1996 850 Stalling at red lights and low speed only

malvern · Post by **malvern** » 22 Feb 2014, 23:50

Just got the car back from two back to back trips to the shop (first it was the transmission fluid dipstick not being reinserted properly causing me to leak 2 qts of fluid, followed five days later by having to replace my front brake pads and rotors). New problem -- the car is stalling intermittently, but only at red lights or in extremely heavy stop and go traffic (I live in LA, so this comes with the territory). When I'm able to give it anything on the gas, it's fine, if a bit throaty occasionally. It hasn't happened at highway speeds or anything above 5 mph. It is not linked with deceleration or acceleration. As I said, I live in LA and this is February and we're in a drought, so conditions have been consistently dry and between 60-75F.

I've been using a workaround until I can get it to the shop again on Tuesday. When I feel the problem about to happen, I shift to neutral with my foot on the brake, and then give it some power, keeping the revs steady at about 1500rpm until traffic starts to move again. But obviously this is not a state of affairs I want to continue with, so I'm trying to figure out what could be the problem.

I've read all 20 pages of the 850 stalling thread, and nothing posted there seems analogous to my situation. I had a new fuel pump assembly (including relays) fitted in September 2012, after suffering from the sort of problems I did read about in the stalling thread. What's happening now is nothing like then, when I was stalling while moving in traffic. This time it sounds rough at idle or the very lowest speeds, and for the first time ever it's started dipping below 1000rpm at idle. Every time I feel it about to stall, I swear my stomach sinks to the floor.

My car dude friend has thought it could be something to do with the fuel injectors, and I put a bottle of Chevron ProGard in the tank on Friday morning. For the 20 minute ride into work, it drove like a dream -- quiet, happy, smooth. Hooray! But in the afternoon, trying to get downtown from the Westside in some hairy traffic, it spluttered and died twice. While I was on the phone with the car dude friend, telling him my troubles were solved. WRONG.

It stalled again today in stationary traffic, but I got it going again immediately. I'm hoping it's not the fuel pump again. I have a law school tuition payment to make in 6 weeks and anything more than $500 is going to make living the next month very, very frugal indeed.

Any guidance much appreciated!

Post by **abscate** » 23 Feb 2014, 06:26

Hmmm...we have too many lawyers and not enough Volvos, so first get your money priorities right.

Ok, I'll be helpful now.

Are you throwing any codes (check engine light on?)

Poor idling on pre 99 cars is often a bad Idle Air control valve hose. Look for tears in this metal item sitting about mid-engine bay, right behind radiator shroud. I'll try to link to pix.

If your car is getting enough fuel for in-traffic, I don't think you have a fuel problem. You need to avoid friends who guess diagnose on these cars and stick with a deliberate troubleshooting procedure. Car fixing isn't a "sound like the Jesus pin" princess any more.

When was the last time spark plugs, distributor cap, plug wires were changed?

What's your history with the car?

Post by **erikv11** » 23 Feb 2014, 06:55

Here is a picture of the IAC valve, with the two hoses that abscate is talking about, the hoses to check for tears are the ones whose ends are circled:

Clean out the IAC, this is something you can do yourself for the price of a can of carburetor cleaner (about $5) and a few hose clamps. The IAC is held in place by a rubber strap and the connections to the hoses. Spray cleaner into the IAC, shake it around until you hear the internal mechanism rotating freely, dump out the cleaner onto a rag or paper towels. Repeat until the cleaner runs out clean. Use eye protection.

If the IAC has hose clamps that look like this then you will want to replace them with screw type, these clamps are one use only:

: dscn7882.jpg (243.52 KiB) Viewed 1693 times

Here is an IAC that is fully removed and ready to be cleaned:

: IAC.jpg (15.65 KiB) Viewed 1693 times

thedancingfiddle · Post by **thedancingfiddle** » 23 Feb 2014, 13:54

I had what sounds like the exact same problem a few years ago - when you step on the clutch coming to a stoplight it would often drop past idle and die completely. In my case the problem was fixed after replacing the plugs, cap and rotor.

- Cedar

malvern · Post by **malvern** » 23 Feb 2014, 16:09

Thanks y'all! I'm currently sitting waiting for roadside assistance to show up because it's now dying at every red light. It's going to be dropped off at the shop for service tomorrow, since I don't have the space or time today to do it myself.

Last time plugs etc were changed was probably about 18 months ago. What you guys are saying does make sense. Going to look under the hood now before roadside arrives.

Raycharles90 · Post by **Raycharles90** » 23 Feb 2014, 16:22

I had a similar problem with my 98 S70 a few years back. Looking back I am fairly sure it was my IAC. I replaced all my vacuum lines which improved the situation but every now and then it would start to die at idle. I did the same as you, pop it in neutral and maintain 1500 rpm. Finally I pulled a few IACs from the local pull a part and stuck one in (after a shop finally identified the problem). Problem solved. I also recently replaced my front O2 sensor which helped as well.

If you get it running as it starts to stumble, tap on the IAC with a wrench or screwdriver and see if it improves the idle. It may be slowly going out.

malvern · Post by **malvern** » 23 Feb 2014, 16:32

Well, I'm stuck without a set of star keys so I can't get the shroud off to check the condition. Bummer.

History is: bought it in September 2011 from a used Volvo dealer. Had been serviced prior to purchase, but the alternator went in the first week. Since then it's had a new radiator, catalytic converter, fuel pump assembly, spark plugs, rotor and caps, front brake pads and rotors, air filter, and regular oil changes. I'm sure I've forgotten some stuff I've had done on the car I now call Steve Austin.

Just saw your post raycharles --I'm becoming increasingly convinced it's the IAC. Which to me is great news since it shouldn't break the bank.

malvern · Post by **malvern** » 24 Feb 2014, 22:14

Well, typically, my mechanic can't replicate the issue when he's trying to diagnose. He told me this morning it's one of three things, none of them serious. But being tired I forgot to ask what the three things are. So I wait while my 850 has a slumber party with his Swedish buddies at the garage overnight.

Post by **abscate** » 25 Feb 2014, 05:23

My mechanic says I can choose what's wrong with my car...his house payment, his boat payment, or his kids college payment. Just make sure he knows you are a lawyer 2B and you will be fine.

Seriously, let us know the good news once done.

malvern · Post by **malvern** » 25 Feb 2014, 16:31

Steve Austin, the $6 Million Car, lives! And under budget.

Turns out what I needed was a new air mass meter and my idle motor serviced. The air mass meter wasn't throwing a code, so the guys went back to what they know about 850s -- but not before eliminating other possible culprits. Sure enough, the air mass meter was toast (or toasty on the way to being toast). My idle motor was filthy and needed a good clean and servicing.

Total: $463.79, which is probably 3/4 labor, since it took them a fair amount of time to replicate the fault and then to drive it around long enough to be confident it's not going to stall again.