Sprinting my C6

Fishy Dave

CCCUK Member
Hello,

Not sure if this is worthy of being in the 'racing' section? In addition to trackdays I have signed up to the Javelin Sprint Series for 2019 in the C6: Javelin Trackdays Sprint Series

What is Sprinting? (Taken from their website)
Sprinting is essentially a driver and car, competing against the clock, on a pre-practised course. Cars will start one at a time, from a standstill at 30 second intervals, so you won't encounter other vehicles to collide with. The average course is approx 1.7 miles long, which helps to keep stress on the car to a minimum. Normally you will be given a chance to walk the course, then drive it behind a pace car, before getting a practice run in the morning, followed by timed runs into the afternoon. Times are displayed after you cross the finish line and results are published throughout the day with an awards presentation once the runs have been completed.

I began sprinting just over 15 years ago, before I started racing, but it's been a good 10 years since the last sprint. Thanks to the format being one car at a time I have convinced my 65 year old Father to give it a try, so on the 31st March at Snetterton he makes his competitive debut, double driving the car with me. This series runs outside of Motorsport UK regulations, therefore is quite relaxed about fireproof kit, extinguisher, harnesses, that sort of thing (which makes sense as none of this is needed on a trackday).
The class breakdown looks good for my car, with class J6 for cars over 2000cc, 2WD (300 - 400bhp). So far it looks like I will be up against an Aston Martin DB7, Honda Integra R, Holden Monaro, probably a VX220 Turbo and more. There are some quite tasty machines in other classes including a pair of McLaren!

I've not started fitting the uprated shocks and arbs yet, but other than that it's pretty much ready to go; let's see how the 200k mile beast does.

Regards, Dave
 
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Fishy Dave

CCCUK Member
Yesterday my Father and I took part in the Snetterton Sprint. A mixed bag of luck, but fun none the less. I will probably do a proper write up in the mag, so will sum up as follows:

+
Dad enjoyed it, in his first ever competitive event and at the age of 65 too. :)
I finished 18th overall out of 58 (4th in class). 3rd in class (Exige V6) was another 5 seconds ahead, too big an ask.
Dad achieved his aim of not being last, beating a BMW M4 and a DB7 too.
It was dry and fairly mild in the afternoon.
Live Timing

-
The powersteering fluid decided to boil/leak, requiring a trip to Halfords and missing a round.
Whilst in the queue just moments before my run I hit the starter button, had a small flash and then no electrics at all. I had to use the emergency release just to get out! Bizarrely it started 15 minutes later and we don't know why.
I have an oil leak, which may be as simple as the catch can leaking.
The oil pressure sender has failed, displaying XXX.
Most annoyingly the engine started to tap at idle whilst on my journey to Norfolk on Friday. It was strange, not in time with the engine. We think it is coming from a head at the back of the block. I should have got the car recovered, but pressed on regardless. I suspect it is a sticking lifter and the noise has become more frequent now. I will get cracking on investigating this next week, unlikely the car will be ready for the CCCUK drift day though, so will use the RX-8 instead. :(

Despite mechanical and electrical maladies it was still worthwhile and considering it was probably the second heaviest car competing it did well.

20190331_145951_resized.jpg
 

teamzr1

Supporting vendor
Hello
What do you mean by a "small flash" ?
By rights if in fact the oil pressure sensor went belly up and reported XXX then PCM should force a no start
to protect the engine from damage.
Have you pulled the airbridge and see if any oil reverbed back out the airfilter ?

Possible the "flash" is some shorted wiring and hence sensor is not reporting to PCM
You can hook up a OBD-II scanner and look for DTCs or borrow a code reader and see if and what reported

The problem to me is what you think maybe a rear cylinder issue
Are you using a thicker weight of engine oil for racing where oil temps run higher ?
Is it possible with using thin oil that in hard cornering that oil in pan was away from where oil pump is
and it could not circulate the oil ?
You need with the OBD-II scanner to see what the PCM reports oil pressure is to know it is not a oil pump issue
 

Fishy Dave

CCCUK Member
Thanks for your reply. :)
I was sat in the queue ready to start my run but there was a delay so I switched off the engine. 5 minutes later I pressed the starter button and for half a second the dash lights came on and went off. At that point everything electrical went dead, I couldn't even open the doors.
No, I haven't checked the air filters yet, but will do so.
I had my OBD2 scanner and it reports no pending or active codes. I have a Tech2 but haven't had chance to check with that just yet.
I have been using a fully synthetic 5w40 for the last year, to give a little more protection at higher temps. I fitted the Improved Racing crank scraper and baffled sump about ten months ago, before going on track and run an extra litre above max too. I haven't logged the oil pressure, but often have it on the display to check, it's usually 50+psi on track WOT and have never noticed it drop below 30 at a hot idle, although I can't always check when lapping of course. :)
I'm mostly putting it down to the high mileage of the engine?
 

teamzr1

Supporting vendor
As of now does the oil pressure sensor report and correctly or still showing XXX ?
If still XXX to me means wiring issue as if sensor itself was kind off bad it would report some value if real low.

