Throttle issues

[knockoutgiant]

Okay so, I've had an issue with my Legacy from day 1 (2003 BL5 5speed turbo)

Issue only happens on track.

Gives me a few trouble free laps but then down the straights it cuts power.

It was alright to start with but just getting progressively worse (With the new engine, EJ25, EJ20 heads, twin scroll turbo etc)

Now barely gives 1 trouble free laps, cuts power, smokes A LOT (Black Like overfuelling) and is just an all round pain in the ass.

Last trackday I done some logging on a scan tool. Coolant temp only ever got to 100 degrees once, IAT was 25-30 so they're not too bad.

Tuner has noticed that one the data logging, it seems that randomly, my accelerator pedal position reads 100% but the throttle position just cuts to 0%.

Anyone come along this kind of problem before?

Car is running a stock ECU just retuned, however I've been having this problem since it was completely stock.

 

[Kiwi_Fozze]

I would start looking at potentially throttle position sensor, or throttle body. These run electronic throttle body so it's not a too far out idea that the throttle body motors themselves could be failing

[boon]

Get some electrical contact cleaner and clean the throttle position sensor real good. (The one at the pedal)

[knockoutgiant]

10 hours ago, boon said:

Get some electrical contact cleaner and clean the throttle position sensor real good. (The one at the pedal)

I will, but curious, why the one at the pedal?

Accelerator position stays at 100% while throttle position dips to 0% randomly

[boon]

3 hours ago, knockoutgiant said:

I will, but curious, why the one at the pedal?

Accelerator position stays at 100% while throttle position dips to 0% randomly

 

Oh, derp, my bad.

 

Mine had some dicky throttle issues which were resolved by cleaning the pedal end but if it's datalogging at 100% then it's not gonna be that.

Guessing DBW throttle issue? Although it could just be an issue with the TPS. I would see what a complete throttle body, with TPS, is worth from a wrecker.

[knockoutgiant]

21 hours ago, boon said:

 

Oh, derp, my bad.

 

Mine had some dicky throttle issues which were resolved by cleaning the pedal end but if it's datalogging at 100% then it's not gonna be that.

Guessing DBW throttle issue? Although it could just be an issue with the TPS. I would see what a complete throttle body, with TPS, is worth from a wrecker.

I was wondering what you were thinking ahah.

Okay so, getting a 2nd hand throttle body unit with motor/sensor from gotasubi. Will put that in next friday, do a oil change and clean whatever throttle stuff I can find then take it to the track on the 3rd and see if this throttle body has fixed the issue. Here's hoping.

If not it's probably the MAF maxing out at 5.0V so I'll have to get a bigger MAF pipe.