Cough

[RB5Bird]

Hi All,

Just wondering if anyone has any ideas what could be the problem, the garage reckons it is the boost solenoid. They had it the other week and cleaned it through, but it hasn't solved the problem.

The symptoms do not show as much when cold. Say you are sat behind a truck at 70 (ish) and you plant your foot down to go past it, at 3000rpm it really coughs and splutters, through to about 3800rpm. This happens in 3rd, 4th and 5th, haven't really noticed it in 2nd, but you probably wouldn't. If you put your foot down nice and gently, it's not too bad, just a slight hesitation.

Other than that the car is fine - starts and runs/idles fine.

Cheers.

[MGZTV8]

Have you tried Tixylix or Covonia?

[JollyGrnMonster]

It could be compressor surgr but I presume this is a new feature and no mods changed on the car?

So most likely a spark misfire - plugs, coils, leads. What years the car? As certain years have common spark related issues

Simon

[markCSC]

Did you/they read the error codes? Doesn't sound like it's MAF related so I'd go with JGM and say plugs/leads/coil

[ScoobieWRX]

I think you might have a boost or Vacuum leak

[RB5Bird]

It's a MY99 RB5, totally standard. It had just had a service, which included plugs. Only noticed it on the way home, obviously once it had warmed up and I'd got through the town centre traffic.
Watching a solenoid on eBay, bit of a risk, but would rather pay £30 instead of £180.

[Terminator X]

Mine did that when plugs were changed to 8's (ran too cold) and sorted itself when 7's were put back in. Plugs?

TX.

[RB5Bird]

Why would the plugs only be rubbish at certain rpm?

[JollyGrnMonster]

In very basic terms the spark is jumping to ground, it takes the easiest route. The pressure, fuel mixture, rpm will effect how easy it is for the spark to jump the plug or to the head via a crack in a coilpack or spit in a ht lead or if coil is weak jumping anywhere.

Usually occurs at peak torque.
So depending on which model, year and mods you have (hence my question) 3000-4000rpm

Simon

[JollyGrnMonster]

If the problem wasnt there before the service then you shouldnt be paying for parts. Take it back. Sounds like plugs have not been gapped (should be 0.7mm) or are incorrect.

[72twink]

JGM - totally, my old long suffering Smoker Sport started doing this, pulled the plugs, closed the gaps to spec and the problem went away, new plugs were bought the next day!

[japgt]

whilst your at it change your local garage to someone who knows what they are dealing with!!!!

[RB5Bird]

Got the solenoid for 31 quid, just hope it works.
Cheers people.

[RB5Bird]

Right, fitted it at the weekend. It has improved it, but it hasn't completely cleared it. Will probably just go for a new one now, as a used one off ebay is just as likely to be knackered - just less knackered.

[JollyGrnMonster]

Your wasting your money

[TAS1981]

Unfortunately there are a million and one reasons why this sort of thing starts to happen. There are also a few things that have the same effect on the car, ie loss of power, hunting, spluttering etc etc especially on the older models now.

I know as I went through most of them....here is a list.

Spark plugs - Pull one and tell us what the code is, check gaps replace - free
Coil packs breaking down? - Are they on the plug on RB5s? Check the tip for cracks, damage or carbon build up.
MAF sensor Spray electric contact cleaner on it (don't touch it)
Boost solenoid spray through (done - its not that)
Detonation / Pinging? - Possible, have you ever tried the Subaru top engine cleaner? Carbon build in boxer cylinder > detonation > boost reduction - I had this on my Classic STI. Octane booster temporarily improved it, engine spray cured it.

Good luck.

[cheesesliceking]

JollyGrnMonster said:

Your wasting your money

+1. The problem occured immediately after parts were changed... Seems simple to me.

[Xtremescoobys]

Me too its the Flux capacitor

[Terminator X]

To the OP - you do realize that JGM knows a thing or two about scoobs?!

TX.

[RB5Bird]

Of course.
Just started a new job and not had time to sort a garage or anything. Think I will be giving him a ring soon though, he's in Camberley isn't he?