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Discussion Starter · #1 ·
Hey everyone, new to the forum.

My girlfriend has an 04’ GLS Convertible M/T w/ 183k and we’ve run into some issues.

DIY intake with cone filter to 3” coupler to MAF

ISSUE # 1
The infamous pressure tube in between the metal charge pipe and pancake started to get loose, replaced that along with the retaining clip for it. Huge improvement right off the bat and no more “whoosh” from under the glove compartment. There is still a “whoosh” while in boost but it’s quite odd, you can make fluctuate and it sounds like it’s right in front of me under the hood. Obviously you hear the high pitched turbo whistle, but as the boost builds a whooshing appears. If I slightly let off the gas, the whoosh goes away and turbo noise is still there, but the second I give it more throttle it comes back. Could it have something to do with the DV, N75, or the heat wrapped hose right behind the valve cover? It spikes every once in a while and it tends to bog down when keeping your foot steady in high rpms.

ISSUE #2
The SAI pump sounded like a plane taking off so I inspected the tubing and found that most of it going to the kombi had dry rot and fallen apart, so I taped it all up and now no more P0411. After letting it sit over night and starting it back up, the cold start idle was really rough. It would sit normally, drop down to 750-800 for just a second then bounce back to normal. Once the car is all warmed up, you can’t even tell it’s on while it’s idling.

I would truly appreciate anybody’s opinions, judgement, and steps in the right direction.

PS No I don’t have VAG-COM :(
 

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First, I would scan for trouble codes and post any you find.

For odd boost noises; you might make a video and post it here, so we can hear the specific sound. A common failure is the diverter vavle; it can affect boost acutation (won't hold vacuum or sticks from being warped from heat) and when the internal diaphragm, won't hold vacuum, it can make strange noises.

Testing is pretty easy with or without a vacuum tester:


The hose, going from the charge pipe to the diverter vavle; is another hose, that can split, cause boost issues and make noise. This can be split but not always obvious; as the split can be hidden from view (hose behind the vavle cover; near the firewall).

Good info here:

 

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The sai system code; can defintiely be thrown by a cracked/split hose. You can repair these hoses inexpensively; by using hose from your local hardware or home improvement center. The black or white plastic/poly sump pump or discharge hose for a washer/dishwasher can be found that exact same diameter. I found I could remove the retainging end and shove the hose in there and it worked perfect and it looked almost identical to the original. The stock VW hoses; become brittle from heat and even if you replace them, will just fall apart, crack, split, again. I used some electrical tape to seal the ends and it has worked fine for me; a cheap fix (only cost me $7).


If you get anymore sai related trouble codes; let us know, we can work through the possible reasons for it.

The rough idle at a cold start; can be a number of issues, a bad coolant temp sensor is a common failure, that will do this until the car warms up and things go back to normal. The bad coolant temp sensor, can cause: hard start, rough idle, rich condition, black smoke from the exhaust, stumble, hesitation and what acts like a misfire (all goes back to normal when the engine warms up).


On a high milage 1.8T: you might check your spark plugs, as the electrodes tend to burn away over time and be sure to use oem NGK plugs. The throttle body, can get dirty on these cars and a full cleaning of this, can help as well. There are many other issues; that could contribute to a rough idle but those are a couple of things to check.

 

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Discussion Starter · #4 ·
Awesome thank you so much for all of that!! We picked it up around August last year for $1200, ran great but had a few codes he couldn’t figure out. I worked my magic not knowing ANYTHING about the 1.8t, cleared up all of the codes and had it perfect for a while, even got it to pass emissions.

We replaced the DV not long ago considering that was one of the issues so i’m hoping it’s not that.

I’ll definitely get a video in here asap, probably this afternoon sometime. It’s not a hiss really, it almost sounds like the windshield defroster is on full blast. I can let my foot off just a smidge and make it go away and to wear it’s just turbo noise but the boost sorta spikes and once it builds again it’s back. There aren’t any codes at the moment but a few days ago before i replaced the pressure tube, it popped out most of the way and it threw a lean and rich code (both my girlfriend and i were very confused) so I popped it back in and cleared the codes and it ran and idled perfect. I’ll definitely be doing the plugs next week, should’ve done that a long time ago. I also cleaned the TB not long ago but I suspect it got pretty gross when the IC pipes were leaking.

What’s a good solution for getting rid of the SAI with the least amount of codes possible? She ordered a catless downpipe the other day because she loves to be loud and we think her cats starting to go, we had a muffler and res delete done when we first got it and over time it’s gotten more muffled. Every so often we’ll get that nice surfer smell while driving and especially when we pull into the garage.

Again I appreciate it so much!!!
 

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For the sai delete; do you have emissions testing in your area? If so, it would need to remain in place and in be in working order. If you are new to VW's and the 1.8T; I would recommend, you just leave the emissions in place and get the car running correctly first. Many want to "delete" everything; which can make things harder to figure out and can add issues to a 1.8T based turbo system, which can be a challenge to figure out, maintain as it is.

Delete kits seem to have resistors plugged in; a close off plate and/or mapped out with a new tune, to eliminate the check engine light.

1.8T resistor

combi valve block off plate


For boost noise; did you check the hose, on the back of the valve cover, it has been known to get split from boost pressure.
 

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Discussion Starter · #7 ·
We do but she doesn’t plan on having it as her daily driver by the time she needs to get them done again, we also know some people who know some people so it’s not gonna be a huge issue. She wants to tune it eventually but i’m not sure if it’s a good idea, have no idea if it’s history and how it’s been treated. Is the resister a 50/50 shot or does it just get rid of the unplugged pump code?

She’s out right now with some friends but once she’s back i’ll check out the hose from the DV and the boost elbow behind the valve cover.
 

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Based upon the eurotuning site; they say, it must be coded out, a software tune being required. There are many other issues to work on a older 1.8T VW and it can take some effort, to get things right. If you are not tuning and modding the car; wanting to keep it essentially a reliable/stock 1.8T, I don't see the "benefit" of deleting things.
 

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Yeah you won't be able to delete the SAI without a CEL. I had mine tuned out, but I was also already tuned. I had issues with my SAI - getting a code for it but the pump was functioning and no leaks in the system. My mechanic couldn't figure it out so it got tuned out.

But you also will have a CEL because of the catless downpipe. You can try an O2 spacer to see if that takes care of it (it often does work), but you will need a tune for that as well if it doesn't work.
 

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Discussion Starter · #10 ·
We are modding it, I just don’t want to tune it right now and put any more strain on the motor at the moment until I know what’s up with it. The “benefit” is that it wouldn’t be in my way anymore, and if it’s got a catless downpipe it’s useless. I mean in reality it runs fantastic and the only issues we have are the pcv system is pretty much oil soaked, and now the “whoosh”. We also just did the brake booster along with the check valves in the line. Had a horrible valve cover leak when we got it and that was the first thing I did. Maybe down the line it’ll be tuned but not anytime soon.
 

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Discussion Starter · #11 ·
Yeah you won't be able to delete the SAI without a CEL. I had mine tuned out, but I was also already tuned. I had issues with my SAI - getting a code for it but the pump was functioning and no leaks in the system. My mechanic couldn't figure it out so it got tuned out.

But you also will have a CEL because of the catless downpipe. You can try an O2 spacer to see if that takes care of it (it often does work), but you will need a tune for that as well if it doesn't work.
I know it’ll throw a CEL with no cat i’m just tryna go for the least amount of codes possible until it’s tuned you know? We were going to order a spacer but totally forgot 🤦🏽‍♂️
 
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