scoobyKid1983

Hi All,

I have been on an off these forums for years but not really had the time to get involved with the community for a while due to work/life commitments.

I really need some technical advice with a question about changing the ECU, but before I do I am hoping someone might shed light on the problem with my car.

Make: Impreza UK Turbo 2000
Year 1999

The car was running fine & boosting fine until my MAF sensor went kaput. The car died and wouldn't even try and turn over. I replaced the MAF sensor and sure enough she fired up but struggled to idle.

to cut a long story short I went through the process of trying to track down the issue so I replaced the following on the car

- 2nd MAF sensor (new) in case the first was faulty
- idle control valve (ebay)
- throttle body inc new gasket (ebay)
- throttle position sensor (ebay)
- removed dump valve back to original
- removed induction back to standard
- new spark plugs/leads & service
- new cambelt
- new vacuum hoses
- TD05 20g turbo (managed to blow the other one up while testing the vacuum hoses!)
- Stainless steel exhaust headers & turbo up pipe
- uprated fuel pump
- replaced inlet manifold & new gaskets with reconditioned and injector rubber seals (one was corroded and brittle).

It now idles ok when warm but is lumpy when cold. It is also very unpredictable when boosting. It can sometimes rapidly hesitate which makes the turbo sound like its got anti-lag before it takes off and when you dip the clutch before 1k revs it drops off and stalls. If it doesn't stall then it bounces up and down a couple of time until it settles at 800 revs on idle.

sooooo the next 2 options that have been suggested to me are coolant temperature sensor or ECU.

I should be testing a replacement temp sensor this week but looking at my ECU (E3) I see some on ebay going with the alarm keyfobs & ignition set.

so my 2 questions are:

1. Do you have any clue as to what the f*ck is wrong with my car as I certainly don't any more!
2. If I need to replace my ECU, is it going to kill my alarm system or do I need to get it all re-coded etc. I have the subaru approved alarm with the blue fob

I am at my wits end with and about to flog it on ebay just to be done with it but I though some scooby experts might have an idea as to what is going on...

Any help would be very much appreciated (if you are local there may even be beer in it for you...)

Cheers
Ben

rb5 stu

On the 99/00 cars the alarm system is run off its own brain so no need to worry about that.

scubbay

iTrader: (61)

Apart from the obvious a smoke test and a compression test would be my next move

rb5 stu

Try the coolant temp sensor first. They can affect quite a few things if they arent reading right. Also make sure its a genuine one as some of the cheaper sensors are crap.

scoobyKid1983

Thanks peeps, Compression test comes back OK. Is there an easy way to do a smoke test yourself? The vacuum pipes have been checked & re-checked, as well as other pipe work in the engine.

Cheers
Ben

tjmatt

iTrader: (1)

Was the turbo that came off a TD05 20g ? And ECU mapped for it? Otherwise not surprising you're having issues on boost and hitting fuel cut.

Is the lumpy idle from immediately as start the engine from cold or within a few minutes of starting with the engine still cold? if it goes bad within a minute of starting then the lambda sensor may be at fault. Have you checked for a vacuum leak - replaced the ICAV seal? Small vacuum leak can have quite a bad effect on idle.


Sorry I only just read your last reply about vacuum leaks...

tjmatt

iTrader: (1)

Also if you changed the cambelt it can be quite easy to get it one tooth out, as it tends to set inbetween two locations.

I would have a search on that topic and check that you have it timed up correctly. This can cause it to run a bit odd and the ECU might struggle with feedback from the lambda if the cam timing is out slightly.

chrispy200+

iTrader: (2)

As said, have you got a dump valve, has it been mapped for the 20g?

MrNoisy

iTrader: (28)

But yeah, sounds more to me like the problem is you're running a turbo the car isn't mapped for, which means you're more likely to kill your engine continuing to drive it.
A standard ECU will NOT compensate for a bigger turbo.
Solution - get ECUTek / Open Source map (if valid) or an ESL or aftermarket ECU and a remap

FMJ

iTrader: (2)

The ECU should be fine to swap with another of the same number.

It's not the alarm to worry about its the Subaru factory imobilisor which uses a transponder in the key. This is why some ECU's come with key and transponder/receiver. However this is only an issue if you are using different keys. Some ebay sellers think when you change ECU you have to have the key and transponder to match but they are wrong.... The two systems are separate.

I would also ask about that turbo? Surely it's been remapped for it? If not there's your problem. I do wonder as you are asking about another ECU which would obviously not be mapped for your turbo and would not work with that turbo without a new map.

If you want to bin the car send it this way.

scoobyKid1983

Thanks for the responses.

I am fairly sure the cambelt was fitted correctly, although I will check this thanks

Unfortunately I was not aware the 20g would need a remap, having talked to people who upgraded to a 16g td05 without a map I thought it would be ok (stupidly)

I have replaced the throttle body at the weekend and reseated the ICAV so I don't think that is the issue.

I doubt the turbo would cause the issue with it stalling and erratic idling though?

tjmatt - if its very cold it will be from the off. Once it is warm it seems to calm down although I still have the stalling issue when pressing the clutch in. Surprisingly it doesnt stall when cold, but I assume the automatic choke is supplying more fuel until it is warm.

Thanks
Ben

FMJ

iTrader: (2)

If you have been boosting with a turbo like that and no remap you could have caused no end of damage.... I would take it to a specialist and ask them to make it work and be prepared to pay for it or just sell as a project. Even with a remap that turbo would probably require bigger injectors and would kill your gearbox fairly quickly etc... You need supporting mods for bigger turbos you can't just chuck them on.

scoobyKid1983

Its only been driven a hand full of times as its been so poorly and I have a commuter car so I don't think I have done any damage. Would the turbo be throwing out the throttle position etc to cause the car to stall?

To be honest I am tired of spending my whole free time trying to fix it! Its got a front mount kit to go on it as well.....

So either get another td04 or sell as is...

FMJ

iTrader: (2)

Hard to tell really as it will have been very very lean at boost. You can't be fed up of trying to fix it when it was only broken because the wrong turbo was fitted lol. If you break it for parts let me know. Yes you need a TD04. Put it right back to standard and see if it works properly.

MrNoisy

iTrader: (28)

OR....get it properly mapped as advised above.
Don't fit ANYTHING else without a map.
I'm surprised you haven't blown the engine already tbh. Your boost and fuelling will be all over the shop with that turbo.
One of our members blew his engine just from fitting a FMIC and then driving the car on boost.

No matter what some idiot people might tell you on those god awful sites like swap shop, these ECU's are NOT self learning and the cars will go bang if you don't have the map adjusted to compensate for the components you change. Arguably a back box you can get away with, but FMIC and bigger turbos are way off scale!

The Rig

iTrader: (13)

What part of the ICV did you replace, the valve itself or the electromagnet part or both ?

you say you replaced the TPS but did you fit it correctly as in the resistance is correct etc ?

scoobyKid1983

Thanks for your advice and replies guys. There is no knocking or smoke so I am hoping no permanent damage has been done!

I'll have a think, I work away during the week so I have very little time to work on it unfortunately. Its taken over 6 months to get it this far.

I can't afford a custom map so it will be a td04 back on unfortunately. If anyone wants a 20g TD05 to fit a 1999 impreza let me know. I can't remember what angle the 99's are off the top of my head.

Cheers
Ben

scoobyKid1983

The ICV came as the whole unit which screwed into the throttle body.

I replaced the throttle body which already had the TPS set so I don't think thats the problem.

Cheers
Ben