AUQ dropping power when hot?

[DPJ]

Also I have just noticed that on a run last night the requested boost is completely different to the other night!

new:

old:

strange

Old - things are working fine, apart from the little hiccup at the end. New - that's because your N75 is opening the wastegate to get rid of boost.......

 

[d_jones]

As its intermittent (to a certain extent) does that rule out a map problem and mean its some faulty hardware?

At this stage I'm not sure wheather or not to start pointing fingers at the people who mapped it.

 

[d_jones]

I had a another post about this problem monthsback but it's a lot easier to start again as that sort of died and will only confuse new findings.

The engine has:

Forge DV
Forge TIP
Forge FMIC
Miltek Sports cat and exhaust
IK22 Denso plugs
Stage 2 software (CC)

When the car has been driven hard for say 10-15 minutes it develops drops in power throughout the rev range.

Looking on VAC COM it's clear the car is dropping boost via the N75 and sometimes it takes the extreme option of shutting the throttle plate to 40% despite the pedal being at 100%!!

In short when the car has been hammered for a bit the ECU decides it needs to drop boost.

What could cause this?

You'd at first think maybe heat soak but the FMIC is rated to well above the circa 235BHP its running

MANY MANY thanks in advance.

 

[RikH]

you mention the N75, that is the clearest option from what i can see
try a new N75 valve

heat soak will affect performance but not to the level you are talking

 

[Sprog]

you mention the N75, that is the clearest option from what i can see
try a new N75 valve

heat soak will affect performance but not to the level you are talking

It's not like the N75 is malfunctioning though - it's doing what it's told. i think the real question is WHY is the ECU telling the throttle to close / N75 to bleed boost!?

Heat soak with an FMIC seems unlikely. I've only ever heard of it when running huge power. After all, its 240 on an FMIC which is supposed to be reliable to 500

 

[DPJ]

I had a another post about this problem monthsback but it's a lot easier to start again as that sort of died and will only confuse new findings.

Sorry, that's not the way it works round here.

 

[DPJ]

I've re-read this three times today. Unfortunately some of the original info is missing.

Did you ever try another N75?

You keep mentioning throttle plate closing when the pedal is hard down. Have you got some log proof of that?

 

[d_jones]

Unfortunatly I don't have them to hand - I may have to log again if needs be.

When logging the block that shows throttle position vs plate position the throttle would stay reading 100% then as the hesitation in power happens you see the plate hit dead on 40% for a split second then resume to 100% (throttle position stays reading 100% all the way through).

ps. the N75 was changed and it didnt help

 

[DPJ]

Unfortunatly I don't have them to hand - I may have to log again if needs be.

When logging the block that shows throttle position vs plate position the throttle would stay reading 100% then as the hesitation in power happens you see the plate hit dead on 40% for a split second then resume to 100% (throttle position stays reading 100% all the way through).

Can you post this log again? perhaps alongside 114?

 

[d_jones]

Thanks for taking the time to reply DPJ.

Do you want me to log 54 and 114 at the same time? If so I will do that tonight!

For now I have managed to dig this out which shows the throttle. On this one it doesnt go to exaclty 40% (not sure where I originally got that figure from - sorry).

