My car is barely running, its stumbling really bad and when I come up to a light it stalls if I don't keep my foot on the gas. The engine is a 383 with a LE cam in it. I changed the plugs, and the old ones looked perfect when I took them out, the fuel pressure is at 42 PSI at idle (its a stock regulator,). It also threw two other codes, right and left O2 sensor lean. The O2s are new, the injectors are new also, anyone have any ideas of what may be wrong? Do you think the map sensor is bad?

 

I got a MAP voltage high code and my car ran so rich it flooded out and died at idle. Depending on the size of your cam you might be running into the same problem I am- high pressure in the intake manifold (not enough vacuum due to larger cam), this code is triggered when the MAP sensor sees greater than 68 KPa of pressure at idle.

I'm a bit confused as to why yours would through lean codes though.

I fixed the problem by getting the rockers as close to zero lash as possible. Going from 1/6 turn to 1/16 turn resulted in the motor pulling about 10 more KPa of vacuum at idle.

 

The thing is, that the car ran fine for about 2 months, and now it just started this. I haven't played with the rockers since. The car smells extremely rich at idle, but I thought it was just overlap. The only thing I changed since then is I put a cat on, and I thought that maybe it became clogged so I put the offroad pipe back on and its still having the problem and the cat looks fine.

 

i think a stuck open egr valve will cause the problem

 

The car has no EGR of Air pump, I forgot to mention that.

 

The vacum at idle is only at 8-9 inches, and the map sensor voltage is at a little over 3 volts at idle. I checked for vacum leaks and I can't find any. Anyone have any ideas?

 

Does the car run bad in open and closed loop? What is your IAC doing? What does your long and short term fuel trims look like? What are your O2's doing? Does the MAP value change with TP?

These are all things you need to look at.

 

The problem is not being caused by the MAP sensor. Sounds like there is something screwing up the vacuum at idle. Is it possible the rockers have come loose and need to be adjusted?

 

The car does run in closed loop. The O2s are all over the place, but I thought that was normal. I'm not sure about the fuel trim or IAC, I'll check tomarrow and post them. Also, I hooked up a vacum canister, and it didn't help at all, and the brakes are hard to push in also. Injuneer, would loose rockers cause low vacum? They are sounding like they're getting louder.

 

what did you figure out??

 

I thought tight rockers caused a loss in vacuum also.

 

supercharged87 I am having a similiar problem. I just put in a cc306 cam p&p heads... my map is reading 2.7-2.9 at idle smelling really rich, but on my datalogger the blm's are maxed out... I just put on better intake gaskets.. no leaks I am running 9-11 inches of vacumn at idle. the only thing I can think of is the tuning needs to be better.. how long has your cam been in there? I have a mail order tune, but I am getting a dynotune in 2 weeks hopefully that will clear it up. but I heard a bigger cam will make the map read higher...for kpa at idle on the map mine is reading 62..maybe you just might need a better tune.

 

What unit values are 2.7-2.9? Inches of Mercury? Are you saying that the intake gasket was leaking and you put a new one on and now it doesn't leak? And that's where the increase in vacuum (9-11 inches) came from? 62 kPa is a close value, but with a dyno tune, you should see that drop, I believe, into the mid to lower 50's.

 

I mean't 2.7-2.9 volts... that is what my map is reading on my autoxray...I put it on a snapon scanner and it showed it in kpa which it was reading 62kpa...my autoxray just shows volts for the map..

 

oh yeah I thought my intake gasket was leaking, but the readings stayed the same before and after the new intake gasket...my cam is a 230/246 and a 244/278 lift on my 1.6rr's... if your cam is bigger than that then the map readings should be alittle higher than mine, I was told my mail order tune is not adj. to my high map readings, that is why I am getting a dynotune to help set up the pcm right...