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(Post Link) post #1 of 42 Old 11-06-11 Thread Starter
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Help Tuned 147 jtd 16v

Hi guys,

I could use some help with a problem I'm having with my modded 147 jtd, hopefully one of you has experienced something similar or knows what could be the issue.

My jtd 16v engine is tuned with a hybrid turbo, FMIC, free-flow exhaust and a K&N intake filter. Last dyno test showed 193hp and 380nm torque....limiting factor still being boostcreep, but this has been discussed enough over the forum and yes, next time I will listen to you guys and NOT go for a hybrid turbo! :-)

My problem is this: I felt the car was not providing the same power output every time, really noticed a difference in acceleration one time vs the other. I also experienced a few occassions with sudden loss of power (as if the fuel supply is suddenly stopped!) under full acceleration, each time around 4200 rpm. Top end speed has not changed a bit from what it did before with simple chiptuning alone. It does get to 220 kph MUCH quicker than before, but after that no noticeable change with top end sticking around 230-235 kph.

I went back to my tuner to have him run some diagnostics and we found that, apart from a registered ECU fault related to the sudden power loss events, that the programmed fuel pressure is in reality (measured while driving) only delivered up until 4100-4200 rpm, after which it starts to slowly drop until it ends up well below the programmed value around 4500rpm.

With this knowledge, I am no longer wondering why the car is not having any higher top end speed than it did before...as by then I am already over 4200 rpm in 6th.

My tuner has been looking for any restrictions in the software that could force the fuel pressure to drop in the end, but he could not find anything. Engine temperature stays ok, helped by the FMIC. Injectors were tested and seem to be ok, so our best guess at this moment is that the fuel pump is simply not able to handle the programmed pressure that long and cannot continue to supply the programmed fuel demand above 4100rpm.

Does this make sense? I have not read about people needing a higher capacity fuel pump with heavily modded jtd's. If they do, what kind of pump are they using? Is the problem with the high pressure pump or with the low pressure one inside the tank?

Any help or ideas on this would be very much appreciated, thanks!

147 jtd 16v, Leather, Navi, Bose, 18inch, Novitec body kit, GTA headlights, Eibach springs, Bilstein shocks, Brembo+Ferodo brakes, Squadra-tuning, K&N airfilter
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it doesn't make sense.... the injection duration becomes a problem at high rpm, but not the pressure or the flow....

I'm sure he missed a limiter somewhere...
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What's your current top fuel pressure and fuel temperature?
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Ahoj Jan.Ko...to nevim.

I will need to ask my tuner for these details, he's the brains...I'm just there for the looks. :-)
As soon as I have some answers, I will post them here.

Are there any other values regarding fuel/air/boost pressure that may be relevant for this topic, so worth asking him about? Don't really wanna bother him every 5 minutes with new inquiries...
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Makes sense...

Maybe fitting a fuel cooler would help.
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@ Cuore Sportivo 155: thanks for the quick reply!

My tuner (Squadra tuning) is the best we have in the Netherlands...it would surprize me if he had overlooked something, but ofcourse there is never any guarantee.

He did have to go beyond the standard tuning area's in order to get the most out of my set-up, so perhaps he has indeed missed something. Would you know of any such kind of limiter in the software that would become active in the mentioned situation and lower the fuel pressure?

Would such limiter be directly affecting the fuel pressure, or would it be trickering something else that in return will have an affect on the fuel pressure?
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I really am thinking it's a fuel temp limiter, like yan.ko is suggesting. the pressure would be reduced to lower the temperature.

easiest way of checking is fitting a diesel cooler, like Peugeot/citroen and others use... it's mounted under the car in the return pipes and keeps the fuel in the tank from heating too much...



I didn't realise you were Dutch and went to Stephan. He'll be doing some work on my car aswell, when the time comes... we'll see how far my fuel pump gets me but I'm aiming for 230-240 bhp...
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@ Tribesman: thanks for the suggestion! Yan. Ko was also inquiring about the fuel temp...
Wouldn't fuel temp. be linked to engine temp. though? At least the engine temp. was not an issue as far as I recall...
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thanks for the advise and the pic! I'll be sure to mention it to Stephan, see if he can confirm anything about the fuel temp. I take it your dutch as well then? Good luck with your project!
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Gino, do you have any data logs of your car? What's the boost and how much fuel are you injecting?

What kind of hybrid did you choose? 52 or 56 compressor wheel?
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I believe boost was around 2700mbar, fuel is programmed at 93, but drops to 80 in the end.

We need to run at such high boost in order to keep boostcreep away for as long as possible, but we're at merely 18% overboost capacity at the moment, so no way to program more power...it would hit boostcreep again.

