I've been working with my 03 for a while and was referred here if I needed more help, and that time has come.

I got the car about a year and a half ago and the previous owners mentioned it started rough, an issue I tracked down to the FPR. I didn't bother with it at first since it wasn't affecting my ability to drive, but a few months ago it died and I've since been finding/replacing parts to revive it.

I took it to a less experienced mechanic that didn't know much about Volvos, but got it to a running state by both disconnecting the MAF Sensor and the vacuum hose port (gold tube in middle of picture, hose disconnected in picture) in the picture below/attached:



HOWEVER, this caused the fan to run indefinitely, killing the battery, once the car was turned off. I got into the habit of simply disconnecting a battery terminal whenever I parked, so that I could somewhat drive it around.

At this point, I assumed the MAF Sensor would be my only issue, as I was getting codes for only it and the thermostat. I replaced the water temp sensor as well. I should also mention I did accidentally push too hard on the new MAF sensor, so that the plastic grill broke in a small section of the circular area, but it seemed stable enough that it shouldn't be a problem.

Once I replaced the MAF Sensor, it seemed to run better with the sensor plugged in, but still only when the hose was detached. Attach the hose, and it would pretty quickly die. At this point, there were periods of time it would seem to run fine when the sensor was connected, but eventually it began to stall at idle and be extremely hard to start on occasion. The fan, however, did not stay on if I started the car with the sensor plugged in.

My next step was replacing the FPR, as that seems to be a pain point for a lot of these S40s, and I knew it would at least help the rough starts, if not solve my problems as many have stated. After replacing it, the same issues arise - it's unable to start while everything is plugged in, if the MAF sensor is plugged in, it runs fine (and now starts fast) but eventually will begin to stall at idle and not start up, and running it the opposite (Sensor detached, hose attached), it may start, but runs so badly it will stall.

We've noticed that the hose that's disconnected doesn't allow air through, sucking on it like a straw doesn't doesn't allow air through. It seems like the port needs that air, but a lot of the arrows seem to point in the opposite direction. I've checked the hoses that are easily available, and nothing seems to be cracked or broken in any way. I'm not entirely sure what to do next. It ran much better with the new FPR, so I'm glad that has helped, but this particular hose is going to be the death of me.

 

Sounds like a bad IAC

 

That would be part bolted in on the bottom of the picture with the INSP LO engraving, correct? It seems like cleaning it is usually recommended, do they usually not fail often and just need cleaning or should I outright replace it? I can imagine the leak on my old FPR dirtied it up quite a bit.

It also doesn't seem to be connected directly to the hose in question, but I imagine it could affect it. Does anyone have any information on the hose so I could at least understand what needs to be doing what here? I haven't been able to find anything and if it is just the IAC affecting it, ignore this part, but at this point it's been such a pain.

 

Correct. You can certainly try cleaning it, since that would be essentially free. I've seen them fail more often than just need cleaning though.

 

Alright, thanks for the help, it seems like the part itself isn't too expensive so if I can't get it running by cleaning it I'll order another.

 

What you've done is open up a vacuum leak. The IAC is essentially a computer controlled vacuum leak to keep the car idling. By removing that hose you have bypassed the IAC. Now I'm not sure where that particular hose connects, but it's function has been neutered. And being neutered is no fun.

 

Thanks for all the help guys, I've now ordered and received a new gasket/IAC and am attempting to replace it, however, I can't seem to remove the plug to the old IAC to replace it. The small plastic clip comes out easily and is pretty much completely detached from the rest of the plug, but I can't seem to pull the rest apart. Is there a trick that could help out? I'm a little wary of accidentally pulling out a wire or something on accident and don't want to create more issues.

EDIT: Got it - starts up in no time now with the new FPR and idles great. Thanks again for the help.