EGT sensor on vw aircooled turbo engine

[lakis1982]

Hello ,

i am building an oxyboxer turbo efi engine and I am thinking of using some EGT sensors in order to use them both for failsafe purposes and better tuning as well.
I am not using an oxygen sensor..

In order to be as accurate as possible (ans also safer) i would like to use one EGT sensor for every cylinder. I am using the ECUMASTER EMU ecu...

Has anyone done something similar ?? Could you point me to the right direction regarding this setup ??? Is it really necessary to use an oxygen sensor??

thanks a lot

[Chip Birks]

Building a modern EFI Turbo setup without an O2 sensor is a bad idea. There are a few people out there that are really good at only tuning with EGT, but they are definitely the minority. Wideband O2 sensors used to be expensive, and therefore not practical for the hobbiest. Those days are long past. You will get way more dialed in and safe if you chose the wideband over the egt. If you are really crazy then go with both.
I have per cylinder WB and EGT on my turbo bug. I use MS3-Pro for my ECU.

[panel]

Chip......4 x WB on your exhaust? All before the turbo eh? Is it crowded with the EGT sensors also ?

[Clonebug]

The EGT gauge on my buggy is the most boring gauge I have. I hardly ever look at it when driving but do check it occasionally when I look at my datalogs.
It really doesn't give me any info I can use. On an airplane it is worth while due to being at full or close to full load at all times except idle. A VW engine is at full load for maybe 10 seconds max unless it is a slow one........not enough to really make a big difference if it gets a little on the hot side.
I usually see 1400 plus degrees for a max.......once I saw 1600 Degrees for a short time.....
The O2 sensor is much more important and at $149-$199.00 is well worth every penny to have one on the engine.

[Chip Birks]

Chip......4 x WB on your exhaust? All before the turbo eh? Is it crowded with the EGT sensors also ?

Takes me an hour to remove my stupid header, 4 egt, 4 WB, back pressure sensor. There is so much wire in the car. But it does make for some cool datalogs...

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[Wally]

Nice Chip! Now we are on the subject and regarding your datalog: There is noticeble EGT difference on 2 cylinders (no 1 and 3?) versus the other 2 cilinders? Doesn't seem to be AFR related though, although there is a fair bit of difference there too. Do you know why the difference?

If I get 4 of each on my engine, I will probably see quite some differences too though

[Chip Birks]

Nice Chip! Now we are on the subject and regarding your datalog: There is noticeble EGT difference on 2 cylinders (no 1 and 3?) versus the other 2 cilinders? Doesn't seem to be AFR related though, although there is a fair bit of difference there too. Do you know why the difference?

If I get 4 of each on my engine, I will probably see quite some differences too though

Your question was one of the things that had me scratching my head from about July on last year. I put a new cam in the car following a clutch swap, and my egt delta got huge. Cylinder #3 also misfires at idle. Might be an injector issue. Should probably have them cleaned and flowed again. They've been in service for 6 years. E85 might not have been very nice to them long term. I don't think the old ID1000s were corrosion proof. There was a time that those egts delta'd 15-30 degreesF across the 4 cylinders if I remember correctly. I think now its well over 100 degreesF. The engine is coming apart in the very near future, hopefully the cause is obvious once I get in there. Considering new rings and possibly a fresh set of cylinders for the season, but we'll see once its opened up.

[panel]

Chip......just to confirm........you have 4 x WB O2 sensors on your exhaust (primaries) before the turbo ? And do you have one post turbo also ? Just curious on your set up that's all

[Chip Birks]

Chip......just to confirm........you have 4 x WB O2 sensors on your exhaust (primaries) before the turbo ? And do you have one post turbo also ? Just curious on your set up that's all

Yes sir, one per primary, and one after the turbo just cuz it was already there. I'm going to build a new header for it next winter, and that system will most likely just have the 4.