Engine stalls or stumbles when press accelerator from idle

Hello
As per the title, my 2017 Jimny idles ok but when I press the accelerator (say to pull away) the revs drop a bit first and sometimes it even stalls.
It started a couple of weeks ago but then seemed to clear up on it's own but it was back again today.
It's not every time but quite often.
Any ideas what I should be looking at?
Car is low mileage and gets a service/mot every year at the suzuki dealer.
(I mentioned it to them at mot time and they gave me some flannel about having the aircon switched on!)
Other than that it's running same as ever.

Thanks

 

My 18 did this a couple of months ago. I twisted the throttle body quadrant by hand a couple of times and gave the return spring the lightest sniff of dry teflon lubricant spray and it's been fine since.

Always assuming that the clutch isn’t harsh or bites at an unusual place I suspect it points to something else, but it is a fairly long list.

The gaff about the aircon is a common one, the aircon does put increased load on the engine, but it is there at tick over so doubt it is that.

I assume if you give it a fair bit of throttle it doesn’t do it?

I am thinking that your engine gets a loss of power at small throttle openings, it could be electrical (is the battery ok, plugs gapped and clean, etc) but it is more likely to be something to do with fuel or air.

Is the throttle body clean?
Have you got an air/vac leak?
Is the MAF sensor working correctly ( try unplugging it and see if the problem goes)?
Is the fast idle/air slide working correctly?
Have you got dirty fuel or water in the fuel? Try a fuel cleaner.
Have you got an OBD reader to check for fault codes?

If it isn’t too bad, you might just want to live with it as finding the problem might take a fair bit of effort.

Robin

Thanks for the quick responses both.

Yes the fault is most apparent as the throttle starts opening. The revs dip and it either stalls or they then pick up. It's quite hard to drive around town so really want to get it sorted.

I'll have a look see if I can find the throttle body and clean it. I'm not familiar with it but I'll look for the spring too. Presumably I can pull an inlet hose off and squirt carb cleaner into the throttle body inlet to clean it?

I'm waiting for the fuel tank to get near empty and I'll put some seafoam cleaner into the fuel in case it helps.

I did scan but there were no fault codes.

Is the fast idle air slide inside the throttle body? Would the same squirt of cleaner for the throttle body clean the slide? (I'm vaguely familiar with the idle valve on my motorcycle but never looked at the Jimny).

If the fault is apparent at the weekend outside the house I'll try the MAF sensor too.

I have read a couple of forum posts elsewhere suggesting coil packs have fixed similar issues but I've priced up quality replacements (NGK) at about £155 so that's quite a big punt to make.

Cheers
Buzz.

The quadrant and return spring are the first things you will see, they are what the cable from the pedal attach to on the engine. Like I say mine was simple and easily fixed.

It sounds like you are on top of it and already looking at the obvious things. I would check the throttle cable and cam, if it is a little slack the throttle position sensor might be registering but the butterfly valve hasn’t opened. Also try Lamberts tip whilst you are there.

You might have deposits in the intake, if these are near the butterfly valve they can cause it.

I had a semi-similar problem with another car last year, went through everything and made incremental improvements but the thing that eventually made it go away was to fully charge the battery and keep it charged.

Good luck.

Robin

I took the inlet hose off the throttle body and gave it a good squirt of carb cleaner/rub down with shop towels. Also directed spray into the IAC valve inlet (in the throttle body). Not much carbon in there - just a bit in the low flow areas by the butterfly spindle at each end. Tried to clean the side of the butterfly too.
Also cleaned the return spring and open/shut the butterfly actuator a few times. Unplugged/plugged the TPS, IAC and MAF connectors.
(Think removing MAF while engine running caused engine light to come on and engine to conk but it cleared after a few stop/start cycles).
Problem was there before I started fiddling and is definitely gone for now - did a short 8mile round trip to warm it up. I realise that another symptom I had was jerkiness when taking foot of accelerator during normal driving - ie going from engine pulling to coasting. Much smoother now.
Fingers crossed . . . .

Thanks for your quick advice/ideas.
Buzz

That’s good news, let’s hope it stays that way. Now you can enjoy your super smooth Jimny.

Robin

Not systematic enough for me and my OCD I'm afraid. Anyway good to hear it's fixed.

How do you mean Lambert?

You'd have done one thing at a time - eg move actuator/lube spring and test, then move on to clean butterfly and test, then clean iac inlet and test, then each electrical connector plug etc?

I didn't really expect to get a result (if it lasts) with such minimal interventions so was just giving it all a quick clean down to rule out easy fixes before considering more involved actions.

I'll be very happy if it does last though!

Buzz

When I'm fault finding I if possible perform a repair and then check for improvement. Eg un/plug a sensor and see if it runs better then repeat on another sensor eliminating options one at once. Like I said though I get a bit OCD about this and I understand I am not normal.