If battery was not dis-connected after this happened and when checking for DTCs showing none then
the problem is something none of the controllers or sensors monitor so more like wiring or mechanical

There was a period where for C6s there was bad crimp connections for one of the battery connections
you might want to check they are OK and clean as if all was dead first place I'd look

I would consider weight of oil you use as example GM states for like C7s for racing to go to like a 15W40 as
5Wx causes too much blow-by and oil use.

I would check oil level, check airbridge, airfilter and the hydrocarbon filters glued in airbridge to see if they are soaked
Noise travels some so maybe see if in fact you have lifter or valve issue or something like a exhaust mount got loose, hope so.

How assured on the mods you used for oil pan/pump are a solid design ?
 

Fishy Dave

CCCUK Member
The pressure still shows XXX, which was more reassuring to me than it showing 0psi or a low figure. On start up the oil pressure needle did the full sweep as usual, before sitting on 0. After 'just' being able to disconnect and reconnect the connector the gauge now sits pegged to maximum pressure, whilst the display show XXX.
I did disconnect both live and earth terminals, cleaned them and reconnected. At that point I could hear some life returning with the occasional relay making a noise and the stereo head unit turning on. About 5 minutes later it started up and was fine for the rest of the day.
That's interesting about the oil weight. I was worried about using a 10wXX or 15wXX due to our fairly cold climate here during the winter months, as I do use it as a road car as well as on track? It does catch a fair bit of oil in the catch can on track. I will check all of those things next week, thank you (pushed for time this week with a race event to organise this weekend).
This is the kit I have fitted: LS2, LS3 C6 Corvette Racing Oil Pan Baffle & Crank Scraper Kit EGM-21X
I'd not read a bad report and the quality of parts and fit was excellent, in my opinion anyway. The oil pump is still the original factory unit.
Thanks again, Dave
 

Fishy Dave

CCCUK Member
I've just uploaded a short video I took on Friday, whilst having the full alignment done. We listened to the engine from above and below, it almost sound like an electrical spark jump, but now that it has become far more in time with the engine and can be heard during normal driving, not just at idle. I have ordered a mechanics stethoscope to help pin point the noise.
 

teamzr1

Supporting vendor
I watched that video several times, does sound like metal to metal
Check the crank pulley and it's belt, or even the one for A/C and see if pulley got loose or the belt idler tension-er is at fault
as that sound is slower then what would be of engine RPMs
If crank pulley got loose, which is common you have a job as the bolt is a torque to yield type and cannot be reused so
to replace the steering rack has to be lowered enough to take out.in long pulley bolt

When you can do a video again and step on gas pedal at idle to change RPMs to see if the noise becomes faster
or louder or stays the same rate.
 

teamzr1

Supporting vendor
The pressure still shows XXX, which was more reassuring to me than it showing 0psi or a low figure. On start up the oil pressure needle did the full sweep as usual, before sitting on 0. After 'just' being able to disconnect and reconnect the connector the gauge now sits pegged to maximum pressure, whilst the display show XXX.
I did disconnect both live and earth terminals, cleaned them and reconnected. At that point I could hear some life returning with the occasional relay making a noise and the stereo head unit turning on. About 5 minutes later it started up and was fine for the rest of the day.
That's interesting about the oil weight. I was worried about using a 10wXX or 15wXX due to our fairly cold climate here during the winter months, as I do use it as a road car as well as on track? It does catch a fair bit of oil in the catch can on track. I will check all of those things next week, thank you (pushed for time this week with a race event to organise this weekend).
This is the kit I have fitted: LS2, LS3 C6 Corvette Racing Oil Pan Baffle & Crank Scraper Kit EGM-21X
I'd not read a bad report and the quality of parts and fit was excellent, in my opinion anyway. The oil pump is still the original factory unit.
Thanks again, Dave

Dave with still showing XXX but you feel there is good oil pressure I would first look for a wiring issue
See if you can locate the C6 wiring drawings and see where the wiring starts and ends from sensor to PCM.
Else if sensor is cheap swap with a new one.
As to main battery terminals, the GM problem was bad crimp of connectors to positive and negative wires to battery
with connectors firmly on battery posts and key on wiggle the battery leads close to connectors and see if all is well
I'd see via OBD-II if the oil pressure parameter shows same as the gauge or just gauge us lying

