n75 valve replacement/test?

[FusLit]

on the 98 jetta tdi I'm throwing a code:
Intake Manifold Pressure: Control Difference Intermittent.
I started tracking down the culprit and have replaced the vacuum line from my intake to the ecu as well as the line in the ecu. Still there, Pete helped me find a boost tube that had a tear in it which I've replaced that and it seemed to briefly fix the issue, now it's back (gotta check the rest of boost tubes this weekend) I have boost for about 10-15 seconds then it kicks to limp mode.

Any idea if there's an easy way to test the n75 valve quickly?

tanks
-T

[BUNNYLOVE]

Yup, run an output test for the N75 with the vag com. It basically turns it off and on. Then blow through the N75 and see if it alternates between the other two outlets or not. If its bad it'll be open or closed all the time.

[FusLit]

excellent, thanks for the tip, I'll do that this weekend.

Side note: where's a good spot to get a roll of braided vacuum line? I want to re-do all the crusty ones in my car. And I have enough car related projects that I'd like to get a roll.

-T

[BUNNYLOVE]

I'm not sure..dealer or GAP maybe? I just use regular vac. hose.

[FusLit]

Also:
is this the best price on a N75 valve?

World Impex: 51.95
http://www.worldimpex.com/parts/pierburg-change-over-valve-n75_69685.html

cost comparison

GAP: 67
http://www.germanautoparts.com/Volkswagen/Jetta/Engine/430/2
-T

[BUNNYLOVE]

I have one you can try if you want before you buy one. I don't use mine anymore anyways.

[evolveVW]

I bought a spool of the braided vac line (rated to use between the injectors) from the dealer for between 20-30 bucks.

[orion2.0]

maybe check for boost leaks by pressurizing the system with an air compressor?

I did that on my TDI and found a few...I even found a tiny leak in my d24 manifold where the weld didnt quite burn in. The hole wasn't even visible but I could feel/hear air blowing out.

Also, could a bad MAP sensor cause your problem?

[FusLit]

Ryan, i'll hit you up if i can't get this figured out later today

-T

[FusLit]

Tested the n75 valve yesterday via the vag-com output test, was able to blow through it and it alternated back and forth between the two outputs.

I need to test the wastegate to make sure it's actuating correctly and not sticking then I guess the next step is to order a boost gauge for the car to see what type of pressure things are pushing when I hit the limp mode conditions.

Was thinking about testing the wastegate yesterday, but I elected to replace my rear wheel bearings instead.

Anyone know a site that you can get gauge pods for a mk3 I've got an egt gauge so was thinking egt + boost? I was thinking a-pillar, but is there a better spot? (I plan on putting the heated seat switch in so that spot will be used) While I wasn't going to move the radio if I didn't have to... I'm not apposed to it. What other gauge besides egt+boost would be good in the 3 gauge spot the radio spot holds (for a tdi)?

-T

[orion2.0]

try Black Forest Industries... thats where i got my pods and gages. It was for a mk4 but they seemed to have a lot of that stuff.

[FusLit]

update:

Picked up a vdo boost gauge, rummaged and found a 3 gauge 1 din pod (goes where the radio sits) in my pile of junkerrr garage. Pretty impressed I was able to find that.

I've also got an egt gauge I was planning on using on my rabbit diesel project, but was thinking an egr delete for my tdi so I can clean the intake figured I might as well plumb an egt to the block off plate.

For the last spot, was thinking about running an oil pressure gauge (I have an old vdo 5 bar gauge, but would need to get the pressure sender) any one have a spare?

At some point I plan on re-making the gauge pod I have, I am gonna try my hand at casting a replacement from aluminum... we'll see how that goes.

McShane, how do you feel about helping me delete the EGR from my spare intake? (i.e. help tig weld some aluminum)

-T

[BUNNYLOVE]

Are you just going to chop it off and put a tube in its place? I can help with that.

[orion2.0]

update:

At some point I plan on re-making the gauge pod I have, I am gonna try my hand at casting a replacement from aluminum... we'll see how that goes.




Dude, are you gonna do sand casting with aluminum? I've wanted to try that forever... especially the lost-foam method. It looks like a lot of fun. Did you build a little foundry setup?

[FusLit]

Are you just going to chop it off and put a tube in its place? I can help with that.

Yeah, That was the plan, I'll give you a shout and we can talk about what I have in mind (might hold off until I get a chip as I'm reading a cel will be caused by deleting the egr.)

Dude, are you gonna do sand casting with aluminum? I've wanted to try that forever... especially the lost-foam method. It looks like a lot of fun. Did you build a little foundry setup?

