Hey guys

Took the car out last night for a spin, all was well for first 30 mins not really givin it any grief so to speak, i then started to get some feeling for holding boost levels for when i take it to be mapped, this is where my problems started.

Was holding boost at 0.5 bar then 1.0 bar etc etc,

I was holding the boost at 1 bar then put my foot down, boost came in and instantly started popping and banging, so i shut off wondering what was going on , i then tried to accelerate again with the same happening and then it just shut all power off as if i had literally hit a wall, throwing my mrs forward in the seat it was that harsh and had the management light come on and flash then go back off.

Car will not boost as it should anymore, it is hesitant and holding back on boost, with a lot of juddering and pops and bangs. I had litterally just filled the car up with fuel (tesco m99) when this problem started and maybe thought it could be down to a bad batch of fuel??? But would this cause the issues stated? It almost feels like car is starving of fuel or there is no spark it is that fierce when it stops accelerating, when driven under normal load there is NO management light but still feels a little hesitant but nothing like mentioned above.

For those of you who dont know the car it is a 2004 blob jdm sti still running the maf.

I can possibly arrive at 3 possile culprits

1- dodgy batch of fuel
2- tired fuel pump (although was changed 18months ago according to receipts)
3- MAF

Any body else had any issues or any suggestions on where to start, hoping to get car in for mapping again sooner rather than later but cant be doing it with these probs

Any help guys and girls??? Would be much appreciated

Cheers

Craig

 

Spark Plugs? When were they last changed? Or loose coil pack (although it would run like an utter pig with the latter).

When my plugs needed doing on my old car, it would boost up until about 4000RPM and then literally bunny hop, pop and stutter.
Changing the plugs sorted it, but I had everyone under the sun saying it would be the MAF....

Also, get yourself an OBD reader (eBay VAG cables are about £15 and come with software - well worth the investment) - if the ECU flashed it will probably have stored the code.

The MAF is often accused of being the culprit, but I personally haven't heard of a single MAF failure on newage cars - tends to be more of a classic problem.
9/10 times it's never the MAF, it's always something else.

What other mods do you have on it? You say you're taking it to be mapped - if it's got a load of mods on it, like a FMIC or something for God's sake don't go out hooning it until it's been mapped!

 

Hi fella and thanks for the reply

Car was serviced within last 3k miles, car has lm450 turbo with front mount, 880cc injectors,CAIK, decat 3" etc etc, have read alot lately about these bluetooth connectors?? Any good do you know? Just thinking i could leave that in the car and if i ever had a light flash again could plug it straight in, car has been mapped with all of the above just looking to get it re done with bob rawle as he is closer to me for future issues or probs, just found it strange it started doing this after putting fuel in and getting use to holding target boost levels like you would when mapping, hopefully the garage i use has the software to read the codes as he done a few newage cars in the past so fingers crossed! Any chance you can point me in the direction of the cable i need

Bloody cars but i still love it

Edit: just seen the ebay reference shall go take a look now

 

Fuel pressure regulator issue?

What's the car due a remap for?

 

Its going to bob Just for piece of mind really and it smells very rich, i know a little rich is the norm but it smells very strong imo, also its boosting at 2bar or so it shows on gauge, RR shows 1.9 bar, has a fuel lab regulator, like i say it was fine untill i held it at determined boost levels so i could get a feel for it ready for when i take it to bob, and ill also be taking the center resonator out of the exhaust as its cracked on the welds all round front and rear of the box (miltek) for a 3" slip joint pipe

I can see many of the obd readers on ebay, what is everyone using as some of them from memory wont pick up the codes on a scooby

 

No manual boost controller still running the OE ECU also, which is why i think my boost gauge reads a little optimistic lol, but it does this no where near full boost?? Or it wont make full boost (last time i tried) dont want to keep doing it to see the outcome lol

 

When you get your car mapped the mapper asks you to hold a certain boost level I.E 0.5 bar to see what the car is doing, then another run at 1 bar etc, some people find it hard to hold a constant boost on the gauge ( like my friend lol, had to do the driving for him ) so just wanted to get a feel for the car as its new(ish) to me thas all, just a bit of practise lol

 

Trial by internet is never that easy!

