Any ideas what might be causing the following?

My modded 99UK wagon (ex Puff the magic wagon) has developed a problem when the throttle is rapidly pushed to the floor when on boost in second and sometimes third gear. It feels like boost has temporarily dissapeared. It doesn't happen if the throttle is opened gradually and peak boost is still achieved. Any thoughts? My gut feel is currently fuelling (although it has had the Walbro upgrade) but I am concerned about the dreaded MAF failure. I have only just joined the ranks of the turbo-charged so I am a bit in the dark.

Thanks in advance.

 

I had that and it was the boost control valve that needed replacing Nothing serious in my case.

 

Thanks Soulgirl. Worked out what one of those is and where it is kept. Had a look and hey presto, some very dodgy looking wiring which I reckon may have been shorting on something in the vicinity. I'll try tidying it up with some decent connectors and see what happens. Thanks for the steer.

 

i have noticed that under say 95% throttle my wrx feels like its pulling better than flat out 100% throttle.

stew

 

This is a bit less subtle. More like pulling really well from say 3,500rpm to 4,500 with the loud pedal full down then sudenly as if you have taken your foot off the throttle completely (repeat this until upper vertebrae collapse). On about two thirds throttle it just swooshes merrily away up to the red line if needs be.

 

mine does similar, if you feed in the power it really flies. if you just plant it , it feels like its holding back slightly. my98

 

Disclaimer- I'm not an expert!!!

If I understand it correctly, MAF failures tend to manifest themselves as an uneven idle, hesitation at about 3.5-4k, or the engine threatening to stall/stalling at junctions. Sometimes all of the above.

If it was just on WOT in 2nd gear I'd say you were just getting the emmissions related boost cut feature built into the ECU but as far as I know this doesn't happen in third. Without knowing more about the symptoms (any strange noises etc?) and mods on the car, it's difficult to advise.

If in doubt take it to your local friendly specialist and have them do an engine diagnostic test and give it a look over.

Regards,

NS04

 

The idle seems O.K. In fact it all seems fine bar this one problem. No funny noises (other than passenger complaints!). It has an EcuTek fitted, would that have eliminated the emissions related boost cut? I also have a SECS monitor which is not showing any fault codes, though I would imagine the dealers diagnostic kit is more detailed. It could use a service anyway so if sorting the wiring to the boost control valve doesn' sort it I'll get a specialist to sort both. Thanks for the pointers.

 

thats what im talking about.


stew