Missing Upon Start Up

Hello. My 05 misses when starting it first time of the day. Runs rough, I stab the gas, good to go. That's the extent of the symptons. I've replaced the coils and plugs. This work was done before it started missing, and imo, there wasn't anything to suggest cause-and-effect.

Let's assume it's not a bad coil, fuel injector? What's your experience say.

Thanks in advance.

 

Are you losing any coolant?

 

A misfire that occurs only on startup suggests a headgasket that is seeping coolant into a cylinder, if you can find which cylinder is misfiring I'd want to pull the plug and look in it with a borescope with the cooling system under pressure for coolant seeping in around where the head meets the block.

 

Nope. Reservoir is good. I'll check the radiator today though

 

Without a proper diag. It’s hard to tell but, I’ve seen this scenario before and was a fuel pump unable to
maintain its anti back bleed causing a misfire in the last injector in the system.

 

Do you have the CEL -- it will tell you what cylinder (P040x where x is the cylinder in question). Pull the plug and check the cylinder for fluid (likely drops). Or other codes may lead to fuel issues.

if you don't want to pull plugs (yet) - check the radiator (vs the reservoir). It should be completely full. If it's not, add coolant. run the engine with the cap off until it is warm and see if it's bubbling.

 

Why did you replace all the plugs and coils? Plugs are understandable at the end of a service internal, why replace coils though? No misfires before these parts were either sold to you or you purchased them?

As far as testing for a blown head gasket, don’t waste any more time or money.

A small leak into the cylinders will not always be noticeable and you won’t get oil in the coolant necessarily either. The coolant on my 08 looked normal when I diagnosed my head gasket failure.

This is quick and easy. Parts stores loan out coolant pressure testers and a decent borescope isn’t too pricey on Amazon (and with a 30 day return window depending on funds, it could be returned). Just did this to find my hg leaking on my 08 having a stumble on startup after sitting overnight / during work. You can compression check while you are doing it too with a compression tester from a parts store at the same time. Once you’ve ruled out mechanical failure, you can reuse your old coils and plugs if you didn’t throw them away to do some A-B testing.

https://m.youtube.com/watch?v=CiwyPgrlbEM

 

Appreciate it, I'll try it out

I had a misfire previously due to bad coils, plugs were at 100k. I'm pretty sure I have a leaking hg. Discolored coolant and sometimes it consumes coolant. Oil looks fine though, I have plenty of power and it's not blowing smoke. Mechanic said drive it until it gets worse and we'll rebuild then. Anyways, that's the story behind that.

 

FWIW mine went about 2 weeks from stumbling on cold start to white smoke billowing on startup. Another thing to consider is that if it is a HG leak into the cylinder(s), it’s going to be steam cleaning and washing the cylinder walls of oil and the piston rings are going to start scraping away the cross hatch on the cylinder walls.

I dumped my short block and got a new one from Toyota to rebuild with my head when it returned from the machine shop due to cylinder wear (and stuck piston rings allowing a quart of oil being consumed per oil change). Two weeks might not be long enough to remove the cross hatch, but I wouldn’t keep it going a long time if you don’t want to have that happen.

 

I'm like 1-2 years since I noticed dirty coolant, and 2-3 months since it started missing at startup.

I love the truck though. If I have to rebuild the top end, I'm having the lower end done at the same time

 

I drove mine for 1 year knowing I was slowly losing coolant before the misfires started and I went through the rebuild