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Discussion Starter · #1 ·
Let me start off by telling you about my car mods that way we can rule things out

APR chip
ghl downpipe 2.5"
boost gauge
Sram intake.
I recently got sick of having the cel on so I add the 42 draft design o2 spacer a week ago.


Now for the symptoms.

No CEL is on and no codes.
Today I was driving and she felt a little sluggish.
So I really put the pedal to the metal. Boost was only at 3psi normally would be at 17psi. Then for a short 3-6 seconds it jumped up to 17psi and stayed there till I got to scared of getting a speeding ticket. Now I cant get it to go over 3psi.


I have cleaned air filter
cleaned MAF
checked for codes (none) but cleared the system anyway.
Checked dv to make sure the hoses are attached and not loose or leaking.

Any one have any ideas?
 

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you also have a MAP sensor on top of your intercooler. They arent known to go bad, but they measure the pressure in your manifold. (manifold absolute pressure)

Check that out. Otherwise its a good possibility you have a vacuum line loose somewhere that only comes loose under load. Theres a bunch so I'd just start checking them all. Which brings up my next question, what is your car idling at for vacuum? Should be anywhere from 18-20" hg

ALSO, check your wastegate actuator and make sure that the locking nut hasn't moved from its factory position. And you may have also put your car into limp mode now that it wont go over 3psi. You can reset that with VAGCOM or by disconnecting battery for a while.

You have some things to look at now! hope that helped.
 

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Discussion Starter · #3 ·
you also have a MAP sensor on top of your intercooler. They arent known to go bad, but they measure the pressure in your manifold. (manifold absolute pressure)

Check that out. Otherwise its a good possibility you have a vacuum line loose somewhere that only comes loose under load. Theres a bunch so I'd just start checking them all. Which brings up my next question, what is your car idling at for vacuum? Should be anywhere from 18-20" hg

ALSO, check your wastegate actuator and make sure that the locking nut hasn't moved from its factory position. And you may have also put your car into limp mode now that it wont go over 3psi. You can reset that with VAGCOM or by disconnecting battery for a while.

You have some things to look at now! hope that helped.
Thanks at idle I am at 20hg. I have to let her cool down more before I get under her.
 

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Discussion Starter · #5 ·
No. I have had it for a year or so with no problems. It is idling about 867rpms. This all happened after the o2 spacer was installed. That is the only thing that is different but dont see how that would be the issue.
 

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Eur0wn3d
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you also have a MAP sensor on top of your intercooler. They arent known to go bad, but they measure the pressure in your manifold. (manifold absolute pressure)

Check that out. Otherwise its a good possibility you have a vacuum line loose somewhere that only comes loose under load. Theres a bunch so I'd just start checking them all. Which brings up my next question, what is your car idling at for vacuum? Should be anywhere from 18-20" hg

ALSO, check your wastegate actuator and make sure that the locking nut hasn't moved from its factory position. And you may have also put your car into limp mode now that it wont go over 3psi. You can reset that with VAGCOM or by disconnecting battery for a while.

You have some things to look at now! hope that helped.
x2
 

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Discussion Starter · #7 ·
Ok so here is the update. Pulled o2 spacer and removed battery cable. Car ran great for 5-10 minutes pushing 15-17psi then back into limp mode. Took car into my mechanic and he replaced the DV valve for free. Still car works fine for 5-10 minutes then goes into limp mode. Do you think the turbo is getting too hot? It has been like 107 degrees out the last few days, and it runs fine until it gets warm.
 

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Well, those turbos are both water cooled and oil cooled, so if it was getting too hot it would likely be a result of coolant or oil temperature. If your engine temps are within normal range, you likely have a different issue. BUT, 107 degrees is A LOT, and its not uncommon for cars to have issues when it is that warm.

Its a long shot, but it may be your O2 sensor because they take about 5-10 minutes to start sending accurate readings to your ECU about exhaust temp, gas content, etc... I don't know why there wouldnt be an engine light though. O2 sensors are the number one cause of those. I have 3" exhaust, with no cat, and I used spark plug non-foulers to space the sensor. My car runs amazing and I have never had an engine light or hit limp mode. But something is out of its efficiency range and its telling the ECU to put your car in limp mode.

You are probably dealing with something that happens within 10 minutes of startup, unfortunately, there are a lot of things that happen in that time. Its not like you turn the car and and everything is within operating specs. My best advice right now is to wait for weather to not be so hot, then start trouble shooting again.
 

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Discussion Starter · #9 ·
Well I juts got back from a road trip (Kansas City to Seattle and back) and the car ran great with full boost as long as the temp outside was below 85 degree (guess-stimate) and I was moving at highway speeds. I found that when I stopped for gas it would act up (boosting at 3psi). I am now thinking that under slow driving conditions and hot weather the engine bay is getting to a hot temperature and I causing the n75 valve to not work correctly. I am assuming that since there are only two wires to the valve there is no feedback to the ecu, and that the ecu is sending the signal and the valve is receiving it but the n75 valve is not working at 100%. So, I am think the n75 valve may be going out. Has anyone experienced a n75 valve go out.


Also while in Seattle I took the whole front end off. Cleaned the intercooler and sensor, and checked for bad vacuum lines.
 

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Bubble Boy
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Have you taken off the nasty carpet crap off from underneath your hood? might help with the heating problem.
 
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