Classic Sti poor running

[Nesty]

Hello folks, my sti has developed a running problem and I was wondering whether you guys could shed some light please. The back story is as follows.:

It's been stood for a while so I had to jump start it a couple of times to get it started, it ran fine on the way to the petrol station (about 8 miles), I filled it with shell nitro + and it started fine but the battery was obviously quite weak. As it was fully warmed up I then gave it some welly through the first 4 gears, eased off the throttle and then when I applied it again it had a bit of a stutter, then ran really lumpy, did not rev cleanly and is well down on power. It doesn't tick over smoothly and when I accelerate the car shudders.

I've since changed the battery as it was toast but it hasn't improved at all and prior to sitting for a month the car ran like a dream and went very well.

Any suggestions would be gratefully received.

Thanks

Tom

[TEKNOPUG]

Could be all manner of things. Have you got a code reader? That would be my first point of call.

[MDMA .]

not sure on your model, but on some, after the battery is disconnected, you needed to do the following -

1) Turn off the lights, aircon, stereo or any system in the car that draws extra current on top of the engine.
2) Disconnect the battery for 30 mins.
3) Reconnect the battery.
4) Before you start the car for the first time, turn the key to the ON position but do NOT turn the engine over. Wait 10-15 seconds so the electronic throttle body or IACV has time to go to the factory programmed home position.
5) After waiting, start the car and let it idle without any load, lights, A/C etc.
6) Every 20 seconds or so the idle will be adjusted up and down as the ECU tries to adjust it towards a stoichiometric fuel / air mix.
7) Leave the engine running for a full 10 mins but DO NOT TOUCH THE ACCELERATOR during this time or turn on anything that will cause extra electrical current draw.
8) Turn off the engine, and leave the key in the OFF position for at least 20 sec.
9) As per step (4) turn the key back to the ON position for 10-15 sec without actually starting the engine.
10) Start the engine and leave to idle for a further 5 minutes without touching the accelerator and without turning on other systems in the car.
11) Turn off the engine again and wait at least 20 sec before restarting.
12) Take the car for a test drive as the ECU should now be fully retrained.

[Nesty]

Thanks for the replies, unfortunately I don't have a code reader.

MDMA, mine is a gf8 95/96 v2 sti, it started to run badly before I changed the battery, do you think having a barely charged battery may have caused this?

Thanks

Tom

[MDMA .]

poor battery condition can cause lots of problems. worth doing the idle re-set ( doesn't cost anything ) just so you know that all that side is ok.

[Stants]

Unless you have a proper ssm monitor the only way to read codes on a classic is using the diagnostic plugs under the steering column, (sorry of I'm teaching you to suck eggs)

[trails]

MAF sensor...notorious in these cars; can be cleaned but normally best of replacing them

[vxr2010]

as above if you clean the maf and it improves then that could be the issue , the mafs are not as expensive as the newer shape cars , cleaning tends to be a temporary fix as when they start going then tend to fail for good

[Ahbefive]

Stants said:

Unless you have a proper ssm monitor the only way to read codes on a classic is using the diagnostic plugs under the steering column, (sorry of I'm teaching you to suck eggs)

This^

Plug the green cables in together under the dash and read the light for codes.

[Nesty]

Evening,

Apologies it's been a while, so I've tried the idle reset as suggested by MDMA to no avail and I've plugged the diagnostic cables together and according to the engine check light there are no recorded faults. I haven't taken off and cleared the MAF sensor as I'm guessing if I that was a problem it would have triggered a fault code?

Any other suggestions or should I resign myself to a trip to Roger Clarks which is fairly local to me?

Thanks

Tom

[Ahbefive]

Did you do the reset before checking for codes?

[Nesty]

Ahbefive said:

Did you do the reset before checking for codes?

No I didn't, what is the reset please?

[Ahbefive]

Disconnect the battery for an hour or so.

[Nesty]

Ahbefive said:

Did you do the reset before checking for codes?

No I didn't, what is the reset please?

[Ahbefive]

Ahbefive said:

Disconnect the battery for an hour or so.

[MDMA .]

Have you checked all connections since replacing the battery? Earths all good etc? I think on the classic, that there is a vacuum pipe that can sometimes dislodge when removing the battery. Or i might have dreamt that up

[vxr2010]

to reset and it works on new age cars too , disconnect the battery and pump the brake pedal about 30 times leave battery off for a further 10 mins or so , job done , there is a way of resetting with the plugs under the dash too but i've used the first method before , have you tried cleaning the boost solenoid i have had one clog before , an easy job with carb cleaner and then do the reset , there is a vacume pipe on the older clsssics that plugs into either the plastic air box or the intake ducting i managed the break mine , i can't remember specific detail of where the pipe was but remember breaking it and having to repair it

[Nesty]

So I finally found out what was wrong with the car, one of the coils had failed. What added further complexity was the fact the previous owner had changed the coils to those of a newage Subaru and taken the old wiring out of the loom. I took it to Roger Clark in the end and they've sorted it out. Thanks for all the advice.