My normally well-behaved Xedos has developed an odd tendency to lurch at low(ish) revs in low gears.
This is most noticeable when pulling away - there is no power below 2-3k revs - and I have to feather the clutch a lot more than I would like. Even then, there is a fair amount of what feels like fuel surge, but I'm not up to speed on how injection systems behave, I'm afraid. The slow running is lumpy and I've wound in the butterfly stop screw, with only partial success. If it had a carburettor, I would suspect the low speed jets, but I don't know what the equivalent would be! It could almost be an ignition problem (HJ mentions this in the car-by-car) but there are plenty of sparks at idle, despite the lumpiness, so I suspect fuel, although at high speed there is no problem.
I'm hoping these are symptoms of something obvious that I'm just unfamiliar with. Since we've had Mazdas, I've got very rusty on fault diagnosis...
TIA
JBJ
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My Xedos did something similar a few years back - a doze of Optimax (now V-power) and a fast run "cleared the tubes"
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Its a shame you have touched the throttle stop, they are factory set. You need to get a proper diagnosis done asap. What fuel are you are using?
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"What fuel are you are using?"
Mixture of supermarket and branded. Until Christmas, I was adding 0.3% acetone (to all my vehicles) but I ran out and need to shop round for more. That must look like the culprit, but I never had any trouble while using it.
As for the throttle stop, I can easily put it back (one turn) where it was.
I don't mind getting a diagnosis, but thought I would ask here first, in case it was something simple...
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Thanks, FK. I'm not sure we have a Shell garage here, but I'll try some injector cleaner, perhaps. And put it back on the acetone!
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hi sounds like you need to reset base idle what colours the diag box black
box you need an ngs tool to reset gray box you can short out ten and ground plugs (dont do this on a black box as will blow the ecu only possible with ngs) (ngs is an old style diag tool phone your dealer first as only dealers open in the 90's will have one new diag tool won't reset properly)
hope this helps
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Thanks, CJ - I'll mention that to my tame garage man. Would that also be responsible for the surge behaviour? It seems to be acceleration related - pulling away quickly in first or second is very kangaroo-like, but it's much less noticeable in higher gears at identical throttle settings. I'm visualising fuel sloshing about and temporarily starving an outlet, but the response time feels too quick for it to be the main tank. Air in the fuel pump (wild guess)?
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Simple and sorted, I'm happy to say. There is a short fat section of concertina hose between the air mass sensor and the throttle butterfly that had a split in it. It's concertina'd to take up the torque movement of the engine, so it was opening up when the engine was under load, which upset the computation of mixture, thus shutting the fuel flow down, which in turn caused the engine to lurch forward, shutting the hole and restoring the power!
A cheap repair and a lesson to me to trust Occam's Razor more! (the simplest solution is usually the correct one).
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I have had exactly the same symptoms in the last 2 weeks - with exactly the same cause - cracks in the large air hose - I've just taped up the cracked hose for now and the engine is running perfectly again. I can have a new hose fiited at the next service.
Thanks to this string I was saved a lot of frustration and cost.
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