2001 C70 T5 Coupe low boost issues

perkunas · Post by **perkunas** » 13 Jan 2014, 09:14

There are no loose wires around the filler area.
MAP actually stands for Manifold Air Pressure, so the location on the pipe makes sense.

Post by **kcodyjr** » 13 Jan 2014, 09:36

Odd. The older ones all had that thing sensing pressure under the hood.

Is it making a proper seal against the pipe?

perkunas · Post by **perkunas** » 13 Jan 2014, 09:37

I think it is. It does have an o-ring. Here's a link to the part in IPD
http://www.ipdusa.com/products/6936/114 ... 40-s60-s80
By the way, atmospheric pressure sensor and BPS connectors differ.

perkunas · Post by **perkunas** » 18 Jan 2014, 08:53

Bumping the thread again about the ECM-262A lower limit fault (P0172).
I found this nifty thread about possible causes:
http://www.volvoforums.org.uk/archive/index.php/t-62869.html
Should I just go for a new MAF? I can get one today for just 100$, all items are on sale in a local auto shop. It is a brand new Bosch item, I have learned not to buy aftermarket parts the hard way

AVIP · Post by **AVIP** » 18 Jan 2014, 16:14

Buy the maf. Even if it doesn't need it now it will soon.

perkunas · Post by **perkunas** » 19 Jan 2014, 03:43

Fortunately the sale still goes on today on the e-store. I will order the part.
Meanwhile, it seems that I should change out the ECT sensor. It has developed a small leak around i (green crud). Or could this be a source of my problems too? There are no ECT sensor related faults set.
The fan works fine (only turns on if I do some hard driving and then have to stop). Unfortunately I don't have a diagnostics system of my own, I would check the live data while driving.

I'll rule something out though. The EVAP system seems to be fine, even though the hoses look aged. The canister purge valve is in a closed position when the car is not running. The vacuum hoses that go to the air intake hose and the intake manifold only let air in if i blow on them and don't if air is sucked out.
Still not sure about the MAF, 100$ is 100$ anyway. The car has been running with a TCV leak for god knows how long before I bought it, so I'm not sure if this might be causing some other problem when now it is fixed.

perkunas · Post by **perkunas** » 09 Feb 2014, 01:40

Thread bump:

So I didn't want to shed the cash for a new MAF. However, I bought a cheap bluetooth OBD scanner. Here's the info that I got for the CEL. It seems odd that the LTFT is at 0%. Maybe the reader will not get the data. Any thoughts on this? I will try to build a pressure leak tester.

perkunas · Post by **perkunas** » 10 Feb 2014, 05:49

I'm sorry guys, but I have to bump the thread again

For some unknown reason, after I reset the ECU by disconnecting the negative cable, my bluetooth scanner started reading live engine data.
Here's a file of the things that I collected.
This one was recorded while driving.
post_reset.xlsx - 53.9 Kb
This one was while stopped in my yard:
idle.xlsx - 28.4 Kb

This data obviously points out that the ECU is cutting fuel at idle and adding it when accelerating.
In my opinion, this does not point to a vacuum leak, the problem is somewhere else, either the MAF or the O2 sensor. If it was a vacuum leak, it would do the opposite, add fuel at idle and cut it when under boost. What could be the problem here?
Anyway, it's the first time when I feel like I'm getting somewhere

After some reading and thinking, it seems to me that the MAF might be the problem. It reads at 6g/s at idle (21.6 kg/h), which looks like twice the normal reading.

perkunas · Post by **perkunas** » 02 Mar 2014, 09:28

Fixed!
What the car needed was new vacuum hoses and a new MAF. Drives much better now.

goodboy · Post by **goodboy** » 26 Mar 2014, 06:00

Right now, I don't want to push the car hard, but I will try to replace the TCV lines tomorrow if I can get to the turbo nipple.

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