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i just took my 2009 C63 to the track for the first time last weekend .... had a blast! I have tracked a 944 Turbo for the past 10 years but will be running the 63 now. A few observations:
The car handled much better than I expected. I had searched the forums and did my best to take everyone's advice about getting braking done early in a straight line, getting the weight on the rear tires early, etc and was impressed with the handling.
Lots of power!!!! 👍
The highest ambient temp was 20c (68f) and the highest oil temp was 120c (248f), so felt decent about the temps.
the one challenge I was having was that when the fuel droppped to between 1/3 and 1/2 of a tank, I would start getting hesitation and stuttering on a long, uphill right hand corner and on a flat, 90 degree hard right. The uphill stuttering would happen through 3rd and 4th gears, the 90 degree was a top of 2nd/into 3rd corner.
i searched the forum and found some posts from people experiencing some uphill hesitation when running k&ns (which I am), but this seemed to be a fuel starvation issue as it was only on right handers (left turns were fine) and when I tossed in another 5 gallons of fuel it would go away for a few laps.
I would guess that the fuel is moving away from the pump in the tank when you go around a hard right hand turn. The easy solution is to run a high fuel load. But this of course will translate to increased lap time.
Other than that you need to install a fuel cell, or see what you can do to baffle the tank to stop it sloshing around.
I'm going to wait for more knowledgeable guys to give their thoughts on fuel starve with this platform. It certainly sound like it could be just that. The Lotus Elise/Exige was known to have a big problem with this. When FI is added, it became a recipe for blown engines. One way to address the problem is to add a surge tank (with a pump). I initially did that with my Elise, but scrapped it and pulled the tank. I had baffles and trapdoors welded in to prevent the fuel from being able to move away from the pump and starve the engine. If someone with more knowledge confirms the fuel starve, I'm happy to discuss what I've done more. I'll see if I can dig up pictures too.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Glad you enjoyed your car on track! They're very capable cars with tons of low-end torque, and wish more people would take them out like you.
I've got to say that the only time I've ever seen fuel starvation was when I was actually totally out of gas. And I tend to run super hard right up to that point, and have never noticed a cut in power until almost dry. So unfortunately I can't add a lot here, but I find it odd that it happens to you when you're almost 1/2 full. That doesn't seem quite right to me.
Yes, it seems very odd that it would happen with over 1/3rd of a tank. But, it was only on right-handlers and did go away for a few laps when I topped it up. However, that could just be because it is cooler for the first few laps too. I was never able to fully fill the tank to see if I could made another entire session trouble-free which I would have liked to do.
I'll put in stock filters next time to remove the k&n potential problems and take my 53l spare gas can to keep it topped up and hopefully solve the issue.
Next up is a set of Powerstop's new Track Day pad to try out (has anyone tried these?) and a square set of 255/35/18 Nitto NT05s for a bit more grip, to balance the car a bit, and especially extend tire life for next session.
i at least took out the baby seat for the session ... my 2 year old was pretty interested in coming along!
In 2009 there are two pumps, a main and an auxiliary, one under each side of the rear seat, so its extra weird that you have this issue. I believe we just have a single now, but Im not sure when that crossed over and I havent had cause to see it.
I had an 09 that I tracked several times without issue but the course I frequent is pretty flat.
No CELs of any kind I take it? You didnt mention any.
Nope, no CEL light came on or I would have started there. Some of the guys on the k&n post said they didn't get a check engine light and it acted exactly like a fuel starve problem.
Interesting that hat there are 2 fuel pumps; the fuel starve just doesn't make much sense to me when it's happening with 1/3rd of a tank. I'll confirm that both pumps are working and get my mechanic to scan for any codes just in case. Then I'll clean the MAFs, put in stock filters, and take my big jerry can to the next event.
i do run a V6 tune and secondary cat delete, but it's run perfectly for months and the issue only showed up on the track.
Thanks for the feedback guys, I really appreciate it. Next track day is mid-June, so will hopefully have a report for then.
Happened with my 350z, same issue, starvation on long fast sweeping rights or very tight corners with fuel under 1/3 tank usually. On these cars, the saddle tank makes it possible for fuel to slide up and over and away from the pump at a higher level.
