Car hestitates and stalls after ECU reset

[TRDcelica90]

Hey!

My car has been bogging down heaps ever since i disconnected the battery.. Its like the car has a massive air leak. Its a gen 2 3sgte gt4.. The AFM is working correctly and i cant think of any other reason why this would happen after it was reset? No error codes? But occasionally the engine light will pop up?

Anyone have any ideas?

Thanks in advance!!

[lexsmaz]

When does it bog down & is the idle low too

[king-szeitszam]

Sounds like what happened with my 1st gen. ended up being a combination of a dodgy FPR and the map being all kinds of retarded.

I know nothing about the ECU your using or the 3SGTE, but I do know that older model imprezas and whatever else had this issue after resets. Basically the ECU would slowly advance timing after a reset meaning that turning her on and hitting the gas hard straight away caused them to stall, and that they ran like shit until they were adjusted. Can't say if this is your problem but if it sounds familiar then try letting the car idle for 10 minutes or so and seeing what happens. The ECU might just need time to learn and get your closed loop air/fuel mixture to what it should be.

if you can get your hands on a log that'd make it much easier for people to try and diagnose what the computer is doing too

[TRDcelica90]

Lexs it bogs down from cold and kangaroo hops to almost a stand still.. I just have to pull over 5 metres from my house and wait longer as it warms up? Im using 1/4 to max 1/2 throttle so not pushing it at all but it has nothing...

Thanks king.. Yeh it seems to relearn the fueling and air mixture as i go along and warm up a bit.. But obviously it isnt ideal as the car could be running extremely lean and i have no idea.. I will look into getting another fuel pressure reg too and see what happens.. Hopefully thats the issue

[king-szeitszam]

does your fpr have a gauge on it? if so just check the pressure at start up then drive it or let it idle for 10 minutes and when it's warm check the pressure again, if it's risen or fallen then you've got a dodgy fpr, probably the diaphragm inside busted.

your ecu should really only need to learn once..it shouldn't have to do it all over again every time you start the car. that said, it'll be figuring stuff out every time you go up a hill or down one, or do anything that you haven't done before- at which point it will struggle (lean-rich-lean-rich-lean-rich).

have you tried just idling it for ages and seeing if it comes good? I'm thinking it's probably trying to work out the right a/f ratio. if you have an o2 sensor then letting it idle is definitely the way to go as fluctuations (i.e revving) will confuse it if it's trying to configure closed loop a/f, because closed loop is essentially used when you're off the gas. my guess is that the kangaroo hopping you're feeling is that lean/rich fluctuation i talked about before, the ecu doesn't know wtf to do so it's using process of elimination trying to get the best mixture- start super rich and super lean then bring it in.

reading that last comment about it needing to warm up made me think about the idle control valve, if that's buggered then the car will refuse to idle nicely until it's warmed up. although the car shouldn't be stalling just because of that, it should just run a little raggity until it heats up. to be honest i doubt your fpr has given up on you just because your computer reset, and it's almost definitely a mapping issue within the ecu.

if you really run out of ideas just take it into a dyno and have it sorted out within a day, that'd really be the quickest way to fix it aside from doing it yourself.

[TRDcelica90]

Update: gone through the car and found one vacuum hose that was split.. Replaced it and some silicone hoses but nothing..

The car will start, rev up to 1000-1200rpm then suddenly die.. Even when i try to use some throttle i cannot keep it running more than 10seconds?? I have checked everywhere for vacuum and intake leaks but nothing??

Anyone have any ideas?? What should be my next move?

[oldcorollas]

is fuel pump running after start?

[TRDcelica90]

How can i check? Its a walbro, installed bout 2 years ago.

[TRDcelica90]

Really stuck :x

[masterofsinanju]

Cold start sensor?

I'm no expert but this sounds a lot like my 23 (stock 1ggze) when I first got it. Idled fine but couldn't accelerate when cold. Fine once warmed up.

Found the cold start sensor was busted. Replaced and now, runs like a champ even when cold.

[TRDcelica90]

Nah its actually getting worse than cold start now.. I cannot keep it running for more than 5 seconds..

Very strange, started it up and drove 5mins down the road, had breakfast then 40mins later tried to start the car and couldnt?? Same symptoms as an air leak but have checked and rechecked every hose..??

Going to check the fuel system now, changing the fuel filter and testing the pump tomorrow.. Hopefully get it sorted

[masterofsinanju]

Got someone who can lend you an ecu to swap in?

[jondee86]

Going to check the fuel system now, changing the fuel filter and testing the pump tomorrow.. Hopefully get it sorted

Yeah, sounds like a fuel issue to me... engine getting just enough fuel to idle, but as soon as you try and accelerate, it goes super lean and stalls. Don't know why it would be related to a reset of the ECU ? Had you been doing other work on the car ? No chance you have crimped a fuel hose or hard line ?

Cheers... jondee86

[masterofsinanju]

I'm totally hypothesising but if you reset a PC and then you get weird glitches etc, you'd be asking if you'd fried something on the motherboard or cpu. In the absence of any changes to anything other than the ECU reset, occams razor says, ECU.

While it sounds like a fuel issue, without having messed with the fuel system itself, seems reasonable to think about the thing that controls the fuel system.

(maybe clean ISCV?)

[oldcorollas]

But occasionally the engine light will pop up?

have you pulled error codes yet?