Hi,

I'm having the typical stalling issue, but with non-typical signs. (i think)

I believe I am having 2 separate issues, but they could be tied together.

First off:
2001 S40 1.9 turbo 78k original miles.

The first and most important is the stalling. Typical stalling problems tons of others have reported: runs fine, will hold idle(sometimes), but then dies for no reason with no warning. It does it regardless of temperature outside, if the car is warmed up or cold, if I'm moving or sitting still(ie, i can come to a stop and it immediately dies, while in gear,while im still rolling), if its in park, drive, neutral, reverse. Ive now been rear-ended once because of it(luckily, no damage) and almost been hit many times. This is scary and dangerous.

The second problem is rough starting. If the car is warmed up, and I shut off the engine and restart it, no problems. When the car has been sitting all night, I go out to start it, and its very hard to start. The cooler it is outside, the harder it is. When it finally does start, it runs incredibly poorly, like its being over-fuelled, and sounds exactly like an old air-cooled VW bug with a small exhaust leak. It barely wants to rev, and will only run with a lot of throttle. It will do this for 15-30 seconds, then something "cathes" and it revs and runs fine, except for the stalling.

Here is what ive done/found out:
I had a check engine light, used my code reader and found 1 code:P0335 Crankshaft Position Sensor Fault. So I replaced it, and cleared the code, however the check engine light will not come off. I am no longer throwing any codes, but cannot get rid of the check engine light.

I have replaced:
thermostat
coolant temp sensor
crankshaft position sensor
idle control valve

I have pulled the S-hose off the Fuel Pressure Regulator, not a drop of fuel in it.

The only other thing I can think of (from my research on this) is the MAF sensor. However, it does not throw any codes for that at all.

Needless to say, im tired of throwing parts at this car, and if it is truly the MAF, I will replace it, but there is no evidence of it being the MAF as far as diagnostic system is concerned. So far, nothing has made a difference, and im not to keen on dropping $400 on a MAF I don't need.

So here are my questions:
1. Why does it keep stalling?
2. Why does it run really rough when cold?
3. How does it all the sudden fix itself from the rough running?
4. Are these two related?
5. If its the fuel pressure regulator, why dont I see any fuel in the s-hose going to the throttle body?
6. If it is the MAF, why dont I get some sort of code?
7. If its the MAF, why does the MAF seem to work fine from 1k-5k rpm, but is faulty at idle?
8. If it is the MAF, why does the outside temperature affect it? Ive never heard of a MAF having a heating circuit....
9. Why do I still have a check engine light, but have no current, pending, or historical faults? I had read somewhere that certain codes thrown cause the car to go into a limp mode, even if you cannot tell its in limp mode. Is the car in limp mode right now? Is the dealers diagnostic tool the ONLY thing that can clear the check engine light/limp mode(if I'm in limp mode)?

PLEASE HELP..the car is un-drivable in its current condition, its just too dangerous in heavy traffic.

 

While it could be a clogged fuel filter, I doubt it since it wouldn't work sometimes.

Likewise, anything effecting the timing would tend to stay bad.

All other symptoms point to a bad fuel pressure regulator. If you have the original filter, I'd change it as well.

 

^ +1

 

Decided to keep it in this post rather than start another.

So here is where I'm at. Replaced FPR..that solved hard start problem. Replaced Crankshaft position sensor, as previous owner tried to "tie into it" and jacked it up. This was the only thing I was getting a code for, buy yet could not get the code to clear. Replaced coolant temp sensor, replaced MAF. Repaired more wiring the previous owner jacked up. Checked all hoses for vacuum leaks..could not find any.

I got it to the point that it would start right up on the first try, however the stalling was still there. One day, it would idle fine when cold, then stall when hot. Literally 2 days later(same temp outside) it would stall when cold, then idle fine when hot. When it is idling fine, I can literally remove the lower inter-cooler hose, and the car continues to idle fine. Makes NO sense. So finally, one day for no reason..the check engine light cleared itself and no more Crank position sensor fault. But it still stalls...randomly and with no pattern. Then, all the sudden, up arrow flashing and car will not crank at all!!! (all this time its been sitting in the garage, not being driven, just slowly working on this) No previous tranny issues, fluid is still reddish, no burnt smell, 78k miles. So I pull PNP switch. Of course with the 01 they went with a non-rebuildable unit..so I drilled out the rivets, cleaned the wipers(newer PNP have 2 wiper arms with 3 contacts each). Put back together with bolts and nuts, installed in car. Works perfect, yet still up arrow and no cranking. At this point, my code reader will not even communicate with the car anymore. When my reader could communicate, it was very buggy, dropped data streams alot, and would have to reconnect several times. And, it could never clear the crank position sensor code..figured it was my reader.

So I finally bite the bullet, pay a specialist to come over and read the codes. Heres what we get: P0602...then failed communications. His reader should have been able to access all modules in the car, buy yet it could not. His reader also dropped data on live streams, and also could not clear codes. I know his reader is cappable..he was driving a 02 x70, and popped it into his car and we accessed many modules, did 2 way tests, ect ect.(although he cannot code or reprogram)

So basically, he says the ECU is faulty, and is not only causing the no start, but is most likely the reason for the stalling. (he thought it might have to do with bad injector drivers on the board)

Anyhow, what I forgot to ask him was: is the 2001 Volvo S40 1.9T ecu coded to the ignition switch? If I get a known, good working ECU, will a dealer have to recode it to work, or can I just pop it in? What about the transmission ECU? Is it coded, or can it be popped in?

thanks,
Brad

 

Call your specialist and ask the question.

Your first post didn't mention anything about the wiring issues. Do you know what the previous owner did or was attempting to do with the wiring modifications? Somthing as minor as a loose connector or split insulation can cause all sorts of issues.

All the electrons need to flow as designed or the parts won't talk to each other or play nice. Wrong voltage or over current into a line could have messed up the ECU. I don't know if you can pull the ECU and have it tested or flashed, but it may be worth trying.

How is your battery? I never had bad running, but did get ghost error lights (intermittant for no apparent reason, Air bag lights) when my battery was going bad.