Hi,

I bought 1998 V-40 2.0i 16v volvo last month.
I noticed weird behaviour with acceleration.
If you imagine the gas pedal point, where you do not neither brake with engine, neither accelerate. And from this position if I press gas pedal a bit more, engine starts vibrating, hesistating. I have to press gas even more to go into acceleration. This is all happening in any gear and in RPM range from 1500-3500.

Ok, I changed plugs immidiatelly and cleaned plug cables which lead from 2 coils to plugs.
It seems to solve the problem.

But I still have broken thermostate - it seems to be always open so engine does not get warm soon. Ok, I know I need to change it, but in the meantime...
...I had a trip for 100 miles. I knew engine is not warm, so I kept under 3000 RPM all the time. But suddenly, after half an hour drive, engine light lit up and motor lost all the power.
I stopped immidiatelly and checked all liquids - all were there and all seems fine.
What to do, I thought.
Ok, obviously computer did recognise cold engine for too long time and shut down motor to prevent damage. So I took a wooden plate and put it appr. 10cm (3 inch) before the front cooler to prevent direct air flow to cooler.
Started the engine and it seems fine.
EXCEPT from that moment on motor keeps changing RPM constantly. In idle it falls down to 300 RPM and then bumps up to 1200 and repeats this all the time.
Also if I press gas pedal to raise to 2000 or 3000 RPM, or during drive, it does not run still - changes RPM all the time, every 3 seconds it changes RPM.

Any idea what would the diagnoses be?
My pocket is permamently broken so I do not have $$$ for expensive parts change and testing via changes, so I would like to diagnose before I put away any money.
Might it be Lambda sonde or some sensor dirty? Or some other failre caused by broken termostate?

Thanx for any suggestions.

 

Have all the codes pulled.
The coolant tempsensor migth have gone bad causing the problem.

 

I was at my service yesterday and tech got few error codes pulled out. It was temp sensor, but this was due to always-open thermostate valve. Replaced thermo valve and cooler was fine again.

Another problem was air regulator valve and air sensor. Got replaced sensor, and valve cleaned.

After this machine run fine for some time, but then it lost 1 cylinder.
Then we found my stupid mistake - I was washing machine some day ago and by mistake sprinkled some watter inside plugs opening - it was filled with watter

Now car runs fine, except of acceleration - I have a feeling that it does not accelerate good. It is kinda lazy, does not kickmy back when I press gas pedale anymore.
I'll obviously need plugs cables replaced, since they were in watter.

 

I would start there.