There's not really a good solution, run the car with more fuel (sucks), or go full custom (plastic tank, can't really add baffles/sump without really getting creative).
As others have pointed out, it is surprising that you're experiencing fuel starve with that much fuel, but assuming it is, it doesn't sound like there are a ton of options. Assuming you can't modify the stock tank and no one produces a reasonably expensive one (I looked into race bladders which were way too expensive for me to justify and other manufacturered baffled and trap doored tanks which weren't bad at $700, but shipping was insane), then it sounds like a surge tank is the way to go. It shouldn't be more than a $1,000 for parts including the pump. I don't know if there are any specialty fitting or anything that might drive up cost though. You just have to find a good mounting place.
Looking forward to hearing about you results from the swap at the next track day.
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
I'm guessing it's something else, because I haven't heard of anyone else here experiencing it, and many of us track our cars frequently. I think there would be some sort of story here if it had happened before. Curious to see what this turns out to be.
Edit: You know what, I think I might know what's going on here. I was just watching the Pirelli TC race at VIR on TV, and remembered the issues I had last year on the final turn going back onto the front straight. It's downhill from the roller coaster to a fast hard high-g uphill right, with lots of compression on the drivers side rear. I was also having some cut-out issues, and I thought for sure I had it pinned down to the traction control going crazy for some reason with that specific combination. Same with turn 1 there (also a hard but flat right), I could have sworn it was the TC cutting down my power and making the car feel just like fuel starvation. I could be wrong, but I'm pretty sure I had plenty of fuel in each case.
Maybe there's something to this - I'll pay closer attention next time on track - but check your TC light and see if it's blinking when you experience the issue (it doesn't always). The dramatic power loss and stuttering when trying to power out of a corner can feel very similar.
Hi there,
nice to take the C63 on track, it's a lot of fun. I have a 2011 model so it should be the same structure as yours.
I take mine to Shanghai F1 track every months, sees 1.1g in curves with Yokohama AD-08R. I have ESP turned off when I track, transmission in manual mode. I run the tank from full to almost empty. I never got the issue that you pointed out.
Hope you can identify and fix the issue soon.
Good tip Blkrokt ... I'll try it with the TC off instead of just in sport. There were a couple laps were I was pedalling it pretty lightly up the hill so would be surprised if that was it.
i really just wanted to check to see if anyone else has had this issue. The more I think about it, the more I can't see it being fuel related. It's very weird that it was only on 2 particular right handers for sure .... there are 2 long left turns at the track (The Ridge by Seattle) that didn't pose a problem. I'm thinking when I topped it up with 5 gallons and it was ok for a few laps, the could be more temperature or some sensor related issue. But then why only on right handers?
Hopefully I don't have to keep the tank at more than half a tank. Not sure if you guys have noticed, but these things like their go-juice and I don't know if I can carry enough jerry cans to make it through a day!! 😜
Thanks for all the thoughts and confirmation this isn't a common issue. I'll start with the basics and take it from there.
This is a WAG because I ain't tracked this car yet.
Is it possible that under these situations with the pumps presumably being old that when the fuel moves away from the pickup so the head pressure feeding the pump is reduced they tend to be less efficient and hence they cannot keep up with the demand?
I like BLKROCT's idea too.
I'm thinking when I topped it up with 5 gallons and it was ok for a few laps, the could be more temperature or some sensor related issue. But then why only on right handers?
You have LSD? Cos all of a sudden my money is on no, in which case we are getting closer to the answer.
Yup, it's a Canadian P30 car with lsd. The rear does love around a bit before the traction control kicks in. I left it in sport this time around because I was on summer Conti Extremes and was my first time on track with the car and could certainly feel when/when not we'd reached the limits of the rear tires.
i had also considered the fuel pump getting tired. If there are two though, that also seems unlikely.
while I was hoping there would be 10 people saying 'this is your problem and how to fix it', I guess we can at least say this is unique. 😩
If its a Canadian P30 car, and you are going to The Ridge, you must be in the lower mainland too? Im in Vancouver.
And if its an 09 Canadian P30 on Conti Extremes in the lower mainland, is this what your steering wheel looks like?
