TAKE 2: rpm dipping dropping to about 750 (IMO) when braking to complete stop

[tolian2]

2000 V70XC AWD 4speed auto with 180K miles:

now with xemodex etm in place of the old one that was original with 155 software update i still get 50 rpm dip/drop from 850 to 800
and sometimes a 100 rpm drip/drop from 850 to 750 when i'm braking at the red light to a complete stop.
No other issues at highway speeds or while driving in city. Fuel economy is good IMO (about 18-20 city, and up to 27 higway in FWD mode now)

Where do i start looking?
For one i know that this car probably never had it's PCV serviced. This also would mean putting in a new intake manifold gasket.

What else could come to mind? Vacuum leaks? Brake booster?

I'm open to your ideas.

Cheers!

[hogie50]

I would start with your own suggestion, especially if the PCV has never been cleaned. It is not horribly difficult as at least the 2000 has the dipstick tube bolted to the top/side of the intake. Replacing the pcv oil separator tank and the tubes that feed it costs around $100 for a kit from IPD. Also make sure you pay special attention to the pcv nipple on the air feed pipe from the air intake housing to the turbo. This needs to be carefully removed and thoroughly cleaned (I used carb cleaner and cotton buds). Like you said, if you are getting a vacuum leak at the intake gaskets you will replace these when you replace the pcv assembly. When you use the servo it will draw down the vacuum. Good place to start. I'm assuming once your foot is off the brakes the RPM comes back up?

[wrightme43]

Can you get it to drop rpm at a stop in park by pressing on the brake pedal?
Can you hear air bypass in the booster?

[tolian2]

Can you get it to drop rpm at a stop in park by pressing on the brake pedal?
Can you hear air bypass in the booster?

hm... i do not believe i tried that.
somehow i was under impression that it only happens in drive from XX MPH to 0 MPH.
i'll make sure to try tonight.

update: as i expected, it happens only when braking to nearly complete stop. also happens when braking before taking a corner. odd...

[tolian2]

one more idea came to my mind:

I have pretty much the same dipping of the tachometer needle with the new to me xemodex unit, as I had with a very original "white sticker"+campaign 155 software ETM.

I bought my xemodex etm used from eBay. And on the website they say to give Xemodex company a VIN number so that they could upload appropriate software to the ECU (am i right?).

Would i need to go to dealer so that he would do the "mating" of ETM to ECU?

[JRL]

http://forums.swedespeed.com/showthread.php?145309-99-S70-RPM-drop-at-idle

Clean the MAF sensor

[tolian2]

http://forums.swedespeed.com/showthread.php?145309-99-S70-RPM-drop-at-idle

Clean the MAF sensor

Do you think that i do not need to go to dealer to "mate" etm to ecu/ecm?

I read that thread a few times while searching for the solution to my problem.
I have cleaned MAF once, but will do it again a few times during a week just in case.

[BillAileo]

Since your xemodex was purchased used off of Ebay and has not been mated with your car I believe you are most likely going to have to deal with xemodex to have the full benefit of the xemodex product....

[JRL]

I agree
You will need to send it to XeMODex and have the software installed, amazed it even runs at all

[tolian2]

I agree
You will need to send it to XeMODex and have the software installed, amazed it even runs at all

i see...
I e-mailed XEMODEX as to what they would have to say about it: go to dealer or send the unit to them.
I did 1000+ miles in the last few weeks: including 900 round trip to Santa Fe after I installed the unit and not a hiccup at the highway. My now-FWD-XC gave me about 27 mpg cruising in the 70-80 mph window on the highway.

[tolian2]

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You might want look at the MAF sensor first, since you are experiencing the same problem. A vacuum leak is another possibility.

Software reload in this case will do nothing to correct this.


XeMODeX Inc.
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