I went through some e-mail correspondence with my tuner and found something else that I forgot to mention yesterday, that may be relevant:

Also the logged air value drops by a 100 (within less than 75rpm) above the 4200rpm mark. So, both air and fuel seem affected at pretty much the same time...air drops instantly and fuel drops slowly. The tuner believed the issues were unrelated, as with less air it should still supply the programmed fuel, but I wanted to mention it anyway...

The turbo is a hybrid with a 52mm compressor wheel, clipped vanes, adjusted VNT setting and some 'internal efficiency' mods...so they say. It spools up pretty much the same as the standard unit did, just a few hundred revs later, but the overall torque and power is maintained much longer now....also at higher revs. Due to the increased powerband, it almost drives like a petrol car now.

I'm not that unhappy with the final result, although I had aimed for 210-215bhp at the start of my project, but I'm seriously considering a GTB turbo conversion when JS-Tuning is offering a straight fit package. I know he's working on it for some time now, but don't think he finished it yet.
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It has been mentioned before, In the Netherlands alfas make less HP from the same amount of fuel as elsewhere...

I believe Squadra uses 10% transmission loss in the calculations, though I feel 12% or even more would be an appropriate numer, especially if you have a wider tyre than standard. this accounts imo alot for the lower measured output. the last alfa I had dyno'd at van der beek bij stephan was 3.0 V6 which seemed to make only 226 bhp and 275 Nm (gta cams and 3.0 V6 injectors, SMF etc built into a 156). But driving it shows that it is a LOT faster than a tuned 2.5 which would be about 220 bhp aswell...

Oh, and no I'm not dutch
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yep, so true! Squadra is probably more conservative with the output measurements than others.
What really matters in the end, is how the car behaves on the road. I don't care too much for statistics...and it is pretty quick!

Oh and no offense..we can't be all Dutch.
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okay, I spoke to my tuner and he confirmed the fuel pressure is at 1600Mbar...the pump is apparently operating on 75% of it's capacity now under normal conditions, meaning it could get close to it's max. when it peaks under certain circumstances. The car (and fuel pump!) ran about 183,000km now, so perhaps the pump is not delivering it's normal potential either anymore.

My tuner does not think it could be caused by the fuel temp. as the software will allow for quite high temps. before applying any restrictions...temps. which are not very likely met under real driving conditions. He did admit not having looked at it though, so there is still a small chance that the temp. is the issue afterall.

Nobody heared of any tuned diesels needing a fuel pump that has a higher capacity than the OEM unit?
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yes...

Coen from Falco motorsport (ebay company etc...) had a custom pump built for his 2.4. mind you he is a bit beyond what we are doing, had a custom turbo, custom injectors, Rover V8 MAF, fuel cooler, gearbox cooler etc...
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and I know mine will run out somewhere around 220-240 bhp...
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Quote:
Originally Posted by Gino147 View Post
I went back to my tuner to have him run some diagnostics and we found that, apart from a registered ECU fault related to the sudden power loss events, that the programmed fuel pressure is in reality (measured while driving) only delivered up until 4100-4200 rpm, after which it starts to slowly drop until it ends up well below the programmed value around 4500rpm.
From what I have understand in your mails, the fuel quantity was dropping, from the programmed 93 cc/i to 80cc/i.
Not the fuel pressure.

Or did you see the pressure was also tapering down?

We should meet soon, then I attach my laptop to it and make some logs and post them here.
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Well as far as I know EDC16C8 ECU this makes absolutely no sense. If you fuel quantity is dropping, this is not related to fuel pressure, or the pump itself. If the fuel pump would not be able to sustain the fuel pressure the injected quantity would not drop. Only ECU would increase injection duration time. This of course is not optimal, as longer injection window, especially if pushed far beyond TDC, produces no additional power, smokes a lot and causes high EMP (and boost creep as a consequence).

If you quantity drops down from programmed, this only means that there must be some kind of limiter in the ECU doing its stuff. As you say that your engine power output is not constant, the easiest explanation would be some kind of temperature dependent limiter. Either fuel, intake air, water temp... AFAIK there is also a "speed dependent" limiter... So if it is only happening in top gear, it could be it...

But any data logs would be nice...
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Sorry for the late reply guys, but thanks a lot for the feedback...it seems we should be focusing on the temps. than.

And Tribesman...you're right, it only seems to be in 6th gear that the car is not willing or able to get across 4200-4300 rpm. It really has no problem to get to 5000 when shooting through the lower gears (3rd and 4th), although in 5th gear I tend to shift around 4200 rpm as I feel the power is wearing off at that point and the car actually is stronger in 6th around 3700 rpm. This is in line with the dyno however, so not that surprizing and likely not related to the problem I see in 6th.

