Idle/Power Problems? Troubleshoot Here

[98T5]

When I was young, cap, plugs and wires were wearing out regularly. Today, Volvo does a great job of securing the wires in order that they don't flex and keeping the temp down in the engine compartment. I never think of those 3 as the culprit for at least 100k miles. Take the cover off and look for sparks at night. spray a very little water on them and listen for change. Change the coil wire as it flexes a lot.
Vacuum first and foremost. no gauge use spray start (careful fire) or propane to try and find a leak, but I went a long time trying not to buy a vacuum gauge, then I got one a life changed.
Pull injector wires off, one at a time. Feel the injectors for abnormal click.
When in the junk yard, I pick up the wire harness connector ends of all important sensors, in order to be able to plug them into the sensors, connect my meter and test them. Troubleshooting is a breeze now.

I like to use an aged cigar smoke to find the vacuum leaks. kill two birds with one stone..

[Ben850]

I wanted to add something relevant to this thread. Only yesterday, I replaced the front O2 sensor.

This should not be overlooked. As I have replaced most all of the parts relating to ignition, timing, fuel delivery and aspiration. I neglected one of the pieces linking it all together.

Old O2 Sensor. I don't think it was Bosch either. The new one is.

Without going into the details of the function of the O2 sensor, it was the cause of power inefficiencies across the board. It is now a completely different and consistent driving experience. Most all previous issues and symptoms are gone and the new parts and simple modifications have begun to operate as intended.

Previously, I would have expected a code for an O2 failure, but being a '93 with OBD I diagnostics, it was not apparent.
I am happy to share this today because it has put my mind to rest of some irksome performance issues, and proved all the parts investments in these areas to be worthwhile.

[echase76]

Ben850 - Thanks for sharing your experience. I can't seem to be able to edit my original post or I would add O2 to the list.

I had a front O2 issues shortly after I bought my car, but being an OBDII it quickly threw a CEL and was easy to diagnose.

Eric

[98T5]

I wanted to add something relevant to this thread. Only yesterday, I replaced the front O2 sensor.

This should not be overlooked. As I have replaced most all of the parts relating to ignition, timing, fuel delivery and aspiration. I neglected one of the pieces linking it all together.

IMG_2178.JPG

Without going into the details of the function of the O2 sensor, it was the cause of power inefficiencies across the board. It is now a completely different and consistent driving experience. Most all previous issues and symptoms are gone and the new parts and simple modifications have begun to operate as intended.

Previously, I would have expected a code for an O2 failure, but being a '93 with OBD I diagnostics, it was not apparent.
I am happy to share this today because it has put my mind to rest of some irksome performance issues, and proved all the parts investments in these areas to be worthwhile.

Good info to know. I was planning to wait on the code like my V70 throws. This way, I can just fix it now and not worry about getting stranded later.

[cn90]

Good thread,

I recently bought a 1998 S70 GLT with 145K, it ran OK but had intermittent idle going up from 800 rpm to 1000 rpm, it was annoying.

So I decided to go the whole 9 yards, I do not know what did the trick but my idle is now dead solid at 800 rpm. Since most of these cars now have some 150K-200K, I'd recommend the following (these were what I did):

1. Vacuum leak (start with elbow on passenger side of manifold and go from there).
- Found a few cracked vacuum hoses, fix them all.

2. Fuel Filter: replaced with new Bosch unit.

3. Cleaned Throttle Body.

4. Cleaned Idle Air Control Valve.

5. Spark plugs, Wires, Cap, Rotor:
- Spark Plug: Bosch copper ---> $2/each
- Wires: Bougicord ---> $55 online
- Cap/Rotor: Bosch ---> $55 online.

So if you car misbehaves with uneven idle, do the 5 steps above, chances are the idle will be solid at 800 rpm.

[echase76]

Thanks for the reply! this is all great stuff that should be done to any newly acquired Volvo. My hope is that this thread can help those folks with misbehaving cars solve pesky and frustrating issues. I know i was beating my head against the wall for a month!

Keep the tips coming!

Eric

[98T5]

I look at these cars as big computers. if you keep the dust/oil off of the sensors and defrag it often by cleaning all the parts like IAC, TPS, intake, etc...and keep your wires "hot" with continuity, these cars last a long time unlike the mostly mechanical parts on American cars.

[Raycharles90]

Looks like a pretty thorough thread so far. I have experienced intermediate idle/acceleration issues since I purchased the car 4.5 years ago (had 124, 000 miles at purchase). I finally think I have it mostly worked out. Replaced all the vacuum lines and rerouted the hose around the manifold. Also replaced the IAC which was intermittently cutting out and was difficult to diagnose. Pulled a couple at junkyard and have a couple extra if someone would like to try that. Went through a cheap MAS then got a Bosch. I had been holding off on replacing the front O2 sensor because many have said it usually is vac lines. I completely agree with what some have said here, if you are unsure and the car has over 100,000 miles, just replace it. Completely changed the performance, steadied the idle and acceleration. For ~$90 on amazon just do it. Takes about 30 minutes.

I think most of us come into the relationship with our Volvo not knowing the maintenance history. Just take your time, go through the possibilities, and keep reading this site. Such a wealth of information that can save many headaches and hits to the pocket book.

So again, if you have checked the vac lines, IAC, plugs etc., try a new front sensor.

[redvolvo21]

Hello,
I drive a 1995 850 Volvo. I recently purchased a mass air flow sensor on Ebay. Unfortunately I bought the MAF for the newer model of the 850 while I drive the older version. The one I bought comes with a housing while the one I should have bought does not come with a housing.
My question is, if I remove the MAF from its housing, will it work in my vehicle?

[m96ag]

For 1999+ cars cracked/bad coil packs can cause a lot of issues similar to those of a bad cap or wires.