Hi all. I have a 1998 S70 standard that's taken to acting up lately and could use some advice.

Last month my car started feeling "odd" for lack of a better word. It wasn't riding rough, or stalling, or doing anything dramatic. It just felt like something somewhere wasn't quite connecting or something somewhere was ever-so-slightly clogged, or something.... Yeah, I know.... Then one day it started to behave better. I realized that all the bad behavior had taken place during an almost two-week-stretch of rainy weather. I think, "electrical issue" and make an appointment with the dealership.

When the day of my appointment arrives, I'm thrilled to find we're due for two more days of rain. I drop off my vehicle, apologize for my vague description of the problem, and tell them I'm happy to pay for whatever diagnostic work is needed for them to get to the bottom of this problem. (Surely they'd find *something*, right?) After two full days, I'm told the technician cannot find anything wrong. I concluded that the issue must not be all that serious -- and if it is of significance, I'll bring the car back when it's more obvious.

Insert a month's worth of progressive deterioration here: Now the problem is evident after about 30 minutes of driving, even on a sunny day. On a rainy day, with my lead foot, 10 minutes of highway driving is sufficient. Plus the car on occasion attempts to stall when I come to a stop after getting off the highway. What's odd is that it's never the first or second time I come to a stop, but shortly thereafter (like 5 minutes later).

Finally, last night, I drove highway speeds for 20 minutes and felt the "odd" behavior while still on the highway. I got off the highway and it persisted. Ultimately it stalled near an intersection. It would turn over, but not start. After about 10 minutes, I tried again and it started up right away. It was hesitant/ran rough, but I was able to move my car out of the way. After 10 or so more minutes of sitting with the engine off, I start it up and things seem fine, so I continue the few remaining miles to my destination without difficulty.

30+ minutes later I get back into my car and decide for safety reasons to take the "scenic route" back -- countryish road, very few stop lights/signs, 35-40 mph driving. Everything's fine for 20 or so minutes. Then it starts running rough. I luck out and pull into a parking lot just as it stalls. I wait 15 minutes and head out again. Rinse and repeat, taking things even slower, downshifting rather than breaking whenever possible, and lucking out with green lights. After another 15 minutes, my check engine light comes on -- within several miles of the dealership. I'm thinking surely they can reproduce this problem now, park the car at the service department, and call a taxi.

Morning comes, then afternoon. At 4PM they call me. Would you like to guess what they can't reproduce? (Me: Did you drive it on the highway for a while? Them: Yes, we put some miles on it.) Also I'm told the "code" associated with my check engine light is "vague" and could indicate this thing or that. I'm afraid I was so stunned that they couldn't reproduce the problem and that they didn't seem to be pursuing many (any?) diagnostic routes, that I didn't write down the code. But I think this thing was fuel related and that thing was vacuum related.

I suppose I should give them credit for not trying to charge me an arm and a leg. But here's what I don't get:

1. Having googled, read the forums here, etc. It seems that while this issue is tricky to pin down, there are "likely suspects." I had authorized them to do up to $1000 of repairs without even needing to consult with me, and told them that beyond that I'd almost certainly authorize it but I wanted a heads-up first. Can't the dealership run tests to rule out at least some of the suspects? As for those that cannot be ruled out, I'm okay with starting to replace parts -- especially if the parts are original -- fully acknowledging that doing so might not solve the problem, but merely rule out other suspects. But they don't seem to want to do that.

2. How can they not reproduce this?? *tired smile*

Tomorrow I'm going to go down there pick up my car, do "laps" on the highway, and hopefully deliver the car back to them in all of its malfunctioning glory. But if they don't look at it right away, the problem will once again be "not reproducible." I'm hoping they'll let me borrow a technician to accompany me on this journey too, but I'm not sure how long they're allowed to be AWOL....

Assuming the worst case ("sorry, we aren't able to find anything wrong with your vehicle"), what would you do were you me? I'm really at a loss.... How unsafe potentially is my vehicle? And, accidents aside, am I risking damaging something more significant because I'm driving while.... whatever.... is malfunctioning?

Sorry to be long-winded. And thank you very much in advance for any advice you can offer!!

 

Sounds like it is running out of gas. I would check the fuel pump relay first. They can be opened up and inspected.

My guess would be relay or fuel pump.

 

Awesome. Thank you so much!!

Assuming that it is fuel pump related.... Tomorrow my plan is to push the car to its limits (i.e. literally doing laps on the highway until it's exhibiting the symptoms -- fortunately the dealership is 2 blocks away from an exit). Is there any reason (safety, damage to my car) that I should *not* do this?

 

You should be fine doing it.

It would really be nice if you had someone to hook up a fuel pressure guage to the car that you could look at while driving and when it messed up you would be able to look and see if the fuel pressure was dropping when it was dying.

