jphughan

Also, this car is apparently extremely sensitive to oil temp.

I haven't had the car looked at yet, but I'm wondering if anyone else has experienced the issues below or has any guesses as to cause.

Driving at CotA today, my oil temp leaving the pit was 160-ish, so I drove the first lap below 4500 RPM. By the time I reached Start/Finish, oil temp was 220, so going down the front straight I decided to go for redline. The car hit an ECU-enforced lower fuel cutoff around 7200 RPM. I upshifted for the rest of the straight, then braked and downshifted to 2nd for T1. Coming down the hill, I had no acceleration getting back on the power. The engine revved completely normally, but nothing made it to the wheels. I upshifted to 3rd, saw the same issue, upshifted to 4th and still saw the same issue. No warnings on the dash came up for any of this, and the clutch was not stuck on the floor. I moved off track and sat there for about 30 seconds idling, then decided to try again just because -- and the car was back to normal. I drove cautiously for that lap and didn't see any problem, so then I resumed my normal pace and the car finished the whole session without any further odd behavior. Can anyone account for this?? Clutch would seem to be the obvious culprit, but what clutch issue would have these symptoms?

And on the subject of the lower fuel cutoff, this car seems extremely picky about oil temp. Last time I was at CotA, when I headed for redline with oil temp at 220, it allowed me to go to the real redline but threw a code and entered limp mode. I pitted, cleared it, went right back out that same session, and had no issues. When I've waited for oil temp to reach 225 I've never seen any issues, so I guess that's the magic number that I'll be waiting for going forward. I'm just surprised that the cold bar over the oil temp gauge only goes to around 165, and yet 220 vs 225 seems to be the difference between smooth operation and bizarre issues. Has anyone else experienced that with their own cars?

Quikag

I've had oil temp to 260-265 and never had any issues.

jphughan

Me too, but my point about temps is that 220 seems to be too COLD, not too hot. I've never had issues from 225 on up.

extanker

if the engine was revving but no "thrust" how is oil temp making this happen......if this is your first manual trans car maybe it was in neutral

bhk1004

Puttering around on the street in sport mode keeps the oil at around 190. I'm sure plenty of people have revved out first and second. Don't think it's the temps.

okie981

I recall reading somewhere that 9A1 engines and maybe only GT4 engines, can't recall for sure, have power limited until the oil is "fully" warmed up. What you experienced should be repeatable in any GT4 if this is in fact an engine protection feature built in to the ECU. So it would rev with clutch in, but if engaged would not develop enough torque to rev?

extanker

ssssooo if ya leave your house on a winter morning you cannot merge into highway traffic until the oil is hot ?

jphughan

The Sport button keeps my water temp at 185, but even driving very casually on the road, when Sport is on my oil temp never drops below 200-205 once it reaches that temp. The oil temp issue I observed on track may or may not be related to the driveline issue; I just observed two issues in close succession and wanted input on both. This isn't my first manual transmission car, but I seriously doubt anyone could have thought they shifted into 2nd, then 3rd, then 4th while actually staying in Neutral the entire time. The gear indicator on the dash also showed the gear I thought I was in each time.

I've experienced the early cutoff before but at a lower oil temp, so it's definitely reproducible, at least on my car. What's strange is that under normal street driving with the Sport button off, my oil temps range from 220-235, which is why I figured 220 was high enough to go all the way to redline, but evidently not.

You must be merging into very fast, closely spaced traffic and/or have short on-ramps, because I have no trouble reaching highway speeds in this car by the end of an on-ramp even shifting at 3000 RPM (when the oil is really cold) and only using part throttle.

Spyerx

That sounds like a clutch slipping. Did it stink?

if motor is revving, in gear/not free wheeling it sounds like clutch slip

Warm car up, go on street, 30mpg, put in 3rd, floor it. Slip?

jphughan

No clutch smell and I tried that exact experiment on the way home and it didn't slip. So weird.

ExMB

I had something similar happen to me on track and wound up getting both the slave cylinder and the clutch replaced. But mine got worse as the day went on. Initially we thought air bubbles since I just had the full brake/clutch flush done the week before.

jphughan

Good info, thanks. I'm a little worried about it getting worse since sudden loss of power to the wheels could be pretty bad if it happens at the wrong place on track, but I probably won't be back out there until June, so hopefully if it's going to get worse it will happen before then. I'm just reluctant to take it to the dealer at this point while it works since it's one of those issues they'll probably feel the need to drive the car to reproduce, and probably drive it hard "to try to make something happen"....

Gofishracing

jphughan

Playing more with the oil temp aspect of my post, I'm not sure the "225 magic temp" theory holds up. Bhk1004's point about lower temps on the road with Sport on incited me to conduct a test. I drove around sedately on the road in Sport mode until water and oil stabilized at 185 and 205-ish, respectively. I was then able to reach redline in 1st and then 2nd without hitting a lower cutoff, even though 220 has seemingly been too low on track. So now I'm thinking that this limitation is coming from some other element that's correlated to oil temperature, but not directly so. I drive for more time on the road waiting for oil to come up to temp than I do on track (~10 minutes vs. ~3 minutes), so is there something else the car monitors that might always take longer to become "fully operational" even when the car is being driven a bit harder? Maybe transaxle temp?

This experience makes me think of my E92 M3 and its very convenient dynamic redline. Would be nice if the GT4 had the same thing to show you where the active fuel cutoff was....

trebien

I was at the track today and talking to John about the issue, and something along these lines was my guess based on the symptoms. It seemed like a failure of the hydraulic circuit for the clutch, but might even just be low on fluid instead of a part failing.

To be clear, my understanding is that he let the clutch pedal out, but the clutch didn't engage... the engine just freely spun, even though it was in gear. Then a few minutes later, it was fine.

The engine can't cut power via de-coupling the clutch... doesn't work that way.

edit: seems like I had this happen a while back when my fluid was low in my Subie Outback.