<<<<<<You many want to look over here at my current and former cars.
Hi guys, for an update on this, this definitely seems to be a fuel starvation issue.
after my last track day, I took the car to get scanned and there was a code for running lean on bank 1. Got that cleared and no codes came back in the few months since then.
did my first session today with almost 3/4 of a tank and had no problems. Right before my 2nd session, the check engine light came on. Went out anyway and starting having the same problems about halfway through the session as the car dropped below half a tank. A guy had a scan tool at the track and the code was lean bank 1 again (I'm assuming the K&Ns are messing with that MAF). Anyway, cleared the code and hoped we had the problem solved.
went out for my 3rd session and the hesitation started immediately and got progressively worse throughout. I'm now down to about 1/3rd of a tank and the hesitation is worse on the uphill right and has started on a flat, 90 degree right as well. Left turns are perfectly fine.
Ran out and completely topped up the tank for the 4th session. Car ran like a champ for both 4th and 5th sessions with no hesitations whatsoever with the full fuel tank.
Any thoughts on this one? There's no code being thrown for either of the fuel pumps, but is it possible for a pump to get 'tired'? Anyone know what the current fuel pressure is supposed to be? I could start by checking fuel pressure at the manifold perhaps? The problem only happens on track at highest fuel loads obviously, but perhaps the pump is a bit weak?
Hi guys, for an update on this, this definitely seems to be a fuel starvation issue.
after my last track day, I took the car to get scanned and there was a code for running lean on bank 1. Got that cleared and no codes came back in the few months since then.
did my first session today with almost 3/4 of a tank and had no problems. Right before my 2nd session, the check engine light came on. Went out anyway and starting having the same problems about halfway through the session as the car dropped below half a tank. A guy had a scan tool at the track and the code was lean bank 1 again (I'm assuming the K&Ns are messing with that MAF). Anyway, cleared the code and hoped we had the problem solved.
went out for my 3rd session and the hesitation started immediately and got progressively worse throughout. I'm now down to about 1/3rd of a tank and the hesitation is worse on the uphill right and has started on a flat, 90 degree right as well. Left turns are perfectly fine.
Ran out and completely topped up the tank for the 4th session. Car ran like a champ for both 4th and 5th sessions with no hesitations whatsoever with the full fuel tank.
Any thoughts on this one? There's no code being thrown for either of the fuel pumps, but is it possible for a pump to get 'tired'? Anyone know what the current fuel pressure is supposed to be? I could start by checking fuel pressure at the manifold perhaps? The problem only happens on track at highest fuel loads obviously, but perhaps the pump is a bit weak?
any thoughts would be appreciated!
Ryan
Ok since you be island boy my bet is you are at the motor circuit in Duncan and you are experiencing this on the climb up and to the right from turn 1 through the 2/3 corner onto the back straight.
You are not experiencing this on left turns because most of the left turns are downhil or short chutes to the bottom The closest left uphill is 13 or 14 (?) and then a short right to go across the hill and come back down through 15 through 19 on to the front straight.
I am thinking why the code lean right all the time? Is there any evidence in the codes of left bank that you don't feel. I am thinkin coincidence here.
Somebody help me out here. Can we detect low fuel pressure in the system some how. Is there a valve that runs fuel to the injectors on the right that is hanging partially closed either because it is failing or the pump pressure is dropping as the tank level falls such that the fuel rail valve is not opening.
I am making WAGs here and freely admit I am not super conversant re the whole system but clearly we have more going on here. I do know that volume and pressure are critical but the tank level just feeds the pump.
Look for other codes that cleared on their own is one thing I would suggest.
2012 C63;1971 280SE 3.5(Sold);2023 EQS 450 SUV 4 Matic (Wife's)
What air boxes are you running? NA with the carbon filters or ROW without? It seems to me the 2009 are very sensitive to running without carbon filters with high flow filters like K&N. They like to throw lean codes as a result. Maybe you should try OEM paper filters and put the carbon filters back as well if you have them. Give that a try and see how you make out. If it works it is a relatively cheap solution except you can't get carbon filters without new airboxes unless someone has a set kicking around that they would give you.
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