Just got 1999 V70R with 212k and car starts/idles fine for the first 10-15 min. and then begins to stumble/idle rough. Runs fine above 2000 rpms. No codes in on VIDA scan, also It has new XeMODeX ETM installed by previous owner and it was programmed by the dealer.
Looking for help and suggestions and idea how to tackle this problem.

 

ECT sensor? plugs into the thermostat housing - hides under the upper radiator hose at the block end. You can unclip the sensor and measure resistance with a VOM - should be a low number (ie under 300 ohms) when warm, a high number (ieover 3000 ohms when cool)

 

So, ECT I have it is spare and reading shows little over 3000. This is spare one I picked up from junkyard and one in the car read around 500 cold. I did an experiment with the spare ECT, I boiled the water and reading was around 300, so I think we found the issue. I will order thermostat from FCP and use the ETC one from junk yard or to be safe should I buy new one from FCP as well?

 

ECT and thermostat has been replaced and no luck same symptoms. Fuel pressure seems it is fine by pressing nipple on fuel rail. Re-scanned for codes and again no codes. Did XeMODeX ETM test by their flow chart troubleshooting and all passed. Perhaps MAF could be the issue?

 

I let it run for 10 minutes until stalled and cap was clean, so it is defiantly condensation. Oil cap and dipstick are clean no milky stuff on it. By the way here in Chicago we had a nice weather in last few days.
Tested coils last night I did unplug coils one at the time when car was running and when I did that engine was performing worst so seems like coils are good. I was told that PO replaced the spark plugs and coils 10k miles ago.

Looked under the car and fuel filter looks like it was replaced.

One observation, after car wormed the temp gauge arrow stayed in the middle 3 o'clock position on the dashboard and the coolant almost reached to the top of the coolant tank. Before replacing thermostat I drained 2 qts of coolant and when I re added the level stays above the MAX all the time. Is it normal ?

 

Can you get any data? If you have any sort of scan tool you can just look at the measurements. That is how I would diagnose engine temperature and air flow measurement problems. The temperature, you can decide if you agree with it or not. The air flow, you would have to compare when the car is running correctly.

When the engine warms up, there are a variety of things it could be doing. It's going closed loop at some point, and that is going to lead to reducing the fuel, but it also may be trying to purge the evap system. Purging the evap system is a deliberate vacuum leak that is coming on at a certain time. heat would also affect the coils some, but that's a little harder to observe. All we know about that is you don't have misfire codes.

 

My guess would be a vacuum leak of some sort. Open loop, i.e., before warmup the engine will be running rich, so vacuum leak is less of a problem. Once it goes closed loop (after warmup when rpm drops) then as indicated above, the mixture is leaned. Then a vacuum leak would be a problem.especially at low rpm. At higher rpm, it would be less noticeable because the leak is a smaller percentage of total air intake.

 

The weird thing is that when I scan for codes with VIDA I do not get any. I started to replace the vacuum lines, also I have yellow label ETM (I was told it is from turbo model) so, I may try swapping it when weather prohibits. Little video on how it runs and dies.

https://photos.google.com/share/AF1Q...h4eUxmRllrOW9B

 

could be the ETM contacts - look around for some sites that rebuild to see if they have content to describe symptoms of a wonky ETM, but best to rule out the basics like an intake air leak or exhaust leak ,incorrect fuel pressure etc. Air leaks can be tricky as some of the hoses are not easy to see so a smoke test may be in order.

 

Previous owner installed new XeMODeX ETM so maybe it is not it. How do I check for an exhaust leak?

 

usually if there's an exhaust leak its around the flex pipe (sometimes the EGR tubes break off too). I've put the car on a ramp then slid under to give a visual check then listen and feel for air puffs while the engine idles. Not sure how wise that is with the engine running so I always double block the tires :-) but its usually pretty obvious when you are at ground level vs in the cabin.

 

Little update: Car runs the same as before no improvement after changing below components and I still do not get any codes with VIDA.

I did compression test one more time and results are a lot better. Believe prevues gage was bad.
C1-155
C2-160
C3-160
C4-160
C5-160

New spark plugs NGK Spark Plug - NGK 6962
I did new PCV job with new blue box parts.
Replaced serpentine belt and idler.
Also replaced all vacuum lines with silicone ones and did cigar smoke test. I saw little smoke coming out of PTC nipple on the intake tube to the turbo. Also when I removed oil filler cap and dipstick smoke came out of there as well.
I did not find any other leaks anywhere else, but I hear hissing noise around by intake manifold by cylinder one where banjo bolt is and PCV (no coolant leaks)

Still have to do fuel pressure test. Went to rent fuel tester from AutoZone and it did not have right connectors.

Running out of ideas. I'm ready to take it to Swedish Car Specialists - Chicagoland's Best Volvo Service and have them look at it.

 

I don't really look at codes. I look at data.

 

@firebirdparts Anything you can suggest on next steps?