Rich Hard Start - The Ongoing Struggle

I would have someone else crank the truck, or video the gauge while cranking and see what it does. Is there no pressure while the truck refuses to start, and then does start once the gauge is reading pressure for example?

 

This was a no start situation, so that's what it had while cranking

 

Hmmmm so it would seem like fueling is probably not the issue. I would check spark next since it would be easy, pull a plug and coilpack and lay the plug on the valve cover and crank it and make sure there is spark. One of the guys on the supercharger thread had it recently where his truck wouldn't start and somehow (dont ask me) all of his spark plugs seemed to shit themselves at the same time. He said they were gross, he swapped them out, boom it fired right up. I'm not saying randomly swap all the plugs, but I would confirm that spark is at least happening when cranking. If it's not that, I would be inclined to replace the MAF sensor.

Do you have anyway to datalog or watch sensor data? It'd be helpful to see fuel injector commanded duty cycle as well as MAF data. I would also be tempted to spray starter fluid in the intake and see if that helps it start. While fuel pressure and fresh injectors would seemingly solve fuel issues, that doesn't necessarily mean the injectors are actually opening---though I would imagine they are. But at the end of the day, either there's no fuel, no spark, or the air sensor data is messed up (assuming it has compression).

I guess that's another question, have you tested compression? I would do that when you test for spark.

 

Well thanks for the help. I'll see what sensor data I can gether next time it starts up.
While it's possible it is spark, I've kept it at the bottom of the list because I never have any issues beyond startup. Once it's running it's smooth all the way through the power band and wot.
MAF is definitely a possibility I just wish there was a way to test it without throwing money at it.
Is there any scenario where too much fuel would cause this? Or would that only be leaky injectors? I just feel like the rich exhaust smell has to be part of it

 

I agree with everything you said, but you would think any issue would also rear its head during normal driving---MAF, spark, fuel, etc. Unless maybe the throttle body is doing weird shit so the idle air control is causing issues...

I figure spark takes five minutes to check off the list, and was trying to save the pain of replacing the MAF when a good chance it's not that. That's why I was thinking if you can get MAF data through an OBD2 scanner maybe that would point to something.

Too much fuel can definitely cause it to choke at startup, but I don't know why it would be commanding too much fuel and even if an injector was leaking that would only affect one cylinder. That's why I was next leaning towards MAF since if the air data is messed up then so is the fueling, since the truck looks at the MAF and says there's X amount of air so I need to inject X amount of fuel. Maybe the MAF is reading too much air or not enough. If you can get voltage off of the MAF we could compare that to a normal truck at startup potentially and maybe conclude something.

 

@snivilous
Found something odd. I was reading through the manual looking at the fuel pressure testing and parameters and it occurred to me my fuel pressure should be higher than 40psi. I totally forgot I put in a separate relay and wired the pump power directly. Also odd that with the key in the on position (engine off) I get no pressure on the gauge. So I went and grounded the VSV relay to see if that changed it and cranked the engine but still only got 40psi. The only thing I didn't do when I replaced the pump was take out the fuel pressure switching valve assembly. Not sure it's the source of my issue since I do get 40psi, but still very strange.

But maybe none of that matters now cause since I installed that pressure gauge the engine sounds like this when I try to crank it -
https://youtube.com/shorts/uEkXyieZSYA?si=qKRf8MEn3krbqfyS

 

Does anyone have any idea why it sounds like that? I hadn't done anything to it before that point, and now it sounds like something is terribly wrong. Negative battery terminal gets pretty hot while trying to crank it as well. If it's the starter I'm gonna lose it, I've already changed it twice cause of this issue

Edit, got it to start. Pulled it into the garage, it was idling there for 15-20 mins. When I hopped back in the seat the temp gauge was was all the way up. ? Maybe I should be suspecting a bad head gasket?

 

What l is the ignition source for the fuel pump relay? Ignition fuse? Pump positive blue wire? The fuel module only sends power when cranking, if using that blue wire. Red from fuel module is neg, blue pos. Not sure if an extra wire for ffv.
Your neg wire should not be getting hot.

 

10A IGN fuse under the hood drives the fuel pump relay. Don't recall the wire colors down below. I think the negative block is heating up from the starter going out

 

I ran through live data and anything else I could find on my scan tool (

$400 MUCAR Car OBD2 Scanner Diagnostic Scan Tool, OE Level All System,28 Services with Oil,EPB,BMS,SAS,SRS,TPMS,Gear,Inject,ABS Bleeding,ECU Fault Code,FCA Autoauth,Wireless Update

https://www.amazon.com/dp/B0CJ32MTHC) and the only thing I saw concerning the maf was air volume, nothing that appeared to show me voltages unfortunately. I'm going to start pulling all the plugs to check the spark and then do compression in a little while, hopefully the starter will hold out till that's done.

 

Well here it is, cold compression of course. I expected odd numbers from bank 1 since the misfires were usually on 3 and 5, but I didn't expect bank 2.
Bank 1 Bank 2
1 - 126 2 - 100
3 - 100 4 - 110
5 - 149 6 - 117
7 - 154 8 - 132

I guess it's time to pull the valve covers and see what's gone wrong in there

Almost forgot, I checked all the packs and plugs for spark, they all looked about the same, nothing abnormal.

