My 02 Jetta Wagon Build

[Blacktree]

The P0420 could be related to the gassy smell, but shouldn't affect engine management. The P0420 usually means the catalyst or the downstream O2 sensor is bad. The ECU doesn't use the downstream O2 for fuel calculations. It's basically just a "fix it" code.

To put things in perspective, my Prius also has the P0420 code. It has an aftermarket catalyst, and apparently the ECU doesn't like that. But the car still gets 60 mpg.

However, the long warmup times can definitely affect fuel economy. That would typically be caused by the thermostat sticking open.

After that's fixed, you could also try an upper grille block, for even faster warmup times. On the Mk4 cars, the upper grille is easy to remove and reinstall. So a grille block should be a piece of cake. Just zip-tie a piece of sheet plastic or whatever to the back of the grille.

[JSH]

Running rich can kill a catalyst.

[V6MustangFTW]

Havent been on here much, and havent done any new mods. Been busy with work, side gigs, etc. Anyway, maybe about two weeks ago when I was driving to work, I noticed the transmission wasnt upshifting. Reverse and park are fine, but nothing will get the car to upshift. Took it to a shop and they say they heard noise from worn out bearings or something, I forgot exactly what they said besides that I need a transmission and the cheapest they can do it is 3400 Anyway, Ive already recruited a family member thats a mechanic thats willing to help me swap it for much cheaper, and I can source a transmission myself for much cheaper as well. Anyway, I'll keep the thread updated with anything new, and if anyone tells me the shop is wrong and all I need is a speed sensor or something I'd be very grateful lol.

[Blacktree]

Man, that sucks. Although I'm not really surprised. The automatic transmissions in these cars are notorious for being unreliable. Hopefully you get it back on the road soon.

[V6MustangFTW]

Update: found a good deal on a rebuilt transmission on ebay, should be here by the end of the month. Anyway, thought I'd share these pics from Sunday.

I got the underside of the hood insulated and bedlined. Pretty much took the whole morning to clean it, it was pretty greasy and filthy. Should have taken a pic but didn't think about it. Then sand, scuff, and laying on boom matt. In hindsight, I should have bought a second pack as it didn't cover as much area as I thought it would, but at that point I could have just bought an oem hoodliner. Anyway, between that and the bedliner, I'm hoping it will insulate enough to speed up warm up times. I used herculiner that I had leftover from another project because it was getting old and I didnt want it to go bad.

(Yes, thats a pcv pipe holding the hood up. Im not gonna buy a strut thats gonna die again and I haven't built a real hood prop yet.)

[V6MustangFTW]

Just noticed I haven't posted any updates in several months. My stepbrother and I are set up to swap the transmission this weekend. Was reading that the oem coolant to transmission cooler tends to either clog or leak and kill the trans, so I ordered a kit to get rid of that and put a regular air to trans fluid cooler. Besides that, havent done much. Been trying to shed some weight, and also trying to figure out if there's any manual steering racks that could fit. Hopefully I'll have some good news next week.

[aerohead]

Originally Posted by V6MustangFTW

Had to google that one... never knew thats what those bumpers were called looks like I could get the oem covers for cheap, but I think I can get creative with some sheetmetal and rivets for free since I already have those laying around.
Also, what do the aero experts here think of that lower lip? Can I take it off, or maybe replace it with something with a bit more clearance? It was already broken and zip tied together when I got the car and it keeps scraping on certain driveways because of how low the car sits.

I suspect that what is there was 'optimized' in VW's wind tunnel.
It's thermoplastic, and body shops have hot-air welders which could fuse the fractures back together. I used a low-power soldering iron to repair my friend's Prius front fascia which was in far worse condition than your Jetta's.
I don't know what's behind those openings. If you believe that your at no risk of cooking something, then blocking them closed has been demonstrated as a drag reduction technique so many times now, it would be a shoe-in for modification.

[Andyinchville1]

Originally Posted by V6MustangFTW

Cd- it doesnt have crossbars but it does have rails. I may look into removing them as i want to remove the antenna as well, just scared its gonna look bald without them lol.
Freebeard- im trying to keep this as a budget build for the sake of ROI, but me being me im sure I'll end up spending some if it gets me some good numbers.

HI,

Did you ever remove the rails ? If so , any real MPG improvements?

My headliner is sagging so if I try to fix that , that would be the best time for me to remove the rack ....

Thanks

Andrew

[freebeard]

The rails have minimal frontal area, act as vortex generators in crosswinds, and kill lift if you get sideways.

[Blacktree]

Regarding the front lip: That's a common issue on the Mk4 VWs. The front end hangs down pretty low, and can catch / scrape on stuff. RockAuto sells a replacement piece, for under $25. Part #VW1093104

Also, it's not uncommon for people to catch the front end on a parking curb, then tear off the lip and/or front bumper when they back out. On my Jetta, the previous owner's wife did exactly that: ripped off the whole front bumper. There's a filler panel available, that helps prevent that. (I also think it makes the front end a little more aerodynamic) VW part #1J5805301.

Unfortunately, it seems that part has been discontinued. But you can probably find some new old stock on ebay or something.