Solved - '04 V70 starts but immediately stumbles and dies... Topic is solved

jrschwit · Post by **jrschwit** » 23 Apr 2025, 08:49

New to me 2.5T with 139K miles, well maintained with extensive records. Previous owner reports no previous problems, though it had not been driven much since Nov 2024. It started and ran perfectly after I repaired a coolant leak and camshaft seal.

On my first test drive (15 miles), I parked it for 10 minutes and it then would start, rev up to about 1500 rpm then stumble and quit. Considerable blackish smoke from exhaust. Left it over night and it started and ran OKish after a few tries, then seemed to "clear its throat" and ran perfectly on the way home. Ran fine for a few more short duration tests. Then I tried another 15 mile drive and the same start-but-immediate-stall occurs after parking for about 15 minutes. Same blackish smoke.

Battery voltage is fine. Fuel pressure at rail shows consistent mid-50s PSI during brief start and run sequence with manual pressure gauge. On several tries, the CEL came on and "reduced engine performance" message appeared. CEL and message would then go away after several more tries. I don't yet have a VIDA setup but that is planned. Generic code reader shows no DTCs.

What to look for first?? Appreciate any ideas.

Vova585 · Post by **Vova585** » 23 Apr 2025, 09:35

Any chance you can get your hands on some decent scanner? I would feel bad to suggest any parts to be replaced without proper investigation. Black smoke can possibly be related to car being "too rich" in terms of fuel air mixture. I would try to check information what ecu receives from engine coolant temp, map and maf sensors together with long and short term fuel trims. If such is not possible at this time you can try to find information about resistance figures of coolant temp and compare to yours. Can take a look at maf sensor and see if no dirt or bug is stuck in there. Can clean it with maf cleaner fluid.
In case you need this car on a road asap- I would suggest to send it to dealer(if there is one close by volvo used to offer free towing for 25miles) and pay them 1 hour diagnostic ($185 in my area) to tell you the issue. Later you can work on obtaining vida(hopefully you are better with computers than me,since I hate everything about it's instalation and interface). Or icarsoft, thinktool, autel..

Post by **cn90** » 23 Apr 2025, 10:45

Probably PEM issue.

But the PEM in that car was replaced using the "newer" one with PN ending in ***225.

Maybe get another PEM from eBay or junk yard (or take one from another P2). In that car, it sits above the metal fuel tank. I wrote the tricks in forum (7-mm socket).

Post by **jonesg** » 23 Apr 2025, 13:34

keep the fuel pressure gauge connected , see what it reads when it stumbles.
crawl under the rear end ,see if it has a black plastic or metal tank.
That will show whether it has a PEM or not, 04 is a split year. Some do, mine doesn't.

Post by **cn90** » 23 Apr 2025, 15:02

Could be gasoline quality issue (water in fuel)?

Vova585 · Post by **Vova585** » 23 Apr 2025, 20:10

I thought 2004 was utilizing the old school fuel delivery system and ford

PEM with its "genius" location came later. Plus the jrsshodt indicate fuel pressure stays stable at mid 50s psi which should be enough to run the car. I still would vote for qualified diagnostic over parts canon

jrschwit · Post by **jrschwit** » 24 Apr 2025, 11:27

Turbocharge pipe connection to intercooler had become disconnected. To provide access to repair the AC compressor clutch bearing, I had earlier removed the charge pipe hose connection at the intercooler inlet. I had difficulty getting the hose clamp in place because of adjacent wiring harness crowding. I was distracted by something or other and did not follow up. I just now noticed it had become pushed off by boost pressure. Reinstalled it and the car runs fine. Requisite dope slaps have been administered.

That said, it is not logical to me that the disconnected pipe would prevent starting and running at idle. I can understand various sensors and the computer sensing lack of boost pressure under conditions that warranted boost thus triggering some response. But what sensor(s) would prevent starting and idling? I'm simply curious and would like to understand.

I appreciate all who responded and provided ideas. I followed up on all, except for dealer intervention - that would have been very embarrassing.

BTW, the PEM checked out OK. I installed another PEM from the same model car with no change in symptoms before I discovered the actual problem. So I've learned something...
Jim S.

Post by **cn90** » 24 Apr 2025, 12:22

Some yrs ago, I worked on the 1998 S70 throttle and did not tighten the hose feeding the idle valve properly, car stalled etc. Took a few min to see the problem, the disconnected hose!

It is basically the cardinal rule... whenever sth goes wrong, go back to where one just did the work. Very often, the problem is there.

Post by **jonesg** » 24 Apr 2025, 14:04

cn90 wrote: ↑24 Apr 2025, 12:22 Some yrs ago, I worked on the 1998 S70 throttle and bit not tighten the hose feeding the idle valve properly, car stalled etc. Took a few min to see the problem, the disconnected hose!

It is basically the cardinal rule... whenever sth goes wrong, go back to where one just did the work. Very often, the problem is there.

the scene of the crime usually has all the clues.

Post by **abscate** » 25 Apr 2025, 00:20

jrschwit wrote: ↑24 Apr 2025, 11:27 Turbocharge pipe connection to intercooler had become disconnected. To provide access to repair the AC compressor clutch bearing, I had earlier removed the charge pipe hose connection at the intercooler inlet. I had difficulty getting the hose clamp in place because of adjacent wiring harness crowding. I was distracted by something or other and did not follow up. I just now noticed it had become pushed off by boost pressure. Reinstalled it and the car runs fine. Requisite dope slaps have been administered.

That said, it is not logical to me that the disconnected pipe would prevent starting and running at idle. I can understand various sensors and the computer sensing lack of boost pressure under conditions that warranted boost thus triggering some response. But what sensor(s) would prevent starting and idling? I'm simply curious and would like to understand.

I appreciate all who responded and provided ideas. I followed up on all, except for dealer intervention - that would have been very embarrassing.

BTW, the PEM checked out OK. I installed another PEM from the same model car with no change in symptoms before I discovered the actual problem. So I've learned something...
Jim S.

Your Volvo precisely meters fuel based on air flow measured way up at the air cleaner. Any leaks in the induction path messes up thst metering. Fuel to air ratio has to be very close to stoichiometric in the cylinders for a gas engine to start, run, idle.