chris-m

my old ls1 worked perfectly with the msd 6010 box and a carb setup. i've now got my new ls6 bottom end in and ready to fire, but not getting there due to lack of spark by the look of it
i'm using my old coil packs etc, and fitted a new cam sensor and crank sensor as a precaution when i built up the new engine. heads and cam were cleaned up and fitted to the new forged ls6 bottom end (weber race engines).
i have decent oil pressure when cranking, but it will not fire.

things i'm convinced are ok;
12v supply and ground to msd box- wiring was untouched on car
cam and crank sensors are new
cam and timing marks were lined up ok when i fitted my cam, new timing chain and sprockets.

i have a funny feeling that maybe i have got the wrong crank pulse trigger wheel, but it shouldnt be as i made it clear i was using an msd 6010 box and needed the ls1 trigger wheel (24x)

now the engine is in i cant easily drop the sump to check the number of teeth. unless i send the msd box back to the states i cant guarantee its 100% ok, unless someone knows a way for me to check the output from the crank and cam sensors?

any suggestions as to how to proceed gladly received as i dont want to take out the engine unless its a last resort. i dont have a spare msd box or any info on how to check coil packs, but there is no way all 8 are dodgy, and none of the wiring has been touched. the last engine span a bearing and was carefully removed.
cheers
chris

chris-m

also to add is there any chance i got an incorrect cam/crank sensor by mistake, both bolted straight up ok?

LS1MCSS

iTrader: (18)

The correct crank sensor will be black. The sensor for the 58X reluctor is gray. I fthere is any way to look in through the crank sensor hole, you can tell a difference in the two different reluctors. You may have to search a little to find a comparison picture.

Nabdrill

iTrader: (19)

I would think that you could unplug the coil harnesses from the MSD box and turn the motor over while testing the coil leads in the connector... should be some voltage there if the box is working, prob have to call MSD to get a test procedure. Or just pull the plugs individually, ground them, and check each for spark while turning the motor over. Do you still have the old cam/crank sensor from your other motor. Maybe try them.

forcd ind

iTrader: (7)

go over everything again, make sure correct coil harness goes to correct side
if you have your old sensors, try them
i built a new stroker, have not put it in yet, but have that fear of the reluctor being off or something, what i have now works great
is there still a tune in the box-maybe a pill missing
not sure if you can see into the crank sensor hole with a mirror or something
i'll look at the one on my engine stand tomorrow and see if its possible

chris-m

thanks for replies. msd have been helpful, if i pull the crank sensor and look into the hole i should see a double pulse wheel if its 24x and a single pulse wheel for the 58x. i can also then check which cam and crank sensor i have while looking. i have asked msd if there is any way to check for crank pulse and i'm going to go over the electrics tonight, but i'm convinced all the connections are fine, but at least i can discount it then.

i also called weber race engines and brian is going to check my build sheet for me so i can confirm 100% on the right crank sensor. i'm wondering if somehow the crank sensor isnt close enough to the trigger wheel etc .

worst case scenario at the mo is pulling the engine but before i do so i can loan a set of working sensors from another guy nearby from his LS6 kit car, then if need be send the msd box back for testing if there is nothing i can check myself on it. i'll take some pics of the crank and cam sensors tonight incase i have the wrong items somehow. i know its not infallable buying brand new bits maybe i got a rogue sensor.
cheers

chris-m

i have the laptop rigged up and i have put a new map on the msd box to make sure its talking to the laptop. its not showing any rpm though when cranking.

forcd ind

iTrader: (7)

when i crank mine over with the laptop hooked up, i see about 150+/- rpm's
so that is a good indication somethings not right

chris-m

thats interesting, my tacho tries to flick slightly when it initially cranks then nothing, certainly doesnt show steady rpm . my understanding is the msd 6010 box has to see a few crank revolutions at first before it will fire anyway, to sync up the cam and crank sensor positions. i'm not sure if a minimum rpm is needed as well, ie to make sure its cranking fast enough?

does your msd display screen on the laptop show rpm as well as the tacho on the car?
cheers

chris-m

i checked last night and have the correct 24x reluctor ring. sensors were checked with an ohmeter and have a reasonably high impedance between the 12v and ground contacts, however i cant check any further than this.

