Engine back together but now surging

Discussion in '94-95 5.0 - Specific' started by mrclean302, Jul 17, 2007.

  1. mrclean302

    mrclean302 New Member

    Messages:
    7
    Likes Received:
    0
    Joined:
    Dec 20, 2006
    I already know about the link on how to fix surging, but I have a couple questions to
    ask first.

    I put new heads and intake on and after about 45 seconds of cranking, it started up.
    Kind of.

    It would surge from approximately 500rpm to 1500rpm, probably higher. I was shocked
    the car started up, this was the first time I've every done this type of work.
    Anyway, it only ran for about 3 minutes and died on its own. I didn't try starting it
    again because I have a little interference problem with two spark plug boots resting
    on the header and didn't want to burn them. GT40P heads with FMS Headers.

    So if anyone has a shorty spark plug part number for GT40P heads let me know.

    Kind of rambling here but here is the real question. I want to know if the car had run for say
    10 minutes or longer, would the computer have had time to adjust itself to the new
    combination and run good enough to drive? Or should I just go through those steps now?

    Thanks in advance.
    George
     
  2. quickstang_1994

    quickstang_1994 Well-Known Member

    Messages:
    2,208
    Likes Received:
    12
    Joined:
    Apr 30, 2006
    Location:
    Cross Anchor, SC
    start checking for vaccum leaks
     
  3. mrclean302

    mrclean302 New Member

    Messages:
    7
    Likes Received:
    0
    Joined:
    Dec 20, 2006
    So this definitely sounds like a vacuum leak? I'm 100% I hooked all lines up.

    What is the best way about finding this?
     
  4. ripper

    ripper Well-Known Member

    Messages:
    3,323
    Likes Received:
    0
    Joined:
    Jan 2, 2007
    It will take more than 10 mins for the puter to adjust. Might take 100 miles, might take 50 miles. You never know. Mine took like 200 miles. Dont beat it for a while. Let the puter adjust.
     
  5. Anrev

    Anrev Active Member

    Messages:
    380
    Likes Received:
    0
    Joined:
    Feb 16, 2007
    Ok so you got all the vacuum lines hooked up. But are you sure they arnt leaking? And are you sure the upper and lower intakes are sealing properly? Get a couple cans of WD40 or carb cleaner and spray down everything and listen for the engine to rev up. Make note of where you were spraying at the time and you'll have located a vacuum leak. Pay attention to the mounting surfaces of the intake where it meets the heads. If you spray along those and you get a surge then you will have to take the intake back off and try reseating the gasket. And make sure you use proper torque sequence and steps.
     
  6. mrclean302

    mrclean302 New Member

    Messages:
    7
    Likes Received:
    0
    Joined:
    Dec 20, 2006
    Turns out one of the plugs I was having trouble with wasn't connected properly. Corrected that and fired her up for a couple
    of minutes. Surging was almost completely gone going up and down maybe a couple hundred rpm until it stalled out again.

    Started it again and it died almost immediately. Tried again and died again. Third time I started it and gave it a little gas
    and she ran perfectly with my foot on the throttle. As soon as I let go it stalls out.

    Any ideas?
     
  7. quickstang_1994

    quickstang_1994 Well-Known Member

    Messages:
    2,208
    Likes Received:
    12
    Joined:
    Apr 30, 2006
    Location:
    Cross Anchor, SC
    tap on the IAC valve.
     
  8. Anrev

    Anrev Active Member

    Messages:
    380
    Likes Received:
    0
    Joined:
    Feb 16, 2007
    Big vacuum leak. Same thing happened to mine. You probably have a leak at the intake manifold.
     
  9. ryclef331

    ryclef331 Well-Known Member

    Messages:
    2,913
    Likes Received:
    9
    Joined:
    Jan 20, 2006
    read the surging article again....specifically the part about setting the idle. Your new mods are allowing for more airflow even at idle. The IAC and throttle body aren't letting that through sufficiently...so you have to adjust. There is an idle screw on the TB (not the one that the linkage rests on). Its on the top (if your car is stock its covered with a little rubber plug). Back that screw out to raise the idle. You CAN use the linkage stop screw but it will also increase your TPS voltage so it will think you're ON the gas when you're actually not causing a slightly richer idle....no biggie really but it still isn't "right."

    I don't think you have a vaccum leak...just need some tuning.
     
  10. mrclean302

    mrclean302 New Member

    Messages:
    7
    Likes Received:
    0
    Joined:
    Dec 20, 2006
    Ok. I'm gonna go through the article again and see what I can do.

    If it was a vacuum leak then wouldn't it still run funny when I raised the rpm?
    It was dead solid when I was holding it at 2000rpm.
     
  11. Anrev

    Anrev Active Member

    Messages:
    380
    Likes Received:
    0
    Joined:
    Feb 16, 2007
    Thats what mine did too. It was leaking where the lower manifold mates to the heads on both sides.
     
  12. ryclef331

    ryclef331 Well-Known Member

    Messages:
    2,913
    Likes Received:
    9
    Joined:
    Jan 20, 2006
    It could be a vaccum leak. I'm not ruling out the possibility but I'd lean towards the idle settings. Both are easy to check