ls1silverado4754

i have a 01 silverado that before this weekend had a 4.8 in it i got a ls1 out of a 98 comaro ss i put the motor in this weekend i had to swap the intake manifold alternator powers steering pump clutch fan pulley oil pan and plate and pick up and crank pulley i put a true tec level three 700 hp tranny kit in my 4l60e a new rev max level 5 torque converter good for 850 hp with a 3000 stall obx long tube headers and i cant get the truck to start with either ecm im getting fuel pressure and power to coil plug it turns over but no spark the fuel pump only comes on with my silverado 4.8 ecm the comaro ecm the gauges go crazy someone told me i have to get my silverado ecm flashed for the ls1 cause they are year pacific the only plug i had to change was the ect sensor was differnt any ideas i checked all grounds and there good

ls1silverado4754

any ideas really need help moving to florida this weekend and need my truck running to get there do i need to get ecm flashed to get spark

VlaDeMaN

iTrader: (1)

what harness did you use? 98 ecm wiring is different than 99-02. i understand that ecm and wiring is wacked on the 98, but it can be repinned to work with 99-02 ecm. what are the digits (i think by the badcode) on the silverado ecm?

ls1silverado4754

i used the wiring harness from my truck and the truck ecm is the only one that makes the fuel pump kick on the 98 ecm makes my gas gauge read empty and the oil pressure is at like 120 if there was a 120 0n the gauge
ill go get my truck ecm and post numbers

ls1silverado4754

the serv no is 12200411 dlrc

ls1silverado4754

please anyone i really need some ideas i heard i could reflash the ecm in my truck to work with the ls1 is that true and can i get that done at a dealership

VlaDeMaN

iTrader: (1)

if you used the truck wiring, then i think you're good with just a reflash on the silverado '0411 ecu. the 98 ecu has totally difference pin wiring.

here are some pinouts if you're interested:

99-02 ls1 - http://www.lt1swap.com/2001_PCM_CONN_PINOUT.htm

99-02 vortec - http://www.lt1swap.com/99-02_vortec_pcm.htm

98 ls1 - http://www.lt1swap.com/1998_ls1_pcm_pinouts.htm

dealership MAY do it. i highly recommend you find a local chevy tuner to do your flash instead because the dealer has limitations to what they can flash. i doubt they'll flash an ls1 program to your silverado. did you install the EGR and airpump? a tuner might even have better programming for your mods and will disable all the auxiliary crap too.

do you have a code scanner?

ls1silverado4754

i can borrow one my buddy has one at the shop i did the swap at shouldnt the silverado ecm still make the ls1 have spark
but what would i scan for if the truck hasnt started to throw a code i took the motor out of the comaro mself and it ran great before i took it out and my 4.8 ran good to so its something from the swap making it not have spark i checked the 3 ground there all good checked just weird has to be the ecm i pulled a plug and had my buddy turn it over no spark checked power at the coil pack connectors and both sides had power on the pink wire i really hope i need to reflash the ecm and that will fix it any good tuners in md or de area

ls1silverado4754

i installed the egr not the air pump do i need that

LT1TransAm

iTrader: (11)

Well no ****** **** the thing needs tuned. Two completely different motors with different tunes in them. Lol

VlaDeMaN

iTrader: (1)

lol so is that it then?

i would say disconnect all the egr/airpump/etc and have the tuner disable them too, if he is good he should know what to do.

ls1silverado4754

thanks everyone guess im off to the dealership to see if they can flash it i dont know any chevy tuners around here

Alvin@PCMofNC

It needs to be tuned but it should at least fire. I would check the simple things.. Grounds. power, fuses.

TheWolfMatt

Might consider sending in one of your ECM's to TSP for a quick program with a list of what you have done to your truck. Let them set up a tune for it and try and not run the truck till you can find a local tuner other than the dealer.

ls1silverado4754

well been all over hell and creation no one could flash it so i set up a appointment at je performance in baltimore tomorrow there going to dyno tune it and do a diagnostics tomorrow ill try to get some videos if anyone is interested thanks alot for the help

gagliano7

Use your truck pcm and have that tuned for the LS1

brandon6.0

iTrader: (32)

i swapped a ecm in my truck once that wasnt the original and all it would do is turn over and not start. Swapped the original back in and ran great! it has to be swapped over to your vin and stuff for a different ecm to work. By the way my truck is a 2000 silverado.

fohovlegotz

Sorry for reviving a dead post but I am about to do this swap. Did you have to do something with the fuel delivery system? (i.e. the corvette filter/fpr)

gagliano7

If you are putting the ls1 long block in your truck and using all the other parts off your truck motor you don't need to change the fuel system. You would have to change things if you were going from a return style to a non return style or vice versa.

CHEVELLEPOSSE

Flash, tune