135i n54 on track stutter when hot

[monkeygod11 4]

9 hours ago, HalfJobHarry said:

My initial testing with the 5" from HZ Racing store (ali express) has been very positive

Glad to hear that, knew a few people have it on here but still was a bit skeptical with it coming from aliexpress!

[monkeygod11 4]

Got back on the track this weekend and logged 3 sessions with MHD (did 4 sessions but forgot to hit the log button first time), my stuttering was present again in each between 2-4k RPM. Had a shadow code for fuel pump plausibility come up but nothing else. I have also noticed my fuel economy has taken a hit, I'm getting 50km less per tank on normal driving and on the track 4 15min sessions used almost 3/4 of a tank!

Thinking HPFP could be my issue maybe? I've put the 3 logs on datazap if anyone who knows what they're looking at would have a look and see if that sounds right that would be awesome. 

https://datazap.me/u/grayman11/2021-07-11-log-1?log=0&data=3-23

https://datazap.me/u/grayman11/2021-07-11-log-2?log=0&data=3-23

https://datazap.me/u/grayman11/2021-07-11-log-3?log=0&data=3-23

[jon dee 500]

Had a look at one of your logs because.... interesting Here is a pic of a section towards the end of log 3. Everything looks good... pressures, temps, AFR etc until around the 650 second mark. You have been cranking on it pretty hard and then the DME starts pulling timing... pulls it and then ramps back up as expected. If I was in the guessing game (and of course I am) I would say that the DME was picking up a bit of det and likely you had hot spots in those cylinders. Did you change to colder plugs before that track day ?

Cheers...

PS: Added a screenshot from Datazap to give you a better idea of what I was seeing...

Edited July 13, 2021 by jon dee
More input Stephanie...

[Matth5 471]

What are the intake temps at that point?

Edit: Peaks at about 56 degrees C. Hmm maybe it's just the tune isn't great... I'd want to back this tune up and try the MHD OTS stage 1 tune. Or 1+ if you upgrade the intercooler. Either way I wouldn't want to keep driving the car hard like this.

Edited July 14, 2021 by Matth5

[monkeygod11 4]

Not done 1 step colder plugs yet, figured I'd wait for a misfire before changing. Intercooler is on the way, should of had it a month ago but have been messed around by supplier 😬

[jon dee 500]

Intake air temperature (IAT) has a direct effect on combustion chamber temperature. And as you can see from this screenshot, there is a rise in the  IAT that coincides with the DME starting to pull timing. Seems the OEM intercooler can't cope with the combined effects of continuous WOT/ high boost operation and the MHD tune. Looks like ambient on the day was around 25deg so the OEM cooler was doing OK until you hit it with that long stretch of continuous high boost.

Interestingly enough, I see ignition timing being pulled in quite a few places, and in one spot at around 2500rpm when out of boost and not pedaling hard. That is obviously a different issue and may or may not be significant I'll take a look tonight and see if I can find any clues. 

Cheers...

 

[monkeygod11 4]

Cheers let me know when you have a good look what you think about high pressure fuel pump being on the way out as a possible cause for the stuttering I'm getting between 2-4k rpm.
 

[Ninjaspartan 23]

11 hours ago, monkeygod11 said:

Got back on the track this weekend and logged 3 sessions with MHD (did 4 sessions but forgot to hit the log button first time), my stuttering was present again in each between 2-4k RPM. Had a shadow code for fuel pump plausibility come up but nothing else. I have also noticed my fuel economy has taken a hit, I'm getting 50km less per tank on normal driving and on the track 4 15min sessions used almost 3/4 of a tank!

Thinking HPFP could be my issue maybe? I've put the 3 logs on datazap if anyone who knows what they're looking at would have a look and see if that sounds right that would be awesome. 

https://datazap.me/u/grayman11/2021-07-11-log-1?log=0&data=3-23

https://datazap.me/u/grayman11/2021-07-11-log-2?log=0&data=3-23

https://datazap.me/u/grayman11/2021-07-11-log-3?log=0&data=3-23

Your HPFP looks good (really good), stays above 2000psi up top which is more than enough. Once you start dipping below 1500 I would start to question it, but not even then. Your low pressure, (fuel tank pump) will generally go/need upgrading before the HPFP. 

When the HPFP is failing it starts to tapper off fast in the higher RPM. 
Example:

(It picked up again because boost dropped to 10psi)

Intake temps are high, so you definately want to fit that intercooler when it arrives.
It would be interesting to see how MHD Stage 1/1+ performs as a comparison. If you haven't already could ask eurosurgeon about the tune. was it intended for track use?

Also just checking do you have DTC turned on? Pushing DTC button to enable DTC and disable DSC.

 

[monkeygod11 4]

42 minutes ago, Ninjaspartan said:

Your HPFP looks good (really good), stays above 2000psi up top which is more than enough.

I'm very glad to hear that, not something I want to have to replace with how much they cost, and my LPFP looks fine as well right? So fuel pumps don't look to be an issue.

