noisey pump on start up

[s2dude]

well i spoke too soon, niether the fuel pump or mark H mod has cured the uneven idle or the flat spot
I went for a propper test run last night and drove the same piece of road a few times to try and figure out exactly where in the rev range it's happening and how best to describe it.
I found that the effects of the problem are exaggerated when going up a steep hill, which makes sense. Accelerating at full throttle from 2000 rpm to the red line i get severe flat spots or loss of power between 3800rpm and 5800. The power does come back in again in spikes. From 5800 to 7000rpm it doesn't seem to be happening but that could be because the power is tailing of anyway and its just less noticeable.
The best way i can describe the sensation is that when the power cuts out its just like when you get wheel spin from going over a wet patch on the road, when the power comes back, there's a big surge, just like when the wheels find grip again.

nip and idub, does this sound like the same thing you're experiencing?

What boost are you getting?
Does that spike up and down also? If you havent got a boost gauge you need to fit one mate
easy job and I have found it to be a great troubleshooting tool. search the forum for a howto

[robk]

dont have a boost gauge at the mo so no idea, i'll probably fit one at some stage soon, i'd be interested to see what max boost it's making

[Jay]

same thing!

come on guys please help on this one...

If you get to the bottom of this problem let me/us know as I have the same thing going on... was going to do the same things eg fuel pump, Mark mod, plus new MAF, new plugs, new leads etc!!!

When mine looses power it sounds like traction control/ rev limiter has cut in, back off a bit and it goes, very intermitant, not affected by the damp (should get worse if HT problem!) driving me mad but to busy to spend time at mo... may get Corey to look when hes well!

Good luck on this one!

Jay

[robk]

....forgot to say earlier, if i hold the car at 4000 ish rpm then floor it, i dont get any cutting out or flat spots.
My extremely limited knowledge of how the waste gate and wgfv works made me think that......At 4000rpm you should be getting something close to max boost? Therefore the wgfv would have the waste gate fully closed at this stage as all the boost pressure is being used by the engine?
If the wgfv is not working as quickly as it should, when you accellerate from say 2000 rpm all the way to the red line, the boost builds very quickly and maybe the wgfv doesn't react in in time and a big chunk of your boost pressure is lost? and that's what causes the flat spot?

Could that be anywhere near the mark or am i just talking out of my hole!
If someone would like to come along and explain how the waste gate and wgfv actually works i'd be very interested

[s2dude]

....forgot to say earlier, if i hold the car at 4000 ish rpm then floor it, i dont get any cutting out or flat spots.
My extremely limited knowledge of how the waste gate and wgfv works made me think that......At 4000rpm you should be getting something close to max boost? Therefore the wgfv would have the waste gate fully closed at this stage as all the boost pressure is being used by the engine?
If the wgfv is not working as quickly as it should, when you accellerate from say 2000 rpm all the way to the red line, the boost builds very quickly and maybe the wgfv doesn't react in in time and a big chunk of your boost pressure is lost? and that's what causes the flat spot?

Could that be anywhere near the mark or am i just talking out of my hole!
If someone would like to come along and explain how the waste gate and wgfv actually works i'd be very interested

This is the factual information you need on wastegate and WGFV operation!!!

clicky

As before...
S2's are bad for boost leaks with the standard crappy hoses. I have had several and they cause all sorts of mayhem, mild leak can just mean a flat crappy powerband, a bigger one can mean surging and so on.
From what I had to do I would say:

First step. Search forum for "pressure test"
get a boost leak test kit
test the system with a compressor

see here for info click

Then if it doesnt leak fit a boost gauge and new wgfv (£30~) (again: search is your friend!)

then report back

[newsh]

Do what he said, plus, clean the MAF connector really carefully.

[newsh]

If a 3B check your static timing, this must be perfect do a search you find a how to on here.
Misfire above 3000 can be Inlet Air Temp Sensor, ideally buzz it through from the ECU. But pull the boot back and check the wiring is ok at the sensor.

[iDub]

Yeah sounds like exactly the same problem as me. I've got a boost gauge so I can see what's going on though.

Did a 275 mile journey in it yesterday. I've worked out that if I keep the boost level below 5 psi then it's pretty smooth. Above that the performance doesn't seem to change much, but it feels like it's surging all over the place. Max boost is 18 psi at the moment. I'm told it's been MTM'd so I think that's actually a wee bit low.

