Still no start - Help please
Discussion
Help Help Help - about to set fire to my whole project and be done with it!
Well some of you know I have been unfortunate with the final bit of my LS7 engine install, with a charge issue in the ECU circuit caused apparently by a faulty alternator, but then later I had successfully run up the engine for about 5 mins with no code errors reported (first time!), and as it got to around 90 deg c, the engine started to misfire. Within about a minute it had got so bad it stopped, and it could not be restarted, only fluffing and banging.
Then I found that a new code error had arisen, 'cam sensor circuit error' !
With all this and the alternator problem, Jeff agreed to replace the ECU reprogrammed with the original, and that has solved the charge circuit issue I had, however not the starting issue it seems. Not a peep, just a single 'bang' when turned over.
And so does it look like a cam sensor failure? That would presumaby account for no start or firing at all?
Anyone experienced this but I am no expert - - seems odd on a new engine!
You experts out there can you suggest some tests etc.? This sensor is in a hell of a place to get to, and you can't see it head-on - Is it an engine-out job?
Please help, otherwise I just might join a commune or sect! (Jeez- that shows my age)
Keith
Well some of you know I have been unfortunate with the final bit of my LS7 engine install, with a charge issue in the ECU circuit caused apparently by a faulty alternator, but then later I had successfully run up the engine for about 5 mins with no code errors reported (first time!), and as it got to around 90 deg c, the engine started to misfire. Within about a minute it had got so bad it stopped, and it could not be restarted, only fluffing and banging.
Then I found that a new code error had arisen, 'cam sensor circuit error' !
With all this and the alternator problem, Jeff agreed to replace the ECU reprogrammed with the original, and that has solved the charge circuit issue I had, however not the starting issue it seems. Not a peep, just a single 'bang' when turned over.
And so does it look like a cam sensor failure? That would presumaby account for no start or firing at all?
Anyone experienced this but I am no expert - - seems odd on a new engine!
You experts out there can you suggest some tests etc.? This sensor is in a hell of a place to get to, and you can't see it head-on - Is it an engine-out job?
Please help, otherwise I just might join a commune or sect! (Jeez- that shows my age)
Keith
Hi Mate
You should be able to get to the cam sensor output wire by the ecu side of the loom and it is not the easiest thing to test. I have a few oscilloscopes that would easily identify if it is working or not, however, if the ecu thinks it is not working, it will not start, or even fire.
Where are you? If you are not too far away I will see if I can come round and try and see what is going on, I also have a new and unused LS7 ecu and loom....
Gareth
You should be able to get to the cam sensor output wire by the ecu side of the loom and it is not the easiest thing to test. I have a few oscilloscopes that would easily identify if it is working or not, however, if the ecu thinks it is not working, it will not start, or even fire.
Where are you? If you are not too far away I will see if I can come round and try and see what is going on, I also have a new and unused LS7 ecu and loom....
Gareth
Hi Gareth,
Sad to say I am in Gloucestershire, the other side of the country - bummer!
This frikkin thing is driving me nuts!
Perhaps the weekend I will attempt to cut a hole in my bulkhead (which is ally- cab not fitted, to see if I can gain sufficient access to see/ access the damn thing.
Cam sensors don't ususally go wrong do they?
Mind you the fact that the engine got to operating temp from cold for the first time, might have highlighted a problem....
If you fancy a trip out over the weekend, I can lay on tea, coffee, cakes, sarnies, and even a takeaway and drinkies - I have a spare comfy bed with room-service...and your own bathroom!
Ahh well, thanks for the thought and offer....
cheers
Keith
Sad to say I am in Gloucestershire, the other side of the country - bummer!
This frikkin thing is driving me nuts!
Perhaps the weekend I will attempt to cut a hole in my bulkhead (which is ally- cab not fitted, to see if I can gain sufficient access to see/ access the damn thing.
Cam sensors don't ususally go wrong do they?
Mind you the fact that the engine got to operating temp from cold for the first time, might have highlighted a problem....
If you fancy a trip out over the weekend, I can lay on tea, coffee, cakes, sarnies, and even a takeaway and drinkies - I have a spare comfy bed with room-service...and your own bathroom!
Ahh well, thanks for the thought and offer....
cheers
Keith
Before I changed the ECU (last weekend) the error code definately said Cam sensor circuit, so either the sensor is dicky/broken, or the wiring is faulty.
The other thing I s'pose it could be is that the T chain has slipped
but that (I hope) is unlikely!
Would be good to know if it would work without the cam sensor connected, at least I could then see if there is a difference.
Oh-woe-is-me!
The other thing I s'pose it could be is that the T chain has slipped
but that (I hope) is unlikely!Would be good to know if it would work without the cam sensor connected, at least I could then see if there is a difference.
Oh-woe-is-me!
C Lee Farquar said:
GarethGTR said:
if the ecu thinks it is not working, it will not start, or even fire.
Gareth
My LS7 with GM ECU will start and run with the cam sensor disconnected. However, it doesn't start as well.Gareth
UltimaCH said:
Cam or crank sensor?
This one, which I assume is the cam sensor? The plug fell out during an event making it harder to start but OK when running. It may have been down on power, not sure as it was raining so I wasn't using it flat out.It will also run with the MAF and intake temp sensor disconnected, I just got a slight hiccup at 4000 rpm.
