2004 V70 2.4L NA, 5sp low idle, stalling

ibs740 · Post by **ibs740** » 11 May 2020, 16:46

Hi All,

Yesterday my 2004 V70, 2.4 NA, 5sp stalled in traffic. It would start then die, 10X starts and died each time so it came home on a hook.
I found a problem in the cable connecting the MAF. Voltage was as speced but the resistance between pins 4-5 was 1.8 M ohm. I found the ECU locking bars were not fully engaged. I tightened them and the car fired right up and drove normally except the idle was low 600 vs 750.

Starting cold the engine has the normal high idle then it drops.

Today I started the car backed out of the driveway and it stalled. When the throttle was let off the engine revs drop and the car stalls.

No codes so I'm guessing it's the ECU.

Thoughts?

Post by **oragex** » 11 May 2020, 18:02

Google up about FPS and PEM. PEM used off Ebay, FPS from Fcpeuro.com
Do not replace the fuel pump (cheap garages want to replace it)

Post by **cn90** » 12 May 2020, 07:21

Or clean Throttle Body.

I wrote the DIY throttle body for my 2005 XC90 2.5T in this forum. Please search for it...

ibs740 · Post by **ibs740** » 12 May 2020, 14:23

Hi, The PEM was replaced in 2016. Used VOLVO OEM

It has 50ish psi at the fuel rail. Not sure if there is a feedback loop including the ECU or just inside the FPS (self measuring)
Throttle body was cleaned a year ago and is usually a gradual symptom. This was OK 1 day NFG the next.
Have a spare FPS so it's fast to change.
Will get back to all.
Thanks

Post by **oragex** » 12 May 2020, 14:53

When it stalls, push the valve at the rail with a piece of paper towel on top of it, see if it got some pressure. There's either no power at the coils or no gas pressure. Was the pump replaced with aftermarket ? Any lights/messages ?

ibs740 · Post by **ibs740** » 16 May 2020, 21:46

ibs740 wrote: ↑12 May 2020, 14:23 Hi, The PEM was replaced in 2016. Used VOLVO OEM

It has 50ish psi at the fuel rail. Not sure if there is a feedback loop including the ECU or just inside the FPS (self measuring)
Throttle body was cleaned a year ago and is usually a gradual symptom. This was OK 1 day NFG the next.
Have a spare FPS so it's fast to change.
Will get back to all.
Thanks

I started the car and let it idle until it reached operating temp and the idle changed from 550-600 to the normal 750 ish and smooth.
Let it cool off and popped the throttle body inlet hose and wiped down the TB bore and butterfly with MAF sensor cleaner (used to have a pair of 91-B230FTs, 740/940 with the hot wire MAFs). Sprayed the MAF also. The TB had a black greasy film in it. Fired it up the next day. It idled nicely, drove as before.
Thanks for the input.

Post by **abscate** » 17 May 2020, 04:07

Continue to monitor.

PEMs fail intermittently, and your used 2016 one is near end of life

Mine failed over about 4 months ,occasional miss under load, very subtle, then one day Nostart