LS7 Trouble
09-06-2013, 07:17 AM
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LS7 Trouble Long one I am afraid to give as much info as possible:
I have a 2007 supplied LS7, built by US supplier that has now been put on the road.. Spec is:
1. Mahle motorsports pistons fitted by GM into a block that was honed .005" to 4.130 by them. The entire rotating assembly was re-balanced by GM.
2. Rod bolts changed to special ARP ones rework to fit the LS7.
3. Cylinder heads modified in the bowl area under the valve approx 20 cfm flow improvement.
4. Custom made Lunati camshaft .612", .610" lift. 115 deg lobe separation angle. - 236 deg intake and 246 deg dur@.050 -
5. Gold valve spring upgrade to dual springs,
6. Machined off oil pressure sender boss from valley cover to allow flipping of intake, drilled tapped, plugged port.
7. Re-plumbed valve cover venting with hard line.
To the Problem:
The engine has covered around 500 miles so far on the road and has had two oil & filter changes – the last one being this week with Mobil 1 0-40 ESP 7.5 litres (exactly the same as what came out overnight.)
Yesterday I went to a Dyno session with my local Power Station and rolling road, and all went according to plan bar one worrying incident.
Started with some warm-up runs, ... two runs in, nothing extreme, just slow build up to 5 k and back down again through the gears... then idle for a few secs.
All OK - then after the last run suddenly the oil pressure dropped like a stone to zero and it sounded like someone had thrown a handful of granite chippings into the engine, the revs climbed on their own to 1.5k revs, then back down all in a matter of a second ...before we managed to hit the STOP button!
The tester/driver was wearing a knock stethoscope, and heard nothing untoward…..but I was not, and it was me that heard it first and signalled him to hit that stop button.
I shot out of the car, saw wisps of white smoke coming out of the air vent and then fearing the worst fell to the floor to view the oil slick with lumps of metal spreading all over the floor....
....BUT nothing! ...NADA . ...Ziltch ????? No sign of leaks, no sign of parts of my engine in places they shouldn't have been!
We both scratched our heads.... had a very close look around the engine bay.. waited for 2 mins, held our breath and fired it up again, expecting a loud clatter!...
It started with no drama!
Oil pressure as before, however rather concerned it has always been higher than I would expect it to be (55 idle - 104ps 5k revs). Is this rather extreme for an LS7? Ideas why that might be!
We did 3 more runs with no drama...
So... what happened??? The test engineer said that he did not hear anything unusual through the stethoscope when it happened, and only saw the red oil warning light come on that alerted him that something was not right... Me - I can still hear the ear-shattering noise in my dreams!
So we are stuck... was this a calamitous event? What caused it? And why did it not affect later runs?
As you can imagine, I can't help worrying if it might happen again...
Any ideas?
I have a 2007 supplied LS7, built by US supplier that has now been put on the road.. Spec is:
1. Mahle motorsports pistons fitted by GM into a block that was honed .005" to 4.130 by them. The entire rotating assembly was re-balanced by GM.
2. Rod bolts changed to special ARP ones rework to fit the LS7.
3. Cylinder heads modified in the bowl area under the valve approx 20 cfm flow improvement.
4. Custom made Lunati camshaft .612", .610" lift. 115 deg lobe separation angle. - 236 deg intake and 246 deg dur@.050 -
5. Gold valve spring upgrade to dual springs,
6. Machined off oil pressure sender boss from valley cover to allow flipping of intake, drilled tapped, plugged port.
7. Re-plumbed valve cover venting with hard line.
To the Problem:
The engine has covered around 500 miles so far on the road and has had two oil & filter changes – the last one being this week with Mobil 1 0-40 ESP 7.5 litres (exactly the same as what came out overnight.)
Yesterday I went to a Dyno session with my local Power Station and rolling road, and all went according to plan bar one worrying incident.
Started with some warm-up runs, ... two runs in, nothing extreme, just slow build up to 5 k and back down again through the gears... then idle for a few secs.
All OK - then after the last run suddenly the oil pressure dropped like a stone to zero and it sounded like someone had thrown a handful of granite chippings into the engine, the revs climbed on their own to 1.5k revs, then back down all in a matter of a second ...before we managed to hit the STOP button!
