Rich Hard Start - The Ongoing Struggle

And then today we are back to having major issues getting going. I'm lost

 

When it starts you said it smokes for a while? clearing out excess fuel right? seems like it floods itself... usually caused by injectors, no spark, no compression, bad timing etc. A fuel pump module wouldn't cause excess fueling to me. even if the pump was running extra voltage somehow, its the fuel pressure regulator that sets the pressure in the rail. so the pump in itself cant really cause over fueling, but it could cause under fueling, which doesn't seem to be the issue. i forget what you've all done but perhaps test for fuel pressure and get your oem injectors flow tested and cleaned. at least that way you can rule out the fuel system. and its good preventative maintenance too.

 

Only for like 10-20 seconds till it smooths out

Injectors, pump, and pressure are good. Remaining suspects are spark, fpr, tb or position sensor, compression, timing. The trouble with any of those (or anything else for that matter) is that there is no evidence of an issue other than at start up. Once it's running its perfect, and the only codes I get are occasional misfires and startability malfunction which are not helpful. And I don't think I'll bother checking compression again cause if it is that there's nothing to be done but to get rid of it.
Going to pull a vacuum on the fpr today, but not sure what good it will do since this fpr isn't actually connected to vacuum, just the air box thingy.

 

Not the fpr, put 20psi on it and it didn't drop at all in 10 minutes

 

Pulled the plugs today, cleaned and gapped.

 

Wild. I wonder if it's not sparking during cranking sometimes. Wonder if you could test for spark or power at the coils during the initial start. I know some older toyotas have the injector and coil power run through the ignition. Not sure if our tundra are that way. I had an issue this winter where my ecu would only come on during cranking. It would fire instantly but then shut off as soon as I let go of the key. Wiggled the ignition wires and suddenly ecu turned on. Been working fine since then.

 

Well another day another test.
Occasionally, somewhere between every idk 500 and 800 miles, I've had to top up the coolant when I notice the temp gauge going up. I don't really think this is normal, but I have yet to find an explanation for it. When I did the leak down test a couple months ago I saw no evidence of bubbles. But yesterday I had to add some again, about 1/2 gallon.
So in my continuing search to cure this truck I decided to try a chemical combustion leak test. But it passed - stayed blue the whole time while I sat and watched it burble away. I had thought that if it failed and I had been getting a little coolant in the chamber it might explain the other main issue. But alas I'm just back to square one as usual. Nothing in the oil btw, looks fresh as fresh can be. And no steam from the tail, just disappearing coolant, no typical coolant leaks either of course

 

Could be leaking coolant only when warm or at shutdown? 1/2 gallon is quite a bit and having to top off is suspect of a coolant leak.

 

Wish I could say. I know it's not leaking internally warm or cold so that's something at least. This engine has totally baffled me

 

Have you tried the oil trick @Vizsla suggested in post 48? IMHO you need to solve the low compression in multible cylinders first since it runs fine after warm. If you're lucky stuck compression rings could be free'd up with Marvel mystery oil or seafoam left in cylinders overnight? Have a peek inside the cylinders with a cheap Amazon borescope with straight and side view. Look for excessive carbon build up on back of valves? Good luck man and hope you find a solution as you're definately busting your ass on that puppy.

 

I know you said you’ve addressed the flex fuel part of this equation, but I can’t help but think that’s the issue. Flooding at startup with regular gas is what a FFV truck would do if it was behaving like it’s got E85 in it. Regardless of what the alc% is showing, it’s giving too much gas on startup. Wonder if it would behave differently if you actually ran E85 in it?

 

Thanks, I never went back and did a warm compression test, but I think the leak down test showed there weren't any actual issues there, just wonky cold numbers

 

I have to strongly agree with you there simply because nothing else makes any kind of sense. I hadn't thought of running E85 in it as a test, that's a great idea because the alternative is spending a ton getting it tuned out without knowing if it would actually help.

 

Two thoughts on the coolant loss topic.

The valley cover plate under the intake manifold is a common leak point. Mine leaks down the back of the engine and transmission but never drips on the ground. I have to add a litre or so per year.

It's becoming an issue at this age where the coolant can eat the head gasket at the small coolant port between the cylinders. Usually won't show combustion in coolant or coolant in the oil. Will smoke a bit at start up and misfire a bit or hard start a bit at first. May go away as it warms up. My friends truck had this issue. He finally realized the problem after chasing misfire codes when his truck had no heat one day due to coolant loss.

 

Interesting, thanks. Did he ever see spark plugs that looked steam cleaned and did he end up pulling the heads?

 

Not sure on plugs but yep he pulled heads. Luckily block and head were true. Zero warpage or damage. Did a full oem toyota gasket set on it. Misfires gone. Rough, smokey start up gone. Been running 100% for a couple months.

 

The valley pan leaking is a known spot for leakage on these engines. That could be the culprit. Still noodling about,, Is there anyway that coolant
could enter the engine from the throttle body? Like a very small internal crack ? Could put a vacuum across the coolant hook up lines and check
if it holds .

 

A few months back I had the intake off and didn't see any visual signs of leakage.
TB is disconnected from coolant

 

Was reading through your thread and saw that you were able to reset your Alcohol %. Do you have techstream to do so? my 2017 FFV isn't having startup issues but its reading 30% or higher recently (was 47% when i went to the dealer). I had the dealer replace the pump under a TSB a ways back and they reset and relearn procedure and it stayed at zero or very low for months, but then i had an issue where i had to disconnect the battery and maybe that did something and the % has been climbing since then. Wondered 2 things...how you were resetting, and if possibly there's any steps being missed that would mess up how the computer does the fuel adjustment learning that could be causing your issue.

 

I have a cordless bi-directional tool I use to reset it, too much trouble to pull out my laptop and start up Techstream just for that. But yeah anythings possible when it comes to missed steps, though with as many times as I've done it the odds are I would get it right at least once

 

might be worth a try, and if you already have techstream and know how to use it, it would be free99 vs the parts cannon