Yea went with VRSF originally but they properly messed me around (long story but their customer service and stock system sucks) so currently waiting on my refund from them to come through so I can order another. Sorry for my ignorance but could the high intake temps possibly cause stuttering?

I have asked Eurosurgeon if the tune was locked or not so I could back it up as it's really fun on the street so don't want to lose it, it is locked so thinking I'll just get the intercooler on then get them to make me a flashable tune (haven't asked if it was ok for track yet but I'm guessing it wasn't with track in mind) then can chop and change with MHD off the shelf maps and see if the issue persists. 

Yep I was running with DTC on.

[Ninjaspartan 23]

6 minutes ago, monkeygod11 said:

I'm very glad to hear that, not something I want to have to replace with how much they cost, and my LPFP looks fine as well right? So fuel pumps don't look to be an issue.

Correct, LPFP looks good form the parts of the logs I looked over, it hangs around 70psi and sits there when under load. Your HPFP will see lower pressures if the LPFP was bad as well. 
Thats a shame about VRSF, I have only had good experiences with them but do hear about stock issues from time to time.

It could be high intake temps, I would expect high temps to cause more issues up top rather than down low. However if you where getting pre ignition to due to hot spots it should throw a misfire code and/or have a code if minor knock was dected. 

Recomendation would be to start changing items related to combustion and intake, just to rule them out. 
Spark plugs (1 step cooler) Not a must but recommend. I used OEM Bosch for a bit with MHD stage 2+ with no isssues (however I did not track it). Only swapped to cooler plugs with a turbo upgrade. 
Coils (if not recently replace) Eldor coils are highly rated. Delphi is also very good. 
Check for carbon build up on the intake ports. 
Check if air filter is dirty.

As others have mentioned it is a bit of a guessing game, best thing is to start elimiating options and go from there.

 

[jon dee 500]

Yeah... what the Ninja said LPFP always around 70psi... jiggles up and down a bit but that is normal and to be expected. HPFP pretty much stays above 2000psi under load with the odd spike down to 1700-1800psi. Again that is fine and you don't have any leaning out as both banks are solid on 11.4 AFR when balls out In fact everything I can see looks to be pretty much in order, so the random ignition trims are a bit of a mystery.

I had a look at the low load/low rpm ignition trims and there doesn't seem to be any obvious reason for them. Unfortunately your logs are not showing any knock counts or actual ignition timing, and those are the readings most relevant for seeing if you are getting det or a little bit too much timing in a few places. I'm not a tuna so there may be factors at play that I don't know about. If you have a stumble / ignition breakdown / misfire that can't be explained, the best thing would be (provided you can replicate the issue) to get the car on a dyno and have a real tuna check it out. 

I had an engine that had so much mechanical noise (false knock) in the same frequency as the knock sensor monitored, that knock detection was useless. It took me a long time chasing ignition issues before I realised I actually had a bit of real knock !!!

Cheers...

 

[monkeygod11 4]

Good we can rule them out, just wish I'd get a code or something to point me in the right direction!

Just throwing random ideas out there but vanos solenoids starting to maybe fail could cause hesitation with no code?

Yea VRSF didn't show they were out of stock on their website, so I ordered then after a bit had to email them to ask what was going on, I ordered 2 things 1 was in stock one out, told me the out of stock would take a month so I said ok, month rolls around and I have to email them again, they then tell me they didn't put aside the item that was in stock before and now it's out of stock and I'll have to wait another month, even though they had my money right from the start. That pissed me off so out of principle I'm ordering from somewhere else even if it's more expensive.

Sweet will start getting those things changed, will wait till get misfire codes before doing the spark plugs, coils are delphi with maybe 10,000km on them, I hope carbon is still ok as had a walnut blast maybe 15,000km ago. I will check the air filter though, had forgotten about that.

Thanks Jon will add the ignition timing and any knock readings I can see in and see if I can get the car nice and hot then do some pulls somewhere quiet. Will get it on the dyno for a tune once I get my intercooler on so will see if they say when it's on there.

Appreciate the help from you guys once again. 

[jon dee 500]

Just a random thought... I was looking at one part of your log where there was a spate of small ignition trims across all six cylinders when the car was cruising just out of boost at 2500rpm/120kph in 6th gear. There is nothing unusual reported in the log at that moment so it is extremely unlikely that you could get detonation under those load conditions. It reminded me of the situation when I was seeing knock in my logs (other car) on the overrun when the engine was in fuel cut ???? Not possible bro !!!

It was false knock from mechanical engine noise. So I was wondering if you might be getting the same ? If you have anything about the engine that rattles metal on metal that could transmit noise to the block, then it might be getting picked up by the knock sensors. For example, if your downpipes were super close together they might vibrate at a certain engine rpm enough to rattle against each other. Since they don't appear to have any gaskets that would insulate against sound transmission, that might reach the ears of the knock sensors.

So if you happen to have a persistent rattle that always occurs under the same driving conditions, it would be worth investigating.

Cheers...

[monkeygod11 4]

Not noticed anything like that before but will have a few drives with the windows down and music off to see if I can hear anything weird.