How many miles on your C6 and when was last time you de-carbed the engine ?
With using lighter weight oil good chance lifters, rockers, valves and tops of pistons carbon up
Add what type of gas you use in your country and if engine runs lean or rich ( use OBD-II scanner and see if Long and short term fuel trims reporting too rich or lean) and if the 4 O2 sensors reports AFR is fine ( around 0.450 - 0.550 mV) at idle
Check with scanner and see if reporting any misfires would help to see if any stuck lifter

Maybe time you decarb engine, Here in USA I use "Seafoam"
It can be put in gas tank to clean fuel injectors and
some poured into oil filler or best case pull at vacuum line and while at idle pour directly into line into intake manifold which then cleans
intake and valves.
Doing that have someone by gas pedal as carbon blows out engine may want to stall so give a bit of gas to prevent that
Crap gas, esp made for damn smog rules will lean up AFR and cause more carbon buildup

0 or 5W oil is solely a way for nameplates to try and get a bit better fuel mileage but again for hot weather and/or Racing reduce blow-by and reverb by using thicker weight Mobil I Synthetic oil

Also what does that Crank scraper do ?
could it be causing the noise you hear ?
 

gavinfdavies

Well-known user
This looks really fun... excecpt my 02 Camaro would need a roll hoop of some form as it's a rag top :-( That leads to only one other option... the wife's Citroen C3 Picasso 1561cc diesel! Well, it does have yellow-stuff pads at least, but might need to get some proper tyres...
 

Fishy Dave

CCCUK Member
Dave with still showing XXX but you feel there is good oil pressure I would first look for a wiring issue
See if you can locate the C6 wiring drawings and see where the wiring starts and ends from sensor to PCM.
Else if sensor is cheap swap with a new one.
As to main battery terminals, the GM problem was bad crimp of connectors to positive and negative wires to battery
with connectors firmly on battery posts and key on wiggle the battery leads close to connectors and see if all is well
I'd see via OBD-II if the oil pressure parameter shows same as the gauge or just gauge us lying

How many miles on your C6 and when was last time you de-carbed the engine ?
With using lighter weight oil good chance lifters, rockers, valves and tops of pistons carbon up
Add what type of gas you use in your country and if engine runs lean or rich ( use OBD-II scanner and see if Long and short term fuel trims reporting too rich or lean) and if the 4 O2 sensors reports AFR is fine ( around 0.450 - 0.550 mV) at idle
Check with scanner and see if reporting any misfires would help to see if any stuck lifter

Maybe time you decarb engine, Here in USA I use "Seafoam"
It can be put in gas tank to clean fuel injectors and
some poured into oil filler or best case pull at vacuum line and while at idle pour directly into line into intake manifold which then cleans
intake and valves.
Doing that have someone by gas pedal as carbon blows out engine may want to stall so give a bit of gas to prevent that
Crap gas, esp made for damn smog rules will lean up AFR and cause more carbon buildup

0 or 5W oil is solely a way for nameplates to try and get a bit better fuel mileage but again for hot weather and/or Racing reduce blow-by and reverb by using thicker weight Mobil I Synthetic oil

Also what does that Crank scraper do ?
could it be causing the noise you hear ?

The OBDII also shows zero pressure, so I'll change the sensor first, my wifes fingers are probably just long enough to reach :LOL:

Good to know about the connector issue, both have been removed, grease cleaned off and terminal put back on.

The C6 has covered 200, 550 miles and as far as I know has never had a de-carb, although it does get a fair bit of full throttle once it's warmed up, if that helps?! I've used Seafoam in the past on a BMW, good stuff, although I'm not sure my neighbours will appreciate the smoke screen!
I use Super Unleaded fuel (minimum 97 RON), where possible I use Tesco or Shell, which is 99 RON. I will check the AFR readings, good tip. There are certainly no audible misfires and no reported error codes.

You got me thinking about the crank scraper. Yesterday my automotive stethoscope arrived, what a brilliant bit of kit, so cheap too, well worth every home mechanic getting on for less than £4! Car Mechanics Stethoscope Engine Diagnostic listen Noise Probe Tool STETHOSCOPE | eBay
I started the car and heard....nothing, just the normal noises you would expect. It sat and idled for more than 5 minutes before the noise started, quietly at first, getting louder and more frequent as the engine warmed. The stethoscope was really useful, with the loudest noise coming from the oil pan, the second loudest point being where the oil pan meets the block (gasket area). Therefore, last night I have started to take the suspension apart to get the pan off. The spring is out, so I've just got to raise the engine, lower the subframe and remove it tonight. I'm hoping it is either oil pick up pipe or the alloy crank scraper that is just expanding enough to brush against a rotating part.
There were no metallic particles on the sump magnet when I dropped the oil (which has only been in there for 500 miles!).
This is a picture of the crank scraper when I fitted it last year, you will see that the tolerances are very close, but precise.

