vspecpgt

this is on my new motor, still in the break in period, only have like 400 miles on her. everything was normal and then this happened. she'll crank really fine, but in order to get her to start i have to push the gas pedal. after she starts she runs fine. i can shut the car off and imediately start it up again normally when its hot.

any suggestions? i was thinking maybe the plugs have fouled since the car isn't tuned yet. but the plugs were pretty new right before the rebuild so i didn't change them. it does the same thing whether Idle Control is plugged in or not.

i'm single, with a big port. motor has only 400 miles, haven't taken it above 3000 rpms. previously the motor was stock port and i'm still running that map. car runs fine when started (up to 3000 rpm anyway, actually it is a bit jerky...)

Snook

iTrader: (12)

The same thing just started happening to me. If I don't give it gas on the initial startup when it's cold it will crank forever without starting. If I just give it maybe 5-10% throttle it starts up faster than any car. On hot startups I don't have to fool with giving it gas it just starts up. Steve told me it's the ISC but I haven't tried switching to another one or anything. I also was thinking spark plugs because I'm starting to backfire all the time lately.

Try spark plugs and let us know cause I won't be chaning mine out for a while so I can't add any input : )

mad_7tist

could be fuel pressure bleed down. does it get any better if you cycle the key twice on to off before cranking it?

vspecpgt

i'm not sure i'll try that when it gets cool again.

i did crank it, then stop and crank it again, it seemed to try and fire then, but i still gave it some gas......

i just spent way to much money on my car, i can't beleive this crap is happening now... damn it!

DaleClark

iTrader: (55)

You'll always run into little bugs and problems after installing a new motor - there's so much stuff that has to be removed and worked with that many times little problems crop up.

I would think it's either the plugs or the TPS needs adjustment. It's likely something simple.

Dale

vspecpgt

whew, that lets me relax a little bit! i'll try and mess with the tps too, its just wierd because it just started happening all of a sudden.

any more info? keep it coming guys...

harrison

FD Rey

I was going to ask you last night Harrison when was the last time you changed the plugs. I figured you put some new ones on it since everything else is pretty much new. You may have to mess with the TPS like the others suggested. It deff sounds like it's something simple, nothing too big of a deal.

mad_7tist

how did the dyno go rey?

FD Rey

Good thanks! Aldo was there. I put down 374rwhp and 315rwtq at 15 psi and never reved over 6800 rpm. I wanted to get to 400rwhp but my turbo is going bad. Whatever, I'm happy with it.

vspecpgt

what color should by spark plugs be? i just checked them and they are pretty black, a sign of running rich right? hopefully thats the problem.... i checked both T and L.

harrisoni

DaleClark

iTrader: (55)

More of a tan is a more healthy color. New engines will foul plugs and the like as they're breaking in.

I'd also run 7's in the leading and 9's in the trailing during breakin. No reason to run super-exotic cold plugs when you're just driving around easy breaking in the motor.

Another thing I thought of is the fuel pressure regulator control. Stock, there's a vacuum line going from the lower intake manifold to a control solenoid, then to the FPR. The solenoid bumps up fuel pressure on hot starts to help easy starting. If it's bypassed, it may or may not be a problem.

Dale

XSTransAm

also check your temperature compensation maps, with the weather getting colder I wouldent be suprised if it were just flooding the engine at cold startup

rx7tt95

If they're black, it's rich. One other thing which might need fiddling with is injector decay when cranking. Essentially there's an adjustment that can be made with the Datalogit which will keep the injectors "on" longer during cranking. Larger ports need more fuel to start, especially when cold. The fact it clears up when hot leads me to believe this might be the culprit. If you can drive down this weekend, I can change a few things for you. If you have an extra 02 bung, we can throw my wideband on it and tune idle and vacuum.
Michel

vspecpgt

michel maybe i'll do that..... swing over sat afternoon or something. i just changed the plugs and that still didn't clear it up.

dunno if this is related, or just part of the map, but say if i'm driving a constant 50mph, it will be nice and smooth and then sometime it will just "burp". it'll skip a beat and then go back to normal.... its not a constant thing, and has no pattern, just happens every now and then.

harrison