2000 S70 Still runs poorly after Xemodex upgrade

Chapelgirl · Post by **Chapelgirl** » 15 Dec 2014, 16:06

Oh, yeah. Also have double checked my air intake system and everything is as it should be.

Post by **cn90** » 15 Dec 2014, 16:17

Unplug the MAF and report back...

Post by **misha** » 15 Dec 2014, 17:23

I think that bad Maf would throw a code.Other than that,car would run extremelly rich with visible black smoke from the exhaust and idle would go up &down continuosly.

Exhaust pressure can be checked just with one hand care chief.Just put it over the end of exhaust pipe when the car is idling.If the exhaust pressure tears it down...cat is not clogged.

draser · Post by **draser** » 15 Dec 2014, 18:11

You can test both maf and cat flow with a code scanner that will show maf signal and engine load at 2 rpms (idle and 1500). You'll need a member with a good running engi e to post his for benchmark.

Chapelgirl · Post by **Chapelgirl** » 15 Dec 2014, 18:42

Watched some vids on how to check the cat using a scan tool where you can monitor the o2 sensors. Visited three local auto parts stores - two only had the little mini scanner and one had the larger one where you can set up certain things to watch but the scan tool wouldn't work. Ugh! I just used my buddy's basic scan tool today so I know it's not my OBDII port as the store suggested. This is getting old.

Unplugged the MAF sensor. Idle became rough and touching the accelerator at all made it almost cut off. It threw a code, too. Now I have a CEL on. I'll have to borrow the basic scan tool again from my work buddy and clear that.

I'm almost to the point of taking it to a shop as much as that pains me. It's getting hard to drive this thing and it's sucking down the gas. Not sure how much more I can take.

-Chapelgirl's husband

Post by **northernlights** » 15 Dec 2014, 21:31

If the fuel economy is really low then that points even more to a clogged exhaust.

Does this car have an air pump? If it does then that gives you a place to attach a gauge. Most vacuum gauges have a pressure gauge included, maybe 0-15 psi. Based on past experience with V8's, I wouldn't expect it to be more than 2 or 3 psi at 2000 rpm, if even that.

Post by **precopster** » 16 Dec 2014, 04:10

Poor fuel pressure? That would explain the high fuel consumption, good idle and revability while still and poor drivability under load. Don't sweat the code because it will become a strored code after 3 successful start/run cycles.

draser · Post by **draser** » 16 Dec 2014, 13:51

What is the mileage on the car? Are the plugs smoked, white clean or brownish? Can you rent a fuel press gauge to test fuel press? Have you replaced o2 sensors? Quick and dirty way to test cat is to unhook the downpipe and kinda push to the side the cat section and take it for a ride in the hills, neighbors will not like it but you'll see if it's plugged up. I'd also get a blue tooth OBD2 adapter and Torque app either free or pro to be able to read car sensors, codes, etc.

Chapelgirl · Post by **Chapelgirl** » 16 Dec 2014, 21:14

I really appreciate all the help. To answer some of the questions -
No. I don't think the car has an air pump.
The CEL indeed went out after a couple of trips out so no worries there - thanks precopster.
168K on the car.
I just replaced the plugs about 500 miles ago before this problem crept up. Installed Volvo OEM plugs.
I have not replaced the O2 sensors.
I didn't realize I could unhook the downpipe. I assumed all was welded together. I haven't looked at it that close.

Another work buddy has the really nice scanner so he's going to bring it tomorrow and we're going to hook it up and hopefully be able to monitor the o2 sensors. I saw a video explaining that sensor 1 should bounce between rich/lean/rich/lean, etc. rather rapidly while sensor 2 should remain fairly constant. Apparently if sensor 2 is bouncing around this is an indication of a clogged cat. Also saw that checking inlet temp vs. outlet temp with an infrared temp gun might help too. They say that a lower temp on the outlet side than in the inlet would also indicate a clogged cat. I have access to a temp gun at work so going to try that too for the heck of it.

If those easy checks don't tell me anything I'll go after fuel pressure.

I'll let everyone know what happens.

Dave

Post by **EstVolvo** » 16 Dec 2014, 23:00

Shouldn't the O2 sensor trigger a code if it is bad?
I replaced my O2 sensor by guessing ... without any need to do so.
I started getting bad fuel economy after switching to winter tires and winter grade fuel - that is when I freaked out and went after the O2 sensor.

2000 S70 Still runs poorly after Xemodex upgrade

Re: 2000 S70 Still runs poorly after Xemodex upgrade