My innocent Volvo may not be so innocent...

"Alfalfa" (alfalfa-romeo) 01/19/2015 at 14:22 • Filed to: alfalfa's volvo

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Having recently acquired a Bluetooth ODBII adapter, I was looking at the various fun running information on my phone on Saturday. My supposed "light pressure" turbo is putting out 12 lbs of boost. It was only about 50°, and I double checked what units the torque app was set to. They're generally reported to run 6-8 psi.

After looking through multiple forums, it seems indicative of either an aftermarket ECU, or HPT swap. I don't have any experience driving LPT's to compare it too, but it feels like it spools like others, from what people describe. You can tell when the boost hits if your paying attention, if not it just feels like part of the regular torque curve.

I'll have to do some digging around this weekend for anything that looks out of place. Hopefully someone knew what they were doing.

Or maybe something is just whack, or I'm reading it wrong.

EDIT: A few details a forgot to mention. '97 850 GLT, VIN check confirms that info.

For your time, here is an 850 that definitely does not have an LPT.

TopSirloin > Alfalfa 01/19/2015 at 14:43

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12 lbs. of boost would be more noticeable than that I'd think, unless you have a boost leak or something. I'd be hesitant to trust the brains of a 20 year old car anyway.. get a boost gauge if you want a reliable answer to your question.

Alfalfa > TopSirloin 01/19/2015 at 14:58

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I thought it would be more noticeable too, but once again, I have limited experience with forced induction. Especially with the lpt, not many people seem to know anything unless they've owned one. I think I'll post in some Volvo forums and try to find out any more specific details before I look into dropping $80 for a boost guage.

TopSirloin > Alfalfa 01/19/2015 at 15:10

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Not a bad idea.. I'm not sure if there's the same cult following with particular Volvo's as VW GTI's for example. There's tons of tuners in the VW community, and people purchasing a used car that was tuned and they had no idea is not an uncommon occurence. With VW tuners, they can tell you if they tuned your car or not based on VIN. Not sure how many big tuners there are in the Volvo community, but couldn't hurt to narrow down your search and place a few phone calls.

Alfalfa > TopSirloin 01/19/2015 at 15:34

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It's not nearly as big as the VW tuning community, that's for sure. I may be able to get a hold of the previous previous owner, maybe he'll know something. The people I bought it from are clueless car people, but they live in my building and we see them fairly often. They bought it from a family member. I'll wait and see what I can learn before bothering strangers, though.

twochevrons > Alfalfa 01/19/2015 at 16:26

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Are you looking at the MAP value or a calculated boost value in Torque? The 850's OBD only reports MAP, which is absolute, while boost is relative to atmospheric pressure. I believe that Torque has an option to calculate boost from MAP using a given value for atmospheric pressure, but I haven't ever used it.

Regardless, turbocharged (and most NA) 850s don't have a MAP sensor, so the value reported to OBD is calculated from the MAF sensor reading. There will probably be some discrepancy between it and the actual manifold pressure.

Alfalfa > twochevrons 01/19/2015 at 17:12

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This is just the kind of info I was looking for! It was the calculated boost, but it just occurred to me that I hadn't done anything with the atmospheric pressure setting. That may be it.

SwedishMachine > Alfalfa 01/20/2015 at 11:51

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My 1996 HPT 855 Turbo regularly spikes at 12-14psi running a custom Euro R tune. If yours is a LPT it's surely running an aftermarket tune or something to be pushing 12psi, or your readings are inaccurate.

I would invest in a quality boost gauge first and foremost, so you can get an accurate reading of boost. The 94-97 850 turbo models use a very simple boost control system as there is no MAP sensor and everything is predicated off the MAF sensor and boost control solenoid (BCS) which relay the boost pressure and airflow readings to the ECU to control the level of boost, which is regulated by a wastegate.

These videos help explain how the turbocharger system and boost control work in modern Volvo cars. I found them very helpful in chasing boost issues and sorting out tuning with my Volvos.

Alfalfa > SwedishMachine 01/20/2015 at 12:00

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Thanks for the info! After looking at the Torque app, I'm fairly certain a misconfiguration on my end caused a misread, but I haven't re-tested it yet.

SwedishMachine > Alfalfa 01/20/2015 at 12:17

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I have never used the Torque App! I still am back in the old days of doing everything manually lol.

Alfalfa > SwedishMachine 01/20/2015 at 12:55

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I mostly got it because it was a cheaper alternative to buying a code reader. It's pretty neat, but can also be distracting with all fancy additional information at your fingertips while driving.

SwedishMachine > Alfalfa 01/20/2015 at 14:22

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I'm assuming this is for android only? I haven't seen this app for my iphone yet.

Alfalfa > SwedishMachine 01/20/2015 at 14:31

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I'm really not sure, it may only be for Android.