Dj_Seph

Ok. I finally found my misfire and it was the MSD dizzy I had on. Put the stock one on and the car runs like a raped ape but new problems have surfaced that need addressing.

The car has gone recently from making 20mpg+ on my commute to making 10-13mpg. This is a hideous drop. I can smell raw fuel just being dumped upon startup and I've been told that the car let's out a bit of smoke when at WOT. What could be causing this? EGR is new, TPS is new, both coolant temp sensors are new, air filter is new, wires are new, cap and rotor are new, coil is new, and O2 sensors are new. I've pretty much replaced every sensor on this vehicle and done a full tuneup. The car rolls out hard under acceleration but I can tell it's not running like it should. Where should I look next? Could it be that my speed density setup just can't handle my fully ported GT40p heads with comp cam goodies? Should switching to mass air be my next step?

Also, the car has recently developed a strange idle. When I first start it, it won't idle unless I rev it. If I don't rev it, it'll just die instantly. Also, once warmed up, it'll idle at 1500-2000rpm and won't come down unles I turn the car off and restart it but it'll idle back high once I go to the next stop. I have changed the IAC that I got from O'Reilly twice to no avail. The most recent one I got, the car just keeps dying on startup and not even reving will make it idle. I pretty much have to instantly get moving and drive for a good few miles before it'll stay running.

Could it be possible I just got two bad IAC's?

mattdel

Sounds like its time to MAF it up.

Dj_Seph

*sigh* I was afraid you'd say that. Links to a dummies write up? I've found a few but they were a little too complicated for me to understand.

mjr46

what cam are you running in this sd set up???

Dj_Seph

Stock cam. I hear that's part of my damage.

mattman320

MAF will help, i had SD on a bronco with similar upgrades and it ran like crap most of the time until i swapped. I had a buddy help me on it because wiring is a foreign language to me. ran great after that, hows your timing and what did you set your gaps at on the plugs? that could be a little bit of it.

mjr46

stock cam should be fine, SD cars have been proven to run okay with larger than stock cams to a degree and with heads and intake upgrade, as long as the vaccum signal that a stock cam produces isn't disturbed, the mods you have should work just fine, your prob is elsewhere, possible vac leak, find someone to smoke test for vac leaks.

Dj_Seph

Hm. I'll do that. Though I've looked at all the lines. They're all connected. Any others I should look for besides the intake vacuum lines?

mattdel

Don't forget that bad intake gaskets fall under the category of a vacuum leak.

Dj_Seph

I just replaced the intake gaskets two months ago....And now all the hoses are new. Still same problem. Only thing I see is that there's a four way vacuum switch that used to go to my cruise control, smog pump, and EGR pressure solenoid on the passenger side. Only line being used now is the one going to the EGR. Could having the other holes open be my problem?