I have a stage 1 R-Tech remap which my mate also has on his MK4 GTi.

His Golf pulls a lot stronger than me in 3rd, i.e. I will keep up with him until I change into 3rd and then it feels boggy.

When it was remapped I was told the ECU was calling for 1 BAR but was not getting it.

Possible faults were MAF & DV so I got a new MAF & a Bailey DV30.

Went to a RR day in Leicester and was expecting 210-ish and it ran 200 and I got told the charge intake pipe was leaking and I should be running a 007p with a yellow spring, both of which I have replaced.

Today I was at my bro's and hooked up his boost guage and went for a spin. It was peaking at 0.9 BAR and tailing off quickly to 0.7 BAR

We checked all the hoses including those under the inlet manifold with no problems found and I also tried his MAF with no change.

I have checked for any fault codes and haven't found any, I am now at a loss.

It might possibly be an N75 fault but does this sound likely?

Any other ideas??

you tried his n75??? let me no if it is that mate i have a spare in the garage at home which i will get our lass to bring down at the weekend when she comes, which you can have

Nah, I didn't try the N75 I tried his MAF which made no difference.

I have been reading up about the different N75 valves and the varying degrees of success people have had but it seems the results are random.

ye i was gonna fit a j but told not to bother , like i said there is a standard one in my garage if you require it mate. call it a token gesture for helping me out this mornin

you need to do a boost leak test Loads of threads about it on here and VWVortex, UKmkIV's and a few others.

Might also be leaking boost past the Crank Case Breather check valve, easy fix is to splice another valve inline.

A search on here for "boost leak test" gives me a page where it is mentioned on a couple of threads but no details

A search on ukmkivs shows a thread where you have to block this that and the other and then presurise the system via a dog can with a valve and an air compressor?

Don't fancy that much lol

the dog food tin idea really does work

If theres a noticeable difference between the requested (command) boost and the actual boost then that usually indicates a leak in one of the vaccuum pipes, check the one between the N75 and the wastegate actuator. Or as you say, the N75 itself.

you tried his n75??? let me no if it is that mate i have a spare in the garage at home which i will get our lass to bring down at the weekend when she comes, which you can have

That'd be great, any chance she could post it?

That'd be great, any chance she could post it?

will have a word and see if she can find it but i should'nt see a prob, txt or pm me your address mate

Text sent, cheers mate

Right, thanks to sivrs I have swapped the N75

I have done a run with VAG Com and logged 032, 115, 120.

Next question... How do I read the results?

I have opened the log file but it seems random lol

if you look at the bit for block 32 first you should see mutiplicative (or something like that) if the value in this field is more than -5 it might suggest a boost leak, block 120 is used to do the Tourqe to BHP calcs. I think on block 115 you should see requested boost and actual boost, find a point in the list where you can see the revs rising (from when you did a pull in 2nd/3rd) and the requested and actual should follow quite close as you accelerate. some of the spreadsheets are listed here

you should be able to post the logs as an image or use a file share site to post a link

Right, thanks to sivrs I have swapped the N75

your welcme mate glad it got there in 1 piece

Right, so, if I do a Block 32, 115 & 120 log as I boot it off the lights and then red line in 2nd that should be enough?

I do not fancy trying the other way of planting my foot in 4th until the red line.

I do not have a problem with doing it, I just have a problem of getting stopped and the very nice policeman chuckling as he tells all his mates that I provided him with excellent data lol

Do a boost run in 3rd, hold it at 2000revs then foot to the floor until about 4000revs then lift off, you should be able to do this within legal speeds.

You only have to redline it in 4th if you're going for a peak BHP run

righto, I'll try this tonight and post the logs

depending on the cable it is sometimes better to do the run seperately for each block. you will get a higher sample rate. A good one for the boost log is to do a 2nd/3rd gear pull up hill.

I've been ill the last couple of nights which has included me just falling asleep at around 7PM

If I can stay awake I'll try it tonight.

Right, I'm gonna do seperate logs for Block 32, 115 & 120.

3rd gear @ 2000 and then plant my foot till 4000?

