Mystery engine issue

Worrad · Post by **Worrad** » 26 Jul 2019, 06:42

Greetings all. It's been quite some time since I've needed to ask for help here - the old girl (2001 V70 T5M, 214 K) has been pretty good to me for a while now. Here's the recent issue(s): I had been feeling some very subtle hesitations or surging when "loafing" along - fairly low revs. Hard acceleration/deacceleration was fine. I decided to run a can of injector cleaner (Techron) through, per instructions. Ran the tank down to near empty before refilling and the issue seemed to improve as the tank gradually emptied. After tank refill, and after the car sat for several days while a suspension issue was resolved, I experienced severe engine malfunction: surging, inability to accelerate, high idle (1500 RPM, I think). Triangular warning light on dash w/ message to the effect of "engine service required" Multiple roadside shut downs and restarts (initially unsuccessful) and the car began to run normally. Warning light and engine service message remained until next shut down, then both disappeared - message did not display when searched for either. Car ran normally through the day's errands - multiple stops/restarts. Same symptoms the next day, and a couple of times since. A couple of days w/ no symptoms. I haven't been able to get the codes (if any) pulled yet. Car runs great if symptoms are absent, undrivable if present. Any advice? Anyone with similar experiences? Thanks in advance.

93SCMax · Post by **93SCMax** » 26 Jul 2019, 08:51

Original MAF? Been cleaned lately? Start here, and also clean the electrical connector with electrical contact cleaner. Disconnect battery 1st.

I had a similar experience a few years back with my 2001 V70 T5. Final solution was replacing the MAF with a used one from the junkyard. Cleaning was only a temporary fix for me. Make sure you get the same PN (Bosch # on side), although some MAF's are interchangeable. Use the battery reconnect procedure to avoid other problems.

I run a can of Techron about every three tanks. I only run premium. The Techron wasn't your issue, and is recommended to avoid injector issues.

Good luck.

Georgeandkira · Post by **Georgeandkira** » 26 Jul 2019, 09:15

Is it turbocharged or not?
Cross the T's and dot the I's first.
Plugs correct? Their age?
Any symptoms of misfiring? This generally throws codes.
Fuel filter age? It could be original. Air filter for that matter.

You have the inferiorly designed, early ETM. People refer to it as the MM (for Magneto Marrelli, I believe). Even if yours was replaced with another old style one at 100K, it's had enough time to fail too. A patch of mylar film (think recording tape) wears out causing erratic behavior. Does your car hunt (near rhythmic increases and decreases in RPMs)?

Fuel pressure consistent? I've read our fuel pumps are hearty beasts but a 20 year old part is always suspect.
There is a regulator on the fuel rail which may statistically be suspect too.

Worrad · Post by **Worrad** » 26 Jul 2019, 10:43

Gentlemen: thanks for the replies. Here's hoping MAF cleaning/replacement will suffice - a quick drive to bring it up to operating temp exhibits no "hunting" behavior, cold or warm. ETM service sounds painful, both to the pocket and in terms of downtime. Plugs are correct (from dealer), a bit less then 2 yrs old - ~15 K/yr usage. Probably original fuel filter, pump and regulator - I got the car at ~ 168K. I'll back check these as well as ETM in the records the previous owner provided. Air filter looks good, but it's been a while, so I'll address that.

Post by **MoVolvos** » 28 Jul 2019, 23:01

Worrad wrote: 26 Jul 2019, 06:42
I decided to run a can of injector cleaner (Techron) through, per instructions. Ran the tank down to near empty before refilling and the issue seemed to improve as the tank gradually emptied. After tank refill, and after the car sat for several days...

The Techron could have been cleaning the injectors along the way and stirred the bottom of the tank. Try changing the fuel filter.

Post by **velorider** » 30 Jul 2019, 02:22

I had a bad maf and the car stalled at idle and drove like crap. I unplugged it to get home. Without the maf the car will use default values. If your is bad a good test is just unplug it. If it runs better you've confirmed it's the maf.

Post by **abscate** » 30 Jul 2019, 04:23

Unplugging the MAF is not a good diagnostic for theMAF. Covered in many threads

Plugs are correct (from dealer), a bit less then 2 yrs old - ~15 K/yr usage

If they used standard Volvo plugs 30k will be end of life. Single electrode only for turbo cars.

There are probably codes pending you can read. You are on the tail end of the life of the MMthrottle body. $500 fix, roughly. Nearest Volvo dealer if software is needed is rutland, I think.

Worrad · Post by **Worrad** » 30 Jul 2019, 05:11

Update: I have ordered a new MAF - it will be here tomorrow. In the meantime, I removed the old one to clean it. Found a loose plastic cover to a circuit board (?!) inside (black rectangular slab), which I snapped back in place - thought "Ah ha!". Upon replacement, experienced the expected initial symptoms, then after several repeats of same, car settled in to essentially normal behavior - still experiencing that subtle surge/hesitation though. Digging into previous owner's records, I found that the original ETM was indeed replaced which sets my mind at ease a bit, but with time and mileage accrued since, is no guarantee of blamelessness. Careful and repeated monitoring has shown no "hunting" behavior, though, so I'm hopeful there. Also while researching the old records, I realized that I'm a bit overdue for timing belt service (!!) so I have an appointment Fri. to rectify same. I will probably have them replace the plugs at the same time, and will get myself a new fuel filter if the new MAF and plugs don't maker her run flawlessly. Thanks for all the replies!

Post by **MoVolvos** » 30 Jul 2019, 20:04

Worrad wrote: 30 Jul 2019, 05:11 will get myself a new fuel filter if the new MAF and plugs...

You said the Techron showed improvement till it emptied. I would eliminate the fuel first because the new MAF and Plugs could mask the problem if everything is old.

Post by **abscate** » 31 Jul 2019, 04:22

Just coming up on your second timing belt replacement. Some recommend Water pump replacement on that schedule, but if you think it was maintained well with fluid changes you can choose to skip and monitor for weeping instead.

If you think you will run for another 30-50k that’s the more economical choice, but you’re risk aversion may vary from mine