Yaris sedan sputters after a cold start!! CT Scott pls help if you're out there!!!!

[tyrone_yaris]

Hi,

For some time now my car sputters for several seconds after a cold startup but then it idles fine and runs fine. If I stop and start the engine again the next time, it starts fine without any sputtering afterwards.

Usually happens when the car is parked overnight or for a long period say 7-8 hours. Replaced all 3 spark plugs with Denso Iridium, did a throttle body and MAF sensor clean too. Also put in another battery to see if it was a battery problem but still the same sputtering after a cold start.:iono:

What could be the cause of this? CT Scott I wish you could give your opinion too.

Thanks

Tyrone

[CTScott]

Since it only does it on a long-cold start, it almost seems like the fuel system is having trouble getting up to pressure. Other people from your part of the world have had issues with the fuel filter being plugged, so that would be my guess.

[tyrone_yaris]

Thanks Scott.

Yes we do not get the best quality fuel out here at all places.

Should I just go ahead and replace the fuel filter? Btw did a scan using the X431 but it did not show up any error codes either, just a rough idle code P1605.

[CTScott]

Replacing the fuel filter is a bit of a hassle. If you could get someone to scan it with the Toyota service tool on cold start, if the filter is really plugged, you'd see it be lean, rather than rich, as it should be during a cold start.

[tyrone_yaris]

Thanks once again.

Ok; Will see if I can get it scanned as you advised and update you accordingly.

[tyrone_yaris]

Replacing the fuel filter is a bit of a hassle. If you could get someone to scan it with the Toyota service tool on cold start, if the filter is really plugged, you'd see it be lean, rather than rich, as it should be during a cold start.

Hi CTScott,

A friend of mine just got an X431 scanner so I asked him to help out. But he couldn't figure out how to tell if its lean or rich when he connected the scanner. Can you guide as to what parameter on the scanner to look for?

Is there any other way of telling if the fuel filter is plugged??? I really need to solve this starting issue. It's like as if the engine is gonna shut down but then it picks up after several seconds.....:cry:

Thanks

[tyrone_yaris]

...Oh and if this also helps...my fuel avg is not good either. Getting about 9-10 km / liter.

[CTScott]

The scanner would need to be one that can read more than just trouble codes. Normally the Yaris ECM runs the system very rich when starting (about 18 for the AFR), whereas once it is warmed up it aggressively keeps the system at 14.7 for the AFR.

[tyrone_yaris]

So if its below 18 shld I presume its a plugged fuel filter?

[CTScott]

So if its below 18 shld I presume its a plugged fuel filter?

Yes

[tyrone_yaris]

Yes

Thanks will keep you updated.......

[seth_man]

other way around, less than 14.7 would be rich and above 14.7 is a lean mixture, cold start air fuel ratio on our cars running properly near freezing should be in the low 12's and will vary a little with ambient temperature

[CTScott]

other way around, less than 14.7 would be rich and above 14.7 is a lean mixture, cold start air fuel ratio on our cars running properly near freezing should be in the low 12's and will vary a little with ambient temperature

Yeah - That's correct - I must have been half asleep when I posted that this morning. 13.8 (which is rich) is the AFR that the ECM targets during cold start. 18 (which is lean) is actually the AFR seen during DFCO.

[ciscobear]

tyrone? I thought you had a Belta? Did you do as I suggested? Another member had a similar issue and it turned out to be her grounds. We suspect the vehicle might have been in an accident and the grounding points were painted over.

[tyrone_yaris]

tyrone? I thought you had a Belta? Did you do as I suggested? Another member had a similar issue and it turned out to be her grounds. We suspect the vehicle might have been in an accident and the grounding points were painted over.

Ciscobear, no I'm sorry it must have slipped my mind...could you pls repost it here again and I will try. I'm zero where these cars are concerned so you'' probably have to explain it as simple as possible :)

CTScott, another mechanic had a look at my car y'day evening and started it. He didnt have a scanner but when he started the car and I explained to him the situation, he said its the fuel pump and not the fuel filter. Reason being that the car runs smoothly after that and there are no jerks or problems in the pick of the car. He says since its only on cold startup it seems to be a problem of the fuel pump pressure initially as it starts up. :iono:

[CTScott]

Ciscobear, no I'm sorry it must have slipped my mind...could you pls repost it here again and I will try. I'm zero where these cars are concerned so you'' probably have to explain it as simple as possible :)

CTScott, another mechanic had a look at my car y'day evening and started it. He didnt have a scanner but when he started the car and I explained to him the situation, he said its the fuel pump and not the fuel filter. Reason being that the car runs smoothly after that and there are no jerks or problems in the pick of the car. He says since its only on cold startup it seems to be a problem of the fuel pump pressure initially as it starts up. :iono:

I would think that if the fuel pump had an issue that it would be visible on more than just start-up.

[tyrone_yaris]

I would think that if the fuel pump had an issue that it would be visible on more than just start-up.

CTScott, I just wanted to confirm from you before jumping to any conclusions. What would be the tell tale signs of a fuel pump issue if it were so, if you could pls let me know?

[tyrone_yaris]

tyrone? I thought you had a Belta? Did you do as I suggested? Another member had a similar issue and it turned out to be her grounds. We suspect the vehicle might have been in an accident and the grounding points were painted over.

....and yes the Belta is what I have. It was imported at 43,226 km but I believe its called a Yaris in Canada/US so thats how I mention it when I post on these forums

[tyrone_yaris]

CTScott could you let me know what other signs would be noticeable of a fuel pump issue so I can look for those???

[CTScott]

CTScott could you let me know what other signs would be noticeable of a fuel pump issue so I can look for those???

