98 V70 AWD, no boost reading

Post by **benpineapple** » 03 Nov 2015, 13:11

Alright, just made an account, first post here. Been viewing this site for too long, time to get involved.

Bought an OBD2 reader that connects to my phone, so I can check/clear the CEL, monitor performance, an all that good stuff. Had some fun tinkering around with it so far. Here's the thing though, I bought it because I was mostly curious about my turbo boost pressure. When I bought my V70, turbo was non functional (broken/cracked lines everywhere). I've replaced as many vac lines as possible without removing it entirely, replaced the turbo control solenoid even. Anyways, turbo works now, car performs much much better. But...the OBD2 reader/app is not registering boost pressure. The gauge in the app does nothing. As far as I know, it should be able to calculate boost pressure from the MAP, right? Or wrong? Either way, I'm way too curious about how my turbo is performing to just drop the topic.

What is the sensor that is right on top of the turbo, on the driver's side of it? Wondering if that and/or the wiring harness is bad.

Thanks!

Post by **Clemens** » 03 Nov 2015, 14:03

I can´t remember why exactly, but I believe to remember that you can´t get the boost reading from the OBD2 scanners on the 850s and early V70s.

Scholz · Post by **Scholz** » 03 Nov 2015, 14:18

I don't think your 98 has a MAP. The OBD2 app I use, torque can extrapolate a guess on my 98T5 but it's wildly inaccurate. Whereas on a car using a speed density algorithm to determine air fuel mixture it works much better. It's my understanding that starting in 99 there's a MAP.

I completely get the curiosity aspect. My turbo was not boosting when I purchased the car. Took ages to run down every little problem because it would always improve every time I fixed something but with no baseline to compare to I still don't REALLY know if it's boosting fully.

jcdillin · Post by **jcdillin** » 03 Nov 2015, 15:08

Yup, tried using Torque here too on mine but it's all over the place.

I ordered one of these for mine for testing.

http://amzn.to/1iBrHfw

Also another really good thing to get if you have a 98 is vol-fcr with a vag-com cable, that way you can read codes from the ECC, trans, SRS etc.

Post by **benpineapple** » 05 Nov 2015, 09:12

Scholz wrote:I don't think your 98 has a MAP. The OBD2 app I use, torque can extrapolate a guess on my 98T5 but it's wildly inaccurate. Whereas on a car using a speed density algorithm to determine air fuel mixture it works much better. It's my understanding that starting in 99 there's a MAP.

I completely get the curiosity aspect. My turbo was not boosting when I purchased the car. Took ages to run down every little problem because it would always improve every time I fixed something but with no baseline to compare to I still don't REALLY know if it's boosting fully.

My 98 V70 does have a MAP (just walked out to my car to double check). It is mounted right behind the hood latch on the passenger side. Would a failing MAP have anything to do with the turbo system? What it comes down to, is I do not know its function. Also, is there supposed to be a vacuum line connected to it?

Yeah I think I need to just pull the turbo and really clean it out, rather than chasing all these little oddities.

Post by **benpineapple** » 05 Nov 2015, 09:16

jcdillin wrote:Yup, tried using Torque here too on mine but it's all over the place.

I ordered one of these for mine for testing.

http://amzn.to/1iBrHfw

Also another really good thing to get if you have a 98 is vol-fcr with a vag-com cable, that way you can read codes from the ECC, trans, SRS etc.

Sweet, thanks for the heads up. That boost gauge looks way better than other ones I've seen. Where did you mount it?

I think I'll look into the vol-fcr vga call. My "AWD" (in actuality, a FWD) is missing its driveshaft, an I'd need trans readings to reinstall the driveshaft. Thanks for the heads up on that.

jcdillin · Post by **jcdillin** » 05 Nov 2015, 10:58

I'm still waiting for the pod to come in, but i'm going to be using one of these.

http://www.gaugepods.com/volvo.html

The sensor your seeing is the Barometric Pressure Sensor, if you look at the bottom it has a nipple that goes no where.

Post by **benpineapple** » 06 Nov 2015, 10:24

jcdillin wrote:I'm still waiting for the pod to come in, but i'm going to be using one of these.

http://www.gaugepods.com/volvo.html

The sensor your seeing is the Barometric Pressure Sensor, if you look at the bottom it has a nipple that goes no where.

Looks sweet. Let me know how those work. Currently shopping around for a decent boost gauge. I'm assuming not all are created equally.

Haha thanks for the heads up on the MAP sensor. Seems like an odd little piece. I've heard it does very little for the engine, and often a failed one won't even set off the CEL.

Post by **abscate** » 06 Nov 2015, 18:31

Map came the following year, on the 1999

You can nicely read out boost via OBD II on the 1999

One of my posse knows a great indie in GRR I will ask her to share

Post by **benpineapple** » 07 Nov 2015, 19:15

abscate wrote:Map came the following year, on the 1999

You can nicely read out boost via OBD II on the 1999

One of my posse knows a great indie in GRR I will ask her to share

Well, looks like I'll be running an analog boost gauge to my dash.

Indie recommendation in GRR would be great. Been here 2 years and have yet to find a rock solid mechanic at a local shop.