Suzuki Swift hesitation when warm
Discussion
So I bought myself what seemed like a bargain little Swift Sport. EML lit, and according to the owner a slight hiccup in driving in very rare situations.
First time I drove it it became apparent that as soon as it got warm, there was a big hesitation at medium loads under 3k RPM. It also has a periodic stutter at idle where as the fan kicks on and off again for about 4 second - not your usual rev rise, but the revs drop to the start of it stalling!
EML light is for Lambda (P0420) but once cleared it hasn't returned and this is apparenlty some common "ghost code" with these cars.
I've checked sensor values like map, maf, water temp and lambda and they all look reasonably sensible. Lambda falls off the chart when the hesitation happens, but I'm guessing that's just as likely to be the lack of combustion as it is the cause of the hesitation.
Pre-cat Lambda, spark plugs and coil packs seem like all good candidates for a change but I'm wondering if anyone has a more informed opinion on where to start?
First time I drove it it became apparent that as soon as it got warm, there was a big hesitation at medium loads under 3k RPM. It also has a periodic stutter at idle where as the fan kicks on and off again for about 4 second - not your usual rev rise, but the revs drop to the start of it stalling!
EML light is for Lambda (P0420) but once cleared it hasn't returned and this is apparenlty some common "ghost code" with these cars.
I've checked sensor values like map, maf, water temp and lambda and they all look reasonably sensible. Lambda falls off the chart when the hesitation happens, but I'm guessing that's just as likely to be the lack of combustion as it is the cause of the hesitation.
Pre-cat Lambda, spark plugs and coil packs seem like all good candidates for a change but I'm wondering if anyone has a more informed opinion on where to start?
Edited by mpit on Monday 28th September 08:06
If it hasn't been serviced recently, do that before you do anything else.
Otherwise, I would start by trying to work out whether the misfire is due to fuel or ignition.
A misfire makes things harder to diagnose, but if it's fuel related you should be able to see the condition that is causing the misfire develop before the engine misfires. If it's an ignition fault the sensor inputs and injector duty cycle will remain steady until it misfires.
Otherwise, I would start by trying to work out whether the misfire is due to fuel or ignition.
A misfire makes things harder to diagnose, but if it's fuel related you should be able to see the condition that is causing the misfire develop before the engine misfires. If it's an ignition fault the sensor inputs and injector duty cycle will remain steady until it misfires.
My bluetooth OBD reader doesn't seem to have too many sensor readings, but what I did notice is the short term fuel trim is going into negative values, roughly inline with me trying to replicate the problem;
https://imgur.com/a/PIwkc0H
Could this indicate a dodgy O2 sensor?
https://imgur.com/a/PIwkc0H
Could this indicate a dodgy O2 sensor?
I had exactly this happen on my 1996 Toyota recently. Lambda would lean to 1.05 for a split second every ten seconds or so and it ran rough when power was applied. MAF voltage increased when the stutter happened.
The cap/rotor/leads were replaced before the problem surfaced. I replaced the distributor housing, which has a hall effect cam sensor inside and a condenser attached to the coil. The distributor gears were not visibly worn, but there might have been enough play to allow it to wander as it meshed with the camshaft. Perhaps the cam sensor was bad, or something else, but replacing the housing worked for me.
I appreciate your car might not have a distributor, but the cam sensor might apply.
The cap/rotor/leads were replaced before the problem surfaced. I replaced the distributor housing, which has a hall effect cam sensor inside and a condenser attached to the coil. The distributor gears were not visibly worn, but there might have been enough play to allow it to wander as it meshed with the camshaft. Perhaps the cam sensor was bad, or something else, but replacing the housing worked for me.
I appreciate your car might not have a distributor, but the cam sensor might apply.
mpit said:
I changed plugs and a dodgt HT lead yesterday which seemed to improve things, but not fix them (stutter was still there, but it seemed to recover much better).
Today I went for a drive and absolutely spanked it. Now the problem seems to have gone away
I had very similar problems on a w169 aAclass that I posted on the forum ages ago. It would be okay cold but then hesitate etc when warm. Turned out to be the leads going to the coil pack had gone brittle with age and also the rubber boots at each end needed greasing up to prevent moisture ingress. It was obvious that something in the engine bay was warming up and fixing the problem or that the combustion chamber was warming and fixing the problem. In my case I had no misfires no error codes. Just cylinder 3 turned out to be a bit of a duffer which you can see under " rough running" on certain ECUs whereby they measure the crankshaft position sensor to see if one cylinder is not providing as much force as the rest. Today I went for a drive and absolutely spanked it. Now the problem seems to have gone away
I'm glad you sorted the problem. Mine was also not 100% fixed after doing the change but a good Italian tune up also went a long way. Probably lots of carbon buildup or whatever on the cylinder that was poorly burning being blown out.
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