12 Crank scraper fits perfectly.jpg

This is the scraper along with the sump baffles.
20180616_144948_resized.jpg

On another note, sadly the Sprint track footage of our best runs was corrupted beyond repair. :( I only have a practise run to show for it.

Kind regards, David
 

Fishy Dave

CCCUK Member
This looks really fun... excecpt my 02 Camaro would need a roll hoop of some form as it's a rag top :-( That leads to only one other option... the wife's Citroen C3 Picasso 1561cc diesel! Well, it does have yellow-stuff pads at least, but might need to get some proper tyres...

It was good fun, particularly sharing the experience with Dad. All sorts of cars were involved, not sure about the Picasso, but anything is possible!
 

teamzr1

Supporting vendor
Hi Dave
Sounds like your on the right track as to the noise problem, just a bitch to have to go all through that work to solve it
Make sure you look at crank pulley and belt at idle to make sure there is no wobble on pulley causing a bit of movement causing
crank to hit the scrapper
Being scanner is not picking up misfire counts it really sounds like that baffle/scrapper is somehow the cause
Maybe one of the end caps hitting that baffle ?
I prefer to use a AccuSump like this 2 quart one

Canton Accusump Oil Accumulator, 2 Quart - 24-026 24-026

well one good reason to have a wife when small hands are needed :)

Does the gas you use have E10 Ethanol in it ?
That crap will cause hotter cylinder charge, lean the AFR up and induce more carbon build up with over 200, 000 miles on it ?
you really need to do a full de-carb and I'd check the sparkplugs as to condition and if gap is still correct after Seafoam is used.

Yes you really needs to check via scanner how the long and short term fuel trims reporting as to what AFR is and assured with
E10 gas, racing around sealevel and hot temps engine could be running too lean

Also check the injector pulse width ON times with scanner would tell us if the injectors are not a bit too small and running over 80% duty cycle
Most C6s that do racing I have to make changes to the PCM tune to set ON time longer under engine load to assure not running too lean,
tripping engine knock and PCM yanking out timing which kills off the torque when it really is needed

Let us know what you find and I hope your doing this with a hoist and not jacked up off floor.


The OBDII also shows zero pressure, so I'll change the sensor first, my wifes fingers are probably just long enough to reach :LOL:

Good to know about the connector issue, both have been removed, grease cleaned off and terminal put back on.

The C6 has covered 200, 550 miles and as far as I know has never had a de-carb, although it does get a fair bit of full throttle once it's warmed up, if that helps?! I've used Seafoam in the past on a BMW, good stuff, although I'm not sure my neighbours will appreciate the smoke screen!
I use Super Unleaded fuel (minimum 97 RON), where possible I use Tesco or Shell, which is 99 RON. I will check the AFR readings, good tip. There are certainly no audible misfires and no reported error codes.

You got me thinking about the crank scraper. Yesterday my automotive stethoscope arrived, what a brilliant bit of kit, so cheap too, well worth every home mechanic getting on for less than £4! Car Mechanics Stethoscope Engine Diagnostic listen Noise Probe Tool STETHOSCOPE | eBay
I started the car and heard....nothing, just the normal noises you would expect. It sat and idled for more than 5 minutes before the noise started, quietly at first, getting louder and more frequent as the engine warmed. The stethoscope was really useful, with the loudest noise coming from the oil pan, the second loudest point being where the oil pan meets the block (gasket area). Therefore, last night I have started to take the suspension apart to get the pan off. The spring is out, so I've just got to raise the engine, lower the subframe and remove it tonight. I'm hoping it is either oil pick up pipe or the alloy crank scraper that is just expanding enough to brush against a rotating part.
There were no metallic particles on the sump magnet when I dropped the oil (which has only been in there for 500 miles!).
This is a picture of the crank scraper when I fitted it last year, you will see that the tolerances are very close, but precise.

On another note, sadly the Sprint track footage of our best runs was corrupted beyond repair. :( I only have a practise run to show for it.

Kind regards, David
 

Fishy Dave

CCCUK Member
I'll reply to your other points soon, but have been hard at work this evening and am half way there to explaining the noise. Where on earth has this metal strip and broken plastic come from? Some sort of cam chain tensioner components? The bolts and nuts are supposed to be there btw.

20190404_205032_resized.jpg

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teamzr1

Supporting vendor
Sure looks like it,
crap another $25 part and have to pull the front of engine apart
Looks like that is not all of the pieces so really need to check timing chain, and try to piece together to know
if you got it all and in fact none of it in oil pump flow path
Is oil pump used have good screen so very small pieces not carried up to valve-train ?

tention.jpg
 
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