another one lives! but with issues :(
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From: the not so stock tribe
another one lives! but with issues :( well it finally fired up last night ( ls1 mustang lx) ! it has a few leaks i have to attend to ( front main seal and a few fuel lines) but there is a more pressing issue.
the problem for now is that the car won't idel and back fires very bad from the exhaust.
if i hold the gas more than 1/3 of the way the car would start and go up to about 2500-3000 with a very faint miss. but if i let off the car would back fire and die.
what could the issue be? i have a 224/224 - 580/580 112 cam in there , and i cleaned up and mildly ported the heads (5.3 heads) myself and lapped all the valves, also running a T.P.I.S harness and a 99 camaro pcm and tune ( tune is from this site for a car with the same cam as mine).
could it be that it needs to have a crank relearn done to it ( timing issue) or can it be a faulty valve?
i also have one o2 sensor connected , ( the other won't reach - getting the extension soon), could that be the cause (although i doubt it since the o2's are not used at warm up)
or could the car have too much base ( idle) timing that it is causing the car to back fire and be hard to start?
i'll be doing a leak down test today to see if it is the valves or not, if it isn't what would you suggest to look into next?
and lastly , thanks to all the guys on here for the great help and support i got during the build up ; i couldn't have done it without you guys !!
the problem for now is that the car won't idel and back fires very bad from the exhaust.
if i hold the gas more than 1/3 of the way the car would start and go up to about 2500-3000 with a very faint miss. but if i let off the car would back fire and die.
what could the issue be? i have a 224/224 - 580/580 112 cam in there , and i cleaned up and mildly ported the heads (5.3 heads) myself and lapped all the valves, also running a T.P.I.S harness and a 99 camaro pcm and tune ( tune is from this site for a car with the same cam as mine).
could it be that it needs to have a crank relearn done to it ( timing issue) or can it be a faulty valve?
i also have one o2 sensor connected , ( the other won't reach - getting the extension soon), could that be the cause (although i doubt it since the o2's are not used at warm up)
or could the car have too much base ( idle) timing that it is causing the car to back fire and be hard to start?
i'll be doing a leak down test today to see if it is the valves or not, if it isn't what would you suggest to look into next?
and lastly , thanks to all the guys on here for the great help and support i got during the build up ; i couldn't have done it without you guys !!
did you have it tuned for the cam.....that cam will not run well with the stock tune.
the O2 sensors should not cause a problem. In any case they are not used for the first couple minutes of start up before they reach the required temp. the car will run in open loop.
just my o2
the O2 sensors should not cause a problem. In any case they are not used for the first couple minutes of start up before they reach the required temp. the car will run in open loop.
just my o2
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From: the not so stock tribe
the tune i put in was supposed to be for that cam , but when i read it with ls1 edit it looked like my stock camaro tune. what should be changed tunning wise for the cam?
the other thing i don't get is why is it hard to start and why does it backfire from the exhaust when i have it runing with the gas down?
i might just take the heads off and put another "untouched" set on to see if the valves are the problem.
any suggestions before i rip the heads off?
the other thing i don't get is why is it hard to start and why does it backfire from the exhaust when i have it runing with the gas down?
i might just take the heads off and put another "untouched" set on to see if the valves are the problem.
any suggestions before i rip the heads off?
I would say fix the tune before tearing into the motor...I am not sure how go about it......may be the guys at PCm tuning forum might help......remember it is the small things that get ya
Last edited by Schitzo; Jun 8, 2006 at 02:17 PM.
first thing id to is slap the stock tune back on it. it wont idle smoothly, and will die easily, but you have a known starting point, and it will eventually catch a idle once it learns.. for it to correct enough, you will need the MAF connected, if its off.
since its backfiring, im thinking misfire.. check if you have coil power to both banks... i know the stock harness uses the same power for injectors and coils, but id check it anyway...
basiclly, go thru what you can first...
since its backfiring, im thinking misfire.. check if you have coil power to both banks... i know the stock harness uses the same power for injectors and coils, but id check it anyway...
basiclly, go thru what you can first...
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From: the not so stock tribe
definatly check the simple cheap stuff first, i learned the hard way 
as for the tune , it seems the tune i got in there is exactly the same as the stock tune i had in my camaro.
another weird thing is that the car seemed to run a bit better with the maf unplugged ??
could the car have too much compression ( it has 5.3 heads - 862 casting), which leads it to detonate while ideling? ( just to double check , what should the timing be at idle?)
as for the tune , it seems the tune i got in there is exactly the same as the stock tune i had in my camaro.
another weird thing is that the car seemed to run a bit better with the maf unplugged ??
could the car have too much compression ( it has 5.3 heads - 862 casting), which leads it to detonate while ideling? ( just to double check , what should the timing be at idle?)
