stuartjfalconer

Hi, Im still having ahesitation problem! My car is a 1999 STI V5. So far I have changed the HT Leads, spark plugs, boost solenoid, cleaned the MAF, Replaced intercooler to throttle body pipe and installed missing restriction pill but still the problem exists. ECU finds no faults? Going to put through dyno to check etherythings ok. Can anyone help please!?

P.S. I have used a 0.8mm welding tip to replace the missing pill. My guage was showing 0.6 kg/mc2 and is now showing 1.3 kg/mc2 Is this ok?

joz8968

iTrader: (13)

bar is all but the same as kg/cm^2, so 1.3kg/cm^2 sounds a tad too high to me. I think a v.5/6 STi runs 1.0-1.1bar, so the gauge should max at c.1.0-1.1kg/cm^2.

The way the MY99/00 2-port BCS works is: the smaller the bore in the pill, the higher the boost, so I reckon you need to fit a pill with a slightly bigger bore through it than what you're currently running. You may have to experiment with ever so slight increases in bore, before you arrive at the correct target boost.

joz8968

iTrader: (13)

See here:-

https://www.scoobynet.com/general-te...ctor-pill.html

It would appear the pill for your car is supposed to have a 1.2mm bore. Have you fitted it in the correct position also? It goes in the short bit of vac pipe between compressor cover nipple and the T-piece.

Splitpin

Is this the one you've posted about before? If so it would be far easier and quicker for us to help you if you'd added this extra information to your old thread rather than starting a new one. Keeping it all in one place makes it easier for anyone trying to help you to work out what's going on without having to try and make sense of your posting history. Luckily as you've got so few posts that's not too onerous a task but please take note in future. Ditto anyone else reading.

Cleaning an airflow meter, especially a 99-00 HFM one is largely a waste of time. It isn't normally dirt that kills them (unless you are running an absolutely sh*t air filter) so if you're suspect about it and don't have any method of checking its operation in use, the safest way to check is just to replace it and see if the car's behaviour changes.

Good bit of ingenuity but the diameter of the hole is too small and a MIG tip is a bit too long. Both will affect the airflow to the solenoid which is why you're getting overboost at the moment. If you can't get hold of a real Subaru 0.9mm restrictor, cut the threaded end of the MIG tip off so you're left with something about 6mm long (smoothing the cut edge nicely) and then ream it out with a 0.9mm drill bit.

No that's overboosting by quite a considerable margin. Boost target should be 1.08 bar through midrange and dropping to 1.01 above about 5500 so 1.3 is far too much. Given that STi5's are already det prone when run on UK fuel (even VPower) at standard boost, your engine will probably not be liking being driven like that for very long.

Incidentally was this "hesitation" present before you fitted the MIG tip restrictor?

stuartjfalconer

Yeah the hesitating was happening before. Im starting to wonder if I will ever find the cause!

stuartjfalconer

Yeah its the same as before. I couldnt work out how to continue with the same thread. Sorry.

Splitpin

I'd imagine a specialist with some diagnostic kit would be able to narrow it down in a few minutes. Have you considered going that route? Has the potential to save you loads of time and agro in the long run.

Same way you continued this one. HTH.

stuartjfalconer

Ive taken the car to subaru and they said that they plugged it in but coulnt find a fault?

stuartjfalconer

[quote]Good bit of ingenuity but the diameter of the hole is too small and a MIG tip is a bit too long. Both will affect the airflow to the solenoid which is why you're getting overboost at the moment. If you can't get hold of a real Subaru 0.9mm restrictor, cut the threaded end of the MIG tip off so you're left with something about 6mm long (smoothing the cut edge nicely) and then ream it out with a 0.9mm drill bit.[quote]

Right, Ive changed the hole its now 0.9mm my boost goes to 1.1 but creeps to about 1.2/1.3 when flat out in higher gears. Is this ok or Am I risking it abit?

joz8968

iTrader: (13)

Ah, it could be "boost creep". This is more susceptible on decatted STi's. Does yours have a decat d/p?

A way to prevent/alleviate it, is to have the turbo's w/g flapper hole smoothed and ported. Or a mapper might be able to do something about it, if you decide to get a remap...

joz8968

iTrader: (13)

Can you note get hold of a pill with a 1.0mm bore and try that?

dynamix

iTrader: (3)

just join the turbo hose to the actuator and see what boost the actuator gives you and also see if this cures the hesitation.

stuartjfalconer

I think when the last guy put the car up for sale he put the car back to standard. I think he refitted the cat, speed restriction etc. Would "boost creep" still happen? also just a thought if the car used to have d cat pipe etc, is it possible that he had a remap and by changing things back to standard, has caused my hesitation problem?

stuartjfalconer

Would this be a permanent solution? what about the other pipe in the t-peice? do I need to blank anything off?

dynamix

iTrader: (3)

It would provide a base level of boost and rule out solenoid or overboost/boost creep related issues.

It will provide a baseline figure and info to problem solve further. Any subaru specialist (not a subaru dealer) will be able to help you down the problem solving route.

stuartjfalconer

If I go form actuator to turbo what do I do with the other pipe in the t-peice? do I need to blank anything off?

FB Tuning

iTrader: (30)

Easiest way is just to disconnect the standard pipes from the boost source and the actuator on the turbo, and run a seperate piece of vacuum pipe directly from compressor cover to the actuator. You can just cable tie the standard pipes out of the way, for testing purposes.