Timing issue
11-03-2019, 12:43 AM
#1
Timing issue So here's my dilemma I just rebuilt my 2001 lq4. Stock pistons stock rods all new bearings and rings. New cam btr turbo stage 2, new timing chain and gears, I set the timing Marks dot to dot heads off and then assembled the top end rewired my harness to fit in my 2000 camaro had it programmed, tried to fire it for the first time today and it back fires through the intake. Pulled the fuses on my harness fir the injectors and tried ether to get it to fire and it just cranks away and back fires. So I have spark and fuel and I'm pretty damn sure my timing is rite considering im the one that did it is there something in missing I mean if I set it dot to dot it cant be off rite. So what's causing my timing issue the tune.
Last edited by William Gilligan; 11-03-2019 at 01:23 AM.
11-03-2019, 01:40 AM
#2
Teching In
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Remember when the cam/crank are dot to dot cylinder is about to fire, not 1.
https://ls1tech.com/forums/generatio...dot-1-tdc.html
https://ls1tech.com/forums/generatio...dot-1-tdc.html
11-03-2019, 08:04 AM
#3
I think he meant to say, dot-to-dot is cylinder #6 firing... remember, #1 & #6 (and #8 & #5, and #7 & #4, and #3 & #2) come to TDC together, but when one is firing, the other is at exh valve just closing and int valve just opening. We build em at dot-to-dot because it's easier to see than actual #1 firing, which is at both dots 12:00.
Shouldn't matter though; the cam sensor knows which cyl is which. Sounds more kinda like you have the coil harnesses for the 2 sides swapped.
Shouldn't matter though; the cam sensor knows which cyl is which. Sounds more kinda like you have the coil harnesses for the 2 sides swapped.
11-03-2019, 08:54 AM
#5
ModSquad
iTrader: (6)
Push much lifter preload will cause this also. How did you measure pushrods?
11-03-2019, 10:13 AM
#7
The truck harnesses have 2 large plugs, one for each side of the motor. It's easy to plug the left one in where the right one goes and vice-versa.
"The simplest explanation that fits all the facts is most likely to be the right one."
"The simplest explanation that fits all the facts is most likely to be the right one."
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11-03-2019, 11:29 AM
#8
I checked the schematics and the wire colors on each plug are on the right side so I dont think it's the coils being backwards but I'll check again. I plugged a scan tool in and didnt see any rpm while cranking. Spark tester lights up shouldn't I see cranking rpm could it be in the tune in the pcm I do see 15* of timing while cranking is this too much or not enough timing
11-03-2019, 01:20 PM
#9
15° is fine.
You DON'T have a "timing" problem. Whatever your problem is, it IS NOT "timing".
The problem isn't the wires at the coils. It's the 2 large plugs that connect each bank of coils to the main harness. Sounds like you have the left one plugged in where the right should go and vice-versa.
Try SIMPLE. Just exchange the plugs. REEEEEEEEEEL EEEEEEEEEEEZY mistake to make, EQUALLY EEEEEEZY to check and/or fix. If it still doesn't run, put em back.
You DON'T have a "timing" problem. Whatever your problem is, it IS NOT "timing".
The problem isn't the wires at the coils. It's the 2 large plugs that connect each bank of coils to the main harness. Sounds like you have the left one plugged in where the right should go and vice-versa.
Try SIMPLE. Just exchange the plugs. REEEEEEEEEEL EEEEEEEEEEEZY mistake to make, EQUALLY EEEEEEZY to check and/or fix. If it still doesn't run, put em back.
11-03-2019, 01:44 PM
#10
Not as easy as it sounds high rise intake and modded harness they dont reach each other it would be easier to ohm them out from the pcm and see if there wired wrong sounds like a easy mistake but I checked the wiring at the plug for the colors that corresponds to that bank and it looked rite doesnt hurt to double check
11-03-2019, 02:32 PM
#11
TECH Enthusiast
Check that your cam sensor and also cranks sensor are plugged in ok. If they are ok , check ground wires. The crank with no rpm signal is the key, wont be coil connectors.....
Grounds on the back of the heads are the usual suspects.
Grounds on the back of the heads are the usual suspects.
11-03-2019, 02:50 PM
#12
FWIW, whatever your problem ends up being, when you do a cam install, it's a good idea to verify things with a degreeing kit. find the #1 intake/exhaust lobe centerlines and make sure they match what the cam card says, and that is usually sufficient to make sure there is nothing wrong with the cam grind or the timing.
11-12-2019, 04:44 PM
#13
So got my pcm bck today put it in and tried to start it again with my solus on it and I get a code code p0336 ckp sensor A (18/24x) out of range. Acdelco sensor any idea got a junkyard harness coming to replace the truck harness I modified to use. Figured i would give it a try any ideas. Fresh rebuild I did. Wont start just backfires
11-12-2019, 07:40 PM
#14
TECH Senior Member
Check cam timing/install.
11-12-2019, 08:17 PM
#15
ModSquad
iTrader: (6)
Did you measure pushrod length, or just throw the kit together? Too long a pushrod (too much lifter preload) would cause this issue. You need to do a leak down test to verify your building compression. Could be cam was ground wrong, or you did the install wrong. Seen it more than once. Weak cylinder pressure numbers would give you an indication of mechanical problems being present. If leak down test shows good numbers, it would be an electrical issue. Help yourself here by eliminating potential issues. You can get a leak down test kit at Harbor Freight for cheap. Easy to do.
edit...what timing set did you install? Is it adjustable?
edit...what timing set did you install? Is it adjustable?
11-12-2019, 11:18 PM
#16
Timing set is set to 0 cam was installed dot to dot did not degree cam and pushrods were the same length as the ones that came out. What about my crank sensor code pushrods wouldnt set that code and either would cam timing well cam timing might but I would expect to see p0366 or something like that for the cam
11-13-2019, 03:49 PM
#17
Well 1 thing for sure it's either cam or ignition timing or a valve hanging open.
You've been asked a couple of times about your pushrod length... If too long the valves are hanging open.
But the p0366 indicates a problem at the crank sensor. So try a new one, and use a good brand. While it's out spin the crank around with a flash light in the hole and inspect the tone wheel/reluctor wheel on the crank to make sure none of the teeth are bent etc..
Check wiring closely at the crank sensor connector, replace the pigtail for good measure if it's old..
Good luck and let us know
You've been asked a couple of times about your pushrod length... If too long the valves are hanging open.
But the p0366 indicates a problem at the crank sensor. So try a new one, and use a good brand. While it's out spin the crank around with a flash light in the hole and inspect the tone wheel/reluctor wheel on the crank to make sure none of the teeth are bent etc..
Check wiring closely at the crank sensor connector, replace the pigtail for good measure if it's old..
Good luck and let us know
11-13-2019, 06:52 PM
#18
I'll do a compression test this weekend if its cam or pushrod related I'll have low compression. I got the crank sensor from 1auto supposed to be acdelco but could be China knock off I got a new one today from advanced I'll swap that out this weekend and the harness too and see wat happens.
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11-15-2019, 11:57 PM
#20
TECH Senior Member