 

That amount of variation is definitely concerning. Ideally those numbers would be in a ~10psi spread, 5 and 7 being very high and then 3 being 50psi lower is very weird. Bank 2 spread is a bit more acceptable, still weird how much higher #8 is. For reference last time I checked my Tundra (probably at 260k at the time) it was around 120-130psi I want to say across the board, I think the biggest difference was like 15psi.

You could do a leak down test before you pull the valve covers, would narrow down where you're losing compression. And to be clear, those numbers aren't particularly bad in and of themselves, it's the spread that's concerning.

 

Yeah I didn't think much at first till I saw 5 and 7.
Let me see what I can do about a leakdown. Is there any good trick to knowing when it's at tdc on compression stroke? or should I just use a balloon

 

Never done one on the 5.7 so not sure, usually I just stick a piece of wire in the spark plug hole and watch it move.

If the engine is just funky and has odd compression and nothing else is wrong and that's what's causing all your issues, I'd have a hard time doing much about it and just accept it'll be hard to start sometimes.

 

Well if it is just funky I'd be getting air through the crankcase right? Surely the odds of that must be astronomical though. And if it is that then it's not worth keeping on with, this is the 3rd starter I've had to put in it in the last 18 months.

 

That or valves aren't sealing well. Even with the hard start I'm surprised the starter would have that much issue.

 

Yeah it just burns em up, but sometimes it can take a while to get it started, sometimes it just refuses.
On another note, I don't seem to have a long enough wrench to get to the crankshaft nut, looks like a 22mm but can't be sure -.-

 

You can pour a little oil through the spark plug holes on the low compression cylinders and check again. If it doesn’t help the piston rings/cylinder bore are likely damaged/worn out, if it does look for valve/gasket issues. IIRC compression on a warmed-up engine with throttle wide open is a minimum of 145 psi..

 

I was just going to post about the compression readings veing real low. 189 psi normal, minimum 145psi with a 15psi variation between cylinders.

 

Yeah I knew with a cold test things would be odd, but with how hard its been to start and the starter crapping out it was really the only option, and the differences are really the most important bit. Hopefully the leak down test will help paint a slightly different picture, if not more than slightly hopefully. I just have a hard time believing it's all gone tits up at 178k miles

 

@snivilous
Leak down test complete, all cylinders passed. 5 of them were nearly perfect, cylinders 1, 2, 4 didn't test as tight as the others but still well within acceptable range.
I took pictures of all of them if anyone is curious about the actual results.

 

With the weird cranking in cold weather and all,,just noodling mind ya,,Temp sensor on the raged edge from going south. Had that happen once and gave it a go and worked for me. Cheap fix , if it is the fix.

 

Thanks, that was one of the first things I tried for the same reason, it was cheap! But alas it wasn't it

 

I'm still wondering if I have dropped an intake rocker. I've seen several incidents of it and it wouldn't show up in a leak down (if my logic is correct). I wonder if I could do a reverse leak down to test for it. Like set the cylinders to the intake stroke and see if any of them don't leak. That would tell me the intake valve isn't opening right? Though it still wouldn't explain why it runs fine once it is started.

 

How is idle air controlled on this engine?

 

It's all through the throttle body and being electronically controlled. There's nothing besides the butterfly valve doing its thing.

 

First let me say thank you to @snivilous for your direction and to @Mdl for your helpful questions.

When I made my last post I had left the truck as it was when I finished the leak down test. I pulled off the TB just to make sure nothing was awry, wiped some grease off of it, and put it back. I figured at this point I would put the rest of it back together and put the new starter in and see if I could get to throw some codes or do something to give me another hint. When I was done I went to start the truck and lo and behold it started right up with no issue at all. The only thing I did before (intentionally) was put the plugs and packs from bank 1 on bank 2, and vice versa.

I hadn't said anything till now cause I wasn't sure if it was just a fluke and I didn't want to jinx it. But 5 days later now and it's starting and running perfectly, startup even sounds different than it did, it sounds healthy now. I don't really believe the issue is fixed cause theoretically if it was the plugs and/or packs the problem should have just moved to the other side. But I'll take what I can get at this point, cause I really don't like using the parts cannon to solve things. I was so happy that day though that I immediately started ripping the dash out to replace the stupid hvac box and I got that all buttoned back up yesterday and I now have heat and AC again along with a cooperative engine.

Thanks again for your time and knowledge. I wish I could give you a definitive solution to it but I suppose I can't have it all

 

@snivilous
Well it was fun while it lasted but now its back. Not as troublesome as before, it only takes at most 5-6 tries to get it chugging and then a stab at the pedal helps it along. I've gotten it to throw codes a couple of times but they're only random misfire codes with no consistency.
I've eliminated the MAF possibility by replacing it. I've no specific reason to suspect it, I just did because I really feel like this has to an air or spark issue considering how rich the exhaust always is on startup. But at the same time I don't have any specific info to fault the coil packs for either. For a second I thought maybe SAIS because of the exhaust but it seems the SAIS wouldn't cause starting issues as it comes in downstream.
So at this point I'm still stumped with no leads and firing the parts cannon at it is still too expensive without better direction.