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View Full Version : Car is still boosting in Neutral!!!!! I am out of ideas...Need some advice



Starting
09-30-2006, 12:29 PM
So I thought my maf died since while driving my car would only boost to 7 psi and it would take about 8 seconds to go 200 rpms at full throttle. I also got a code of p0102-mass air flow sensor:singal too low. I cleaned the maf and reinstalled it to see only that the car was boosting in neutral. The maf code was gone at this point but I replaced it to hopefully solve boosting in neutral. WHAT IS CAUSING THIS??
I replaced the n75 because I was unable to blow through it at any point during an output test, but it did click fine. There is no shaft play on the turbo. There were voltages to both the maf and n75 and all fuses are ok.

The line from the n75 to the wastegate is not kinked.
If I run the car without the wastegate connected to the n75 the car boosts.
If I run the car without the n75 the car still boosts.
If I run the car without a maf, n75 and tip it still boosts.

Wastegate seems to be fine, not lose at all and opens when I push on it but is this my problem?

Car is a 98.5 A4qm1.8t with a GIAC k04 program, K04 turbo, 5 bar fpr, Ecode test pipe, Borla Exhaust.

I really appreciate any advice because at this point it only seems like it could be the turbo itself or the ecu.
Thanks for reading the long post.

BranCKY3
09-30-2006, 12:40 PM
What's the problem? It's boosting when you give it gas in neutral?

Starting
09-30-2006, 12:42 PM
Yes the car is creating boost in neutral.

GraysonF
09-30-2006, 12:43 PM
how much boost and gas? if i rev my engine in neutral, i get boost, but only about 6-7psi

Starting
09-30-2006, 12:44 PM
~15 Psi

GraysonF
09-30-2006, 12:50 PM
how much gas do you give it? is it floored? or just moderate throttle, or even no gas? maybe your throttle cable is stuck open?

Starting
09-30-2006, 12:52 PM
with the gas basically full throttle. the problem is a car should not boost in neutral at all. the car should only boost when there is a load on the engine.

BranCKY3
09-30-2006, 01:04 PM
Everyone's gauge reads +boost if you go full throttle in neutral.

TQMB5
09-30-2006, 01:13 PM
^^^mine doesnt it stops at 0

Starting
09-30-2006, 01:14 PM
No turbo car should boost in neutral. There is no load on the engine. When a load is applied ie. the car is in gear then the turbo will boost. I am going to log boost in a bit.

BranCKY3
09-30-2006, 01:21 PM
The engine might not see pressure but the hose leading to your boost gauge will. My turbo can get to 10psi without load when I launch, and my turbo is much bigger than yours.

onemoremile
09-30-2006, 02:33 PM
i can't get past 0 when revving out of gear.

SeanF
09-30-2006, 03:00 PM
uneducated guess, is a wastegate malfunction...

reason i say that is that is what should be opening when the car gets to neutral pressure (atmospheric pressure) to keep from boosting in neutral correct?

i could be way of, im just thinking of what could be possible

Starting
09-30-2006, 03:04 PM
Sean F I am also thinking something is wrong with the turbo and the wastegate is the obvious choice.

I took the car for a drive and it is driveable it seems. It still boosts in neutral though.

I went to log channel 115 but forgot the number. I will have to do it later.

audiluver
09-30-2006, 03:36 PM
where did you get the idea that a car won't boost in neutral. true you shouldn't get full boost or any at all, that just depends on the size of the turbo, engine etc. my rx7 would make about 8 lbs of boost from the first turbo. As far as load goes, spinning an engine around is load. Look at a scan tool sometime and it will give you calculated load. Even revving the engine you will get about 20% load depending on the issue. The question in your case is why does it produce 15 lbs. And i wouldn't think it could be a turbo or wastegate problem. If you're revving your engine your wastegate should be closed. Where are you measuring boost and with what device?

ceas
09-30-2006, 03:38 PM
don't worry about it, you'll launch harder that way :-P

Starting
09-30-2006, 04:01 PM
Originally posted by audiluver
where did you get the idea that a car won't boost in neutral. true you shouldn't get full boost or any at all, that just depends on the size of the turbo, engine etc. my rx7 would make about 8 lbs of boost from the first turbo. As far as load goes, spinning an engine around is load. Look at a scan tool sometime and it will give you calculated load. Even revving the engine you will get about 20% load depending on the issue. The question in your case is why does it produce 15 lbs. And i wouldn't think it could be a turbo or wastegate problem. If you're revving your engine your wastegate should be closed. Where are you measuring boost and with what device?

