help

[darbydarby]

Ok guys Ill try to make this short as possible........

I just put a sn-89 sc on my stock 5.0 motor.....Everything was running fine,I realised that I had bosch platinum 2's in the car and heard that it was a sc no-no so i switched to autolite 25's gaped at .35,the car ran better than ever! then on the way home later that day the car started running like crap,checked the spark plugs and all looked to be fine except two plugs had absolutely no fuel smell to them....So we figured maybe my injectors might have finally crapped out.....The car starts and runs,it just feels and sounds like crap,kinda just stuttering,almost like how a car feels/sounds when it has a huge exhaust leak and its robbing severe power(no its not a leak i checked lol).
Following day we replaced the worn out 19#'s with some 24's, also put a gt-40 intake and c&l mass air on the car...the spark plugs are now getting the gas but The car still has the same problem! the motor has NEVER been rebuilt,they think it could be the timing chain possibly....The motor is not overheating,using fluid, and oil pressure is staying constant........Something is draining the motors power and I cannot figure out what it is.Tomm I am switching to autolite 24's ,they also think i might have screwed up the other plugs..any ideas what could be wrong????PLease help!any ideas or opinions are greatly appreciated!

[Chuck]

Try and figure out if one or two of the clyinders arent firing properly.

I would start with the 2 plugs that didnt smell like fuel. Start the car and get a broom stick or long screw driver, place one end on the suspected cylinders fuel injectors and your ear on the other and listen to them. You will here a ticking if the injector is working properly.

You may be haveing a problem with your 10 pin connectors at the back of you intake.

The only reason I suggest this is because I have seen it happen before and the symptoms you describe are exactly what was happening to the car I was looking at the time.

Let us know what you find out.

[regattacoupe]

how did you screw up a plug? drop it? never used a dropped plug....i learned the hard way...start pulling plug wires and see it changes.....wear some gloves! LOL

[darbydarby]

alkso the fmu is disconnected with the 24# injectors, does that need to stay on?because the car seemd to be getting too much fuel when it was on.

[darbydarby]

if anyone can answer this question..please feel free to.

[Chuck]

Leave the FMU on.

If you remove it the car will go lean at WOT and hurt something.

[darbydarby]

Ok thanks a lot for the info.......It was just weird when we cranked the car up with the #24's and the fmu on it just seemed to dump too much fuel.and the car wouldnt start for the rest of the day.

[Chuck]

The FMU should have no effect on idle or cruise.

The FMU doesnt do anything until you get into boost.

If you mixed up the feed and return on the FMU it could cause it to hold the fuel pressure up after you get into boost and not let it come back down.