127 replies to this topic

[550]

lcc014, on 16 April 2011 - 05:54 PM, said:

I don't think so because I had the same problem with the old air hose. It would tirgger the CEL sometimes, that was it. After I replaced that hose, RPM drop symptom still there.

Ching-Ho Cheng

A post MAF / Pre turbo leak can cause all sorts of fun issues.

The problem with this RPM drop is that I believe many things can cause this same issue. (Making it seem like the same issue needs to be fixed)

Unfortunately there is no definitive fix.

[turboVULVA]

550, on 17 April 2011 - 01:48 PM, said:

A post MAF / Pre turbo leak can cause all sorts of fun issues.

The problem with this RPM drop is that I believe many things can cause this same issue. (Making it seem like the same issue needs to be fixed)

Unfortunately there is no definitive fix.

Doode one of my s70s did the same thing! I suffered for months. I changed my timing belt tensioner and pulley and it went away!

[Modus]

550, on 17 April 2011 - 01:48 PM, said:

A post MAF / Pre turbo leak can cause all sorts of fun issues.

The problem with this RPM drop is that I believe many things can cause this same issue. (Making it seem like the same issue needs to be fixed)

Unfortunately there is no definitive fix.

+1

It does sneek up on you, I know it happens to me often. I'm still trouble shooting. (timing belt and such was replaced on mine, still same)

[crazykn]

I probably should update what I did to fix my car. Turns out my RPM drop was my transmission. In the end I ended up with a brand new transmission from Volvo directly ($2600) and well that fixed the problem for good. Upon inspection of the old unit, turns out i was flooded with metal shavings. Apparently the magnets on the bottom of the pan were full and couldn't really hold more, so without a transmission filter in this tranny, these particles probably circulated and clogged and jammed the valve bodies, reducing transmission fluid pressure...

I'm just happy my S70 T5 now drives like new again.

[lcc014]

crazykn, on 20 July 2011 - 07:31 AM, said:

I probably should update what I did to fix my car. Turns out my RPM drop was my transmission. In the end I ended up with a brand new transmission from Volvo directly ($2600) and well that fixed the problem for good. Upon inspection of the old unit, turns out i was flooded with metal shavings. Apparently the magnets on the bottom of the pan were full and couldn't really hold more, so without a transmission filter in this tranny, these particles probably circulated and clogged and jammed the valve bodies, reducing transmission fluid pressure...

I'm just happy my S70 T5 now drives like new again.

I also had my transmission replaced about 30k miles ago, so did the timing belt and belt tensioner. RPM drop still exists, so my RPM drop does not related to timing belt or transmission .....

Ching-Ho Cheng

[Modus]

Found My Problem it's the IAC!!! It had a problem when the temp was below 45 degrees. Even when engine warmed up the temp of the metal parts out side the engine were still cool, till the whole engine bay would warm up I would have the RPM drop. This took up to 20 minutes after starting depending on temp.
The idle would always hunt for 850, very annoying.

Bit the bullet purchased a new IAC from FPC with the 15% last month.

WOW no more RPM fluctuation when coming to a stop, No more RPM drop when it's cold. Noticeable acceleration difference too.

The only thing I can gather is the IAC lost it's resolution point electronically, I didn't measure resistance between the old and new but do plan on taking the old bugger apart.

[volvos70turbo99]

dang this thread is still going, I have not really noticed this problem recently, i did clean my iac awhile back and done a lot more to my car since then, but it may just be the iac like modus said. Modus im guessing you tried cleaning your iac first?

[Modus]

Yes I cleaned it, many times, the valve flapper flapped around really easy too.

The guess is over time the electronic stepper motor inside the IAC unit looses it's fine resolution point. Thus creating fluctuating idle when comming to a stop under load.

No more RPM drop comming down at stop lights, stop signs and street corners. Car seems more awake. Drives better too.
I also am not going to worry when the time might be when I sall out. It's all fixed now. It feels good.

I cleaned it many times. Replaced other things seeing if it would help. Like coil, vaccum lines, idle control, MAF. All I needed was the IAC. I think as things age this needs to be expected.

GL to you.