shutter during acceleration

tom4342 · Post by **tom4342** » 25 Jan 2016, 14:46

Would running regular gas in a 98 v70 awd turbo cause a slight shuttering during acceleration? It never did before.

Post by **erikv11** » 25 Jan 2016, 16:14

Not likely, no. Ill effects of regular gas (from running lean) are cumulative over time.

However if you got "bad gas" which does happen this time of year, yes.

tom4342 · Post by **tom4342** » 25 Jan 2016, 17:02

Well been running regular for 3 or 4 years so maybe its added up

Post by **erikv11** » 25 Jan 2016, 18:16

Ah ok I thought you meant just one tank of regular.

The turbo engine is made to run like 91 octane. The main risk of running regular (lower octane, like 87 or even 89) is burning an exhaust valve, which would be worse symptoms than stuttering during acceleration. You could try switching to higher octane, the car's ECU will figure out that you did and adjust, and it is a good idea, but I doubt it will fix the stuttering.

Are there any codes, is the Check Engine light illuminated?

Post by **benpineapple** » 26 Jan 2016, 06:55

If you have an OBD reader, I'd reset the ECU once you fill with premium. Shudder could be a lot of things, especially if it's a rogue symptom with now CEL.

Does the V70 feel like it has much power, or is it pretty tame typically?

tom4342 · Post by **tom4342** » 30 Jan 2016, 08:05

A family member has the car so am going by what she is telling apparently it still has plenty of power might tell her to run a can of sea foam through it

tom4342 · Post by **tom4342** » 30 Jan 2016, 08:06

Only code showing is large evaporative leak which i have yet to nail down however that never seemed to affect performance.

Post by **erikv11** » 30 Jan 2016, 20:54

If it is still stuttering after getting new, known-to-be-good gas, I would consider, in order:

- ignition parts. What is the age on cap-rotor-wires-plugs?
- throttle position sensor. The only way I know to test this is to swap in a good one, like from a junkyard. Not a great troubleshooting strategy if you don;t have a spare part.
- MAF sensor, but these often (but not always) throw a code. What brand is it, what is the age on it?
- vacuum leak. Again, it should throw a code, but they don't always.

Post by **abscate** » 31 Jan 2016, 05:03

Is it shuddering ( low frequency vibration) or stuttering (m-M-missing) ??

Cees Klumper · Post by **Cees Klumper** » 31 Jan 2016, 10:23

Could it be a worn driveshaft bearing?