2000 C70 2.4L runs very rough with 9 codes.. please help!
 

Hi

I just purchased my first volvo in this horrible condition.. I like it other than the maintenance issues... :(

Anyway, this 2000 Volvo C70 2.4 is running very rough to the point of stalling at times. RPM's jumping from like 500 to 1500 on idle. The dashboard is a Christmas tree with all kinds of lights! While driving it is okay but as soon as I come up to a stop light it starts to do the RPM jumping thing. Once it warms up the jumping becomes less violent but still definitely present and the car will stall sometimes on intersections. SUPER scary! Engine coolant temperature gauge on the dash acts normal.

Took it to Advance Auto and here's the codes they pulled:

P0103 - Mass or volume air flow A circuit high input
P0118 - Engine coolant
P0452 - Emission system pressure sensor
P0238 - Turbocharger sensor A
P0236
P0134
P0113
P1332 - No DTC definition


I took off and cleaned the ETM thoroughly to no avail.

Can anyone please provide any insight as to where in the heck do I start troubleshooting this beast??

Thanks in advance!

Hi and welcome to the forum.

Looks like you already started. You can either start replacing parts that are related to the codes or you can test them to see if they are good or not.

The first thing I would do is clear the codes, replace the ETC sensor and see what comes back. Check for vacuum leaks and test the PCV system.

Thanks rspi!

The PCV system checked out okay with a lot of vacuum.

Here's a video I took of the volvo earlier today. The kind of popping or knocking noise you hear spontaneously is what seems to be backfires. Like backfires back into the intake kinda backfires. It sounds a little different in real life than on camera...
Let me know what you think.

can anyone give any suggestions?? Where do I start with with this stupid thing?! :( should I go ahead and send my ETM to xemodex to rebuild it for like $450?

Did you service everything the codes alerted you to? Plugs etc?

So just wanted to post an update as to what the problem was. It looks like the volvo might have been "sparked" which means someone tried to jump start it and connected the jumper cables positive and negative to the opposite terminals on the battery. I took apart the ECM (main computer for the engine) and inspected it inside very well and found a burnt out lead/wire on the main circuit board. I cleaned it and soldered a new wire in it's place and it fixed all of my issues!! All the lights on the dashboard went away and my cruise control along with the A/C started working!!! This sounds pretty easy but trust me its been a nightmare! But.. it's kinda fine because I was able to locate the one problem for a lot of my issues. Thank you everyone for all your help and I hope this helps someone in the future too.

Peace!
KA3AX

Here a close up photo of the burned out lead on the ECM board:
Attachment 16683

And this is how I soldered a wire to the ends of the lead. Basically just traced where it went and soldered to those spots.
Attachment 16684