	Group A:	'054			
		Engine Speed	Operat Cond	Throt Pos	Throt Angle
	TIME	700-2520 RPM	Idle etc	0-100%	0-100%
Marker	STAMP	 /min		%	%
	0	1630	Enrich.	30.6	13.3
	0.59	1880	Part Throttle	27.1	10.2
	1.2	2140	Enrich.	31	18
	1.71	2360	Part Throttle	27.1	12.9
	2.3	1990	Idle	0	2.4
	2.97	1280	Part Throttle	23.1	7.5
	3.51	1410	Enrich.	39.6	14.9
	4.11	1510	Enrich.	87.5	85.1
	4.72	1640	Part Throttle	100	92.2
1	5.32	1780	Enrich.	100	100
	5.82	1890	Part Throttle	100	100
	6.33	2010	Part Throttle	100	100
	6.93	2180	Enrich.	100	100
	7.43	2330	Part Throttle	100	100
	8.04	2530	Part Throttle	100	100
	8.59	2550	Part Throttle	100	100
	9.18	2550	Part Throttle	100	100
	9.75	2550	Part Throttle	100	100
	10.35	2550	Part Throttle	100	100
	10.85	2550	Part Throttle	100	100
	11.35	2550	Part Throttle	100	100
	11.86	2550	Part Throttle	100	100
	12.46	2550	Part Throttle	100	100
	12.96	2550	Part Throttle	100	100
	13.48	2550	Part Throttle	100	100
	14.08	2550	Part Throttle	100	100
	14.75	2550	Part Throttle	100	100
	15.32	2550	Part Throttle	100	100
	15.88	2550	Part Throttle	100	100
	16.41	2550	Part Throttle	100	100
	17	2550	Part Throttle	100	95.3
	17.6	2550	Part Throttle	100	40.4
	18.2	2550	Part Throttle	100	52.2
	18.81	2550	Part Throttle	100	100
	19.41	2550	Part Throttle	100	100
	19.91	2550	Part Throttle	100	99.2
	20.58	2550	Part Throttle	100	100
	21.17	2550	Part Throttle	100	99.6
	21.71	2550	Idle	0	5.5
	22.22	2550	Overrun	0	6.7

 

[DPJ]

Thanks for taking the time to reply DPJ.

Do you want me to log 54 and 114 at the same time? If so I will do that tonight!

......

Yes, a power run showing that the throttle closes.

The log you posted would seem to suggest a throttle body fault...... (or pedal)

 

[d_jones]

Could a throttle body fault caise it to also cut boost via the N75?

More specifically when you let off the throttle does the wastegate always open to get rid of boost?

If so then maybe the fault all along is whatever is causing the throttle plate to close and its not the ECU trying to drop boost any way it can??

ps. sorry for any stupid questions.

 

[DPJ]

Could a throttle body fault caise it to also cut boost via the N75?

More specifically when you let off the throttle does the wastegate always open to get rid of boost?

If so then maybe the fault all along is whatever is causing the throttle plate to close and its not the ECU trying to drop boost any way it can??

ps. sorry for any stupid questions.

When the throttle plate closes, you have vac in the line to the dv and to the N75......

 

[d_jones]

We did some 54/114 runs tonight and it took 5 runs to get it to go wrong. It wasnt as bad as normal and the only reason I can think of is its only 10.5 deg tonight and its usually at least 5 more.

Anyway here is 54/114 at a pathetic refresh rate....

	Group A:	'054				Group B:	'114				Group C:	 Not Running	
		Engine Speed	Operat Cond	Throt Pos	Throt Angle		Eng Load Call	Corr. Load	Engine Load	Bypas Dut Cyc/0-100%			
	TIME	700-2520 RPM	Idle etc	0-100%	0-100%	TIME	<=150%	<=150%	15-150%		TIME		
Marker	STAMP	 /min		%	%	STAMP	%	%	%	%	STAMP		
	1.37	1680	Part Throttle	100	94.5	0.77	124.1	122.4	83.5	95.3			
1	2.52	1910	Part Throttle	100	100	1.91	135.3	134.3	97	95.3			
	3.62	2170	Enrich.	100	100	3.12	179.7	177.6	114.3	95.3			
	4.63	2470	Part Throttle	100	100	4.12	188	186.6	139.1	95.3			
	5.73	2550	Part Throttle	100	100	5.13	191.7	194	175.2	95.3			
	6.78	2550	Part Throttle	100	100	6.23	191.7	198.5	191.7	83.1			
	7.94	2550	Part Throttle	100	100	7.42	191.7	206	191.7	80.4			
	9.15	2550	Part Throttle	100	99.6	8.56	191.7	203	191.7	81.6			
	10.36	2550	Part Throttle	100	100	9.77	191.7	209	191	86.7			
	11.48	2550	Part Throttle	100	100	10.96	191.7	203	182	92.5			
	12.7	2550	Part Throttle	100	100	12.08	191.7	200	172.9	95.3			
	13.89	2550	Part Throttle	100	100	13.36	191.7	197	166.2	94.9			
	14.98	2550	Part Throttle	100	98.4	14.39	191.7	192.5	160.2	95.3			
	16.09	2550	Part Throttle	100	99.2	15.5	191.7	189.6	156.4	74.5

