Starting issues

Being your throughly went through the fuel system and looks like you covered the ignition system.

Happens only when hot. Is making me wonder.

The fluid levels not changing like you not loosing antifreeze?

Compression good?

I wondering if your having a crank sensor or maf or anything of the ignition electrical side tasting good but still intermittently failing with it gets hot.


Did they check all these components when the engine is at operating temperatures.


Being it's not just dying going down the road and your are fine till restart or start. It almost has to be something involved in the starting process itself. Sorta would eliminate the crank and maf sensor.

Unless you have one heck of a vacuum leak when the engine is warm. That would make it hard to start as well.

How's all the vaccuum hoses looking? PCV value not stuck open?


I just trying to come up with ideas for you at this point. As I see you been working on the the rig for quite sometime.



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while not your problem maybe, I just had to replace a coil pack.I did have a check engine light. however in reading, a coil pack can test good cold and have issues when warm.
It may not be a coil pack, but like others have said, maybe something that tests good cold, after it is warm, then starts to fail. Ive known fuel pumps to do that too on a bmw and a volvo but I dont think fuel pump is your issue since it runs good after starting.
good luck
 
I didn't do compression but it was all solid before the top end rebuild. I had a leak between cylinders 4 and 6 before the repair. This starting issue wasn't that bad before the rebuild either.

fluids fine.

He was testing the A/F numbers running and everything checked out. One hose had a crack but I knew that, it was the fuel pressure one that goes to the air box (I had it electrical taped). He replaced that.

I think I left the report of all the inspections in the car so he has it. Otherwise I'd list all the many things they ruled out.
 
Oh. You had top end rebuild. Did anything else get worse? Low power?? I am wondering in the rebuild they knocked the cams off or the timing belt off a tooth.

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I did the top end myself following the FSM and helpful videos. I did make one boo-boo upon reassembly. I accidentally overtorqued the heads down. So I re-did it with new bolts and head gaskets. It wasn't driven in this state, I realized it the day after and slapped myself for it.

Speaking of the cams though, his thought is too much of a valve grind from the machine shop and incorrect puck sizing creating nice spacing on the bench but maybe zero lash once torqued down....?
 
Might be worth pulling the valve covers off and check the cams and the valve spacing.

Good idea to verify and check that all. Its possible the clearances are off.

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I'm an amateur at every sense of the word, but had similar issues starting when warm. While reading through forums in general, one person talked about the coolant temp sensor at the top front end of the engine next to the fuel rail. I gave it a shot since it was easy, but I got lucky and haven't had the issue since. The old sensor looked fouled up. I thought it was worth a mention. Best of luck!
 
Azhen said:
I'm an amateur at every sense of the word, but had similar issues starting when warm. While reading through forums in general, one person talked about the coolant temp sensor at the top front end of the engine next to the fuel rail. I gave it a shot since it was easy, but I got lucky and haven't had the issue since. The old sensor looked fouled up. I thought it was worth a mention. Best of luck!
Click to expand...
So in your case, the ECU was being told the engine was cool. Thus running really rich and the engine not going into closed loop.

Did it take forever for the engine to start when warm?

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For American vehicles the engine temp, IAC temp and trans temp should be within 10 degrees of ambient temps locally as well as all three being close to that local temp after sitting 8 hours.


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That's exactly what I have him doing at the shop, taking valve covers and checking lash. I can do that too...but he can get the proper pucks if needed much faster than I can.
 
brillo_76 said:
So in your case, the ECU was being told the engine was cool. Thus running really rich and the engine not going into closed loop.

Did it take forever for the engine to start when warm?

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Click to expand...

Sorry for the late reply brillo, but yes sometimes it did take forever to start, and sometimes I got lucky after a few tries. It would stutter then die. I generally waited for it to cool off to get it to start. I cleaned the MAF sensor and throttle body and gave the IAC a really good cleaning with no results. I installed a new fuel filter with no results. I then tried the coolant temp sensor and got lucky. Thankfully there are so much information and good people to do write ups, that an amateur like me can just follow it. But I'm still trying to put the big pieces of the puzzle together of what makes an engine tick. I've only really started working on engines the past couple of years. *♂️
 
They didn't get around to it over the last two short holiday weeks. I went to get it back bc I needed it for skiing Monday. When they get more time I'll bring it by.

When I got home I let it sit for about 10 minutes then tried starting it up again (hot soak test). I used my IR gun to check the temps. Before 2nd firing, Cylinders 1-3-5 were all around 165-180 measured at the neck of the exhaust manifold. Cylinders 2-4-6 were 127ish, 143, 90 respectively.

Started it up, with difficulty, then let it run for a minute or two. Cylinder 1-3-5 now heated up between 195-215. Cylinders 2-4-6 took longer to get hot. 2 danced from 150-160, 4 120-160, and 6 190-200 eventually but I had some weird readings at first being dramatically low. Not sure if this test offered much insight other than one half it tending to heat up longer and loses it faster. Now...the exhaust header on this side was the replacement since I got a stud stuck in the original. It's out of a 1st gen tacoma and the build of if is slightly different, although the mating surface is the same. So MAYBE it's a different metal thickness???

