I think my car is trying to kill me. I'm at my wits end

TrstnBrtt · Post by **TrstnBrtt** » 26 Dec 2018, 19:20

I have a 2006 XC90 2.5T. Always kepts up with oil changes and maintenance (basically it’s been cared for). It’s always given me an ECM-120B code. It shows up in scans but won’t trigger the check engine light, but a few weeks ago the check engine light came on with ECM-121B. Both codes are related to the MAF. The car was running poorly and would frequently stall, sometimes it would die right after I started it and didn’t even have time to get it in gear. I had tried cleaning the MAF before but I always got the 120 code. So I gave in and bought a new Bosch MAF. Changed it out and no change. It still ran badly and the light was coming and going. Around this time I had my brakes done (important to mention for background that about 8 months ago I had to replace the right rear wheel sensor). I exchanged the new MAF for another one believing it could be defective as I couldn’t find any air leaks past the MAF. When I installed the new one I disconnected the battery and let the car sit for a few hours. When I reconnected it and went to go for a drive the throttle would barely do anything, and the low traction light was flashing. The 2nd MAF was cooperating but I would let off the throttle and lightly accelerate and the low traction light would stop flashing and the car would take off. It does that at every acceleration from a stop until the “service ABS/Tracs” message and “Brake assist service required message comes on. When I scanned the car with VIDA it reported the right rear wheel sensor had no communication (the same one I changed out a few months ago). I took the fuse for the ABS pump out because I had a long trip for Christmas to drive and couldn’t figure out what the problem was. I drove about 700 kilometers and made it to my destination just fine. This morning I went to leave and was driving up a steep mountain grade and the car just stopped accelerating. I got the “reduced engine performance” message and I couldn’t get the car going until I put the ABS fuse back in. I made it back on the highway and the check Engine light came on again with those same 2 MAF codes. It’s now back to running terrible and dying on idle and even when I do get it going the ABS module seems to be choking the throttle (I assume). I have no idea where to go from here and am thinking I should just cut my losses and buy something newer/more reliable. I commute 110 KMs a day and rely on my car and I don’t want to be throwing parts at it, and after it throwing itself in limp mode up a snowy mountain surrounded dead by other cars where I could have been hit I don’t have a lot of confidence in it. The problem I have with that is I’ve already got a lot into it. I had the Timing Belt and water pump done last year, it’s got 4 brand new Michelin’s on it, the brakes are less than a month old... the list kinda goes on since I drive it so much.

Post by **SuperHerman** » 26 Dec 2018, 22:59

Have you tried smoke testing the car for leaks? See here: https://www.brickboard.com/AWD/volvo/16 ... r_low.html

It is possible you have a bad ECM, but you really need to smoke test it for leaks, but before that you need to check all your connectors and wires (not fun but you could have a wiring issue).

I am also at a loss why the ABS is coming into play, but I would start with checking for an air leak.

It is too early to cut and run - other than a bad ECM you most likely have a small problem causing havoc.

For the ABS sensor issue you need to dive in and check all your wiring and connectors - you could have a short or broken wire or faulty connector. The system is pretty simple so a single wire issue can take it down.

What happens when you disconnect the MAF - engine run wise?

TrstnBrtt · Post by **TrstnBrtt** » 26 Dec 2018, 23:44

Thanks for the head’s up. Having it smoke tested was my next thought. Unfortunately my work doesn’t have one so I’ll see if I can get it in somewhere while I’m on vacation time (I don’t know why every time I have time off something detrimental happens to this car). The reason I mentioned the ABS was because as soon as I disconnected the battery ABS sensor code came up and it’s been driving even worse since. I’ll report after it’s been smoked.

Post by **abscate** » 27 Dec 2018, 00:45

The ABS and poor running are two separate problems

You need to diagnose fuel, spark , air leaks separately to address poor running.

Monitor the fuel pressure at the rail with VIDA or fuel pressure gauge. Spec is a rock solid 55 psi ( I'll double check that for Xc90)

What are history of coils and spark plugs? 30-100k is replacement interval, so every other year for your commute pattern

The sensor could be a connector problem or perhaps seated too deeply in the caliper. VIDA Will also offer clues here

TrstnBrtt · Post by **TrstnBrtt** » 27 Dec 2018, 09:40

Well finding someone that will smoke test my “fayncy fore-ieghn Vol-vo” is proving to be quite difficult.. not sure why, but all that aside, the plugs are about a year old. Never replaced any coils on it. It hasn’t been throwing any misfire codes. In response to the question above it doesn’t die when unplugging or re-plugging in the MAF while the engine is running

Masscomguru · Post by **Masscomguru** » 27 Dec 2018, 20:33

you can try to track down a leak after the MAF using propane or carb cleaner.

Definitely sounds like a leak somewhere. The ABS is a second issue.

Post by **cn90** » 27 Dec 2018, 22:10

Consider cleaning the Throttle Body!
I wrote a DIY on my 2005 XC90 without removing the Intake Manifold.

Post by **SuperHerman** » 27 Dec 2018, 22:44

If you have an air compressor with a regulator valve and some fittings, you can just use straight air and test a few of the systems fairly easily. 3-4 psi should work, but you are listening for leaks rather than looking for leaks. For the bigger pipes some use an assortment of plastic pipe fittings (usually caps). One cap usually has a hole drilled out and an air source fitting installed. Plenty of videos on line where people fashion all sorts of plumbing hardware to work in their application. Also look at VW and Audi examples. Nothing different on a Volvo than any other car for a smoke test. Key is to isolate the zones being tested.

Post by **cn90** » 29 Dec 2018, 17:07

Another culprit for stalling is bad PEM.
If you have a good used PEM, swap it and see what happens.

TrstnBrtt · Post by **TrstnBrtt** » 10 Jan 2019, 12:36

Alright been awhile since I updated. First things first The easy fix was the ABS sensor on the right rear wheel. Not sure why the new one died so quickly but considering it was the sensor and not the tone ring inside Of the hub I’m happy. Second is the MAF code I’m getting which hasn’t been an easy journey. I had it smoked at work and there seems to be no leaks, confusing. So I took out the throttle body and cleaned it. I’m still getting the 120D code which is NOT triggering the Malfunction light, however my car does die upon starting sometimes still. My next step will be to test the harness that connects to the maf although I’m not hopeful that it’ll be that easy.