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Cold start . Rpm dips

Help, Advice, Owners' Discussion and DIY Tutorials on S40 and V40. In this forum you'll find S40/V40-specific owners asking and answering questions on maintenance, ownership, repairs, tutorials and almost every do-it-yourself thing you can do to save money owning these Volvos.

1996 - 2004 S40
1996 - 2004 V40

Ivano2937
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Cold start . Rpm dips

Post by Ivano2937 » Wed Jan 31, 2018 8:58 am

I have a 2004 Volvo v40 that seems to have idle problems.

When it has been off for a long time and I try to start it. It won't start unless my foot is all the way in on the gas pedal then I have to keep my foot on the gas until the temperature needle is in the middle.
If I let go of the gas anytime before that the car will stall.

After the temperature needle is in the middle the car runs fine but when I shift into reverse or drive the rpm dip down to about 750 to 790 enough for me to feel the car shake and make me worried about stalling.

I took my car to get a tune up recently and the mechanic said it needs the O2 sensor and maf replaced.

My question is : does this sound like it would fix the problem?
And are these parts plug and play.. I would be spending 400$ at the mechanic...

Thank you



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RickHaleParker
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Re: Cold start . Rpm dips

Post by RickHaleParker » Wed Jan 31, 2018 10:07 am

I took my car to get a tune up recently and the mechanic said it needs the O2 sensor and maf replaced.

The MAF sensor alone could make quite a difference and it is easy to change out.
Try disconnecting the MAF wiring harness and see if the enigine starts better.

2004 Volvo V40 Mass Air Flow Sensor with Housing (MAF)

Image
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Ivano2937


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

Ivano2937
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Re: Cold start . Rpm dips

Post by Ivano2937 » Wed Jan 31, 2018 12:17 pm

So when I disconnected the harness the car started a bit better but still had to give it gas to keep it consistent .

The car stayed on but when I put the harness back on the maf it turned off and I had to wait till the car was warm for it to stay on.


Any advice on what I need to buy or change?



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Re: Cold start . Rpm dips

Post by RickHaleParker » Wed Jan 31, 2018 2:36 pm

I think you got more going on then what the mechanic said. I suspect it is not getting enough air ... when you push down on the throttle your giving the engine more air, the engine control module decides how much fuel.

Try removing the air filter see if it makes a difference but do not leave it that way.
It could be a your Idle Air Control Valve is defective or dirty. Try cleaning out the IAC.

It would be helpful if you had a code reader or Vida-DiCE. You might take it to Autozone and get a free code scan, get the codes and post them here if if you do.
These users thanked the author RickHaleParker for the post:
Ivano2937


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

Ivano2937
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Re: Cold start . Rpm dips

Post by Ivano2937 » Wed Jan 31, 2018 3:48 pm

RickHaleParker wrote:
Wed Jan 31, 2018 2:36 pm
I think you got more going on then what the mechanic said. I suspect it is not getting enough air ... when you push down on the throttle your giving the engine more air, the engine control module decides how much fuel.

Try removing the air filter see if it makes a difference but do not leave it that way.
It could be a your Idle Air Control Valve is defective or dirty. Try cleaning out the IAC.

It would be helpful if you had a code reader or Vida-DiCE. You might take it to Autozone and get a free code scan, get the codes and post them here if if you do.

Thank you sir for your helpful advice. I just drove it without the maf senor harness I'm not sure if this is dangerous but it seemed to retain the rpms at a manageable area when I put the sensor back on after driving the rpms would drop from about 850 mark to 750 on park .

I guess what I'm worried about is that when I start it when it is cold It sounds like it won't turn over and have to rev the engine for it to start then i have to continuing to push on the gas until temperature needle reaches the middle and then I can let go of the gas and car will not stall.


My mechanic did a tune up and changed the plugs and more things I can't remember exactly but I don't think it's a misfire issue because he even said he took care of it. He gave me a paper with codes because he diagnosed it too. That's when he spoke to me about the O2 sensor and maf


Also my check engine light when away when I disconnected the harness.


Thank you sir for your help and advice I will take it in when I can to get the codes .

Thanks to this forum also



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RickHaleParker
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Re: Cold start . Rpm dips

Post by RickHaleParker » Wed Jan 31, 2018 3:53 pm

He gave me a paper with codes because he diagnosed it too.

Post the codes off that paper, or did you mean he showed you the paper?


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

Ivano2937
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Re: Cold start . Rpm dips

Post by Ivano2937 » Wed Jan 31, 2018 9:47 pm

]
RickHaleParker wrote:
Wed Jan 31, 2018 3:53 pm
He gave me a paper with codes because he diagnosed it too.

Post the codes off that paper, or did you mean he showed you the paper?
This is what he gave me.
Hope this makes more sense.

Thank you for helping me out.
Attachments
IMG_20180131_204200089.jpg
IMG_20180131_204230110.jpg



Ivano2937
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Re: Cold start . Rpm dips

Post by Ivano2937 » Thu Mar 15, 2018 2:27 am

So I ended up going to the junkyard and finding 3 s40s/v40s and I got to choose a fairly clean looking iac. I installed same day and to my surprise it works and my car is driving perfect only. The check engine has disappeared.

But!

Now I smell gas fumes inside while I drive.
I popped the hood and the engine smells like fuel.

Prior to changing the iac valve I never smelled fuel.
I'm concerned now.

Gas mileage is the same and I don't see any leakage .

Help please



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alschnertz
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Re: Cold start . Rpm dips

Post by alschnertz » Thu Mar 15, 2018 4:13 am

Changing the IAC shouldn't have opened up any fuel line.
Are you sure it's a raw gasoline smell and not something else?
Did you have to use some kind of penetrant to get things apart?


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RickHaleParker
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Re: Cold start . Rpm dips

Post by RickHaleParker » Thu Mar 15, 2018 9:25 am

Is the engine dirty?
Did you get grease or oil moved around as you changed the IAC?
You sure it not heat burning off oil or grease.
If the engine is dirty, take it to a car wash and wash off the engine, see if the smell goes away.


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

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