LS3 - Long crank(5 or 6 seconds) with no spark, THEN it starts. (RESOLVED)
05-01-2018, 09:36 PM
#1
LS3 - Long crank(5 or 6 seconds) with no spark, THEN it starts. (RESOLVED) My friends 2011 Camaro SS has developed an irritating issue.
Status... New Battery, New GM Starter, New plugs, new wires.
Behavior : Last year Steves car started having trouble starting when Hot. He drove to/from Sturgis and on the way back (to Upstate NY), every time he stopped for gas, he had to let it set there for an hour or so till it cooled down before it would start (it spun over lazily). He and I tried all the usual culprits, new battery, new (autozone rebuilt) starter, new plugs, heavy cable from battery to engine, remote solenoid, copious heat shields, etc. No change .I talked him into buying a brand new GM starter and we put that in last weekend. Viola! (temporarily) It now spun over quickly and started after just a second of cranking. But, he drove about 30 miles and when he shut it off, it wouldn't start 'normally'. It still spun over quickly but you have to crank about 6 seconds and it only starts in the 'default' mode (Stabiltrack?) . We pulled plugs and O2 sensors. They were light tan. I scanned his car with my HPTuners. It only shows O2 heater circuit issues. Fast forward to today, I pulled a plug wire off cylinder 1, leaving the coil side connected. Then took a spare spark plug and grounded it against the coil bracket while Steve cranked it. What the ??? There's no spark at all till about the 5 second mark, then it fires up and the engine would start. No spark till then though, and it's always in that limp home mode. Any ideas ?
Status... New Battery, New GM Starter, New plugs, new wires.
Behavior : Last year Steves car started having trouble starting when Hot. He drove to/from Sturgis and on the way back (to Upstate NY), every time he stopped for gas, he had to let it set there for an hour or so till it cooled down before it would start (it spun over lazily). He and I tried all the usual culprits, new battery, new (autozone rebuilt) starter, new plugs, heavy cable from battery to engine, remote solenoid, copious heat shields, etc. No change .I talked him into buying a brand new GM starter and we put that in last weekend. Viola! (temporarily) It now spun over quickly and started after just a second of cranking. But, he drove about 30 miles and when he shut it off, it wouldn't start 'normally'. It still spun over quickly but you have to crank about 6 seconds and it only starts in the 'default' mode (Stabiltrack?) . We pulled plugs and O2 sensors. They were light tan. I scanned his car with my HPTuners. It only shows O2 heater circuit issues. Fast forward to today, I pulled a plug wire off cylinder 1, leaving the coil side connected. Then took a spare spark plug and grounded it against the coil bracket while Steve cranked it. What the ??? There's no spark at all till about the 5 second mark, then it fires up and the engine would start. No spark till then though, and it's always in that limp home mode. Any ideas ?
Last edited by mightyquickz28; 11-30-2018 at 09:26 PM.
05-04-2018, 08:59 AM
#3
Log it with the scanner when it won't start. When it's cranking are you getting a RPM signal?
It won't start if there's no CKP signal but it will start with no CMP signal. The CKP controls the coils and the injectors. Have you checked to see if you are getting an injector pulse when it won't start?
It won't start if there's no CKP signal but it will start with no CMP signal. The CKP controls the coils and the injectors. Have you checked to see if you are getting an injector pulse when it won't start?
05-04-2018, 09:16 AM
#4
TECH Senior Member
I bet it's the cam sensor.....
05-04-2018, 07:40 PM
#5
There isn't a crank/tach signal during cranking nor once it does start.
Log it with the scanner when it won't start. When it's cranking are you getting a RPM signal?
It won't start if there's no CKP signal but it will start with no CMP signal. The CKP controls the coils and the injectors. Have you checked to see if you are getting an injector pulse when it won't start?
It won't start if there's no CKP signal but it will start with no CMP signal. The CKP controls the coils and the injectors. Have you checked to see if you are getting an injector pulse when it won't start?
05-23-2018, 11:08 PM
#10
We replaced both the crank sensor and the cam sensor. NO CHANGE. Steve is sick of this. He hasn't been able to enjoy the car this past year because of this issue. He's pulled the entire turbo kit off and will be going to a supercharger. In the meantime, he's pulling the wiring harness off to look and see if that's got issues.
05-27-2018, 10:23 PM
#11
He will probably find a bad connector or chafed wire. I had a buddy who did a swap and SWORE his harness was not his starting issue, until I showed him the scan in HPT. At least you guys are headed in the right direction much quicker than my buddy did.
