Hi Guys

Car is a 2002 WRX with the following mods

Eclipse Performance 255L pump
K&N Panel Filter
Decat Uppipe
Decat Downpipe
Milltek cat-back
NGK PRF7B Plugs - 1k miles old (full service at same time)
Remap

The car is surging at motorway speeds, 4th or 5th gear, light to medium throttle as it comes on boost. Heavy throttle can stop the sensation. The surging can be violent enough to rock the whole car.

An additional piece of information after reading some other threads is that I have a t-piece and pipe fitted for a boost guage but presently the guage isnt fittted as it is being moulded into the dash. The pipe is 'sealed' with insulation tape. It is by no means airtight and air can be heard escaping. Today whilst coming back from Autosport at the NEC I had a fiddle by squeezing the pipe and the surging characteristics changed.

Also, occassionally, when the car surges like this I get the EML and the codes P0301, P0302, P0303, P0304.

Now its obvious to me that I need to get a better quality pipe for the boost guage (cheap nasty thin wall rubbish at the minute) and to get the guage back in and seal the leak. But, what else do I need to start looking at?

 

Deal with the air leak first,this alone can cause surging. If your gauge is not connected you must plug it with a suitable air tight bung a bolt may do this. If it still does it you may need it mapping for your mods.

 

Hi mate. Those codes show a misfire on all 4 cylinders. How long has this been happening? Has it been doing it since you sealed off the boost pipe? If your loosing boost through the pipe it would cause it to run a bit rich, and could cause a missfire (but maybe not as bad as you described). Can you not just fold the end of the pipe over and then seal it with a cable tie? That will stop any leakage.

Try that first and see what happens. If adjusting the pipe changed the characteristics of the surging then its likely to be the culprit.

 

Thanks for the answer guys.

The map was done at the same time as the plugs and service, directly after the mods were finalised.

In honesty I'm unsure how long the problem has been there, I.e. Was it underlying and the mods have accentuated it, etc.

I will plug the pipe and fold/tie as a belt and braces to see how it behaves

 

Right, I've just done that and there has been a definite difference. The car sounds different and 'feels' smoother, though that is likely a placebo effect?

The car still surges! Starting at 3k revs through to almost 4k, not as violently as before but more analogue, I.e. On/off/on

 

And to answer the earlier question, its been doing it for the last 3/4 months, since the modding started with the Eclipse pump and uppipe. I always assumed it was because I needed to get the map done

 

How much boost is it running?

Unusual with those mods to get surge, is the boost hose plumbed to the manifold or perchance into the boost control pipework at the turbo?

If it was leaking when mapped it would effect it.

Simon

 

I haven't had a guage on it since the map so don't know the boost am afraid, but, I have it in my head that it went from 1bar to 1.3bar, does that sound right? The leak will have been present at the time of mapping. The car has had several map sessions, during one it was highlighted that the boost couldn't be maximised due to something in a pipe, that was then swapped for an STI spec one?

P.s. The guage pipework goes to the manifold as per a how-to I found on here

 

Well leak when mapping wont help but would expect it to be noticed.

The restrictor pill in the 2port boost solenoid pipework is smaller on the sti and will bring boost higher.

 

Thinking it through - during mapping sessions the boost guage pipework was removed and replaced with mappers own guage and associated pipework so presumably wasn't present

 

The CEL codes are fairly commonplace on a bug wrx with a faulty neutral position switch. Would occasionally flash CEL at high revs too. Simple fix.

As for the surging, if the hoses are leaking then it isnt going to help but could be another issue. Needs investigating though - have a word with you mapper or if they cant help I am mapping in durham next week ...

 

Thanks for that Duncan, yes the CEL can also flash at high revs. Where is the switch? Is it easy to replace? Is it something I should be fixing or one of those things that can just be deactivated by the mapper?

Have already spoken to mapper who is keen to have a look at it, otherwise I will be in touch, thanks

 

The switch is on the side of your gearbox and just tells the ecu that the gearbox is in neutral (Hence the name) - doesnt affect performance on wrx's but does throw up random CEL, mostly misfire codes or cam position sensor faults. It is possible to switch them off in the map but it would probably be better to fix the issue than mask it.

This doesnt account for the surging though, this is a separate issue.

 

Thanks for that, I'll get the switch sorted.

 

Right guys, this has been back with the mapper for a couple of days who has diagnosed a faulty 'boost valve', he stated that it would likely be cheaper to pick up a second hand Greddy one. I am going to check with him but I assume that he means a boost controller? He said that if I switched to a Greddy I would have to make sure that I got the electronics and the actual valve.

Does this all make sense as when I search for Greddy's all I can find is the electronic controller?

 

not really sure why a mapper would recommend that ???
assuming he means the boost solenoid, just pick up a 3 port, usually loads for sale.
Might be a good idea to try another mapper

 

no, its not the solenoid, I checked. He's the mapper I use and I will be sticking with him.

He stated that the boost valve on the car is faulty and that aftermarket ones are usually cheaper than Subaru ones, which he says are very expensive

 

Boost solenoid or map sensor?

Problem seems unlikely to be map sensor and boost valve would normally be referring to boost solenoid which could be faulty but usually work or dont work ie. boost or actustor pressure, usually have several to fit and check there and then, they arent expensive.

Simon

 

La la la he no hear you

 

I've obviouosly misunderstood what he is saying and am aware that I am painting him in a bad light which is not the intention. The lack of knowledge is most definitely on my part not his.
It is certainly NOT the solenoid, I have discussed moving to a 3-port with him and know it is not that.
He keeps a staggering array of spare parts but unfortunately does not have this part in stock. I will speak to him and get him to confirm the part in question before I return to ask a more informed question.

 

 

Typical scoobynetter response. I openly say that it is me getting my facts wrong and still get told I'm not listening because you want me to sack my mapper. Think you need to re-evaluate who it is that isnt listening

 

 

Choose to totally ignore all the advice you have been given here if you wish, its your car !

Maybe you can talk to your mapper and find out exactly what they suggest you change ?