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S70 engine revs to 4K and beyond at start up?

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

NYSmoosehoove
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S70 engine revs to 4K and beyond at start up?

Post by NYSmoosehoove » Sat Apr 20, 2019 4:07 pm

Long time lurker here—
One year owner of previous s70 t5 98 and recently procured my second.
After making numerous fixes to the new model I have but one problem;
Engine turns over at start but very hard,
Then— as if my foot was on the peddle, the engine revs up past 5k in a matter of seconds.
I recently made several repairs to the new car,
I bypassed the heater core, using the 5/8ths U-hose method,
I replaced the PCV system entirely, as well as the radiator, thermostat and housing, coolant resivoir, maf, and the lower radiator hose as well as the upper two coolant hoses and the cars air filters.
I changed the throttle body gasket, and the boost pressure sensor behind the air filter.
Additionally I changed the spark plug leads to oem and added a new spark plug cap.
From my research I’ve deduced that perhaps my issue is a knock to my TPS sensor? Or perhaps an issue with my vacuum lines?
I started the car once in neutral and it seemed to curtail the excessive and unstoppable revving for a few seconds more than when starting from park.
I’ve also noticed that there’s a bit of a gasoline smell in the engine bay when the key is in second position. (Fuel injectors were changed to white tops from my old model, but they look all in place and the correct depth in each port)
I changed the relays in the main fuse box, and thought perhaps there could be an issue with the fuel pump relay, or again vacuum lines in some capacity—
I have the computers from my old model and have considered swapping them as well.

Any ideas?
Thank you all-
Z
Last edited by matthew1 on Sun Apr 21, 2019 3:55 pm, edited 1 time in total.
Reason: Edited title. Please, no "???" in titles.


Previous:
White w/Black Alcantara ‘98 s70 t5 185k>215k “Freyja” (Belgium)
Current:
Black w/two tone taupe/tan ‘99 s70 N/A “Vallkyrie” (Belgium)
83k>

Sommerfeldt
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Re: S70 engine revs to 4K and beyond at start up???

Post by Sommerfeldt » Sat Apr 20, 2019 11:58 pm

It sounds most of all like your throttle body is stuck open. Have you checked? Also look and see if you disturbed something when you changed that gasket, and make sure it’s even and sealing.

Any codes?

- S


'96 855 T5, R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.

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RickHaleParker
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Re: S70 engine revs to 4K and beyond at start up???

Post by RickHaleParker » Sun Apr 21, 2019 3:13 pm

(Fuel injectors were changed to white tops from my old model
What was in there before?

Orange - 315cc/min
White - 350cc/min


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.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

NYSmoosehoove
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NYSmoosehoove

Re: S70 engine revs to 4K and beyond at start up???

Post by NYSmoosehoove » Sun Apr 21, 2019 3:23 pm

Sommerfeldt wrote:
Sat Apr 20, 2019 11:58 pm
It sounds most of all like your throttle body is stuck open. Have you checked? Also look and see if you disturbed something when you changed that gasket, and make sure it’s even and sealing.

Any codes?

- S


Unfortunately, it’s been raining in NY where I am the last two days so I haven’t had a clear opportunity to take it down the the throttle body again, I’m thinking tomorrow that will be my first course of action.
On the note of codes, I can’t run the car enough to read them. There’s no CEL at start up, just normal service light, and srs which goes off after one second. The ABS control module is done for and I plan to swap it, so that light is on as well, but probably unrelated from what I understand, as the car ran fine despite its issues when I test drove it before buying.
Last edited by NYSmoosehoove on Sun Apr 21, 2019 3:27 pm, edited 1 time in total.


Previous:
White w/Black Alcantara ‘98 s70 t5 185k>215k “Freyja” (Belgium)
Current:
Black w/two tone taupe/tan ‘99 s70 N/A “Vallkyrie” (Belgium)
83k>

NYSmoosehoove
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NYSmoosehoove

Re: S70 engine revs to 4K and beyond at start up???

