Dreaded Previa Whistle AND CEL code 71 cured with new muffler

[pdgizwiz]

My '94 N/A Previa has whistled since I bought it about a year ago. It has also had a Check Engine Light on, due to code 71, related to EGR gas temperature. I have been putting off both a new muffler and cleaning the EGR port all this time. Finally I got around to putting a new muffler on. The whistle vanished, as I'd hoped it would. But soon afterwards, I noticed that the CEL had gone off as well. A pleasant surprise, to say the least!
The new exhaust seems a little louder than the old. I was a bit disappointed by that at first, but the unexpected CEL cure more than makes up for it.

The exhaust "silencer" I bought is a Bosal 284-285. One of it's quirks is that it has a support post welded onto the pipe near the flange that attaches to the cat pipe. The stock setup involves a separate part that integrates the support post and a nut plate on the front of the flange. I guess that it's common to torch the nut plate, thinking that the welded nuts are seized with rust. I took the lazy approach and, rather than cut the post off of the new pipe, I used it in the rubber mount and found some nuts to replace the nut plate.

**update** Code 71 returned a week later

[timsrv]

When mine started whistling I checked Toyota and couldn't justify paying $400 for a muffler, so I went to the salvage yard and pulled an OEM one off a Previa there. I had my doubts about used (salvage muffler had more miles than mine) but I lucked out. Been on there running quiet for over 5 years now.

These mufflers have stainless steel exterior, but the insides eventually rust out and in some situations they can become restrictive. I'm guessing that's what was happening with your old one and the back pressure caused the EGR to run hot. Glad it was in the muffler and not the cat. Tim

[pdgizwiz]

I had the same difficulty justifying the cost of an OEM muffler, with the Bosal at less than a third of the price. It came by way of a big river in Africa. It was a gamble that I decided to take, and so far, so good. I hope my mileage improves - I'll have to do a bit of a road trip to find out.

[timsrv]

Yes, as much as I can appreciate having a stainless steel exhaust system, I would never pay Toyota's prices for replacement parts. I think I paid $20 or some ridiculously low price for the used one (I think I got my money's worth but admit it could have already failed internally at time of sale). Regular aluminized steel isn't all that bad. You'll probably get at least 10 years before that needs attention again. Tim

[TheMAN]

or upgrade while you're at it :D
http://web2.airmail.net/theman/previa/exhaust.jpg
http://web2.airmail.net/theman/previa/exhaustinside.jpg
http://web2.airmail.net/theman/previa/jasma.jpg
http://web2.airmail.net/theman/previa/stamping.jpg

so many choices, and it all depends on how much attention you want ;)

[cvtroger]

I will have to address the whistle down the line. I've read it could anything from the flexpipe to the muffler.

I have 1 new cat (first cat) and I think after I change a few things out, I'd like to look at the getting an exhaust done. I've never been into raspy type sound, but I love a deep tone sound.

2464
While was never planning to go bosozuko, I got a hook up from one of my drift buddies for a custom exhaust and I loved the sound it made.

[TheMAN]

new muffler will definitely take care of the whistling noise... there's no other cause on these vans
MPGs improved with my catback exhaust and of course it's louder, but when following it from another car (not a luxury car, and with radio off), you can't really hear it... so it's not really that loud... it has a deep tone and you really can only hear it from inside... if you're light on the throttle, it's not much louder than stock

[pdgizwiz]

Alas - Code 71 has returned. I'm back to procrastinating about the EGR cleanup now, I guess.
I'm stumped as to why it vanished in the first place now.:dizzy:
There's no way my new muffler has clogged so soon. The whistle is still gone, at least!

[timsrv]

When the code vanished before, was it because you cleared codes, or did it disappear all by itself? If you did not physically clear it, I would clear it now, then wait & see if it returns. Tim

[pdgizwiz]

At the time I thought it had disappeared all by itself, because I noticed it as I took a test drive after replacing the muffler. In retrospect, I was probably fooled. A few days earlier the battery went dead, due - I think - to a sticky door switch and lights that were left on. I swapped batteries, so it's very likely that the code was reset at that point and I didn't notice it.
Well, it was too good to be true.

[cvtroger]

When my previa was put back together, it did not have a code and when I drove the freeway, a code popped up. The shop cleared the code and a few days later, it popped back up.

After the brake and light inspection, the shop had it smogged, but it failed and they replaced the first cat and 02 sensor. Then the van passed smog.

Then the code came back and that is when I asked them about it and they said they will take the van again, but I'd have to pay for the parts. When I found that write up on zenseeker, I was eager to work on my it myself.

After I cleaned it, I cleared the code myself and it has came back.

- EGR intake gasket - 25628-76010 - this is on the far right side next to the exhaust.
- EGR valve gasket - 25627-76010 - used for the EGR valve to the intake manifold.
-Air inlet duct gasket - 22273-76010 - this is where the air goes into the intake manifold and where the EGR port gets plugged.

I also replaced all the hoses on the EGR matrix and a few others under the driver seat/under the van. I kept getting codes P0130, P0133 and initially thought it was my 02 sensor, but I found one of the small hoses underneath the driver side easily coming off, not to mention a couple of other small hoses looking really worn. After I replaced them, better gas mileage and no more codes.