jhavelaar

Hello, I'm new to these forums but I recently bought a 2006 Scion tC and recently I have had an issue where it will start rough but only after sitting for a while. Car does burn oil a bit but there are no other issues. I have replaced spark plugs, cleaned throttle body and MAF sensor. Thinking it may be the fuel pump but then I would expect overall performance to diminish which it hasn't whatsoever. Still runs great, accelerates fine, handles highway speeds perfectly. It only takes about 3 seconds to start but it will hang for a bit and hesitate until it does start up and then it's fine. A little bit of a squeak comes from the engine as well, not a loud squeak like a belt but a lighter squeak when the engine hesitates while starting. Idle is a bit low ~600-700 RPM.

Let me know of any advice! Haven't been able to find any info online about this specific problem for this car, so here I am!

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alxm

Sorry to hear about that. Is your engine light on? If you don't have an OBD scanner tool. I would suggest to stop by an Autozone for a scan. Sometimes there will be trouble codes that don't light up the engine light but are stored. These can be read with an OBD tool. The codes will help in better identifying where the trouble is.

If you don't have any codes. Then you might have a failing ignition coil, injector or oxygen sensors. Hopefully you'll find some trouble codes to help guide you.

jhavelaar

I ran it by my local auto parts store a while back and had two codes for some out of position steering sensor (minor thing and unrelated, I assumed?). Is it possible that a failing fuel injector would cause the rough start only after sitting for a while? And also wouldn’t failing injector coils and oxygen sensors make starting always rough? It only starts rough after sitting overnight, that’s why I thought it could be a loss of fuel pressure over time due to a faulty fuel pump. Thank you for your feedback, let me know what you further think.

62Fender

Have you tested the battery and alternator? Some chain-stores do it for free.

alxm

No worries. Yes failing injectors can cause those symptoms. In your case the injectors or the oxygen sensors are strong suspects. If you have a multimeter you can check the resistance of each injector. Check it when the car has not been run for a long time and the coolest. Usually in the mornings. Our injectors need to be checked as close as possible to 68 degrees F. And should read around 12 ohms flat with a deviation of +/- 0.4. So no higher than 12.4 and no lower than 11.6. I've had my injectors act up with as little as 0.5 deviation at 12.5 ohms. You'll need to remove the plastic black engine cover. You can probably check them while still installed on the car. Just need to get the multimeter leads back there. Disconnect the injector connector and test.

jhavelaar

Oh wow ok! I do have a multimeter so I’ll get on that and test tomorrow. Thank you so much for your help as I’ve been absolutely clueless. Will post results tomorrow. It’s going to be a bit colder than 68 though, probably around 60 at most, hope that’s ok. Also how would you explain the slight squeak/squeal sound? It happens a little when the car does its hesitant start, and then whenever I’m in drive and stopped before the car is fully warmed up. After a bit of driving and I come to a stop light it won’t squeak as much... also I found a bit of thick built up oily residue coming from the valve cover gasket... I don’t know if that pertains to this issue but I know I’ll probably have to replace that (have noticed some oil consumption). Also, I looked back by the injectors and noticed on the far right that it’s a bit wet (just noticeably wet not like dripping wet and very grimy) on whatever bolts and whatnot is under there, I tried to get some with a towel and smell if it was fuel but couldn’t really tell... could be losing fuel pressure over time somehow? Anyways, will check the injectors tomorrow. Thank you so much for helping me out, honestly wasn’t expecting anyone to help out, I really appreciate it.

jhavelaar

the previous owner replaced the alternator and battery (putting out around 12.6V right now - isn’t that slightly high?) So that shouldn’t be the issue but if my venture with the injectors and oxygen sensors doesn’t show anything then I’ll check the alternator next. Thank you for responding!

alxm

That temp to check should be fine but expect a lower ohm resistance than 12 ohms. Probably will be around 11.8 ohms if your injectors are good.

The squeal sound may be your water pump pulley if you do not think its the belt. It's hard to see any water leaks or corrosion from the top of the engine bay. You may need to get under the car to see any leaks there. If you have a jack and stands be safe under there. Always use jack stands.

Our engines tend to burn oil unfortunately. Keep an eye on oil level every week or couple weeks. The valve cover gasket replacement will help a little. Also check your oil pan gasket.

No worries.

drizzoh

Sorry for not reading the whole thread, but I just saw this post and am about to leave work for the day but wanted to chime in. I had this issue in the past when I installed plugs that a local tuning shop pre-gapped for me but did so incorrectly. The gap was about 2x too large. Would start great when cold but when getting gas or similar it would have a tough time getting restarted. Regapped and the issue went away. A hesitation issue - if for throttle when accelerating could be due to failing coil packs as well if the tC1 utilizies a coil-on-plug system. Check for hairline cracks in the coils to see if there are any - if so you could have found the problem. If they're still original, might not be a bad time to replace them anyway. But if it's only having issues when doing the warm start, check your plug gap and for vacuum leaks (while the car is idling spray carb cleaner on all of the vacuum lines and intake tubes and see if the idle pitch changes - if it does you've found your leak). Good luck man.

jhavelaar

Thank you so much for the info. I did in fact install the plugs but they should have come pre-gapped from factory. That’s not the problem though, as it only has a rough start after sitting for a while. UPDATE: I have found that when I leave the key in the “on” position for a few seconds before turning all the way on, then the car starts great every time. Is this guaranteed to be the fuel pump and could I go ahead and spend the $135 from partsgeek for a new filter and pump or could it be something else? Again, thank you and thank you all for the input. I also checked the fuel injector resistance and some of them were a bit low (11.3) but my new findings lead me to think they aren’t the issue. Help is much appreciated! If I don’t get any input I think I’m going to go ahead and order the new pump and filter... Thanks again!!

jhavelaar

I did the test a few days ago when the car was cold and got some pretty low values (11.3 was the lowest). I’m not convinced I did that test all too reliably, I’ll try and do it again soon. Check out my update above, I think that might change what you think. Let me know if I’m really on the wrong track here thinking it’s the fuel pump because of the solution by holding key in “on” for a few seconds before starting.

I cleaned off the sides of the valve cover to see how fast it was leaking and there hasn’t been anything coming out of the gasket so it can’t be too bad, probably won’t replace that just yet. I don’t have a jack or jack stands yet but I use some planks stacked up to raise the front of the car on my slanted driveway (raising the front and keeping the car relatively flat). I’ll investigate about the water pump pulley, thank you for the info on that. I’ll wait to look into the squeak noise until after I’ve solved this starting issue, as long as I know they aren’t connected...