Suzuki Alto Mechanical Question

[hightower]

Yeah, it's a Fazer forum I know. But it's just you folks are so good to me, I just know you'll have the answer.


Phone call off missus, on her way in to work this morning in her 54 plate Suzuki Alto 1.1, she says it was revving at about 1,500rpm. Now, when cold the car revs at about 2,000rpm and gradually lowers as it warms up - which is by design on this motor. But she was maybe about 8 miles from home at this point, so the car should be revving normally.


She says it was revving normally at idle (~900rpm) and then it started revving at 1,500rpm. After about 5 minutes she says it dropped back down.


It doesn't sound to me like the car is cold 8 miles from home, so what could be causing this? I read somewhere it could be a throttle potentiometer, although don't know (grasping at straws) so if someone can offer a hint?


Thanks,

[rustyrider]

Sticking throttle cable, sticking throttle butterfly, sticking auxiliary air valve, split or fallen off vacuum tube, I'd check all of these before going down the TPS route.

[Frosties]

Might be worth considering the thermostat. If it's not shutting properly then the engine revs will rise to try to reach it's optimum temp.

[hightower]

Wonder if I can get it plugged in to a computer to see if there's any errors.

[unfazed]

Check the colant level in the radiator, you may have a leak as low coolant can play havoc with the choke system and have strange effects on the throttle system.
If coolant is low top it up and problem should resolve itself, then check for leaks when cold and hot.

[CRH]

air flow meter?....had same thing happen to my zafira last year!!..changed it and been fine since?...unless its recorded a fault on ecu dont think by having it plugged in will show up??...if its anything serious the management light will come on?..then it will have recorded the fault!!

[raff113]

I say air flow meter, had the same issue with my multipla

[redthunder]

Does the car have an EGR valve? Had an astra a few years ago and idle problem just required a good cleaning of the egr valve with some carb cleaner

[Dead Eye]

Sounds like something to do with the automatic choke to me, would be best off following what unfazed said to start with imo

[hightower]

Thanks for replies fellas, will start off with the most simple as always, and work my way through.

[Fraser]

Start by checking ALL the pipes are still attached and not split, then move up to clean all multiplug connectors with a proper terminal clean/lube aerosol spray. Depending on mileage and how well its been serviced, the next place to look is the throttle butterfly housing which will prob need a good clean, you need to jam the throttle on full ( obviously without the engine running) to able to clean out all the crap which accumulates where the butterfly closes.  ONLY use cleaning products that are "air" safe, ie WD40 , other products look like they are ok but will damage your Lambda / Oxygen sensor. Unless your Alto has done a lot of miles its unlikely to be any of the sensors, they are incredibly tough bits of kit to break.

[hightower]

After having a little think about things, (and experiencing the issue myself today) I'm starting to think it's the Engine Coolant Temp Sensor, as when it starting revving the temp gauge was lower than normal. But the wife has just picked me up and it was running fine, and the temp gauge was normal too. I've found a good manual which tells me to test the resistances on the unit - so will drain the engine, remove the ECT sensor and test. A new one is only £15, so hoping it's that.


House move in a couple of weeks, it's going to have to wait a few by the looks of it.