Fuel pumps typically fail completely, where they just stop pumping fuel. In that case the vehicle would either not start or would only run for a couple of seconds and then die.

[tyrone_yaris]

Thanks for the explanation.

Just another development I thought I would share with regard to my problem.

I was told by someone to switch the key to acc wait about 20 secs and then pump the gas pedal a few times before starting. I did exactly that this morning and yday evening after the car was parked for about 8 hours and voila it started without that sputtering sound on both occassions :)

What could this mean???? Could anyone explain?

[tyrone_yaris]

This morning I started the car and it started fine........strange. I did not wait 20 secs or pump the gas pedal. Although I switched it to acc and waited a few secs. Will check again this evening after work when the car will have been parked for about 8 hours and see.

Was there something choking the fuel filter that passed through or something?????

[CTScott]

This morning I started the car and it started fine........strange. I did not wait 20 secs or pump the gas pedal. Although I switched it to acc and waited a few secs. Will check again this evening after work when the car will have been parked for about 8 hours and see.

Was there something choking the fuel filter that passed through or something?????

It is possible that whatever was blocking it dissolved or got washed off by the fuel sloshing in the tank.

[tyrone_yaris]

It is possible that whatever was blocking it dissolved or got washed off by the fuel sloshing in the tank.

Hmmm...can I use a fuel system cleaner? The ones they put into the fuel tank like Liquimoly or will they be harmful in the long run?

[CTScott]

Hmmm...can I use a fuel system cleaner? The ones they put into the fuel tank like Liquimoly or will they be harmful in the long run?

A fuel system cleaner won't hurt, but likely also won't help much. If there is stuff in the tank that was plugging the filter, but eventually washed off, i may still be sitting in there and may repeat the plugging. It may not be a bad idea to eventually drop the tank and clean it and the filter. I just pulled the tank out of one of my Yaris this week, so I could do some welding above it, and it really is not that much work to do.

[tyrone_yaris]

A fuel system cleaner won't hurt, but likely also won't help much. If there is stuff in the tank that was plugging the filter, but eventually washed off, i may still be sitting in there and may repeat the plugging. It may not be a bad idea to eventually drop the tank and clean it and the filter. I just pulled the tank out of one of my Yaris this week, so I could do some welding above it, and it really is not that much work to do.

Wow...thanks I can ask my mechanic to do that for me then. Can the fuel filter also be cleaned instead of replaced? I thought it had to be replaced.:iono:

[CTScott]

Wow...thanks I can ask my mechanic to do that for me then. Can the fuel filter also be cleaned instead of replaced? I thought it had to be replaced.:iono:

It ideally should be replaced. It is a mesh pad, so while I had mine out I blew it out with the air compressor.

[tyrone_yaris]

It ideally should be replaced. It is a mesh pad, so while I had mine out I blew it out with the air compressor.

Ok; thanks for your kind help. Really appreciate it.

[tyrone_yaris]

Just wanted to update for the benefit of those who contributed and others who may read my post.

The other day while talking to my car electrician he told me that he was 99% sure, in his experience that its the starter motor that probably has to be serviced/repaired. So he told me to lets give it a try before going for the expensive fuel filter replacement.

When he removed that starter (which was a pain) as its right under the airfilter box, infact at the bottom. Not much space. The bushes were cut and had to be repaired and also the inner spindle was loose. (Forgive me but I'm not familiar with the technicalities :-p) :iono: Anyways, he cleaned up the whole thing and after getting the bushes repaired, he fixed it back and now that sputtering problem at startup seems to have vanished so far, 3 days down the line since he did it.

I remember on my 1st Gen vitz too he solved a similar problem regarding startup where he diagnosed the armiture was damaged and needed replacement including the bushes in the starter.... which resolved that problem too.:iono:

[CTScott]

Just wanted to update for the benefit of those who contributed and others who may read my post.

The other day while talking to my car electrician he told me that he was 99% sure, in his experience that its the starter motor that probably has to be serviced/repaired. So he told me to lets give it a try before going for the expensive fuel filter replacement.

When he removed that starter (which was a pain) as its right under the airfilter box, infact at the bottom. Not much space. The bushes were cut and had to be repaired and also the inner spindle was loose. (Forgive me but I'm not familiar with the technicalities :-p) :iono: Anyways, he cleaned up the whole thing and after getting the bushes repaired, he fixed it back and now that sputtering problem at startup seems to have vanished so far, 3 days down the line since he did it.

I remember on my 1st Gen vitz too he solved a similar problem regarding startup where he diagnosed the armiture was damaged and needed replacement including the bushes in the starter.... which resolved that problem too.:iono:

I definitely would not have expected that from your description of the problem.

[tyrone_yaris]

I definitely would not have expected that from your description of the problem.

Tell me about it :) Neither did I. All who saw and heard the sound thought it would either be a fuel filter / pump issue.

I'll just wait and see. Time will tell.

[wufai]

Hi Tyrone, thanks for updating the post. The same thing just happened to my Yaris this morning. I never had this issue for the 4 winters I drove it. My problem is I'm guess I sued 10-30w syn motor oil instead of the 5-30 recommanded. it only happened to my once and I'll be back if this issues continues for me.

[tyrone_yaris]

Hi Tyrone, thanks for updating the post. The same thing just happened to my Yaris this morning. I never had this issue for the 4 winters I drove it. My problem is I'm guess I sued 10-30w syn motor oil instead of the 5-30 recommanded. it only happened to my once and I'll be back if this issues continues for me.

My issue still persists though not as bad as before so I'm gonna have to go for the fuel filter option as CT Scott mentioned when Iget some funds / time :redface: