lsx guys, car tries to start, but wont fire.
10-16-2008, 07:48 PM
#1
TECH Regular
Thread Starter
iTrader: (10)
Join Date: Oct 2005
Posts: 403
Likes: 0
Received 0 Likes
on
0 Posts
lsx guys, car tries to start, but wont fire. 98 firebird Ls1 swap.
Car is reading computer, it has a mail order tune to get it running and broke in.
I dont have a FP gauge but the lines fill up with fuel and all, the car builds upwards of 50 psi oil pressure.
I have checked all grounds, everything looks good.
I DID notice a small (vacuum) looking line coming from pcm (in the harness)
it is plugged up by the pcm, then dissapears into the harness and comes out close to behind the intake (not plugged up here)
Other thing, car is tuned for an 85 mm truck maf, im trying to start it on a 75mm stock maf (awaiting my 3-5 pin adapter)
any ideas?
it tries to crank, and it will pop, sounds real close to firing, but wont.
other additional notes; there is a n20 plate on it, that has no lines going into it (so possible SMALLL vacuum leak) low fuel, but still about 2 gallons in it.
brand new battery, so i have juice.
Car is reading computer, it has a mail order tune to get it running and broke in.
I dont have a FP gauge but the lines fill up with fuel and all, the car builds upwards of 50 psi oil pressure.
I have checked all grounds, everything looks good.
I DID notice a small (vacuum) looking line coming from pcm (in the harness)
it is plugged up by the pcm, then dissapears into the harness and comes out close to behind the intake (not plugged up here)
Other thing, car is tuned for an 85 mm truck maf, im trying to start it on a 75mm stock maf (awaiting my 3-5 pin adapter)
any ideas?
it tries to crank, and it will pop, sounds real close to firing, but wont.
other additional notes; there is a n20 plate on it, that has no lines going into it (so possible SMALLL vacuum leak) low fuel, but still about 2 gallons in it.
brand new battery, so i have juice.
10-16-2008, 08:03 PM
#2
On The Tree
iTrader: (3)
Join Date: Mar 2004
Location: North Hollywood, CA
Posts: 166
Likes: 0
Received 0 Likes
on
0 Posts
My old car kind of did this when we did a cam swap. According to my mechanic, something about the cam sensor being off or loose caused the issue. After the sensor was reinstalled, motor came back to life. Just an idea.
10-16-2008, 08:15 PM
#3
TECH Enthusiast
iTrader: (28)
Join Date: Apr 2008
Location: Grayson, KY 41143
Posts: 593
Likes: 0
Received 0 Likes
on
0 Posts
Yeah definitely check both crank position sensor, and cam sensor before you crank the guts out of it. bad connection, not fully installed into the block, even wires partially pulled out of the plug itself can cause this to happen.. Since your at least getting a pop once in a while doesn't sound like an ignition fuse or anything.
10-16-2008, 08:17 PM
#4
TECH Regular
Thread Starter
iTrader: (10)
Join Date: Oct 2005
Posts: 403
Likes: 0
Received 0 Likes
on
0 Posts
yep checked fuse, but it does occasionally pop, hate to pull a stupid, but where is the cam and crank sensor, i DOUBLE CHECKED all sensors, just not sure where these are.
10-16-2008, 08:37 PM
#5
TECH Enthusiast
iTrader: (28)
Join Date: Apr 2008
Location: Grayson, KY 41143
Posts: 593
Likes: 0
Received 0 Likes
on
0 Posts
crank sensor is above starter in side of the block 10mm bolt holds it in...cam sensor is behind the intake in a hole where the distributor would have normally been also held in with a 10mm bolt..I would just un plugg and check the actual end of the harnesses plug for them both before I pulled either one out. Does the tach register when the engine is cranking?? if not then it is most likely the crank sensor not the cam
10-16-2008, 09:32 PM
#6
TECH Regular
Thread Starter
iTrader: (10)
Join Date: Oct 2005
Posts: 403
Likes: 0
Received 0 Likes
on
0 Posts
it does show via hptuners i get 100ish rpms. It shows im getting oil pressure, etc.
and damn them are both bitchy sensors to get to, i gotta drop the starter for crank sensor i suppose, is the cam sensor the one that fits LOOSELY in the fast intake, and you have to put rtv on it, wait, thats the map sensor i believe.
and damn them are both bitchy sensors to get to, i gotta drop the starter for crank sensor i suppose, is the cam sensor the one that fits LOOSELY in the fast intake, and you have to put rtv on it, wait, thats the map sensor i believe.