The car is scheduled for a service interval next Monday, so will have the dieselfilter replaced as well...that would at least rule out the chance of the filter being (mildly) clocked. Already added some fuel additve to clean the injectors etc...to my last tank of fuel, so anything in that area would be dealed with soon.

I'll see JS soon, we can make some logs...hopefully that will reveal more.
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Yesterday me and Gino147 went for a drive.

I have to say that 147 of him really goes like mad. It should be 15-20 hp higher in power than mine but the difference in acceleration seems huge.

Ofcourse I made several logs which I will post later when I have put them in Excel graphs.

For now I can say:
- the loss of power is coming from the fuel quantity that's tapering down from 94cc/i when passing 4000 rpm.
- Fuel pressure is fine, the goal and measured pressure are nicely 1600 bar.
- Also the fuel pump duty cycle is with 72% max under the 80% border.
- Airmass is tapering down too above 4000 rpm.
- MAF voltage hits 4800 mV at around 4000 rpm and sort of flattens out.

Based on the above, my guess is the MAF is just going out of range, so in that case I am very curious what MAF Luis has.
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In EDC15 ECU, each sensor signal is checked whether it's within certain voltage range <97.75 - 4799,61mV> (in case od my 8V MAF), then it's translated according to linearisation map and checked once again for range <-25,20 - 597.0kg/h> (there are also other plausability checks for rpms, water temp and so.). If it doesn't pass all the checks, signal is not plausible. I don't think this process would be a much different on EDC16 and newer.

I found the upper limit of my translated signal - 597.0kg/h = ~1250mg/i @4000 rpm is pretty low and had to be adjusted accordingly (as well as voltage upper limit, upper rpm limit, iq limit (not sure if it reallly is)).


Btw. how about exhaust gas temperature? AFAIK that's another EDC16 iq limiter that would come into play.

Btw2. that acceleration difference is question of smoke map in ECU. I bet you have better fuel consumption than Gino

[SIGPIC][/SIGPIC] Squadra Moravia

156SW 1.9JTD: GTB2060VKLR turbo, performance cam&head, WM injection, 6speed Q2 gearbox, 4p Brembo brakes, 2.5" stainless exhaust, FMIC, upgraded sensors, lowered & stiffened suspension, own remap
GTV 3.0V6 24v: C30-94 charger, short gearbox with Quaife ATB, big 4p Brembo brakes, SMF, lowered suspension, custom freeflow equal lenght x-pipe quad tips exhaust

Last edited by yan.ko; 23-06-11 at 11:31.
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JS JTD: I'm pretty sure that there is either a lack of air or air measurement limitation as you suggested and the smokelimiter kicks in, or one of many temperature limiters kicks in. Fuel supply is out of the question... it just doesent make sense.

This is a MAF map in EDC16c8 ECU:

Code:
MAF Map (32x1)

MAF Map(Voltage)/kg/h

		mV																															
		0	156	371	665	997	1329	1486	1623	1838	2111	2190	2326	2498	2649	2786	2908	3050	3177	3348	3495	3622	3744	3851	3949	4047	4130	4242	4345	4526	4692	4844	4980
		-33	-30	-20	-10	 0	 10	 15	 20	 30	 45	 50	 60	 75	 90	 105	 120	 140	 160	 190	 220	 250	 280	 310	 340	 370	 400	 440	 480	 560	 640	 720	 800
At 4000RPM 4.8V should read something like 1450mg/inj? That is A LOT of air. I have no idea what AFR is he running but if I take a 17:1 as a conservative guess then there should be enough air for 101mm3/inj. Even at 18:1 there should be enough air for over 94mm3/inj.

yan.ko alfas EDC16 does not have EGT limiter. At least not EDC16C8. There is EGT sensor on EDC16c39 with DPF, but that one is after the turbo, so I guess it is there only to monitor the DPF regeneration...
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Good to see 8V is the same :-)

Code:
air flow(MAF votage)/kg/h

mV																							
	0	156	806	997	1329	1618	1838	2111	2190	2326	2498	2649	2786	2908	3050	3177	3343	3622	3739	3949	4130	4345	4692	4980
	-36	-30	-6	 0	 10	 20	 30	 45	 50	 60	 75	 90	 105	 120	 140	 160	 190	 250	 280	 340	 400	 480	 640	 800

I would suggest to extend at least both upper limits for MAF plausibility check to 4980mV and 800kg/h.

Last edited by yan.ko; 23-06-11 at 12:09.
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Yes both MAFs are the same. Only newer JTDm engines use different MAF, but again the same for both 8V and 16V...
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Just one question out of the topic. Does your 16V use 3rd plunger disconnection functionality of the fuel pump, TribesMan?
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