<disclaimer> It is something that you could get hurt badly with, so be aware of that, safety first, etc blah blah</disclaimer>

I'll be doing greensand casting I've built a small propane fired burner and foundry as a proof of concept and my buddy has some petrobond sand he's gonna let me use so I'll be casting in that. 9Yet another hobby that i'm interested in but don't seem to have enough time) It's been put on hold for a bit. Now I have a small project so this will be my first attempt at casting in sand, I've only got some proof of concept ingots from when I did test fires before so it'll be a bit of a learning experience.

For some more reading check out http://www.backyardmetalcasting.com

[orion2.0]

thats great...Ive wanted to try that for a long time. You should video it when you make the part.

It would be nice to make a re-usable cast for an upgrade part... then bang out a whole bunch to sell.

I researched this a lot when I was looking for a intake manifold upgrade for my TDI... I explored the idea of casting a custom one but I couldnt come up with a way to keep the interior hollow. I suppose the best way would be to cast 2 halves and then weld them together.

[FusLit]

thats great...Ive wanted to try that for a long time. You should video it when you make the part.

It would be nice to make a re-usable cast for an upgrade part... then bang out a whole bunch to sell.

I researched this a lot when I was looking for a intake manifold upgrade for my TDI... I explored the idea of casting a custom one but I couldnt come up with a way to keep the interior hollow. I suppose the best way would be to cast 2 halves and then weld them together.

you would cast it around a core and bust the core out once it's finished casting. But the setup I have most likely is not large enough to do castings of that size. I've collected a couple books on the process if you've got questions that you can't get answers to. I prob won't be video taping, who would want to see hot metal go all over me anyway x-)

-t

[VRsuper6]

I prob won't be video taping, who would want to see hot metal go all over me anyway x-)

-t
oh i do todd!!! i'll come over and record it for you! hahaha

[orion2.0]

you would cast it around a core and bust the core out once it's finished casting.
-t

Thats a thought I had...which would work for a 1-time piece. It would just be a pain to do many replicas that way. I'm glad I went the d-24 manifold route instead.

One idea: make a modded d24 manifold for a TDI... cut it in half lengthwise. Then use each half to make a re-usable 2-part mold out of concrete or something solid (so 4 parts total). Then each half can be easily replicated and then welded together and touched up. Those would sell like hot cakes on TDIclub.

[FusLit]

oh i do todd!!! i'll come over and record it for you! hahaha

Don't you owe me money? Tell you what, you can drive to the ER for me to help pay some of it off ;)

Thats a thought I had...which would work for a 1-time piece. It would just be a pain to do many replicas that way. I'm glad I went the d-24 manifold route instead.

One idea: make a modded d24 manifold for a TDI... cut it in half lengthwise. Then use each half to make a re-usable 2-part mold out of concrete or something solid (so 4 parts total). Then each half can be easily replicated and then welded together and touched up. Those would sell like hot cakes on TDIclub.

hmm, as far as I know the core is easily broken down after casting. I have a few books on casting pattern making and casting, I'll look through how they built engine blocks as I know it's similar. Would be interesting to attempt, but I figured I would go for something a lot less complex walk before run so to speak *grin*

-T

[VRsuper6]

do i owe you money???

[FusLit]

do i owe you money???

Nah, but at some point I would like replacement parts (starter, blinker stalk) Its on the tab, I'm not sweating it. (since we all know how fast my projects run...)

-T

[VRsuper6]

haha ya, i actually still have half the stalks :D only used the blinker part, not the MFA/wiper one

[allstarrme]

I've also got an egt gauge I was planning on using on my rabbit diesel project, but was thinking an egr delete for my tdi so I can clean the intake figured I might as well plumb an egt to the block off plate.

For the last spot, was thinking about running an oil pressure gauge (I have an old vdo 5 bar gauge, but would need to get the pressure sender) any one have a spare?
-T

The EGR is in a different spot on the 1Z/AHU than the mk4's so you can't really put the EGT sensor in the blockoff plate as its not in direct exhaust flow. the best spot i saw for one was a spot i think stealthTDI had posted on TDIclub, but it requires the turbo to be removed for installation, plus cleaning the metal shards before they can harm your turbo.

i would just turn down the EGR with VCDS, leave the selenoid plugged in and delete the rest of the EGR system. i wouldn't bother making a race pipe out of the stock manifold, its a terrible manifold to waste any time on it. get a D24 or pd 130/150 or some sort of upgrade. I pulled my own D24 intake from the yard for around $25. i have thought about getting a 2 piece audi one or 5cyl eurovan intake and cutting them down as well to test against the D24.

you can get the proper oil pressure sensor for a VDO from 42draft or egauges.com. its the one with M10 X 1 threads, also Cabriolets in the yard have them.

