Help Needed, starts but wont run
09-24-2010, 08:48 PM
#1
9 Second Club
Thread Starter
iTrader: (13)
Join Date: Apr 2006
Posts: 155
Likes: 0
Received 0 Likes
on
0 Posts
Help Needed, starts but wont run Ok, so I have built a turbo transam, DIY truck manifold kit, tc78, proflo intake, nice 317 heads, full fuel system. The day I finished it, my friend and I started it up, car fired right over, idled smoothly, for the cam thats in it, had good throttle response, everything great. Had a small fuel leak, shut the car off, repaired the problem, started it again, ran REALLY rough, but didnt die, rev'd it a little, and still when it came down didnt die. Shut if off again(another fuel leak). NOW all it does is start, and shut off, maybe 3-5 seconds run time....WTF!!!!!!!!!! If I try to give the car throttle while starting it, it kills it quicker, doesnt loose fuel pressure, shows 9-11 in. of vacuum when it fires, dies off when the car dies... Going crazy, has fuel, has spark, has a tune for the fuel system and turbo in it....I DONT GET IT, what the hell happened??? Im really gettin fed up...dont know what to do anymore guys... any help would be appreciated. Thanks, Dennis
09-25-2010, 11:23 AM
#5
yes it has a 2-bar MAP on it
Now like he said if we keep the throttle blade shut it kinda idles for about 8-10 seconds but its a REALLY rough idle, if you WOT and start it, it fires up to about 3k rpm then dies instantly. So more throttle is worse then closed.
Trending Topics
09-25-2010, 02:41 PM
#10
TECH Enthusiast
Join Date: Jan 2004
Location: New Zealand
Posts: 608
Likes: 0
Received 0 Likes
on
0 Posts
do you have bigger injectors ?
has the tune been modified to take into account big injectors and rescaled for the 2 bar MAP sensor ?
You could put the std MAP sensor and injectors back in just to start it and trouble shoot leeks etc, but don't drive in boost !!!
has the tune been modified to take into account big injectors and rescaled for the 2 bar MAP sensor ?
You could put the std MAP sensor and injectors back in just to start it and trouble shoot leeks etc, but don't drive in boost !!!
09-25-2010, 02:46 PM
#11
yea, Speed Inc. flashed the computer with a run file for the injectors, MAP, speed density etc. We unplugged the MAP and it would start up but not try and catch the idle, plugged it back in and then it would try to catch itself but still cant. I have a stock PCM for my car and we plugged that in (stock PCM from a f-body) and it does the exact same thing, no change in anything which i thought was kinda weird. Pulled every plug wire off and everyone has spark, pulled off the main feed line and it pours out like a garden hose, pulled off the elbow to run it on "motor" and no change. No matter what we try, unplug, change etc we cant get it to do ANYTHING different.
09-25-2010, 05:11 PM
#13
9 Second Club
Thread Starter
iTrader: (13)
Join Date: Apr 2006
Posts: 155
Likes: 0
Received 0 Likes
on
0 Posts
It pretty much cant be tune related...It does the same EXACT thing on a tuned and untuned computer....speed inc. is one of the best in chicagoland with turbo fbodys....and it doesnt change it a bit....Im thinkin its a huuuuuge vacuum leak, more than likely coming from the intake again....intake looks great, and makes great power according to a lot of people....imma bring it in for scrap if i have to pull it off again...
09-25-2010, 06:42 PM
#14
9 Second Club
iTrader: (2)
Join Date: Jul 2002
Location: on the dyno tuning in MD
Posts: 2,583
Likes: 0
Received 1 Like
on
1 Post
You absolutely sure they changed the MAP scaler in the tune for the 2 bar sensor? If it's doing the same thing with a stock computer (which wouldn't be scaled for a 2 bar), then I would look at that first... don't care how many they do, there is always the chance a mistake was made...
09-25-2010, 06:54 PM
#15
LS1Tech Co-Founder
iTrader: (34)
If you can't hold the idle at 1500 rpms by hand, that will give you some things to think about. Do you have anything plugged in to look at your L trims, and to see if anything is going on with respect to adding/pulling fuel? Have you verified that base fuel pressure is holding?
09-25-2010, 06:57 PM
#16
LS1Tech Co-Founder
iTrader: (34)
Just watched the vid. I'm assuming you've check stuff like making sure that the injector harness is plugged in and undamaged, but since it won't run on any cylinders I'd be looking into the fuel system, and maybe also make sure the crank sensor harness is not messed up.
09-25-2010, 07:18 PM
#17
well we hooked up my home-made pressurized tester to simulate boost and we have air leaking around all 8 injector bases. We sprayed soapy water around um and they bubble up like crazy so assuming its a big time vacuum leak from that. If not it had to be fixed anyways.
09-25-2010, 08:15 PM
#18
I don't think that's your problem here. You sure you have gasoline getting in the holes? It doesn't sound like it. Do you have the ability to scan? If the TPS isn't reading currectly, it will throw the computer into clear flood which means no fuel and will display 100% on a scan.
09-25-2010, 09:19 PM
#19
I don't think that's your problem here. You sure you have gasoline getting in the holes? It doesn't sound like it. Do you have the ability to scan? If the TPS isn't reading currectly, it will throw the computer into clear flood which means no fuel and will display 100% on a scan.
