01 V70 T5 geartronic 113k miles.

I have infrequent episodes of engine shutting off (all other electronics remain on) while coming to a stop at a stop sign/light. Restarts right away but RPM will cycle a little and feel sputter on acceleration for a little bit and all is back to normal.

- No codes using BSR Volvo code reader
- Switched fuel pump relay with the fog light relay (same part number) and still have this problem.

MAF is original, plugs done at 90k, ETM replaced awhile back along with latest ETM and TCM software.

Does this now pretty much point at the fuel pump since it only occurs during stoppage?

 

It is possible a fuel pump but it would also do it while driving if it was the pump.
Has the throttle body been cleaned lately?

 

Thanks Tech. Def doesn't shut down while driving although I can barely feel little bumps in the power (uneven accel) while going up steep hill most of the time.

Throttle body cleaned at 87k miles (10/2005) as it was having ETM failure type symptoms. Cleaned it myself and looked like it didn't need it. Volvo put new ETM + software in at 90k miles (12/2005)

I just realized another interesting pattern

- Shutdown never happen on the first drive cycle after starting from cold.
- Subsequent drive cycles (like when running errands). Engine will shut down coming to a stop soon after start.
- Once, I felt a little hesitation on a subsequent drive cycles getting onto hiway but engine didn't shut down.

I mainly take this car to/from work so it is a cold start single drive cycle in the morning and the evening. I never get this problem in this usage.

 

Etm???

 

I would try cleaning the ETM first.

 

Thanks tech. Having done the ETM cleaning before (a bit of work to get to) I thought I share some more observations I made recently before tackling the ETM.

- I think the bumps in the throttles going up hill is just my imagination. Strike this symptom.
- If the car sits overnight or whole day at work (9 hours), it drives fine after starting
- If the car is driven and warmed up, then shut down for say 45min or so, the next start will often result in engine shutdown within just a few stop signs/lights as I brake to stop. But if the car is driven onto highway immediately, no problems occur.

I wonder if it could be brake booster/vacuum related? I had the common hissing brake booster 40k miles ago and it went away after I played around with the rubber bellow (I guess I must have resealed it) So I never fixed it and brakes work fine.

Curious if this provides more insight?

 

Bad humor. Do not read if you're expecting useful information.


Maybe your Volvo has been consorting with a Prius or some other hybrid and thinks it should automatically shut off its engine at stop lights?


My guess isn't Volvo-specific, but it sounds like one of three things to me given the parts you've already replaced might warrant an examination.

First and cheapest, fuel injectors. When cold, extra fuel is pumped in. When warm, they "lean out" so you may not be getting sufficient fuel. Dirty? I know Volvo doesn't recommend any cleaning, but there are chemical cleaners that mix into the gas. Try some Chevron Techron from a bottle. Not cheapest, but it has cleaned injectors for me before.

Second, and I can't explain why this isn't in some trouble code, is O2 sensors reading wrong and causing fuel injector pulse width to decrease causing the warm stall due to fuel starvation at low rpm.

Third, and a remote possibility but one I've dealt with in the 80's on GM cars, is that the torque converter lockup isn't disengaging at the right time so it acts like a stick shift car when you're stopping and forget to depress the clutch. We fixed that with wire cutters, losing the lockup function but it was way cheaper than going into the trans.

Have you looked at your tach as this is happening? Fluttering? Or just drops to zero?

 

Thanks malaka, replies below.

Haha, actually, I've been thinking the Volvo brand would benefit quite a bit from Hybrid. I hear Ford's hybrid system just bolts between the engine + transmission. But Volvos are transversely mounted and probably have little room for this system?

Put a can of BG44 in the tank about 1500 miles ago. Actually, this problem wasn't present before this I think.

When this happens, the RPM just drops to 0 instantly. No fluttering beforehand. Upon restart, the RPM cycles between 600-800 RPM and after I gas it a little, all is back to normal

 

Check the idle control valve since you have the exact symptoms of one that is starting to stick. You can try shifting to neutral when coming to a stop and holding some revs with your foot so it doesn't stall (much easier to do with a manual tranny with heel/toe). It will be worse if the a/c is on (more load to correct).

Try cleaning it will carb cleaner. If it helps, you can keep doing this every 1000 miles or buy a new one.

 

The OP's car is a 2001 and does not have an idle motor.

 

my bad. i forgot the cutoff year.

 

No problem that is how we all learn.
The 98 was the last year for the idle motor on the S/V70 series.

 

Just a quick question regarding theory of operation. I took a look at VADIS and here is what I understand about how air flows to the manifold

1. ETM controls the flow of air into the manifold, even in idle
2. Accelerator Position Sensor basically provides the amount throttle opening through ME7
3. During braking, APS input is disregarded, throttle opening is set by ME7

Is this understanding correct? If so, then idle speed air flow is just ETM + ME7 computer. So as tech suggests, maybe the throttle body is dirty and sticking.

Kinda curious how the ETM would get dirty so quick (23k miles since new) given there was barely any trace of gum during my previous cleaning with much more mileage on the previous throttle unit. I suppose my car's mileage is higher and maybe more oil is being dumped into the intake system through leakier turbo seals?

 

The throttle bodies get dirty easy not sure why but I know they do.
Yes your theory is correct.

 

Sorry to keep on posting back with additional symptoms of this problem. Given it is intermittent, I'm gaining more precise understanding of the symptoms over time. I thought I post the latest clear recognition of a symptom to see if it triggers any additional thoughts.

I had the following happened last night (it happened once before but I was uncertain). After the car was parked for about an hour at dinner, I drove it out of the parking lot and gradually go up a slight incline. Engine is revving at about 2k+ and doing about 30mph then it would instantly drop to 1k with no power but the engine doesn't shut down. the drop is so fast that the car jerks once due to the big momentum change. I naturally back off the accelerator and then reapply, after a couple of seconds, the engine revs up to 2k and all is fine. Happened 3 times during a 1 mile stretch. Then onto the highway and didn't occur on the remaining 20 mile drive home through highway and city streets.

Given the engine didn't shutdown, does it rule out anything like the fuel system?
The RPM drop is so fast that it jerks the car. Might it be transmission related?

 

Sounds like an ETM issue.

 

This random shutdown problem seems to have disappeared for the moment. But I still get a few intermittent slight RPM drops once in awhile when the cars warmed up.

And now I have a brake booster vacuum leak (the hissing sound). I'm guessing this might be my random shutoff while braking problem?

A little history on my brake booster. Had hissing 4 years ago, pulled the bellow off and reseat it and hissing magically want away for 4 years and probably 40k+ miles. Now the hissing is back intermittently.

Think my random shutdown during braking might be due to the vacuum leak? Brake did feel uneven/pulsing a couple of times in the last couple of weeks.

 

Leaking brake booster will cause a running/idling problem.

 

Not sure if this will help any, but my '94 850 is suffering from the same affliction. Low rev counts and shuddering felt through the body work when stopping hashly when the engine is still cold.

I've taken mine into the shop, and the best the mechanics can offer me is this:
199 Requires Throttle Position Sensor
Which should run me about $250 CDN. I haven't gotten around to it yet as the problem is intermittent and seems to be avoidable if care is taken braking.

Hope this helps some.

Cheers.

 

Okay, untangling this cars problems one at a time.

Replaced the hissing booster and still have intermittent shutdown. Got 3 ECU code once that pointed to MAF, accelerator pedal sensor and ECU internal. Since wife has a 01 XC70 and I have a 01 V70 T5, I decided to swap her MAF and bingo... problem found.

Cleaning my MAF and if that doesn't work, I guess I'm ordering one.