I'll see if i can find that picture for the EGT sensor. you could mount the gauges down in the cubby but they are hard to see while hitting full boost and keep your eyes on the road. i put my stereo down there as it needs much less attention.

[VWTUNING]

I'll see if i can find that picture for the EGT sensor.

StealthTDI has done some cool stuff, well documented on his site too: http://www.stealthtdi.com/


Here's some pics of the EGT:

http://www.stealthtdi.com/Albums/MechanicalUpgrades/preturboegt.html

http://www.stealthtdi.com/Albums/MechanicalUpgrades/egttap.html

[FusLit]

Makes sense, I'll see if I can track down the d24 intake, thanks for the heads up on the egt. I'll check out the stealth tdi site.

-t

[FusLit]

god, that background image on that site is hideous thank god for adblockPlus. I think this pod install could quickly spiral into huge upgrade time... :-X

nozzles, clutch, turbo, intake... Iol

-T

[orion2.0]

yesss...the more modded TDIs the better:ssmile:

[FusLit]

so after reading through this guy's site I see this.

http://www.stealthtdi.com/SGII.jpg


Instrumentation

I fabricated a custom gauge panel that mounts in the place of my cupholders. The Exhaust Gas Temperature (EGT) and Manifold Pressure ("boost") gauges are commercial grade by ISSPRO. The LEDs indicate lift pump and water injection status. The SCAN GAUGE II (SGII) acts similarly to trip computers found on today's newer cars. It can display Current MPGs, Fuel Rate, Voltage, Coolant Temp, Intake Air Temp, Engine RPM, Vehicle Speed, Manifold Pressure, Engine Load, Throttle Position, Max Speed, Avg Speed, Max Coolant Temp, Max RPM, Driving Time, Driving Distance, Fuel Used, Trip MPGs, Tank MPGs, Distance to Empty, Time to Empty, and Fuel to Empty. The SGII can be calibrated for improved accuracy; plus, it has a scan tool which displays diagnostic trouble codes and clear the Check Engine Light

I miss the my old glx's multi function which told temp, mpg, etc and the SGII might be a decent replacement for some of it.

-T

[FusLit]

might have a lead on a d24 manifold
-t

[VRsuper6]

lol @ stealthTDI

he just got replaced this past summer, but he was the Detailer (person who assigns people orders and where to go) for E3/4/5/6 Electronics Technicians in the Coast Guard (my specialty) and actually is the one who wrote my orders to come here :D he uses the same handle on CG forums too haha

[FusLit]

The EGR is in a different spot on the 1Z/AHU than the mk4's so you can't really put the EGT sensor in the blockoff plate as its not in direct exhaust flow. the best spot i saw for one was a spot i think stealthTDI had posted on TDIclub, but it requires the turbo to be removed for installation, plus cleaning the metal shards before they can harm your turbo.

i would just turn down the EGR with VCDS, leave the selenoid plugged in and delete the rest of the EGR system. i wouldn't bother making a race pipe out of the stock manifold, its a terrible manifold to waste any time on it. get a D24 or pd 130/150 or some sort of upgrade. I pulled my own D24 intake from the yard for around $25. i have thought about getting a 2 piece audi one or 5cyl eurovan intake and cutting them down as well to test against the D24.

you can get the proper oil pressure sensor for a VDO from 42draft or egauges.com. its the one with M10 X 1 threads, also Cabriolets in the yard have them.

I'll see if i can find that picture for the EGT sensor. you could mount the gauges down in the cubby but they are hard to see while hitting full boost and keep your eyes on the road. i put my stereo down there as it needs much less attention.

Tomorrow, I'm sending a check out for the d24 intake and that should ship out by the end of the week.

I'll prob run through the j-yards over my christmas break or check out select for the pressure sender. (thanks for the lead on the correct one)

And I agree the radio spot is prob the best spot to put the gauges, semi-eye level, not to far out of the way.

Ryan, I'll be in touch to talk about welding the intake up :)

-T

[FusLit]

Boost gauge has been run in the temporary gauge holder. (waiting for some warmer weather to cast some aluminum) The radio has been re-routed to below and I've also placed the egt and oil pressure gauge in the pod to see how they'll look

http://fuslit.org/photo_gallery/picKLE-cache/misc/car/tdi/20091231_boostgauge/IMG_1807_640.JPG

haven't driven anywhere since I've gotta re-place the slave cylinder and change the transmission fluid. Will be putting things up on blocks tomorrow and doing that.

-T

[FusLit]

update: I've done a bit of maintenance on the car over the past couple days.