we then checked all the wiring connectors and replugged the msd box back in, and did a test crank with the plugs out. i am getting a spark now at all 8 plugs with them out. when we put them back i think the compression is making the engine crank a little slow. (tight new engine). my starter isnt massively powerful as its an adapted starter onto a custom bellhousing to mate up a porsche g50 box to ls6.

is there a minimum cranking speed the msd box needs to see before it will fire the plugs and sync up the cam/crank signals?
cheers

forcd ind

iTrader: (7)

w/o the plugs, did you see cranking rpms on the laptop? sounds like your getting what others have had, too slow an engine turnover to fire the MSD
not sure if MSD has some kind of cap. setup that would store a spark and release it to help, i would call them and tell them what you found
you might try a booster bat., charger-is your bat wirging large enough for the system, so resistance doesnt hurt it

chris-m

i didnt try it with the laptop on last night as it was getting late and i just wanted to check all 8 plugs for a spark. i'll try tonight with the laptop hooked up to see if it shows cranking rpm. i assume you watch the 3 dials on the laptop to see any movement?

i have a plan to link up another battery if need be to give me enough juice to spin it over better, and am awaiting a reply from msd as to minimum rpm at cranking.

i've also got a timing map ready with around 10deg ignition at cranking to hopefully make it easier to start as the old map was like 15-16deg cranking
cheers

forcd ind

iTrader: (7)

i just blow up the 3 dials, easier to read, look at the rpm one-good luck

TJ

iTrader: (10)

you need to make sure the battery is on full charge, and also have a nie size battery charger in the 'engine start" mode.
a new motor is very tight and will require lots of power to spin over fast enough.
i had this same problem with my 408, and a buddys 370 not too long ago. you might have to do this a couple times until the motor heat cycles a few times.
its aggrevating, youll be chasing your tail for days. i did.
motor turns over 1st crank after 3-4 crankings.
dont be afraid to give it fuel. youll think you are going to flood it, but pump it as you crank and it will bust off.
done several of them this way now. hard to get them fired off.

chris-m

sounds very much like what we are getting as its very slow turning it with the plugs in plus i have breaking in oil in there as suggested by weber racing.
oil pressure comes up no probs so far. main thing is i hope it is just this and not an msd/crank pulse issue, but seeing 8 sparks last night with plugs out tells me it cant be far off right or the msd box wouldnt fire any of them?

TJ

iTrader: (10)

what crank is in the motor? there are a few issues you could run into if it was a stroker callies crank, but i think any stock stroke crank should fire up no problem.
try it with some juice poured to it and keep getting the fuel to the motor til it starts to fire.
hope a cranking rpm issue is all it is.

LQ9CHEVELLE

iTrader: (2)

I can second this motion, ive had a couple carbed LS1 motors, and none of them would even think of starting if the battery voltage dropped below a solid 12V while cranking. Those MSD boxes are very fussy about voltage. Try it with a battery charger hooked up, or a fresh battery with very good clean connections. My motor would literally act as though the ignition wasn't even hooked up, even though it had enough power to crank over

S10xGN

iTrader: (11)

I'm gonna be cranking my motor up in the next month or so. After giving it some thought, I decided to "0" out any advance untill 600 RPM's, then start adding my curve. Theoretically, this should eliminate any buck-back by having too much advance and should make the motor spin over faster, right?

Russ

chris-m

Success! (partial at least!)

the issue was definately slow cranking speed due to the new motor being tight and the msd not liking it. i rigged up a fresh pair of batteries linked in series at 24v direct to the starter and solenoid on their own, so seperate to car electrics. this was applied for short bursts only so as not to burn out the starter. the car fired first attempt! i saw 230rpm cranking speed straight away, and the car fired literally first time, after numerous previous failures using the normal (fully charged) car battery at 12v.

i had to kill the engine after a few minutes anyway as a water hose started to leak slightly but the engine sounded great for those few minutes :-)

many thanks to everyone who contributed, moral of the story is the msd box likes to see a good strong battery voltage and decent rpm when cranking.

also out of interest i changed my map to make it easier to crank by knocking back the initial timing to about 12 degrees, but i had already tried it at that before with a single battery so it was the starter /cranking rpm as the main issue.

TJ

iTrader: (10)

i played with mine anywhere from 0-20. it actually starts up quicker now. i have 22 in it. all dependant on the motor combo too.....