New MAF but now negative boost errors.

[Russ_20vt]

New MAF but now negative boost errors. Updated...

PLEASE SEE PAGE 2 FOR BIG UPDATE, THANKS


Hi Guys got a new problem since fitting my new MAF.

Before on my old maf i was reading 115gs and i am now reading 150gs so thats that problem sorted.

Now on a logging run my car hit limp mode in 4th gear at about 4000rpm and came up with the fault code:

17964 charge presure control neative deviatation.

Now from searching and reading up this is the actual boost not reaching the requested boost and ive yet to do a log of this as i dont know how to?help please?

So it could be a Boost leak or a possible N75 valve issue. But doesnt the n75 usally make the car overboost when it goes tits up?

Its weird how since getting better maf flow readings it decides that it cant produce enough boost, any ideas?

Thanks

Russ

 

[Martyn]

Check all the hoses dude and if you can get Vag-Com and log blocks 002,115 and 118.

 

[DPJ]

logging blocks 003, 118, 115,020, 031, and 032 are a good starting point.

Do no more than 2 at a time to get any reasonable samples.
003 and 020, then 115 and 031, then 118 and 032.
This gives you, airflow, actual timing, timing pull, requested boost, actual boost, target air fuel, actual airfuel, n75 duty, inlet temp, actual boost, and then finally fuel trims.

115 is requested & actual boost

 

[Russ_20vt]

Thanks guys will log 115 then! but if my boost is down what could be causing this?

 

[Martyn]

118 is N75 duty...that should tell you if you've got a leak / shagged N75.

 

[Russ_20vt]

Ok thanks martyn, will do a log and report back here after.

Thanks Guys!

 

[Simon L]

I was repeatedly getting this error. Always in 4th gear around 4k, under full throttle.

I tried changing the N75 from J, to a C, and to an F. With no difference. I did get different boost delivery, but still the same error.

Recently ive bypassed the vacuum chamber and valve on top of the engine. No more errors.

 

[Martyn]

Oh yea. Do the N249 bypass too (as mentioned by Simon)

 

[jonathanp]

out of interest is there a block that shows the n249 duty?

 

[Martyn]

Nopes!

 

[Russ_20vt]

Hi simon yes i read some of your posts on this but never found if you solved the problem. I guess not then untill you bypassed the chamber, how long have you been runnning it like this for and is it safe?

 

[Simon L]

Russ, i couldnt figure it out, the N75 duty didnt look like i had a leak (ie it was 95% through the range). MAF values were consistant. No one had an answer that worked.

And it seemed to mainly happen in very cold temps, or when i had been driving "hard" for a sustained period of time.

I've had the N249 off for around 2 weeks now, and i've tried to make it limp, but it wont, so far

Quite a few folk have done it recently, and a few have had it done for a while, no problems reported so far.

I've noticed DV response is MUCH quicker. But apart from that no other real change.

 

[Russ_20vt]

Thanks simon got some more logging in, couldnt figure out how to test the N75 on vagcom, is it Load on 118?as Load is also shown on 115?

Got some graphs of my actual vs Requested, sorry for so many.

2nd Gear had wheel spin issues i think

3rd Gear

4th Gear

Whole run including 5th gear

Do they look down by to much? ive not done this before so im unsure of my results.

Thanks

Russell

 

[Simon L]

What remap have you got? Or are you standard?

 

[Russ_20vt]

As far as im aware it was remapped by a guy who used to work for AmD, i bought it already remapped. The previous owner has since bought another ibiza and is back on here so hopefully he will spot this thread and give us more light on the subject lol. Have i done the graphs right? i just looked at some of your old ones and mine look nothing like them.

 

[Russ_20vt]

4th Gear spreadsheet.

 

[m0rk]

looks like you can't meet requested boost.... got a leak? or a knackered DV?

 

[Russ_20vt]

Maybe a leak, checked the DV only the other day and its only 6 months old. Could my N75 be stuffed?

 

[Russ_20vt]

Anyideas daytime people?

 

[flashbsd]

any advice on bypassing the n249 people? photos and basic instructions?