil pressure sending unit had a leak.

 

could the intake gasket leaking cause it? i just thought about it the light came on after removing the intake to inspect the lifters.

 

Just a thought, but if setting the pcm for 38lb injectors runs better and your o2's are reading low, it probably is running lean. Are you running open/closed loop? MAF or SD?

 

maf, running open, and o2,s are bad. trying to figure out if the intake gasket could be causing the high map code.