chetmo

iTrader: (10)

Ok, I have a 98 v6-ls1 swap car, and still have some issues. We put the tech2 on it, and everything seems to look ok,
*I have compression.

*I have 50 psi oil pressure when trying to crank.

*I obviously have fire as im getting popbacks/backfires.

*I have fuel (not positive on pressure at the moment) but fuel rail sure as heck fills up, I can hear pump kick on, etc. (have maybe 2 gallons of gas in tank).

symptoms; Car will turn over freely, with occasional backfires, and a rare popback(out of intake). It seems as if it is out of timing, but i have been reassured a few times its not the timing, I have talked to my engine builder as well that informed me it shouldnt be this. He reassured me it would be a ground or harness issue. I have checked my grounds, but could something like this cause the car to act like this? Any other ideas on what could create this issue. I dont get to go back home often, and im headed back home saturday to try and fix the issues

random things that shouldnt matter but i could be wrong;

* for some reason I had a drivers side valve cover with no rear pcv port(just got a correct one in mail and will be replaced)

* vacuum port isnt plugged in underneath the map sensor (was told it controls the AC airflow,etc)

Wesmanw02

iTrader: (4)

Sounds like the motor is way out of time, on either the camshaft or ignition timing. My guess would be that the camshaft is 180 degrees out, which would cause the backfire out the intake that you are getting. The ECU controls the ignition timing based on input from the crank and cam sensors, so as long as those are hooked up and functioning, base ignition timing should be right.

I would definitely pull the timing cover and check that the timing is set correctly. Backfiring out the intake is never a good thing, and should enver happen if the cam is timed properly.

ae13291

iTrader: (8)

check the ignition timing bro

ae13291

iTrader: (8)

it will also throw a obd 2 code if its overly advanced or timing retarded

chetmo

iTrader: (10)

no codes are getting thrown, thats what leads me to believe timing might not be the issue. A local gm mechanic told me to I needed to pull the front cover, but the engine builder said I could, but I would be wasting my time that there is no way that cam is in wrong (sponsor on here, Ls1 based shop) and that I could pull it, but he is confident my issue is somewhere else.

waterbug1999

iTrader: (3)

Check to see if you plugged the coils/harness in the right order.

When I did my H/C install years back, I completely took off the part of the harness that connects to all 4 of the coils on each side. Well, when putting it all back together I had them backwards. The car would crank, but just pop and backfire. I know it only plugs in one way, but if some reason its twisted, you can have the plug for #1 on #7 and the plug for #2 on #4 and visa versa. if that makes since.

chetmo

iTrader: (10)

no codes are being thrown, thats whats confusing.

I will have to check on that, cause I have 98 coils tigged up to a 99+ coil bracket, how could I tell, if i remeber it was plug and play?

ae13291

iTrader: (8)

i guess u might be misfiring. see if u can barrow some of the correct coils and maybe it might work. the 98 pcms were differant as well so i think those cils might be ur issue

chetmo

iTrader: (10)

they are the stock 98 coils, just on a 99 + bracket. wouldnt it throw a misfire code?

waterbug1999

iTrader: (3)

The firing order is still the same, and it shouldnt matter..

When you get to the car, just unplug #1, #3, #5, #7 connection from the coils, which is all 4 on the driver side, and turn it around and see if it will start. Mine still popped but it would run after I did this. I switched the other side and it idled like a champ.

chetmo

iTrader: (10)

ok im pulling the pass. side valve cover to swap them out (read first post to see why) basically put all those coils on the other side?
the 98 coils are all individual, I didnt know it could matter, If so im SURE there fubared up in order, that would make no sense though.

ae13291

iTrader: (8)

lol my bad i thought it was like different connections.

waterbug1999

iTrader: (3)

The coils themselves, just leave alone.. Turn the harness around.

Ok, you have the BIG MAIN connection that breaks down into the 4 smaller connections that plug into each coil, right?
Now, unplug the 4 from each coil pack and turn it 180* (or flip it). So, just grab the main connected part (the BIG MAIN), and turn it over.. So, the one you had plugged into the 1st coil pack is now plugged into the one in the very back and the middle two do the same.. Make sense?
Its still plugged into the main harness, but by doing this you changed up the firing order.

chetmo

iTrader: (10)

I will try that, any other ideas?

chetmo

iTrader: (10)

UPDATE; I have been digging around, and it seems to possibly be my coils, there is obviosuly numbers on the 98 coils that go to correct cylinders, i KNOW i didnt do this, does anyone have numbers that would be on the coils, that would allow me to match them up to the cylinder?

waterbug1999

iTrader: (3)

It doesn't matter what coil goes to what cylinder.. They are all a coil and mount the same.

chetmo

iTrader: (10)

thats what I thought, I will jack with the harness like you mentioned.

waterbug1999

iTrader: (3)

Sent you a very detailed drawing to better explain. lol

chetmo

iTrader: (10)

Thanks I will try this.

waterbug1999

iTrader: (3)

good luck.