Edited 22 April, 201016 yr by Bertee

Right, the log is here

Thursday	22	April	2010	21:55:31	
06A 906 032 HN		1.8L R4/5VT         0002			

Group A:	'002			
	Idle speed	Engine load	Inj. period	Air mass in
TIME	700-820 rpm	15-25%	2.0 - 4.0 ms	2.0-4.5 g/s
STAMP	 /min	%	 ms	 g/s
0.01	2160	54.9	6.12	22.61
0.42	2160	55.6	6.12	22.86
0.91	2200	55.6	6.12	22.89
1.31	2200	63.2	7.82	38.72
1.83	2280	107.5	11.56	53.64
2.23	2360	123.3	13.26	60.72
2.63	2480	134.6	14.62	66.92
3.03	2560	142.1	15.64	73.89
3.43	2720	146.6	16.32	79.72
3.83	2840	148.9	16.32	82.36
4.23	2960	151.9	16.66	91.61
4.64	3080	154.1	18.36	92.33
5.04	3200	155.6	19.38	97.03
5.44	3360	156.4	20.06	101.69
5.86	3480	158.6	20.4	104.33
6.24	3600	157.9	20.06	107.42
6.64	3720	156.4	20.06	111.69
7.06	3840	155.6	20.06	113.28
7.55	4000	153.4	19.72	118.33
7.97	4040	139.1	15.98	56.39

Group A:	'020			
	Idle Stabilization	Idle Stabilization	Idle Stabilization	Idle Stabilization
TIME				
STAMP	 CF	 CF	 CF	 CF
345.25	0	0	0	3
345.65	0	3	0	3
346.05	0	3	0	3
346.45	0	3	0	3
346.87	0	3	0	3
347.37	0	2.3	0	2.3
347.77	0	2.3	0	2.3
348.17	0	2.3	0	2.3
348.58	0	2.3	0	2.3
394.43	0	0	0	0
394.83	0	0	0	0
395.25	0	0	0	0
395.65	0	0	0	0
396.14	0	0	0	0
396.65	0	0	0	0
397.05	0	0	0	0
397.45	0	0	0	0
397.85	0	0	0	0
398.25	0	0	0	0
398.77	0	0	0	3
399.16	0	0	0	3
399.56	0	0	0	3
399.97	0	0	0	3
400.36	0	0	0	3
400.76	0	0	0	2.3
401.16	0	0	0	2.3
401.58	0	0	0	2.3
401.98	0	0	0	2.3
402.4	0	0	0	2.3


Group A:	'032			
	Idle O2 Adapt	Run O2 Adapt		
TIME	-10.1	-10.1		
STAMP	%	%		
0.01	-1.3	8.6		


Group A:	'115			
	Engine Speed	Engine Load	Spec. Boost	Actual Boost
TIME	700-6800 RPM	15-150%	990-1800 mbar	<=1800 mbar
STAMP	 /min	%	 mbar	 mbar
0.1	2080	113.5	1960	1520
0.5	2200	124.1	1990	1640
0.9	2320	132.3	2030	1760
1.3	2400	140.6	2060	1880
1.71	2560	147.4	2070	2000
2.21	2720	154.1	2010	2080
2.61	2880	158.6	1960	2120
3.12	3040	159.4	1890	2090
3.52	3160	157.1	1910	2070
3.92	3320	157.1	1950	2060
4.32	3440	157.9	1990	2060
4.72	3560	158.6	2000	2040
5.23	3760	155.6	2040	2040
5.63	3880	151.1	2060	2020
6.03	4040	151.1	2080	2030

Logs 22.04.10.pdf

I've plotted the boost log as a graph but work computer won't let me post it on Photobucket so will try and put it up tonight.

It looks like it is calling for 1 bar at 2200 revs but then the requested boost dips down to 0.9 bar at about 3000 revs. The Actual boost starts quite low at only just over 0.6 bar at 2200 but does take a while to pick up, it is peaking at 1.1 bar at about 3000 revs but for the first 500 revs or so it takes a while for it to catch up with the requested boost.

So basically it calls for 1 bar at 2200 revs but it doesn't get it until 3000 revs.

I'd check the vaccuum hose between the N75 valve and the wastegate actuator on the turbo is not loose or deteriorated. Then maybe check the N75 by replacing it with a known working one

Edit: heres the graph, pressures converted to bar and adjusted by subtracting 1000mbar for atmospheric pressure

Your actual boost seems to hold nicely up the revs but there is that delay at first before it achieves what it needs

Edited 24 April, 201016 yr by chicken_eyebrow