cannot start
 

Hello All,

after so many years running car with zero issue, I got problem. My wife stop at shopping mall and car didn't start after. My first assumption was 'air mass flow sensor' due to I got a few times rough start (when car stated I got 1500 RPM and after 1-2 minutes settle below 1000 RPM).

I cleaned sensor but when I start car, it does work for 10-15 sec and shut down. I disconnected sensor and car is working (barely) but I could move car for a few meters.

I have tried scan car with VIDA but diagnostic tab was gray (I assume that I can scan car without running engine or I am wrong).

Finally, I have message on screen 'engine service is required' but I got in past a few times and I turned off ...

My guess is that I have problem with PCV system (clogged) but I could be wrong ...

A few questions:

1. Is VIDA could scan codes if engine is not working ?
2. what do you think about next step ? I have a few diagnostic tools (generic) but my preference is VIDA

Alex

What year model and engine?
It's not a clogged PCV causing your won't run problems. Look elsewhere.

Vida will scan the control units with the engine not running, key on - try your other scanners

Have you checked fuel pressure? Is there gas in the tank? At least 1/2 tank? When was it last filled up? (fuel sender gives false reading, car runs out of gas, customer does not realize that, tows car in, we put in gas, then fix the gas gauge problem)

2007 XC70 2.5l ....Mileage 330,000 km (250 k miles)

I found the other scanner (Torque) and I got a few codes which I have deleted. Once I deleted codes, I started car and drove for 10-15 miles (20 km) without any problems.

As for codes, it would shorter if I put what I didn't get :)

P101/P102 - Mass Air Flow Circuit Performance Problem - iy could be due to I disconnected car to be able start first time
P0133 - O2 Sensor Circuit Slow Response (Bank 1 Sensor 1) - is before or after catalytic ? Where is located and how accessible it is
P0170 - Powertrain (Fuel Trim (Bank 1)) - no idea what it is ...? BTW, where is located this sensor ?
P2178 and P2188 - system too rich off idle bank1 - I assume it is related to code P0133. True or False ?

I have car for long time and trying keep car ....I like that car and I will do whatever is possible to put back on the road.

Bank 1, sensor 1 - is the front oxygen sensor - that code does not mean it's bad, so don't replace it.

Fuel trim - Fuel trim is a calculated value (not a sensor) The AMM measures what goes in, the front O2 sensor measures what comes out of the engine. The ECU knows what to expect, it knows what the O2 is supposed to be reporting after combustion. If the ECU has to make the mixture richer or leaner to get the O2 to report the right thing - the ECU has trimmed the mixture. Too much trim and you get a ----------- fuel trim code.

Many things can cause fuel trim codes - air leaks, fuel pressure, pcv systems not working properly, a bad sensor signal, leaky injector ----- the list can be lengthy.

So if you know the PCV system is clogged - I would fix that first, particularity since if clogged it can force front seals out making a mess and doubling the cost/time of the job. If you do the pcv, make sure the metered orifice, the impossible to get back in banjo bolt under the intake manifold is perfectly clear or replaced.

I appreciate for detail explanation....

After I cleaned AirMass Flow sensor and cleared codes, it back to normal but I feel it is question of time when I am going get another issue. I read that sensor should be cleaned with every air filter change. For now, I am going run a few longer rides and with hard press on pedal :)

As for O2 sensor, I am not touching for now ...

S.

If you decide to clean your MAF from time to time, just make sure to use a MAF cleaner product, not carb cleaner. The MAF has a wire grid that if it gets dirty or oily (say from a failed PCV oil separator or a bad turbo seal) it'll need to be cleaned. If your car is in good shape and are not driving dirt roads and keep up with the service interval for the intake air filter you can relax on cleaning the MAF. As to the O2 sensors, they get a bad rap. Anytime there's a fuel trim fault code, the O2 sensor is listed in the possible causes. Other things like the MAF, intake air leaks, temp sensors can mess with fuel trim so don't be quick to assume the O2 sensor is bad.