10-16-2008, 09:42 PM
#7
TECH Enthusiast
iTrader: (28)
Join Date: Apr 2008
Location: Grayson, KY 41143
Posts: 593
Likes: 0
Received 0 Likes
on
0 Posts
cam sensor is on the back of the block beside the oil pressure sensor it is really fun to even reach forget about ever pulling it out with the intake still on
Trending Topics
10-16-2008, 10:03 PM
#9
TECH Fanatic
iTrader: (6)
Join Date: Nov 2001
Location: NV
Posts: 1,224
Likes: 0
Received 0 Likes
on
0 Posts
....just to add as well, that vacumn line plugs into the back of the intake. Beside the map sensor. It is vacumn for your hvac controls.
Not sure, but maybe a crank relearn needs to be done as well. It could be off with a new short block. Reading the old block settings.
Not sure, but maybe a crank relearn needs to be done as well. It could be off with a new short block. Reading the old block settings.
10-16-2008, 10:16 PM
#10
TECH Regular
Thread Starter
iTrader: (10)
Join Date: Oct 2005
Posts: 403
Likes: 0
Received 0 Likes
on
0 Posts
once again sorry for ignorance, I never had to mess with that on hptuners with the sixxer, where is this found, and im also VERY rusty with hptuners, as car has been down for sometime (aka no hptuners used lol).
is it in the scanner or editor, i assume scanner, but i thought i read the car has to be RUNNING to do a crank relearn.
p.s. is it CASE learn under vcm controls in the scanner?
is it in the scanner or editor, i assume scanner, but i thought i read the car has to be RUNNING to do a crank relearn.
p.s. is it CASE learn under vcm controls in the scanner?
10-16-2008, 10:22 PM
#11
TECH Fanatic
iTrader: (6)
Join Date: Nov 2001
Location: NV
Posts: 1,224
Likes: 0
Received 0 Likes
on
0 Posts
I have hpt, but still very new to me as well. You can search crank relearn and it comes up with some good info. I'm getting ready to go through all the same things. Swapping to a stroker. I haven't studied the crank relearn yet. I just know it can cause what your car is doing as well.
10-16-2008, 11:41 PM
#14
TECH Enthusiast
iTrader: (28)
Join Date: Apr 2008
Location: Grayson, KY 41143
Posts: 593
Likes: 0
Received 0 Likes
on
0 Posts
unless you have very small flexible arms and eyes in the tips of you fingers I would say NO. but I guess you can try there is only one 10mm bolt so get it out and then just pull it up, they usually have to be pried just a bit with a small flathead to get them started out that is why I think it is impossible to do with the intake on, troubleshoot everything else and save the funnest one for last maybe you won't have to mess with it after all
10-17-2008, 07:22 AM
#17
On The Tree
iTrader: (3)
Join Date: Nov 2005
Location: Georgia
Posts: 190
Likes: 0
Received 0 Likes
on
0 Posts
I hate to get simple, but mine was doing the same thing. It was running insanely rich and it eventually fouled out the plugs. We turned it over and over and it would pop everynow and then... but never fire. I swapped the plugs and it was good as new. Pull a plug, there's a good chance they might be fouled.
10-17-2008, 07:58 AM
#18
TECH Resident
iTrader: (148)
Join Date: Dec 2006
Location: Crete, NE & Berthoud, CO
Posts: 848
Likes: 0
Received 0 Likes
on
0 Posts
sounds like fuel pressure 2 me. spray some highly flamible liquid (like maf cleaner) into the intake and try to start it. if it starts and dies...its fuel. I had a pump go bad on me once and the car would pop and almost try to start, had fuel in the rails, just not enough pressure to run. If you did a swap, the v6 cars i believe run a different pressure than the ls1 cars.
10-17-2008, 08:51 AM
#19
TECH Regular
Thread Starter
iTrader: (10)
Join Date: Oct 2005
Posts: 403
Likes: 0
Received 0 Likes
on
0 Posts
im almost pos. we run on same pressure, I have a walbro 255, i also just purchases my module for my gauges, so i can check Fuel pressure. I will swap crank sensor tomm. and see what happens.