I can't see it being a spark plug issue based on what you have said about the symptoms, as it appears you have a problem effecting the overall running of the engine (if it's that violent).

Assuming it fires up and idles fine, it sounds like an overall fuelling issue or something specifically with the MAF.

Get it checked out by a Scooby professional.

 

Yea may just get it up to bob as he's probably the closest to me, also Andy at ace motorsports in newbridge, its never missed a beat until yest, cold starts can be a little rough on idle now and again but thats neither here nor there when its warmed properly, but it was violent the way it stopped boosting, was at a constant 1 bar then just accelerated to see where it reaches full boost, started to go then literally almost seemed as if it stopped, looked like the mrs was at a heavy metal concert the way she was rocking her head lol , it was bought from a member on here James Walker and in turn came from a James scattergood before him or a name similar to that so you may know the car

Any suggestions to a code reader that works? Or the cable i need, checked ebay but there are loads on there, is it a straight forward dl16 plug im looking for??

Found it

 

Got under the bonnet tonight whilst we still had some light, and checked all the breathers, wiring etc, was giving it a bit of a rev under the bonnet to listen for air leaks and could hear a slight hissing, followed the chav valve vacuum pipe back to manifold where i found a tear at the end of it which was just on the edge of the nipple of the inlet, cut it back and re connected and what do you know
Car is fine again now and have noticed that the boost only hits 1.6 bar on my gauge rather than flying off the 2bar step! So all in all fingers crossed i have found the prob! Car also idles a little smoother now so must have been like it for a while, i did have a quick squint when i got it home that all was good and didn notice that! It was facing down so couldn see the tear, was the same when i test drove it and the only thing that struck me was the 2bar of boost, but that said on the RR print out it states 1.9 bar of boost??? And now im showing 1.6 So im a little confused, best to get it up to Bob i think sooner than later to go over it all, just need to sort the exhaust blow now and we good to go!

need to get that chav valve gone asap! It makes hell of a clunking noise when you rev the car under the bonnet opening and closing, im sure there is an underlying problem there somewhere! Last owner said it started to stick on him so he took it apart and cleaned it, think im just gonna get shot an go the DV less route

 

sounds like boost cut..

boost control line come off the actuator or boost solenoid?

 

Hi Simon

The vacume pipe that goes from the top of the dump valve to the inlet was split, i have cut away the split and rejoined and all seems to be ok now would this cause boost cut as well? Before i found the split, my boost gauge would read 2bar and now its been repaired is showing 1.6 so i assume the problem has come from that area, or at least all seems well atm

 

wouldnt expect dumpvalve vac line to cause that no, would expect it to lower the boost and make it run rich.. but without knowing how it is plumbed etc... obviously it was the problem if its now fine with it repaired

 

Forgive me because I have only skim read this. Check the boost / vacuum pipe from the manifold to the OE fuel pressure regulator looking for a split. The pipe should be dedicated but if anything is T'd off it examine that too.

 

Well so far so good lol, taken it out for a good run, giving it all different types of driving, cruising, WOT, short blips, holding different boost levels and it has not replicated it yet so fingers crossed, the vac line runs from the nipple directly under the throttle body / tps sensor direct to the dv, and since re connected tidy the boost level as mentioned has dropped so no idea

Cheers for the reply Harvey, it has a fuel lab fpr on it but have just been out to check the vac line again ( just incase lol ) and all seems good on that front, with no joins and direct to the inlet with a short run of approx 15cm of vac line

Fingers crossed i found the culprit, shall report back if it happens again, going out again later for a late night run so i can open the taps a little more and see what happens.........................

 

Glad you managed to sort it mate - always nice when it's something daft like that