I am measuring with my boost gauge. It has never read more then 0 while in neutral and then I have the maf problem and it began to. It is reading normal vacum and boost while driving so I am having a hard time believe that it is wrong. I am going to log acual vs requested boost tomorrow.

SeanF
09-30-2006, 04:04 PM
ok, i just tested in my car for you....

if i floor it in neutral, the gauge shoots to the 0 mark, stay there for a second and slowly climb, all of this in the time it takes to get from idle to 6000RPMs, it got up to about 5psi.

and in neutral, the wastegate should be closed, once it reaches the atmospheric pressure, it should open to stop from going over right? the n75 valve causing it to do so?

Rosati
09-30-2006, 04:25 PM
did you try resetting the ecu?

Fellas, hes saying all of a sudden hes making boost in N when he didnt before, he knows his car.

The FD is a rotary engine audiluver , plus the 13bs have much more compression than our 1.8t's

Quattrocket
09-30-2006, 04:39 PM
I have never heard of that one before. i would say its got something to do with the wastegate though.

Starting
09-30-2006, 05:14 PM
I haven't tried resetting the ecu but have done a tba.

I am also thinking it may be a wastegate problem. A person on AW mentioned a way to pressure test the wastegate so I am hopefully going to do that tomorrow.

Quattrocket
09-30-2006, 05:58 PM
What mods do you have? if the turbo is shot theres your chance to upgrade!!!! i have a k03 you could have but there is a crack in the housing. you could swap the wastegate off it though.

Starting
09-30-2006, 06:05 PM
mods were in the first post. k04, Giac programming, ecode test pipe, borla exhaust.

If the turbo is dead the car might be seeing a car cover and some blocks in my driveway. Don't have the time to upgrade like I would like right now.

Quattrocket
09-30-2006, 06:07 PM
oops how did i miis that.

BranCKY3
09-30-2006, 07:55 PM
Your gauge will show boost in neutral! I'll make a video of mine if you want me to. It's perfectly normal, your turbo isn't blown because it can make boost without load.

SeanF
09-30-2006, 08:00 PM
me like videos

Poopie
09-30-2006, 08:46 PM
i can make 8lbs of boost out of gear. k04 pc16 with a fmic. It could be that your engine is seeing a higher load out of gear. Vag to see what the engine load is in neutral. It could be a wastegate problem like you said as well.

98a4
10-01-2006, 11:42 AM
I get 2-3psi out of gear. I didnt read the entire thread to be honest, but

N75 and wastegate actuator is where id start.

Or mabye a bad boost guage?

mike-2ptzero
10-01-2006, 02:35 PM
If it was a issue with the wg the car would over boost while in gear. The wastegate doesn't open while out of gear since it only opens when the boost level the ecu is asking for is reached and most of the time that means the wg stays shut till full boost is reached. The reason you dont hit high boost levels is because there is less fuel being used since the load readings at the ecu aren't high enough to make power which produces exhaust gas to turn the turbo.


I was able to produce 7-10psi while revving out of gear with a K04 on my 2 liter.


BTW did you run the line directly from the compressor housing to the wg actuator? This should cause you to see no more then 5psi, if you see more then it is a wg or wg actuator issue.

audiluver
10-06-2006, 06:22 PM
Thanks for the headsup on the rotary engine in the fd i owned for 3 years i wondered why it looked small and those dozen or so engines i built for rx7s looked so weird. Oh and about compression, not quite accurate there either.

onemoremile
10-06-2006, 07:55 PM
i did manage to make 5-6 psi if i gave it WOT in neutral. i've just never seen the point of flooring a car in neutral. this is a k04 on a 99.5.

BranCKY3
10-06-2006, 08:25 PM
Originally posted by onemoremile
i did manage to make 5-6 psi if i gave it WOT in neutral. i've just never seen the point of flooring a car in neutral. this is a k04 on a 99.5.

Some of us have to build up boost before we launch [:p]

Rosati
10-06-2006, 08:33 PM
Originally posted by audiluver
Thanks for the headsup on the rotary engine in the fd i owned for 3 years i wondered why it looked small and those dozen or so engines i built for rx7s looked so weird. Oh and about compression, not quite accurate there either.


I hope she ****in blows on you now, douche

your a real big man , shittt

you really put me in my place OK so my compression was off by .5

you cannot compare a ****in Rotary engine w/ a conventional 4 cylinder whether turbo or not.....

Enjoy your rx7 , i bet its your penis extension