The tester/driver was wearing a knock stethoscope, and heard nothing untoward…..but I was not, and it was me that heard it first and signalled him to hit that stop button.
I shot out of the car, saw wisps of white smoke coming out of the air vent and then fearing the worst fell to the floor to view the oil slick with lumps of metal spreading all over the floor....
....BUT nothing! ...NADA . ...Ziltch ????? No sign of leaks, no sign of parts of my engine in places they shouldn't have been!
We both scratched our heads.... had a very close look around the engine bay.. waited for 2 mins, held our breath and fired it up again, expecting a loud clatter!...
It started with no drama!
Oil pressure as before, however rather concerned it has always been higher than I would expect it to be (55 idle - 104ps 5k revs). Is this rather extreme for an LS7? Ideas why that might be!
We did 3 more runs with no drama...
So... what happened??? The test engineer said that he did not hear anything unusual through the stethoscope when it happened, and only saw the red oil warning light come on that alerted him that something was not right... Me - I can still hear the ear-shattering noise in my dreams!
So we are stuck... was this a calamitous event? What caused it? And why did it not affect later runs?
As you can imagine, I can't help worrying if it might happen again...
Any ideas?
09-06-2013, 07:05 PM
#2
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Sounds like you got a weird one! Oil on the floor with metal is never a good thing! Have you drained the oil to see what it looks like? I don't see how there can be oil all over the floor and yet the source cannot be found. The oil PSI is good though. My bottom line is that oil coming out of a motor in anyway except an oil change is bad. I think you might be seeing bearing problems down the road...
09-06-2013, 08:02 PM
#3
Sounds like you got a weird one! Oil on the floor with metal is never a good thing! Have you drained the oil to see what it looks like? I don't see how there can be oil all over the floor and yet the source cannot be found. The oil PSI is good though. My bottom line is that oil coming out of a motor in anyway except an oil change is bad. I think you might be seeing bearing problems down the road...
....BUT nothing! ...NADA . ...Ziltch ????? No sign of leaks, no sign of parts of my engine in places they shouldn't have been!
09-06-2013, 09:38 PM
#4
I had cam bolts back out on the cam gear once.
So the cam was moving back and forth.
When the cam was far off pressure was bad and
It was really noisey.
When it wasn't so far off things seemed fine.
So the cam was moving back and forth.
When the cam was far off pressure was bad and
It was really noisey.
When it wasn't so far off things seemed fine.
09-09-2013, 03:10 AM
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Well! - With heart in mouth, took it to a prebooked Silverstone track day Saturday, and 'carefully' did some circuits on the international circuit. We got to use the new International Wing Garages and building and it was fantastic!
Car did not miss a beat (albeit in poor tune) and 150mph straights were exhilarating for an old man like me. Oil pressure climbed to 117 psi at one point???? Had more problems with a notchy gearchange that anything else...
Back to the engine problems...
Knock sensors not working at all with no ECM errors... tried many threshold variations but nothing... changed sensors....nothing..
Also running 35 deg ign, with no knock which seems just wrong... Engine builder assures us it is 11-1 compression....
Car did not miss a beat (albeit in poor tune) and 150mph straights were exhilarating for an old man like me. Oil pressure climbed to 117 psi at one point???? Had more problems with a notchy gearchange that anything else...
Back to the engine problems...
Knock sensors not working at all with no ECM errors... tried many threshold variations but nothing... changed sensors....nothing..
Also running 35 deg ign, with no knock which seems just wrong... Engine builder assures us it is 11-1 compression....
09-09-2013, 05:12 AM
#6
Your last update will need a lot more detail...doesn't sound like this is in a car that came with a production LS7 so what's the wiring situation? Did you convert the car from something, or did someone else? Is it something like a C5 or C6 that you swapped in? I have heard of tuners turning off the 02 sensors in the tune...may be one of the main reasons why your tune is so bad.
The devil is in the details. Also, if you lost oil pressure and swear you heard "death noises" I would seriously consider pulling the engine and give it a look thru. You are on borrowed time and the problem could be really simple to fix. If you let it go you could be in for a lot more expensive solution.
Good luck with your build, sounds fun though!
Dave
The devil is in the details. Also, if you lost oil pressure and swear you heard "death noises" I would seriously consider pulling the engine and give it a look thru. You are on borrowed time and the problem could be really simple to fix. If you let it go you could be in for a lot more expensive solution.