Here was a 003 run as well if it helps....

	Group A:	'003			
		Idle speed	Air mass in	Throt Angle	Ignit Angle
	TIME	700-820 rpm	2.0-4.5 g/s	0.2-4.0%	0-12 BTDC
Marker	STAMP	 /min	 g/s	%	 °BTDC
					
1	6.05	1520	27.44	87.8	15
	6.65	1640	30.56	93.7	12
	7.24	1760	34.83	100	12.8
	7.87	1880	39.86	100	10.5
	8.53	2000	46.47	100	9.8
	9.05	2160	56.25	100	9.8
	9.66	2320	69.69	99.6	8.3
	10.16	2480	85.56	100	5.3
	10.66	2680	104.44	100	5.3
	11.26	2960	110.78	100	5.3
	11.78	3160	127.75	100	9
	12.37	3400	129.64	100	6.8
	12.87	3640	141.81	100	7.5
	13.38	3840	148.78	100	8.3
	13.91	4040	155.78	100	8.3
	14.56	4280	163.28	100	9
	15.1	4560	167	100	8.3
	15.69	4760	170.06	99.6	8.3
	16.21	4920	171.83	99.6	9.8
	16.82	5120	175.69	100	10.5
	17.4	5320	174.31	100	10.5
	17.91	5440	178.75	100	14.3
	18.52	5640	177.61	100	15.8
	19.02	5760	177.33	100	16.5
	19.62	5920	178.44	100	16.5
	20.2	6040	180.56	100	16.5
	20.76	6160	182.67	100	17.3
	21.34	6280	182.39	100	16.5
	21.94	6400	181.25	100	15.8
	22.44	6520	182.67	100	15.8
	22.94	6600	182.39	100	16.5
	23.44	6680	183.36	100	18
	24.06	6760	182.08	100	18
	24.65	6840	184.42	100	19.5
	25.16	6920	117.58	41.2	4.5

 

[d_jones]

Just to add to this I'm starting to think (after reading something on VWV about different N75s) it's because I have an N75F (I bought an F to replace the F).

One chap on that forum who seems to have tried them all says he would get rough top end power on the F.

Should I get a J or K instead (or whatever other random ones they do)?

 

[DPJ]

Really, listen to the huge majority, the N75F is fine - you don't want another one and it's not affecting anything here.

I'm confused, you say your problem is higher up the rev range, yet your 054/114 log from yesterday doesn't show a power run - (it shows constant throttle speed of 2550.. but from the load I'm guessing you were at WOT .). I can see throttle angle briefly drops to 3.12.

There's not (imo) sufficient evidence of the problem here.

Your 003 log looks absolutely fine.

I still guess that there's an intermittent pedal/throttle body / wiring prob that's giving you the problem - I don't think it's related to MAF/MAP/N75/Boost leak etc.

 

[d_jones]

Just an update on this - as a stab in the dark we tried an N75K and its been fine since (touch wood).

Looking on some of the American fourms this cutting of power is quite common. Its when the turbo surges basically. From what I can make out the faster responding N75s smooth out the surging and hence stops the cuts in power.

 

[caveo]

Hi mate we met at Awsome RR day and your right its a little strange that we BOTH have custom code maps and the power drops ALOT at 6000 rpm , see my graph here http://www.seatcupra.net/forums/album.php?albumid=114