JoshRS

Hi All,

Pulling my hair out here! I have a standard S2 which I brought out of 2 year storage.
Starts fine, doesn't miss a beat when warming up but suddenly runs lumpy as hell when warm enough!
I've replaced dead fuel with super unleaded plus fuel system cleaner.
Replaced coolant temp sensor - definitely not that.
Fully serviced, oil, filter, cambelt, changed fuel filter etc.
Emissions are fine (checked suring MOT)
Checked leads and plugs but I don't see how it could be an ignition problem if its fine when cold.
I can only think its a fuelling issue?? What tests should I do next?? Heeeelp.

Thanks!

OAP Pete

From EX Auto sparks with Bosch....retired now 78.... all i can say is when you had the emisions done was it noted there was "Fluctuations" in readings when Hot as a leaking injector would give your fault...normal they clear for a while only to come back again...even the 5th cold start injector can give this trouble...if you can get the car to a help-full garage and see what the "Co "is when the idle is bad...normal "Co " is 1.3 / 1.5...if its a fuel problem it will be proberly closer to the MOT limit on these cars 3.5...you have changed the "Yellow Temp Sensor"...thats good...if the "Presure actuator" was faulty then this would also certainly give this Fault....but not give Fluctuations in Idle...but way way High emisions, so i come back to a "Co " check when Hot and giving the trouble, should you want to know how to "Test all 4 injectors".....plus the 5th cold start injector for leaks, ive wrote before hear, but will write again. i can say slight Leaks affect Idle only on these cars....power / performance good. Presure actuator fault....performance poor.....very very smoky / stinky on exhaust.... best i can say. hope of help. Peter

JoshRS

Thanks Peter that's really helpful! So could be a leaky injector, CO reading would point to it. So likely new injector or just recondition the faulty one?

OAP Pete

Yes just takes small leak ...not a perfect spray from injector...then the idle "Tumbles" / shakes "...sometimes clears, but dont go out and purchase new till you have tested, unless your OK on getting new, will run through the Test...all 4 injectors must be removed with there pipes connected, bit of a job...but can be done, wipe all 4 "nossels" perfectly dry and clean, unplug the Fuel pump relay, you will see the numbers 30 Red wire and 87Red/Black ONLY in the relay holder, you need to bridge these 2 terminals with a short piece of wire, no need for Ignition on, as soon as you bridge the fuel pump will run, there will be some pressure at injectors 30psi but these injectors dont start to open till 45psi...... , carefully look at all 4 injectors, there must be no Fuel leaking / oozing from injectors, there is a small valve in these injectors, any leaking are U/S....thats the test....on the 5th cold start injector same test, has to be removed with its pipe....pump running...no leaking...now this pipe has Full pressure at it 80/90psi , so extream care hear...again no leak should be seen, very very rare back in the day that injector gave trouble...but again should be tested. thats the Test, hope of help. Dont get 87 / 30 wrong in the relay socket or damage will result. these injectors cannot be repaired, they dont like lead-free petrol....so Fuel injector cleaner in tank helps a lot. Peter