Good luck with your build, sounds fun though!
Dave
09-09-2013, 05:44 AM
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Forgive me, I am a bit of a novice when it comes to this US engine...
The ECM supplied originally was swapped out by the same engine builder in 2009 due to a problem ... Loom carefully extended (original too short) so ECM in cab.
HP Tuners kit including wide-band ... Have many logs now, and AFR recorded as well as all the other stuff expected...
Originally the engine came in 2007 with a MAF for a 6ltr (I just found out)... and we maxed out the table yet could not deliver enough fuel (kept hesitating at 3k revs) so removed MAF and went for speed Density. Hesitation problem went away, smooth right up to 6k. Next problem was to investigate the Knock sensor problem P0324 - knock control system error, that later became P0324 - Knock Sensor module performance (SES) error, with nothing showing in table 2 of HP Tuners scanning logs.
We increased the sensitivity (threshold) right down to 50mv to see if we could get anything at all - (log should have picked up a pin dropping) but the weird thing is that the P0324 error went away and the knock sensors are still not recording anything at all (with no errors) - Used stethoscope to check for knock on load at low revs - definite detonation but nothing recorded by ECM - wiring of sensors checked, OK, and wired to correct pins in ECM (according to the pin-out chart I have) -
Abandoned the Knock sensors for now and set timing advanced using steth at higher revs - no knock even at 35 degrees, so suspected low compression engine, yet builder says 11-1. If that is the case then would expect 24 degrees to be max????
Totally confused...
So 3 problems
1. Oil starvation at idle (momentarily) - fixed we hope by adding a spring coil to oil inlet pipe (suspected collapse) noise was probably hydraulic lifters losing pressure.
2. Timing seems to be way too high for an LS7 yet no knock
3. Knock sensor issue
We are thinking about changing the ECM now... don't know what else to do...
The ECM supplied originally was swapped out by the same engine builder in 2009 due to a problem ... Loom carefully extended (original too short) so ECM in cab.
HP Tuners kit including wide-band ... Have many logs now, and AFR recorded as well as all the other stuff expected...
Originally the engine came in 2007 with a MAF for a 6ltr (I just found out)... and we maxed out the table yet could not deliver enough fuel (kept hesitating at 3k revs) so removed MAF and went for speed Density. Hesitation problem went away, smooth right up to 6k. Next problem was to investigate the Knock sensor problem P0324 - knock control system error, that later became P0324 - Knock Sensor module performance (SES) error, with nothing showing in table 2 of HP Tuners scanning logs.
We increased the sensitivity (threshold) right down to 50mv to see if we could get anything at all - (log should have picked up a pin dropping) but the weird thing is that the P0324 error went away and the knock sensors are still not recording anything at all (with no errors) - Used stethoscope to check for knock on load at low revs - definite detonation but nothing recorded by ECM - wiring of sensors checked, OK, and wired to correct pins in ECM (according to the pin-out chart I have) -
Abandoned the Knock sensors for now and set timing advanced using steth at higher revs - no knock even at 35 degrees, so suspected low compression engine, yet builder says 11-1. If that is the case then would expect 24 degrees to be max????
Totally confused...
So 3 problems
1. Oil starvation at idle (momentarily) - fixed we hope by adding a spring coil to oil inlet pipe (suspected collapse) noise was probably hydraulic lifters losing pressure.
2. Timing seems to be way too high for an LS7 yet no knock
3. Knock sensor issue
We are thinking about changing the ECM now... don't know what else to do...
Last edited by BRDee; 09-09-2013 at 06:00 AM. Reason: adding bits
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09-10-2013, 06:06 AM
#8
Was it an electric oil pressure gauge or mechanical? Maybe with the other electronic things going on it never actually lost oil pressure? If the ecu went momentarily haywire the engine could sound bad.
Confirm timing with a timing light to make sure you are getting what you are programming in. Possibly the reluctor wheel is off or slipped on the crank?
Confirm timing with a timing light to make sure you are getting what you are programming in. Possibly the reluctor wheel is off or slipped on the crank?
09-10-2013, 08:51 PM
#9
I agree w Quick Carl the Reluctor Wheel could have slipped....altho if it did you would see weird hp gains w just 1 Degee of timing added and than add another Dergree and so on and so on it would be in- consistent.
