Hi all,

I'm new to the whole subaru scene, bought a 2005 (hawkeye) Impreza STi and so far to be honest I haven't had the best of times! Well, this one has turned into a money pit as it span a rod bearing and after spending a fortune on rebuilding her with forged internals, ported heads, SS valves, stage 2 cams, GTX3576R and so on I'm still having a niggling problem that will not allow me to get the car ran in.

As in the title, When the car is started from cold the initial idle hunts from about 2000rpm to around 800 the settles down after about 5-10 seconds, after that it idles fine and revs freely with no signs of cutting out. As soon as the car warms up (say quarter way up on temp gauge) the idle does become slightly erratic as the revs drop as low as 400 then climb back to 800, sometimes it will idle with no hunting and just ticks over as if there is no problem. The worst bit is that if you rev the car even just slightly it will rev up then just drop straight through the idle and just cut out.

I originally changed the MAF sensor for a Denso item (not bought from subaru but a motor factors that a friend works at) and this made no difference, it also still does it with the MAF sensor unplugged.

Iv'e changed both front and rear Lambda sensors for genuine Denso items (same as above) as after the MAF I came to the conclusion this was the only other thing it could be.

Ive checked for air leaks and did not find any. I've been through the whole system with easy start at all the possible leakage points and higher RPM engine response you would expect from easy start.

The car is throwing up no CEL's apart from the TGV deletes i did a few weeks ago.

Sorry for the long winded explanation! Any help would be greatly appreciated, I can't wait to get the car ran in and producing some power!

Cheers

Graham H.

 

What ecu are you using? Some can have idling and cold start problems. Who mapped it for you?

 

I'm still on the standard ECU but was mapped by an ECUTek rolling road. I bought the car already mapped so do not know who did the work. The idle issue was something that just came on out of the blue. I was planning on going to an after market Alkatec ECU after running in, would you recommend getting the ECU with a standard 320hp map on to run the car in?

What idle issues are these ECU's know for. I know nothing about the engine managment side of things.

 

Car needs setting up, the tumbler deletes is enough to throw the map out

 

You're expecting the existing remap to cope with the new mods, even during running in?

 

I was told that running the standard injectors and keeping the RPM's low wouldn't be an issue, as advised by a popular Subaru specalist.

I was sure it was an ECU issue due to the mods but the car was doing exactly the same thing before it was rebuilt, it has got no better or worse. This is an issue that is beyond me. Can anyone recommend someone working in the Lancashire/Merseyside area to take a look at it?

 

Sounds like a long standing map issue