I've cleaned the MAF and the MAF connector, and that made ****** all difference. I'm going to do a blink test tomorrow and see what it tells me.

I've just ordered a hose to replace the IC O ring, so we'll see what happens there. If it does nothing, I'll be ringing MTM and booking it in, as I've not got the cash to keep replacing parts.

[s2dude]

Boost leak.
have you done a pressure test yet?
o ring 1st..then any other hoses that are leaking!
18psi?? is that a one off or consistent? if your boost levels are inconsistent (going on discoveries with my car anyway) it may well be a pressure leak.


edit//

MTM?? they will charge a fortune. Much better taking it MRC or Quattronics.....will cost a lot less most likely

[robk]

right, i fitted a boost gauge yesterday and by about 3000rpm its making 22.5psi which i think is 1.53 bar. It only holds this pressure for a second then gradualy drops to 15psi - just over 1 bar by 6000rpm. What should it be doing? is this normal? I would have thought it should hold max boost for much longer.

I had read all the threads on boost leaks and pressure test kits already and buying/making a test kit is definitely next on the list of things to do.

I was talking to S2central on friday as i have one of his homefries on loan at the moment. A very knowledgable and helpful bloke he is too. One of his thoughts was that
given the crappy fuel we have here in ireland (max 95ron and no optimax available) and the current MTM ecu i have fitted, knock sensors could be coming into play.

Anyway, all advise points at boost leak testing first so that is what i shall do.

[Davidsinclair05]

I Had this problem

Take off your MAF sensor and spray with Carb cleaner and check your vacuum tree.
It was a long running problem but this cured it big time!!! Car has NEVER run as good as it does now.

http://www.s2forum.com/forum/showthread.php?t=19170

[iDub]

MTM?? they will charge a fortune. Much better taking it MRC or Quattronics.....will cost a lot less most likely

Shows that I'm not even reading my own posts before I send them... I meant MRC. I'm in Northampton, so they're only about 30 mins away.

The 18 psi is constant. It'll hold that from about 3500 rpm (ish) until redline in most gears. I would have thought the MTM chip would have sent it over 20 or so.

From reading the forum (a lot...) it seems a lot of people have problems running 95 octane fuel. I'm also running it on 95 at the moment. Would this also affect the off-boost performance?

[robk]

well, i've not quite fixed the problem entirely but have reduced it a huge amount. At the back of the fuel rail there is what looks like a pressure regulator with a metal pipe leading to it. The 2" rubber hose that connects the pipe to the regulator was very loose, tightening this seems to have more or less got rid of the flat spots. It's still loosing boost pressure quite rapidly though so im guessing that there are still a bunch of other leaks to be found

[alg]

well i spoke too soon, niether the fuel pump or mark H mod has cured the uneven idle or the flat spot
I went for a propper test run last night and drove the same piece of road a few times to try and figure out exactly where in the rev range it's happening and how best to describe it.
I found that the effects of the problem are exaggerated when going up a steep hill, which makes sense. Accelerating at full throttle from 2000 rpm to the red line i get severe flat spots or loss of power between 3800rpm and 5800. The power does come back in again in spikes. From 5800 to 7000rpm it doesn't seem to be happening but that could be because the power is tailing of anyway and its just less noticeable.
The best way i can describe the sensation is that when the power cuts out its just like when you get wheel spin from going over a wet patch on the road, when the power comes back, there's a big surge, just like when the wheels find grip again.

nip and idub, does this sound like the same thing you're experiencing?

sounds like a boost leak and/or DV.........as you say boost tails off towards the redline and is at its highest under load(up a hill

[s2dude]

Shows that I'm not even reading my own posts before I send them... I meant MRC. I'm in Northampton, so they're only about 30 mins away.

The 18 psi is constant. It'll hold that from about 3500 rpm (ish) until redline in most gears. I would have thought the MTM chip would have sent it over 20 or so.

From reading the forum (a lot...) it seems a lot of people have problems running 95 octane fuel. I'm also running it on 95 at the moment. Would this also affect the off-boost performance?

it needs Super Unleaded. 98 ron.
Tesco's is best