2002 XC70 Splattering/Misfiring esp. under load

[tonymite]

2002 XC70 Splattering/Misfiring esp. under load - changed 2 coils, haven't attempted OBD reading via laptop (yet) ... Plugs seem(ed) OK, Air Flow Meter readings via Multi-Meter look steady ... have yet to check fuel pressure but seems more like an intermittent spark issue...

Any thoughts?

[M-R-P]

You need to read the codes mate. The coils you changed may have been the wrong ones.

[tonymite]

P.S Every now and then during gear changes, it does exhibit puffs of black smoke (un burnt fuel) out the back..

[tonymite]

Is there a way of reading the codes without OBD2 instrument/PC/Laptop (software) i.e bridging pins on OBD connector and reading flashes somewhere say on dash or computer??

[LeeT5]

2002 XC70 Splattering/Misfiring esp. under load - changed 2 coils, haven't attempted OBD reading via laptop (yet) ... Plugs seem(ed) OK, Air Flow Meter readings via Multi-Meter look steady ... have yet to check fuel pressure but seems more like an intermittent spark issue...

Any thoughts?

Looking at the low post count, are you new to Volvos?

Why did you change 2 coils? You obviously know there are 4.
To say 'the plugs seem(ed) OK', on a turbo charged car would generally mean, if in doubt - replace! Assuming the cars been serviced correctly and at the correct mileage intervals, I would also hope your using genuine plugs? In this instance 'OK' isn't good enough, especially if your attempting to rule them out. Just fit new ones!!

The absolute first thing you should always do on any P2 (other than a visual inspection of the oil etc) is to plug in good quality diagnostics. If you don't have access to this then you really are out on a limb. A generic 'cheap' code reader that you bought or borrowed that cost around £15 off ebay is more likely to hinder, than help. Vague, would also be another word I'd use to discribe the sort of ££££e you can get for £15 off ebay.


Is there a way of reading the codes without OBD2 instrument/PC/Laptop (software) i.e bridging pins on OBD connector and reading flashes somewhere say on dash or computer??

In a word....No!
bridging pins of any sort in the OBD port will likely fry the CEM or ECM without you even knowing.

The symptoms you desrcibe though could really be any of the following (This is not an exhaustive list either):

Boost hose detached, split or otherwise not 100% sealed.
Cracked IC (Intercooler) - Causes ECM to see unexpected boost values and therefore trys to adapt but can't because of an unmetered air leak (Will also cause poor idle / hunting)
MAF - Dirty / faulty / blocked
BPS (Boost pressure sensor) - Faulty / Dirty (can cause juddering under load)
ETM (Electronic Throttle Module) - Faulty / Dirty <<< will cost you £300 and needs software at Volvo Dealer.
Throttle potentiometer - faulty (that's the foot pedal end!)
FPS (Fuel pressure sensor) - They either work or they don't!
PEM - Pump electronic Module (lives under the car next to the fuel filter and regulates the fuel via the ECM) ££££ing expensive and requires Volvo software to work!!
Broken plugs / contamination on the electrode tips
Cracked valves
Blocked fuel filter
Ignition coil/s failing (highly unlikely and extremely rare on P2 cars with OE coils) but when a coil fails, it always does so under load or when hot!
Bad Earth or broken wiring harness on ignition or any related component to ignition.
etc, etc, etc!

.........Can you see the need for good diagnostics now?

Hope you get it sorted though :wink:

[tonymite]

P0700 VOLVO - Transmission Control System (MIL Request)
P0300 - Cylinder Misfire Detected Random Cylinders
P0302 - Cylinder 2 Misfire Detected
P0134 - O2 Sensor Circuit No Activity Detected Sensor 1 Bank 1
P0304 - Cylinder 4 Misfire Detected
P0303 - Cylinder 3 Misfire Detected
P0305 - Cylinder 5 Misfire Detected
P0301 - Cylinder 1 Misfire Detected

Going by MY Logic - I'd say O2 Oxygen/Lambda Sensor as it says "No Activity Detected" and I wouldn't suspect ALL cylinders be affected. Is there a resistance reading to check whether O2 Oxygen/Lambda Sensor is faulty on its own?

[LeeT5]

Fault is the O2 sensor or wiring to the sensor.