10-17-2018, 07:40 AM
#12
Just wanted to say, the way we fixed it was to buy a new harness. We never got around to diagnosing the old one. We were focused on getting the car on the road again. Took out the old one, put in a new GM harness and she starts fine now.
05-12-2019, 03:05 PM
#13
Small update: After a week or two, the issue started happening again. Cold starts were magnificent, hot starts it would typically go into fail/safe mode and the engine would crank slowly. Steve was really frustrated but we found a buddy that has a shop and he found a high torque starter that actually fit the LS3. It's a Tilton 54-40011 "super starter". Lol.. it comes with a dyno sheet. About $400 a copy. It really spins the engine quickly now.
05-22-2019, 07:26 AM
#15
Sorry for the late response, yes, he does. Some other things have developed as well.
So with the new starter, the engine cranks and starts every time , without default to failsafe mode. So Steve decided to take it to a local well renowned LS tuner in nearby Connecticut(Steve and I are in Upstate NY), Steve drove the car over there and hoped to see it dyno tuned and drive it home that same day, albeit in the afternoon. Well, he called me about an hour after he arrived (9am?) and his tone had one of a bit of despair. I, not knowing anything was amiss, expected to hear about a glorious dyno figure. Instead he said the following..
Steve left the car there and awaits the call that the car is all ready.
So with the new starter, the engine cranks and starts every time , without default to failsafe mode. So Steve decided to take it to a local well renowned LS tuner in nearby Connecticut(Steve and I are in Upstate NY), Steve drove the car over there and hoped to see it dyno tuned and drive it home that same day, albeit in the afternoon. Well, he called me about an hour after he arrived (9am?) and his tone had one of a bit of despair. I, not knowing anything was amiss, expected to hear about a glorious dyno figure. Instead he said the following..
- Before the tune, they like to look the car over to make sure everything is in place, secure, etc. Right off the bat, they found my new harness was touching the headers in two places. I don't understand how that could happen. You know me and you saw me tie everything securely and away from any hot surfaces, right? (I did)
- Several of the header bolts had backed out a thread or two. Again, You saw me go over every bolt twice, making sure they were all tight, right?(I did, and if anything, in my estimation, Steve overtightens bolts/nuts. I would not want to work on his engine, lol)
- Worse, you know the crank bolt that has to be torqued to 2xx ft lbs? The mechanic walked me over to show me, to my "When I think what could have happened" horror, he turned the bolt out with his bare fingers. (He was to find out later in the day that his DragonSlayer crank snout was NOT damaged).
- Lastly, the tune, an amalgamation of his initial Stroker N/A tune, a moderate turbo tune by a local shop and my own attempts to address his VE and MAF turbo tune were woefully off from the needs of his now Supercharged 416.
Steve left the car there and awaits the call that the car is all ready.
07-15-2021, 02:55 PM
#16
New update on this condition:
So my friends car is still fine but he and I were going to help out a fellow police officer with her engine replacement. She, too, has an LS3 that bit the dust. We ordered the parts and got the machine work done, got it all assembled with a BTR custom cam/kit and installed it. After the last bolt was tightened and the fluids were checked, battery voltage verified, we said a prayer and cranked it. Ugh.. Barely turning over. Wth? We checked all the connections and charged the battery again. Same thing , barely turn over and then 'clickety, click". Jumped it with a pickup truck. Same thing. Off to Autozone to get a brand new battery. Same thing. Got a new starter. Same thing. Got a high torque starter. Same thing. A buddy of ours suggested adding two ground straps going from the shock towers , terminating on the heads. Well, I'll be. Cranked up nice and effortlessly.
So my friends car is still fine but he and I were going to help out a fellow police officer with her engine replacement. She, too, has an LS3 that bit the dust. We ordered the parts and got the machine work done, got it all assembled with a BTR custom cam/kit and installed it. After the last bolt was tightened and the fluids were checked, battery voltage verified, we said a prayer and cranked it. Ugh.. Barely turning over. Wth? We checked all the connections and charged the battery again. Same thing , barely turn over and then 'clickety, click". Jumped it with a pickup truck. Same thing. Off to Autozone to get a brand new battery. Same thing. Got a new starter. Same thing. Got a high torque starter. Same thing. A buddy of ours suggested adding two ground straps going from the shock towers , terminating on the heads. Well, I'll be. Cranked up nice and effortlessly.