It now sports:
- new slave cylinder
- new radiator (no more leak!)
- new harmonic balancer and removed the tensioner arm re-greased it as well as the the bearing in the roller (should be interesting to see how long that lasts)
- new front brakes/rotors (fixed frozen sliders, who uses anti-seize as brake slider grease... the prev owner that's who)
- ecodes are now in place. (fixed some harness issues)
- swapped over the rear bumper skin that I had that isn't as ratty as the one w/two puncture marks in it. and found where the leak in my trunk is coming from (I think) But that's a fix for another time, once I get more of a chance to figure out what I'm going to do with that (I'm going to have to drop the gas tank I think...) and need the stuff to fix things once I get in there...

Planning on catching up with Ryan McShane this week to work on the d24 intake get that thing hammered out (hopefully it'll go without a hitch.) While that's going on, planning to remove the exhaust manifold and drill/tapping it for the egt probe.

I've continued to try and track down where I think my cel / limp mode is coming from, I believe the previous owner might have had the hoses on the N75 Valve in the incorrect order (maybe?) I also tested the boost regulator and the actuator arm on the turbo was stuck (well had very very very minimal movement when I applied pressure to the hose) So, I dosed it in pb-blaster and worked it until it freed up (Which I'm happy about since I really didn't want to mess with the turbo if I didn't have to) The car's still up on jack stands, thinking about changing the transmission fluid while I've got it up in the air. But I'm tempted to see if the slave cylinder takes care of my shifting issue w/out messing with the fluid.

But seeing how it is 11 degrees out, might as well do it I suppose.

While Seems like that took a lot longer to do than I had planned, but I've been pretty under the weather during that time so I'm glad I got it done ... and on the plus side of things, I'm feeling almost 100% again! (and I have 5 more days vacation!)

-T

[FusLit]

http://fuslit.org/photo_gallery/picKLE-cache/misc/car/tdi/2010_in_da_snow/IMG_1803_640.JPG

no Cel, no leaks (as far as I can tell), turbo waste gate and boost gauge appear to work as expected.

Pulled it back inside to check things out in the am and will dump it outside until I get the intake/exhaust finished.

Overall, i'm happy with it....

doh drivers side turn signal is out :-/

-T

[car_whore]

Might as well go with a bigger turbo while you have the manifolds off :wink:

[VRsuper6]

Might as well go with a bigger turbo while you have the manifolds off :wink:
x2!!!!

[FusLit]

I have a bigger turbo but currently it won't fit on my downpipe... maybe... idk, before I go bigger turbo i need to/should do a new timing belt & rollers since the previous owner only put a timing belt on but no rollers... probably should chip it and put in bigger nozzles?

Honestly I'd rather put the money into finishing the lump that is sitting in the other drive bay...

Anyway, I decided to do some getto body modifications... (I mean remove rust) so I sanded down the rust bubbles por15 on the roof and hood, and was going to roll both with bedliner. (maybe trunk as well since it's not even the same color as the car anyway...) stay posted it's gonna be awesome... if anything I figured it would repel rock chips? Any reason not to? (Figured it'd keep some of the rust at bay while I search for a different shell)

http://fuslit.org/photo_gallery/picKLE-cache/misc/car/tdi/2010_paint/20100105-roof/IMG_1801_640.JPG

Oh and Ryan stopped by, we tested my n75 valve because, while it works it's not smooth (very jumpy) we swapped over the one from his car and it's much much much smoother. gonna try and clean the one that is on my car, and if that doesn't work order a new one I guess.

Also, we did this with the big bandsaw I have in the background there, it seemed to work pretty decent. (Which may or may not go on the tdi, haven't decided yet) Appears that it would bolt right up with very minimal clearance issues.

http://fuslit.org/photo_gallery/picKLE-cache/misc/car/tdi/d24_intake/2010_chop/IMG_1805_640.JPG

Also, pulled the exhaust manifold from my spare tdi head and checked to see if the egt probe would fit, it appears to be super big, so it looks like I'll be researching/ordering a new from aircraft spruce one to use.

http://www.aircraftspruce.com/menus/in/probesandsenders_egt.html

-T

[FusLit]

- Cleaned the n75 w/carb cleaner we'll see if it works.
- did a quick rear drivers side door sand/por15 paint of a rust spot to help stop the spread of that
- Roof is bedlinered we'll see how it holds up. Doesn't look terrible in real life but i might get some non-textured bedliner for the hood.

http://fuslit.org/photo_gallery/picKLE-cache/misc/car/tdi/2010_paint/20100106-roofdone/IMG_1808_640.JPG

I declare this thread done :)
-T

[RichB]

Looks good Todd!!!

P.S. Duct Tape FTW! :ssmile:

[Brightdub]

You gotta be mad gangster to rock the tdi! I finally got my fox running perfect lol. Maybe I'll try and find myself a tdi to run for the winter since the audi will get torn apart. I need a mk3! Looks good btw.