RevvinKevin

My buddy has a 1986 5.0 (speed density) that he recently aquired and knows nothing about the history of the car.

The engine looks to be stock (with orange 19 lb injectors), but it has a Crane cam installed (according to the sticker on the core support), somewhat lumpy cam and sounds good.

The problem: it runs WAY too rich..... lots of black smoke out the exhaust.... all the time, idle, 2000 RPM, 3500 RPM it still smokes. It sounds and smokes like any carbureted car with a stuck choke!

We put in new plugs and O2 sensors... no change. I checked the fuel pressure.... it's right at 39-40 psi.

Does anyone have any ideas or suggestions???????

Thanks in advance!!!!!

primetime5.0

lean out the fuel pressure i have mine set at 32

Joel5.0

First....SD systems + a lumpy cam = A/F on the rich side....not a good combo. [sm=badidea.gif]

You might want to check if there is something else that might be causing the A/F to get that rich (MAP & EGR comes to mind), to be sure that's the case, suggest you check the system for codes running a KOEO/KOER self-tests and post back the codes you get. Hope this helps.

ZachW04Stang

The low vacuum caused by the cam is making the map dump fuel because it thinks the car is under load.

ikeybmg

how bad is it smoking? if its really bad, id check the pcv valve.

Tims 88GT

it would be blue smoke if it was the pcv valve. Zach hit that one right on the head, thats the problem. because the map sensor adjust the fuel to the vaccum/load on a sd car. it is going to give it a lot of fuel because it wants it to idle smooth and about 20hg in vaccum. the best thing to do is set the idle so it smooths out, it may be 1200-1400 rpm depending on how wild the cam is. and then reset the computer. that should help.

97vette

I would also check the vacume hose that goes to the map sensor. It may of came off or has a split in it. I think it is behind the upper intake.