I always do that and I also add a light to the fuel pump wire to see if I am loosing power to the fuel pump when the pressure drops.

 

Tech, you are a genius!!

I did my "laps," but sadly the car chose to die at the wrong end of the highway. Funny how that works. :-) Anyway, the death was a tad more spectacular: I was going 40 mph on the exit (an S-curve) rather than coming to a stop. So rather than wait and attempt to drive it back, I phoned the dealership from the exit and explained the situation. They sent the shop foreman out to render assistance. :-)

When I mentioned what you had said, the foreman's reply was that he just so happened to have brought a fuel pump relay. Mine turned out to be far hotter than it should have been. Nice call!

I asked the foreman to follow me back to the dealership just in case. While nothing significant happened, that "odd" feeling was still there. Then the foreman drove my car. He can feel "it" too. (Yea!) He's going to hook up a fuel pressure guage and drive my car around over the next couple of days, giving it the appropriate driving duration. (I didn't tell him that part of your suggestion, but I grinned when I heard him say it.) So another nice call.

Thank you again so much for your timely (and mighty accurate) advice!

 

Glad you are finally getting somewhere with it keep us posted on the progress.

 

One thing I want to add to all of this: NEVER accept part replacement as a diagnostic procedure. Essentially anything can be tested in some manner, often with basic testing tools. Throwing parts at a car to try to figure something out is a sign of a bad mechanic/ diagnostician (we refer to these guys as parts installers.) On the other hand, I've seen many different cars have an intermittent problem that simply cannot be diagnosed unless the car is experiencing the problem at that time. In those cases, the only thing to tell the customer may be that they need to bring the car back when the problem is occurring or when it gets worse. Trust me- we don't think you're an idiot when that happens, in fact, whenever I have to do it, I mentally beat my self up with the notion that the CUSTOMER might think I'm incompetent!

As for the fuel issue- an excessively hot fuel pump relay indicates excessive current flow through the relay, or corroded/ burned contacts in the relay (which can, themselves, be caused by excessive current, leading to a cycle of worsening of the problem!) Excessive current flowing through the relay either means that the fuel pump is failing and creating excessive load, (often times, this will only show when the pump is hot from use, resulting in symptoms like you are describing) or that there is a plugged fuel filter, which causes the pump to work harder, resulting in excessive load (and eventual pump failure!) Another possibility is that there is some damaged insulation on the wiring to the fuel pump- this kind of jives with the initial occurrences of the problem being when it was raining- water getting into the positive wire to the pump could create a path to ground, thus causing the pump to shut off/ not receive enough voltage to run correctly. This could also lead to corrosion of the wire under the insulation, which will create resistance, and thus a higher load (hot relay!) and low pump speed/ no pump operation.

My suggestion: if the mechanic finds low fuel pressure, try replacing the filter first (needs to be done anyway if the pump is replaced, and should be done as maintenance at 100,000 miles, though it's often overlooked) Then, if that doesn't solve it, have the mechanic check voltage at the fuel pump- if it's lower than battery voltage by more than .5 volts, there's a problem in the wiring, however, this isn't a definitive check- if voltage is okay, apply battery voltage directly to the connection for the pump where the wiring harness plugs in, and see if fuel pressure becomes normal. If so, again, there's a wiring problem. If not, the pump is bad. And yes, MOST mechanics should know to do these checks, but they're often forgotten/ skipped, as wiring failures aren't that common- however, your initial symptoms sound like it's a definite possibility in your case. Good luck, and I hope it doesn't cost too much to fix. Sounds like you have an honest and caring mechanic, too- there's way too many out there who, upon being told that the customer is willing to pay up to X amount of money to fix the problem, will make sure that the repair bill approaches that amount, even if it's a simple and cheap repair.

 

And the winner is: The MAF. Rather than risk misreporting the details, this is from the report:

Hopefully my saga is over. :-)

 

Uh... wow, that is a heck of a misread from the MAF... Glad to hear the problem is fixed, and glad to hear you have a trustworthy, competent mechanic.

 

Glad all is better now.

But I would like to say one thing about Carrots post above. When I was at the Dealer they suggested that the fuel filter was to be replaced with every 30K major service. I reccomend that as well because I have seen many fuel filters really dirty after 30K.
When I pulled them off the car and dumped the excess fuel out it was almost black.

 

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I was just going by the manufacturer's original recommendations. More frequent changes don't hurt anything, and I suppose if you're doing a major maintenance service, why not?

Your recommendation that timing belts be changed at 70k is a good idea, so maybe I'll start looking at doing fuel filters earlier. That being said, these cars have gigantic, high- capacity fuel filters, as compared to most other cars. However... they're also probably the easiest filters in the world to change, and more frequent changes won't hurt anything and can only help.