Also, here is that long synopsis from the shop that I left in the car:
"tested fuel system before and after the fuel pressure regulator and sound to be within spec, found slight fuel system bleed down but fuel pressure comes back to spec as soon as engine is cranked as designed. fuel pressure at spec when extended crank condition is observed, tested camshaft position sensor due to improper routing of wiring pigtail (when I reassembled it I could not for the life of me get it back into the plastic clip on the front), tests within spec, tested the throttle position sensor and it was within spec, tested the throttle motor and it was also within spec, tested throttle motor clutch circuit and it was found slight high reading but could be temperature variant, found mass air flow sensor reading at 10.8 GPS at idle when spec is around 3.4-3.8 GPS. Cleaned MAF and found the reading lowered but still not within spec. Replaced MAF and now current reading is 3.6-3.8 GPS but extended crank is still intermittently present. Added new engine grounds and engine still cranked long. unplugged A/F sensor in exhaust to put system into open loop, engine still cranked long. bypassed fuel pump relay to try priming system before a start. Also cranked long, installed noid light and spark tested and cranked engine over to see if we were losing a signal while cranking, had spark and injector pulse. Bypassed the purge valve to see if fuel is being induced into the intake when engine is off, no change. The engine is running lean, we pinched off all vacuum lines and leak checked the intake manifold, found no signs of leaks. We have ruled out everything but an internal engine issue. I suspect that the valve clearance is out of spec. This could also cause the engine to run lean. The valve covers will have to be removed to check for a lash issue."
 
UPDATE: Engine codes

Finally for the first time driving home today CEL came on and my scanguage showed P0440 (evap emission control) and P1135 (air/fuel heater circuit bank 1 sensor 1).

So...he mentioned it was running lean. Could it be that exhaust valves are out of adjustment, so they're being held (open?) causing those cylinders to run lean?

I say this because upon original cylinder head removal, I had three cracked valves, all exhaust I think. Both on cyl 4 and one on cyl 6. So those would have to be new, then ground down. If there was any error grinding those down then the original pucks could be out of spec...right? I'm searching for possibilities here. And those two cylinders just happened to be the "coolest" on my hot soak test.
 
Finally!

Mechanic fixed the evap code and the heater fault as well, issue still present. I gave him the go ahead to just take valve covers off and check valve clearance. A few were tight (8 thousandths) and a lot were loose (spec is 11-13 thousandths) but that wasn't HUGE since none were zero lash.
The issue...he took the timing cover off and the belt was LOOSE! So after turning the car off, the cams were turning not engaging until it was just right again. I put all new OEM parts in when I did this,water pump, idlers, tensioner etc everything...or so i thought. I got them off ebay labelled OEM, in boxes and sealed in bags with stickers etc. That seller is ripping people off. He ordered an Aisin kit just to show me and it's definitely different.
I will say the ONLY issue I had reinstalling this was the no. 1 idler pulley. I did notice the casting was just a bit (1-2mm) thicker than mine and when I torqued it down, it did not spin freely, if anything at all. So it was so tight that the tensioner couldn't even push on it into the belt. It passed all manual tests cranking it over by hand with my timing marks, but when the engine was running it did not. So all this time, that POS idler pulley that I'll admit I should have stopped on, caused this. so to make sure we are swapping the WHOLE kit just to be safe and it has a 2 year warranty from him on it.
Just goes to show that despite stickers and boxes, unless you know what to look for you can get taken for a ride. I did notice the bearing color was black and not the typical Koyo red, but again I didn't let it phase me. My feelers perked up when I torqued it down but I just thought (oh well it's new) and let it go. That was the mistake that caused months of frustration, nearly a grand in diagnostics, and now a new kit. I should be getting the vehicle back tonight.
 
I'm glad you finally figured it out. Sometimes it's the smallest thing that has a huge impact! What was the ebay seller you got the kit through?
 
motorbabyus i believe. They have nothing listed now in their store despite over 5k sales. I tried both a paypal and ebay resolution. paypal already denied as it's over 180 days. Lesson learned, get OEM from a reliable source
 
$2200 later after a new MAF, EVAP system seal, O2 sensor (to clear that code) and new timing belt kit.....it's still doing it!!!!

It's not as bad, granted I've only had it for a week. But the cold morning starts are solid (except for one day) and the afternoon startup from work to home sputters for 3-4 seconds. In the last two days it's now taken two key cranks (mainly because I won't let it sputter longer than 5 seconds).

well shit...everything else was fine except the valve clearance. They were all out of whack from the machine shop...but none were zero lash. Could those really cause this? What about something else we didn't discuss...the ignition cylinder in the steering column, or anything else from key to start?

I'm so frustrated.
 
Does the engine crank over at the same speed during the hard starts as when it works immediately? And when you say sputtering, im imagining it trying to fire and maybe getting a couple pops and blurbles but not actually getting running, is that correct? Or is it running, but just really poorly?

Also for the Evap code, what did your mechanic do to fix it? The gas smell outside the vehicle is a symptom of a stuck valve in the evap system. And potentially i bet that could lead to some rough starts if the evap system is not scavenging properly.
 
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