Post by NYSmoosehoove » Sun Apr 21, 2019 3:25 pm

RickHaleParker wrote:
Sun Apr 21, 2019 3:13 pm
(Fuel injectors were changed to white tops from my old model
What was in there before?

Orange - 315cc/min
White - 350cc/min

Also whites, just not as clean and the o-rings seemed to be getting up there in age, they were most likely the originals.


Previous:
White w/Black Alcantara ‘98 s70 t5 185k>215k “Freyja” (Belgium)
Current:
Black w/two tone taupe/tan ‘99 s70 N/A “Vallkyrie” (Belgium)
83k>

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Re: S70 engine revs to 4K and beyond at start up???

Post by RickHaleParker » Sun Apr 21, 2019 3:39 pm

I think you got something dumping fuel in the intake or cylinders. When you start it up, the excess burns off.
I would dope the fuel with tracer dye and track down the fuel leak you smell in the engine bay.
You sure them injectors are not leaking.


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.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

Sommerfeldt
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Sommerfeldt

Re: S70 engine revs to 4K and beyond at start up?

Post by Sommerfeldt » Sun Apr 21, 2019 4:53 pm

You shouldn’t need to run the car to read codes, though the ECU might not have time to set any.

You could have something dumping fuel in the cylinders, as RHP says, but you’d still need lots of air to rev up and keep revving. Check the TB and move on to injectors, since those are the things that have changed.

And see if there are codes.

- S


'96 855 T5, R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.

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RickHaleParker
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Re: S70 engine revs to 4K and beyond at start up?

Post by RickHaleParker » Sun Apr 21, 2019 5:49 pm

Sommerfeldt wrote:
Sun Apr 21, 2019 4:53 pm
You could have something dumping fuel in the cylinders, as RHP says, but you’d still need lots of air to rev up and keep revving.
Fuel dump + Intake Air leaks. For example: Leaking Intake Gasket, fuel runs down from Fuel Rail passes the intake gasket, accumulates in the intake ports. Start it up and you got excess fuel and air.

First figure out where all the extra fuel is coming from. He is smelling fuel .....


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.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

Sommerfeldt
Posts: 1113
Joined: Tue Jul 29, 2008 1:25 pm
Year and Model: 1996 850 T5
Location: Oslo Area, Norway
Has thanked: 49 times
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Sommerfeldt

Re: S70 engine revs to 4K and beyond at start up?

Post by Sommerfeldt » Mon Apr 22, 2019 1:02 am

RickHaleParker wrote:
Sun Apr 21, 2019 5:49 pm
Fuel dump + Intake Air leaks. For example: Leaking Intake Gasket, fuel runs down from Fuel Rail passes the intake gasket, accumulates in the intake ports. Start it up and you got excess fuel and air.

First figure out where all the extra fuel is coming from. He is smelling fuel .....
And what happens if you put your foot on the gas pedal before you start the car...?

Better to check the easy things first, then see if more complicated stuff is going on.

- S


'96 855 T5, R bumper and spoiler, Koni Yellows & blue H&R springs all 'round.

NYSmoosehoove
Posts: 5
Joined: Sat Apr 20, 2019 3:38 pm
Year and Model: 1999 S70 N/A
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NYSmoosehoove

Re: S70 engine revs to 4K and beyond at start up?

Post by NYSmoosehoove » Wed Apr 24, 2019 4:31 pm

Hey folks,
Problem solved—
And by that I mean the engine bay caught fire... looked like one of the vaccuum hoses that runs off the intake manifold had broken, and additionally the gas smell was most likely liquid build up where the injectors sit.
Started her up after a little work on the throttle body and WOOSH.
That’s that story.

Next up— a 2000 SE hopefully.


Previous:
White w/Black Alcantara ‘98 s70 t5 185k>215k “Freyja” (Belgium)
Current:
Black w/two tone taupe/tan ‘99 s70 N/A “Vallkyrie” (Belgium)
83k>

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