Now 35 is way to much for an Ls7 at that CR, more like 27-28 area
If your pcm is set up for the Ls1 style Knock sensors and your car has Ls2 style Knocks in it it wont read spark knock at all, my C5 Zo6 has an Ls2 in it w the Ls1 Pcm the car came with and i cant get a knock reading to save my life on my Data Logs w HP Tuners because its never going to see knock w out me changing backt o the Ls1 style Knocks
Example of what the different knocks look like .........The two round ones in the pic are Ls1, the single one w the bolt going threw it is the Ls2
http://www.camaroperformers.com/proj.../photo_10.html
Whats your Pcm your using out of?
Year? Make? and Model of Car or Truck?
Now 35 is way to much for an Ls7 at that CR, more like 27-28 area
If your pcm is set up for the Ls1 style Knock sensors and your car has Ls2 style Knocks in it it wont read spark knock at all, my C5 Zo6 has an Ls2 in it w the Ls1 Pcm the car came with and i cant get a knock reading to save my life on my Data Logs w HP Tuners because its never going to see knock w out me changing backt o the Ls1 style Knocks
Example of what the different knocks look like .........The two round ones in the pic are Ls1, the single one w the bolt going threw it is the Ls2
http://www.camaroperformers.com/proj.../photo_10.html
Whats your Pcm your using out of?
Year? Make? and Model of Car or Truck?
04-10-2014, 07:28 AM
#10
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Update Since September I have done a Silverstone Track day with no problems, and put it to bed for the winter...
This is an Ultima GTR with a non-production LS7 circa 2007 - the E38 was supplied at the time from the engine builder.
Come Feb I decided to try to get this thing tuned on a rolling road.
Upshot was that since the previous tuner was using HPTuner stuff, and had converted the system to Speed Density (which sorted the hesitation problems I had), and he had also reflashed the E38 with a custom OS - the new tuner (could not get hold of the prev one any more), who uses EFI Live had a problem in that the OS would not be recognised by EFI Live... but that's another issue to be dealt with later.
My overriding issue is the knock sensor problem (P0324 - Knock Sensor module performance (SES) error), and to recap, settings and sensitivity was changed to try to diagnose, but resulted in the KS not even registering any more (and we had already discounted the sensors by changing them, as well as check the wiring continuity plug-to-plug).
So with no Knock sensor protection, I am nervous! Especially as the dyno run (done gently-ish) exposed knocking problems using the dyno equipment.
Incidentally, the dyno run showed 550bhp at the wheels! Not too shabby for a poorly tuned engine...
..ad therefore there is an urgency to rectify the problem.
I presume the quickest and best way of trying to solve this is to get another E38 from somewhere? Being based in the UK, that might be a tall order though!
Guys how do I go about this, and what do I need to do to be sure it is a straight replacement?
Cheers
This is an Ultima GTR with a non-production LS7 circa 2007 - the E38 was supplied at the time from the engine builder.
Come Feb I decided to try to get this thing tuned on a rolling road.
Upshot was that since the previous tuner was using HPTuner stuff, and had converted the system to Speed Density (which sorted the hesitation problems I had), and he had also reflashed the E38 with a custom OS - the new tuner (could not get hold of the prev one any more), who uses EFI Live had a problem in that the OS would not be recognised by EFI Live... but that's another issue to be dealt with later.
My overriding issue is the knock sensor problem (P0324 - Knock Sensor module performance (SES) error), and to recap, settings and sensitivity was changed to try to diagnose, but resulted in the KS not even registering any more (and we had already discounted the sensors by changing them, as well as check the wiring continuity plug-to-plug).
So with no Knock sensor protection, I am nervous! Especially as the dyno run (done gently-ish) exposed knocking problems using the dyno equipment.
Incidentally, the dyno run showed 550bhp at the wheels! Not too shabby for a poorly tuned engine...
..ad therefore there is an urgency to rectify the problem.
I presume the quickest and best way of trying to solve this is to get another E38 from somewhere? Being based in the UK, that might be a tall order though!
Guys how do I go about this, and what do I need to do to be sure it is a straight replacement?
Cheers
Last edited by BRDee; 04-10-2014 at 07:37 AM.