Launching!
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From: shasta lake, north cali
did you by any chance switch some of the wire around for the coil packs and such while doing the work to it. if you switched some around i would assume it would be like missrouting plug wires you may only be firing on five or six cylinders which the unburned gasses would collect in the pipes and ignite and blow out the pipe.
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On The Tree
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From: Austin, Tx
I'm with these guys on the coil pack being the problem.
I had my harness backwards on the driver's bank and it would do exactly what you explained, idle weird, backfire out the exhaust, and idle better but with a miss sound at higher RPMs....
I flipped the harness around and it ran like a charm. And if you look in my sig, my cam is very close to yours and I'm on a stock tune, the ECM will idle perfectly fine with this cam.
I had my harness backwards on the driver's bank and it would do exactly what you explained, idle weird, backfire out the exhaust, and idle better but with a miss sound at higher RPMs....
I flipped the harness around and it ran like a charm. And if you look in my sig, my cam is very close to yours and I'm on a stock tune, the ECM will idle perfectly fine with this cam.
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From: the not so stock tribe
DOHHH!!!!!!!!
THANK YOU SOOO MUCH STEVEN!
i just remebered something, when i was putting everything together i took the pass side coils off to clean the tray they sat on, when i put them back on i remember having a hard time routing the coil harness like it was before i removed it!
it all makes sense now, there were two plugs that seemed like they never had combustion on that side too.
guess we'll find out tommorow when i try that!
i feel so smart
THANK YOU SOOO MUCH STEVEN!
i just remebered something, when i was putting everything together i took the pass side coils off to clean the tray they sat on, when i put them back on i remember having a hard time routing the coil harness like it was before i removed it!
it all makes sense now, there were two plugs that seemed like they never had combustion on that side too.
guess we'll find out tommorow when i try that!
i feel so smart
heh, i need to keep that solution in mind for the future.
on a motor with a distributor, that would have been teh first thing id check, but i was only thinking about the spark plug wires... and its almost impossible to cross thoes.. lol.
i could see someone doing that to the coil wires.... good idea.
on a motor with a distributor, that would have been teh first thing id check, but i was only thinking about the spark plug wires... and its almost impossible to cross thoes.. lol.
i could see someone doing that to the coil wires.... good idea.
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From: the not so stock tribe
yeah, the crossed plug wires came to mind but, but the little genious in me was telling me " it's an LS1 , you can't miss wire any thing on it!" i should listen to me a lot less from now on .
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From: the not so stock tribe
well i flipped the harness and fired her up and it came to life right away!
it idled great for the cam it had ( a tad high , but no worries). i have no idea where its idling rpm wise ( no tach) but it idled none the less.
took it for a spin and it ran good, it had a slight miss at around 2000-3000 rpm but i'll figure that out later.
funny ting is the car doesn't shutoff when the key is turned off ; i had the switched 12v wires going to the pcm wired to the glove compartment light , since it remains on while cranking, so i'll have to find another source somwhere else.
i figured out why ( i think) the car pukes oil from the front main seal. i sealed all the valvecover holes and didn't put a breather on ( and i set the ring gap a bit loose for future N2O use) so the car was building pressure in the crankcase and the easiest way out was through the front main seal.
i guess all that is left is fix a few leaks , clean up the wiring insidethe car, put the rest of the interior in , and set toe.
i can't wait to floor it and see how fast it feels with 2.73 gears!
it idled great for the cam it had ( a tad high , but no worries). i have no idea where its idling rpm wise ( no tach) but it idled none the less.
took it for a spin and it ran good, it had a slight miss at around 2000-3000 rpm but i'll figure that out later.
funny ting is the car doesn't shutoff when the key is turned off ; i had the switched 12v wires going to the pcm wired to the glove compartment light , since it remains on while cranking, so i'll have to find another source somwhere else.
i figured out why ( i think) the car pukes oil from the front main seal. i sealed all the valvecover holes and didn't put a breather on ( and i set the ring gap a bit loose for future N2O use) so the car was building pressure in the crankcase and the easiest way out was through the front main seal.
i guess all that is left is fix a few leaks , clean up the wiring insidethe car, put the rest of the interior in , and set toe.
i can't wait to floor it and see how fast it feels with 2.73 gears!