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Power Hesitation at Cruising Speed, No Codes Topic is solved

Help, Advice, Owners' Discussion and DIY Tutorials devoted to the second generation C70, S40 and V50 Volvos -- awkwardly model year 2004 ½ onwards -- plus where to go for advice and discussion on Volvo's sporty C30 Coupe powered by Volvo's ubiquitous inline 5-cylinder power plant.
benpineapple
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Power Hesitation at Cruising Speed, No Codes

Post by benpineapple » Mon Apr 08, 2019 8:22 am

Hello!

Odd little issue with my 2006 V50 T5. Started about 1 week ago. Issue typically happens when cruising on the freeway, after 5-15 miles on the freeway, the car will hiccough or stumble a bit. Speed barely dips, RPMs barely change, it almost feels as if the transmission slips then re-engages. It has been getting worse over the past few days, car will hesitate while cruising then kind of slam back with a shake I can feel. Has only happened once, but the car dropped 5MPH, then once it "caught" again the car went back up to cruising speed on its own. That particular instance is making me think perhaps more related to throttle control instead of transmission?

No codes are being thrown. Took it into my shop, VIDA didn't show any transmission codes, or other current codes thrown.

Anyone else had this issue? Not sure if relevant, but I had changed the oil 2 days before the issue presented; I typically use Castrol GTX, but used Penzoil full synthetic this time. Don't think an oil change should or would cause any issues, oil level is normal.

Thanks!


2006 V50 T5, 116xxxM

1998 V70 AWD [RIP at 249,255M]
1990 240 [SOLD at 220xxxM]

benpineapple
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Re: Power Hesitation at Cruising Speed, No Codes

Post by benpineapple » Tue Apr 09, 2019 7:14 am

Update: after 1.5 weeks with the symptoms, and 3 tanks of gas (bad fuel/water in fuel now ruled out), car finally threw the following confirmed codes: P0090, and P0193, with an additional P0088 code pending. It's looking like the fuel rail pressure sensor is failing. Couple threads on the code on Swedespeed. I'll report back once I get it replaced. If anyone thinks it could be something else in the fuel system, let me know! Thanks.


2006 V50 T5, 116xxxM

1998 V70 AWD [RIP at 249,255M]
1990 240 [SOLD at 220xxxM]

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RickHaleParker
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Re: Power Hesitation at Cruising Speed, No Codes

Post by RickHaleParker » Tue Apr 09, 2019 7:38 am

Before replaceing the Fuel Pressure Sensor, check the Fuel Pressure Sensor loom for:
  • 1. Contact resistance, oxidation or poor contact in connectors or connections.
    2. Short-circuit to supply voltage in the signal cable
    3. Open-circuit in the signal cable
    4. Open-circuit in the signal ground cable
Have you measured to Fuel Pressure to determine that it is in spec?
That would tell if the Sensor is a liar or not.
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benpineapple


Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0, Plant Torslanda Sweden.
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1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

benpineapple
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benpineapple

Re: Power Hesitation at Cruising Speed, No Codes

Post by benpineapple » Tue Apr 09, 2019 7:44 am

RickHaleParker wrote:
Tue Apr 09, 2019 7:38 am
Before replaceing the Fuel Pressure Sensor, check the Fuel Pressure Sensor loom for:
  • 1. Contact resistance, oxidation or poor contact in connectors or connections.
    2. Short-circuit to supply voltage in the signal cable
    3. Open-circuit in the signal cable
    4. Open-circuit in the signal ground cable
Thanks, will get out the multimeter and check those items before installing the new sensor (if needed).


2006 V50 T5, 116xxxM

1998 V70 AWD [RIP at 249,255M]
1990 240 [SOLD at 220xxxM]

benpineapple
Posts: 288
Joined: Tue Nov 03, 2015 1:01 pm
Year and Model: 06 V50 T5
Location: MI
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benpineapple

Re: Power Hesitation at Cruising Speed, No Codes  Topic is solved

Post by benpineapple » Wed Apr 17, 2019 8:57 am

Follow-up:

Wiring loom and connections for fuel pressure sensor is fine. Replaced fuel pressure sensor, reset OBD codes, no issues since. Have driven ~200 miles since sensor replacement with 0 issues.

One thing about replacing the sensor I will say, the fuel rail will still have pressure and be full of fuel even if the car has sat for 2 days. Only way to clear out the fuel before removing the sensor, is to pull the fuel pump fuse, and start the car, then wait for it to stumble and stall out. Then trying starting it again. I did not do that, and had a mess of gas come out of the fuel rail. Thankfully had tons of rags under it already, not much gas spilled. I waiting a half hour before reconnecting the battery to make sure all fumes had evaporated.


2006 V50 T5, 116xxxM

1998 V70 AWD [RIP at 249,255M]
1990 240 [SOLD at 220xxxM]

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