Possible fuel pump fault?

[WYK]

Hi everyone, long story short. I bought a PFL Legnum from Sydney about 3 weeks ago. (I was meant to introduce myself on the forums but haven't got around to it lately, used to drive a blue Evo 2 with the plates "WYK" if anyone here have seen me)

Went for a drive with couple of mates at mount Dandenong last night, and suddenly I whenever I put my foot down in 2nd or 3rd gear, it's all smooth and boost will kick in but after 3500rpm it cough and misfires, feels like fuel starvation - but I'm not sure. It comes and goes. Sometimes it goes fine till 5000rpm and it coughs a little but mostly at about 3500rpm.

Techsport at Bayswater did a service about 600kms ago with fresh iridium spark plugs so spark plugs will be less likely. Doesn't feel like bad coil/leads too.

So im guessing it could be fuel pump, fuel filter or injectors or something else.

Where do I start?

Cheers guys!

 

[WYK]

Car is completely stock by the way, the only modifications is coilovers, rear strut brace and also evo 7 wheels

 

[naughtika]

could be boost cut...

I know boost cut is a bit more violent, but I've been on several cars where their boost cut is similar to what you've explained

 

[TME_Steve]

Boost cut is a complete cut. Sounds ignition, could be coil packs etc but if it goes super lean you'll see this problem as well. Plugs are one thing, but you still potentially have 15+year old leads and coilpacks. Then fuel pump and don't forget fuel filter. Also a Wideband used correctly would show if lean. Check the plug condition to might show something.

 

[WYK]

After spending several hours on the forum last night, sounds like i might have dodgy coils.
I'll do this in a few days at my mates place, I live in the city so i don't have any tools or space for me to work on my car

I'll service my coils with this tutorial (http://www.ozvr4.com/threads/how-to-service-your-coil-pack-and-stop-the-misfiring.5566/#post-94868), check my spark plugs and replace the fuel filter to begin with

I think its less likely to be spark plugs, Techsport just replaced them less than 800kms ago.

If anything needs to be replaced I'll upgrade it to something aftermarket. Coil fails = COP kit

 

[NuffNuff]

When it was spluttering were you just coming out of a corner hard with less than half a tank of fuel? I get fuel starvation severely in the dandenongs in my vr4. I always go up with a full tank

 

[TME_Steve]

Silly question. What is the spark gap. Should be 0.8mm, check is not 1.1mm

 

[Jye]

Hi everyone, long story short. I bought a PFL Legnum from Sydney about 3 weeks ago. (I was meant to introduce myself on the forums but haven't got around to it lately, used to drive a blue Evo 2 with the plates "WYK" if anyone here have seen me)
Went for a drive with couple of mates at mount Dandenong last night, and suddenly I whenever I put my foot down in 2nd or 3rd gear, it's all smooth and boost will kick in but after 3500rpm it cough and misfires, feels like fuel starvation - but I'm not sure. It comes and goes. Sometimes it goes fine till 5000rpm and it coughs a little but mostly at about 3500rpm.

Techsport at Bayswater did a service about 600kms ago with fresh iridium spark plugs so spark plugs will be less likely. Doesn't feel like bad coil/leads too.

So im guessing it could be fuel pump, fuel filter or injectors or something else.

Where do I start?

Cheers guys!

How did you go with this issue, i have the exact same symptoms and ive replaced plugs leads and coils

 

[Tony_T]

Jye, with the engine idling, give the top of the air flow meter some sharp raps with your knuckles or something. They develop bad solder joints on a couple of resistors which makes them vibration-sensitive and so as your revs increase and with that the frequency of vibration it can cause incorrect fuelling. If the engine varies significantly with your rapping, it will need the joints resoldered. I posted a detailed procedure here somewhere. It may not be that, of course, but it is an easy test to check. Also if it is the AFM unplugging it will make the car drive better but with some fault codes due to the sensors being missing.
Just a thought in case it helps.