Idle surge and running rich. Input please
 

Well as my profile states I have a DSS 331. It runs fine but I can't seem to get it to idle smoothly. It will hunt from 600 to 1000 rpm and sounds like it is going to die. I can smell the unburnt fuel out of the exhaust. Occasionally when I shut it off it diesels a little. I am running 8.5:1 compression, should I lower my fuel pressure from the usual 38psi? I am running 24lb injectors. Is it possible that I am flooding the engine because of the low compression? I can tune it with the throttle plate adjustment and the tps monitor but then it changes the tps voltage range and the problem doesn't go away, so I am curious if it is something else. Should I go to a hotter spark plug? Any thoughts or ideas would be greatly appreciated.

Re: Idle surge and running rich. Input please
 

when u have bigger injectors u dont want to lower the fuel pressure...with the 24's u should be around 44 psi...did it just start to do this or did u change something and then it changed ....is the maf calibrated for the 24's? the tps voltage should be around .9v at closed throttle ...did u check for vacumm leaks?is the check engine light on?

Re: Idle surge and running rich. Input please
 

hey just thought of something is that cam has like 218/228 duration it should run a bit rough .idk if u just installed the motor or what

Re: Idle surge and running rich. Input please
 

Your fuel pressure should be at 38 psi with the vacuum off.

To set idle and TPS.

Back off the idle adjustment screw until you can fit a .10 feeler gauge between it and the plate. Then turn in the adjustment screw 1/2 turn. Now adjust the TPS voltage to .93-.99.

If the bad idle persist you may have a vacuum leak or a bad mass air meter.

Pull codes if all else fails and post back up.

Re: Idle surge and running rich. Input please
 

Seems like I always bring up the same things in these forums, LOL......What's your timing set at? And yes I have to ask, what size and type of Mass Air Meter are you running, does it have the right tube in it for the 24lbers?

Re: Idle surge and running rich. Input please
 

Hey everyone, thanks for the input so far. I haven't had a chance to spend time with the car. Yes they are always the same answers to the same question. I will try to baseline the throttle plate. I know the mass air meter is correct for the injectors as I bought them together as a set. Timing is at 14 degrees. I am leaning towards the possibility of a vacuum leak. Will keep you posted.

Re: Idle surge and running rich. Input please
 

Just a quick post to thank all you of for your help and input. About a week ago I finally had some time to work on the car. Changed the upper intake gaskets (yes plural I have two 1/2" phenolic spacers). The car seemed to idle fine in the driveway. I haven't driven it as it is not a winter car, no heater. I will eventually re baseline the throttle body and see how it goes from there. As for the TPS it is always at .98 volts as I have the digital TPS monitor installed. Thanks again and Happy Holidays.