In short: yes. It's very problematic to drive under 2krpm for a longer period (say, a minute) without the jerking. That effect intensifies when you turn on the A/C. It seems like the engine is starting to jerk just when the A/C compressor clutch engages even if it was running fine for some time under 2krpm.
Yes it does.
Since this engine is not equipped with MAF sensor and only MAP sensor, it's a dead end.
Same for the EGR that was completely removed some time ago.
The road test was done, but nobody could determine why does it happen.
I'll check the clutch switch in the morning, however I clearly state that I don't touch the clutch pedal besides the time when I want to change the gear, so the only option would be that it broke because of wear.
I've checked the clutch sensor and it's working fine. When the pedal is pressed I get infinite resistance reading, and if it's not pressed, I get about 0.4 Ohms, and that would be the resistance of the cables.
I also disconnected the plug, checked how car behaves getting info that the clutch is always engaged and then I've short-wired it to get the opposite effect. Either way the car was still juddering.
Besides that I decided to check if accelerator pedal is being read correctly and when I held the engine at about 1500rpm, it started to gain RPMs but itself. It stopped at about 2krpm and then it sometimes dropped to about 1850rpm and after a short while got back at 2krpm. I repeated the test a few times and the result was always the same. When I held the engine at ~1400rpm, it didn't speed up, so it's clearly related to the certain RPM range which may be related to that kangarooing.
It's the "fly-by-wire" version, there are no steel lines here. I guess the question about "vibrations" doesn't cover that case.
Also, my reg number won't tell you a thing as I'm not from UK. I can give you my VIN, but I'd rather not reveal it to the public.
Yes, it's from March to be exact.
I'll wait then, I hope you'll be able to come up with something as guys here hit the dead end and it's all guessing festival right now.
I haven't done a test like that. I'll get proper hoses and I'll check it.
edit: It'll take a day or two more, since I couldn't find a hose with so small diameter during the weekend.
Okay, I did the test and after over 10 minutes of idle running the cups I've used as a tank for the fuel that was meant to flow were empty. Since I've used transparent (3mm inner diameter) hoses, I've measured the distance the fuel travelled and counting from the distribution belt the results were: 10, 14, 20 & 8 centimetres.
It seems that the amount of fuel is unbelievably low, therefore everything seems to be ok [regarding the videos I've seen on the net when someone points out faulty injector(s)], but I'll let you be the judge.
It's after about 620 seconds of idle running.
Maybe the amount of fuel is so small because of the modifications that the car/engine underwent. Factory 75HP/140Nm has been recently tuned to 112HP/250Nm, so more fuel should go into the combustion chamber (why would it happen even on idle, when there's no load on the engine, I don't know, maybe it's just the way it works?).
Anyway, besides adding Skydd during the winter, I didn't add anything else. Would you recommend adding a bottle to a full fuel tank (or similar amount) or something I've seen on the net, like plugging the fuel feed line that goes from the filter to the pump to the cleaner bottle and running the engine just on that?
Ok, I'll check it and I'll report back.
I've performed the cleaning and unfortunately I can't see any improvement, the car still stutters.
I already did something like that with FORScan, I even have saved the logged data and I can't see anything suspicious.
I've triple-checked the TPS and it's readings are okay on all 3 resistance/voltage sensors. Also it was replaced some time ago for a brand new one, as the old one has caused some problems (excessive wear; incorrect readings led to engine shutdown at certain throttle position).
The MAP data also looks okay, I could easily compare the output voltage/pressure with the analogue reading (I have a boost gauge).
IAT data looks okay - on various loads I can see a reading between 28-38 deg Celsius (outside temperature was 20-something on that day).
And that'd be about the sensors I have access to, not counting ones like CHT, ECT, etc.
And if the injector(s) would be at fault, wouldn't that stutter occur in the whole rev range?
Small update: I've replaced the functioning but old IAT with a brand new one. The readings were a bit different (about few ohms), but in the end it didn't change the cars behaviour. I've tested MAP readings on other sensor - it was 1:1 with the original/current one.
Dunno how the system here would treat my response now, as the question is marked as closed (strange...), but if it'll work, could you answer my question please?
Oh, great it's working :)
And regarding injectors - replacing the nozzles (for bigger ones) would be far cheaper than checking & fixing the current ones (assuming they're faulty). Would that be okay?
Okay, I'll do it in the nearest future and get back with the results.