convert california vanagon to 49 state

nigel austin · Post by **nigel austin** » Sun Dec 30, 2001 5:33 pm

some exhaust system parts for my california 1982 vanagon T4 motor are difficult/impossible to find so I plan to convert it to the 49 state exhaust. Where I live I don't need the low california emission level. And I don't like the hot california catalytic converter right under the left cylinder head. My concern: the california engine has an oxygen sensor in the exhaust with a wire to the computer; the 49 state system doesn't. Should I get the new exhaust modified to take the sensor or just leave it off? I'd really appreciate advice from anyone who has been down this path. Thanks.

germansupplyscott · Post by **germansupplyscott** » Mon Dec 31, 2001 12:06 pm

hello,

i have a similar set-up. i live in toronto, but my 1979 bus was CA spec. when i bought it earlier this year, it needed an engine rebuild, and also new exhaust.

i kept the O2 sensor, by welding a nut onto the exhaust just after the heat exchanger, and threading in. it need to be somewhere that gets very hot. you need the sensor, because your ECU requires it to set the mixture and will go into permanent "warm-up" mode - meaning too rich, if you leave it off. the only sound way to eliminate the O2 sensor is to change most of the other FI system components, too. (ECU, harness, Air meter). if you needed the parts to make this swap i might be able to help - i have an AC vanagon which has the needed bits. the O2 sensor is a good thing to have, though, so long as the rest of the FI system is in good shape.

my experience is a bit different from yours, since i have a bus, not a vanagon. in order to keep the heat going, you will have to use vanagon heat exchangers no matter what, since they have different warm air channels. i'm not sure what you can do to simplify your exhaust, but perhaps there are simpler vanagon systems than the CA spec. i know my van had a very complicated system, and changing to an earlier spec meant less parts and cheaper parts.

scott lyons

ray greenwood · Post by **ray greenwood** » Mon Dec 31, 2001 2:15 pm

You could also put the sensor into a block of metal sandwiched between the tail pipe and main muffler section and go to a 3 wire sensor...self heating....which actualy runs better...or even stay in the stock location and go to a 3 wire sensor. The CO sensor was usually on the forward side of the muffler and had trouble maintaining and reaching temperature anyway. Ray

germansupplyscott · Post by **germansupplyscott** » Mon Dec 31, 2001 8:08 pm

ray,

so if i understand you, the three wire unit is just the output signal plus supply and ground? i might need to replace my O2 sensor soon, so i might consider going to a three wire, if it is as simple as you say. how does the ECU (designed for one wire sensor) interpret the cold sensor signal if it is self-heating, and do the three wire units output signals in the same range as a one wire?

scott

nigel austin · Post by **nigel austin** » Sat Jan 05, 2002 6:35 pm

Thanks Scott and Ray for your information. Great web site! I wondered why VW rearranges the exhaust system on the California Vanagons by putting the cat. converter upstream of the left heater box. Presumably to get the O2 sensor into gas hot enough for it to work properly. So the solution to my problem seems to be a heated (3 wire) sensor before the muffler. My local parts shop has one for about $75. I haven't found out yet whether the sensor's two heater wires simply connect to a 12 volt supply switched by the ignition switch or whether a heater controller is needed that switches the heater off before it gets too hot and on again before it gets too cold. Does anyone know?

nigel austin · Post by **nigel austin** » Sat Jan 05, 2002 6:36 pm

Thanks Scott and Ray for your information. Great web site! I wondered why VW rearranges the exhaust system on the California Vanagons by putting the cat. converter upstream of the left heater box. Presumably to get the O2 sensor into gas hot enough for it to work properly. So the solution to my problem seems to be a heated (3 wire) sensor before the muffler. My local parts shop has one for about $75. I haven't found out yet whether the sensor's two heater wires simply connect to a 12 volt supply switched by the ignition switch or whether a heater controller is needed that switches the heater off before it gets too hot and on again before it gets too cold. Does anyone know?

germansupplyscott · Post by **germansupplyscott** » Sun Jan 06, 2002 10:53 am

nigel,

i don't know either. we'll have to wait for ray on this one. i would like to know the answer, too.

scott lyons

[This message has been edited by punkinfair (edited 01-06-2002).]

ray greenwood · Post by **ray greenwood** » Tue Jan 08, 2002 9:10 am

Sorry I took so long...Yep! Just connect up to + and ground. The long looping exhaust system was made for several reasons all based around the same problem. The original CO sensor needed ahot spot...just like you noted. The three wire system gets rid of that problem. Also they wanted to get the sensor as far away from the tail pipe as possible, lest it get contaminated by lower pressure air entering the tail-pipe when letting off the pedal in high speed over-run situations. I believe there are also some issues with keeping the catalyst hot enough. There needed to be a little bit of back pressure also. The catalyst needs about 600 degrees to begin operating. Just like punkinfair noted...either weld a bung into the end of the muffler farthest from the tail pipe (there is actually a chamber in each end so you cannot put it in the midle on that exhaust...you can with a damper type muffler). Ray

regis101 · Post by **regis101** » Tue Jan 08, 2002 6:09 pm

Greetings. I read a post that talked about placement of the O2 sensor. It stated that 20 inches from the head is a safe place. I haven't been able to compare this with factory placement on the 79 and newer models. In my case, 78 Westy, this would be pretty much right after the exchanger. Ideal for me. I could put it in the J-pipe on the factory set-up, or in the header-pipe on aftermarket stuff.

ray greenwood · Post by **ray greenwood** » Wed Jan 09, 2002 4:48 pm

Do you mean putting it in the down pipe just down stream of a single cylinder? I would not do that. It will be noting the exhaust of just one cylinder...it needs more of an average. Depending on the muffler type, there are only so many places it can be put. If you use a heated three wire version...you get a few more choices as heat is no longer the factor. In the factory non- 2-0 exhausts...those that just use the long muffler with two sets of two inlets and a single outlet, you only have two choices really. There is a chamber in each end with a pipe or cluster of pipes depending on the make...connecting these two chambers. You really should be in either chamber, but not so close to the gooseneck tailpipe that letting off the gas causes a shot of outside air to flash by the sensor...causing a lean setting. Ray

regis101 · Post by **regis101** » Wed Jan 09, 2002 8:25 pm

Yes, I agree with you. The post i read dealt with a 914. Two-into-one header pipe. I would not want to put a sensor into one pipe and not do the other three. Excessive, but it would monitor all four. It would be nice to find a place to obtain a nice general reading. This is why the heated sensor is worth the money. I don't think the most of us are trying to re-invent anything; just trying to do some tuning. The factory info states that the un-heated sensor works best at 600 degrees. Where is that? About twenty inches back. I like your idea of a sandwich block between the flange and muffler. One on each side would be cool. It would even work on my 78 Westy system. I smell a patent here.