Hi
Okay, I bow to superior experience, although this must be the only ecu that I have worked with that will run without a cam sensor. The ecu's that I am used to will continue running (in limp mode) if the cam sensor fails and the engine is already running, but will not start. Thanks for the heads up!
Sorry, weekend is full, a few hours is no problems, even a 100 miles, but cant do a weekend (as inviting as it sounds!).
Gareth
Okay, I bow to superior experience, although this must be the only ecu that I have worked with that will run without a cam sensor. The ecu's that I am used to will continue running (in limp mode) if the cam sensor fails and the engine is already running, but will not start. Thanks for the heads up!
Sorry, weekend is full, a few hours is no problems, even a 100 miles, but cant do a weekend (as inviting as it sounds!).
Gareth
V8 Vum said:
Another quick question to be sure:
Does anyone know what pressure reading to expect in the fuel reg on an LS7 on startup?
Just trying to eliminate everything.
cheers
Keith
4 bar, Keith when the engine was running did you have any of the vacuum hoses open? Do you run a fly by wire throttle? Does anyone know what pressure reading to expect in the fuel reg on an LS7 on startup?
Just trying to eliminate everything.
cheers
Keith
You can disconnect your ecu and that will reset the throttle body as that is what has put it in limp mode. The camshaft sensor will be upset by open vacuum hoses or running the engine with vac hoses on then removing them.
Kyle,
This was the sequence of events:
November ish - Everything connected (apart from rocker breather), clean ECU codes after sussing out the alternator failure
Started and ran great for about 5 mins - FBW throttle responsive...
5 mins later-ish got to 90 degrees temp, engine started to run a little rough, shortly degenerating to fluff & Bang no throttle response, finally cut out altogether.
Cam circuit fault error code shown
Cleared all codes, disconnected and reconnected the ecu - NO START, JUST A FEW FLUFFS AND BANGS.
Cam circuit fault error code shown
Because I had so many issues before, Jeff swapped out the ECU with maps
Arrived Xmas
Reconnected new ECU reset everything - NO START - Just the same!
So ?????????
Cheers
This was the sequence of events:
November ish - Everything connected (apart from rocker breather), clean ECU codes after sussing out the alternator failure
Started and ran great for about 5 mins - FBW throttle responsive...
5 mins later-ish got to 90 degrees temp, engine started to run a little rough, shortly degenerating to fluff & Bang no throttle response, finally cut out altogether.
Cam circuit fault error code shown
Cleared all codes, disconnected and reconnected the ecu - NO START, JUST A FEW FLUFFS AND BANGS.
Cam circuit fault error code shown
Because I had so many issues before, Jeff swapped out the ECU with maps
Arrived Xmas
Reconnected new ECU reset everything - NO START - Just the same!
So ?????????
Cheers
Edited by V8 Vum on Saturday 8th January 11:06
GarethGTR said:
Sorry, weekend is full, a few hours is no problems, even a 100 miles, but cant do a weekend (as inviting as it sounds!).
Gareth
Gareth,Gareth
Never mind...how many miles to GL20 8JA ?
If you are prepared to buzz over for a couple of hrs, then fantastic, however I guess its going to be too far for you in reality...175 miles from maidstone although mostly motorway!!!!
cheers old man! Really appreciate the thought!
Re: J. Salmon RCR-40 Build
Quote:
Originally Posted by A-tomic
Jay,
Your crank sensor CRP 58X for the LS7 should be GM# 12585546 and the cam sensor should be GM#12561211.
There is another crank sensor for the Gen 3 motors CRP 24X 12360228. Make sure you have the right one. I'm not sure about the voltages.
Dave
Dave,
That's what we determined. We also determined that the sensors in the engine are newer 5V sensors, but the harness is outputting 12V. The wiring doesn't exactly match the schematic from fast. The harness is keyed for the plugs on the new sensors, but like I said the voltage is wrong. So we tried a 12V sensor and the plugs are not right.
It comes down to needing to talk to FAST and/or Kinsler. That's tomorrow.
-J.
______________
This is a clip from the GT40s.com website and a build log for a friend that had similar problems. Looks like a mismatch between the sensor and the ECU.
Best of luck, hope you get this sorted soon.
Ken
Quote:
Originally Posted by A-tomic
Jay,
Your crank sensor CRP 58X for the LS7 should be GM# 12585546 and the cam sensor should be GM#12561211.
There is another crank sensor for the Gen 3 motors CRP 24X 12360228. Make sure you have the right one. I'm not sure about the voltages.
Dave
Dave,
That's what we determined. We also determined that the sensors in the engine are newer 5V sensors, but the harness is outputting 12V. The wiring doesn't exactly match the schematic from fast. The harness is keyed for the plugs on the new sensors, but like I said the voltage is wrong. So we tried a 12V sensor and the plugs are not right.
It comes down to needing to talk to FAST and/or Kinsler. That's tomorrow.
-J.
______________
This is a clip from the GT40s.com website and a build log for a friend that had similar problems. Looks like a mismatch between the sensor and the ECU.
Best of luck, hope you get this sorted soon.
Ken
I would whip the spark plugs out and check them all before you do anything else. Any water in the oil? Oil/carbon in the water? (You may have already done this).
Check fuel system pressure and spark at plugs and work back from there depending on what you find.
I may be teaching my mother to suck eggs but I would go back to basics before looking into the electronics.
Paul
Check fuel system pressure and spark at plugs and work back from there depending on what you find.
I may be teaching my mother to suck eggs but I would go back to basics before looking into the electronics.
Paul
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