1995 Subaru Legacy - what went wrong?

No good deed goes unpunished. This great old car has lasted years, a bit beat up but smooth and dependable. We inherited my Mom’s car so made plans to give this one to some friends in Colorado. Before the cross country road trip, we took it to a repair place saying “change the oil, make sure its road-safe, and tell us if there is anything we have to fix.”

They recommended we change the timing belt (never had, at 120k) and repair a torn boot. Not wanting to give our friends a problem waiting to happen, we decided to do the work (some $2000!). Now - the car runs like crap. The accelerator rev’s up and down randomly (almost stalling at lights and bucking/surging while driving). It’s horrible. It’s still at the shop - I won’t take it back til its safe.

What went wrong?

This could be something as simple as a disconnected vacuum hose, or a disconnected Mass Air Flow sensor (MAF). After doing the timing belt job, it is possible that the mechanic failed to reconnect one of these items.

Or it could be something totally unrelated to the work that was done, and could simply be coincidental in a 15 year old car that has been poorly maintained. Why do I say “poorly maintained”? Because that timing belt was due for replacement about 8 years ago, based on elapsed time. (The specified interval is “every 105k miles or 7.5 years, whichever comes first)

I suggest that you check your maintenance records, and if it has been more than 30k miles since you replaced the spark plugs, plug wires, air filter, fuel filter, coolant, brake fluid, and transmission fluid (if it has an automatic trans) then those things need to be done now. It is also possible that the fuel injectors need cleaning.

Bring the car totally up to date with maintenance if you want it to run properly.

I have no idea what $2000 was for. A timing belt should have been around $500.

The car was likely due for a timing belt however the 2.2L Subaru engine was not interference so it would only lead to a break down but no other ill effects if snapped.

The rev up and down hopefully is related however could be a simple failure of another part and simply bad coincidence. The car is in fact 15 yrs+ old and stuff breaks.

Thanks for vacuum hose idea or MAF

I was exaggerating in my frustration - belt was done years ago at 60k or so. Had all the rest done as part of this service (so belt was indeed around $500 and labor another $500 and other maintenance was the rest).

I agree with the vacuum leak or MAF possibility.
Something else to consider is the possibility that a camshaft was installed a tooth, or plural, off.

When a camshaft(s) is off the marks this affects the manifold vacuum and a can of worms can be opened up.

The easiest way to verify a problem with any of this is by connecting a vacuum gauge. This is very simple to do and will show in 2 seconds if something is out of whack in these areas.

All - Thanks for the input. Indeed, it turns out to be the Mass Air Flow sensor. It was very useful to have your ideas when the shop called to say that this was the problem.