I realize this is very hard to diagnose & advise “hands off.” I thank you in advance.

Recently had it checked out by a pro. His method & diagnosis in the 4th & 6th paragraphs.

Some back ground. New coil packs (CP) on cylinders 2 & 4 replaced about 3-4 months ago and 8 months ago respectively. All new plugs w/CP 2 - about 1K miles from today. This new problem surfaced about less than 2 months ago. I, along w/the pro, initially suspected coil pack as that’s what solved the first & second go-arounds above.

Consistent Symptoms ONLY at cold start:
1. after starting, running rough.
2. After ~10-15 seconds “Check engine” flashes
3. Shut down
Attempt restart. As of two weeks ago, “1” repeats, naturally followed by 2 & 3.
Third time is a charm, it runs fine! The other head scratcher: once I drive it long enough (7-8 minutes) for all under hood to get hot, restarts are no problem - even after sitting almost 2 hours last week.

I’ve done a little forum reading that mentions cleaning electrical contacts. Please recommend a solvent and dumb down any suspected contact location descriptions or other possible causes

The pro’s method and diagnosis: he switched the #4 & #2 CPs. Said problem remained w/ 2. As of last week...
Zero oil in coolant
Zero coolant in oil

He believes either a cracked or block OR that bank’s head gasket.
Doesn’t make sense to me considering last week I drove it around doing several errands over the course of 5-6 hours around Athens*, GA w/out so much as a hiccup.
*first errand 30 minutes from my house. Last about 15.

I hope this makes sense. 1000 thanks for reading this far. Tony

A cold-start misfire like that is very often a sign of a bad head gasket on these V6 trucks. A leak-down test on the engine will tell you for sure.

In my case, I had the exact same symptoms you're describing. Cold start misfire on cylinder 2. I pulled all 6 plugs and did a leak-down test and found that all 6 cylinders were great, no leakdown issue (~7% on all cylinders). I noted that when I pulled the plug from cylinder 2 (after the truck sat for a day) the plug was wet with fuel. No other plugs were wet. I suspected a leaking injector, and replaced all 6 with eBay remans about 3k miles ago. Since then I haven't seen the problem return.

-Rob

Thanks for your reply.

Did my cold “restart” process temporarily clear your problem? That is, I ALWAYS hafta shut down and restart at least once

An unrelated question: I subscribed to MY thread yet no email. I just discovered, to expect an email demands a second click.

Again, thanks for your reply. I may hafta buy a spark plug socket

Update: when sitting over night, if I turn the ignition to “run,” but wait about 15 seconds, before activating the starter motor, it starts & runs on 6 cylinders - consistently 😊.

So I believe I’m replacing an injector but before I do, as a final check, I’m gonna pull the spark plug in question* after sitting over night.
* O’Reily’s scanned the #4 as the problem child.

Thanks so much for your testimony

Tony

Subject line says it all. Thanks

bank’s head gasket leaking?

Did you solve the problem? Has a top mechanic given you a diagnostic?

I have 2005 V6 4runner (150,000 miles) and it runs and starts like when it was new!

Never missed or stumbled like yours?

change oil and filter every 5000 miles.

Also a 42 foot Performance with three F225 Yamaha 4 strokes - ran for 12 years before blew the starboard PH.

BTW. the fish on the deck fetch $500 each at the local restaurant. I fish alone .. a.e. Captsolo
I bait, hook, reel in the fish, cut them on my built in 6 foot cutting board, bag them and put them on ice, then drive 50 miles to port, and bring them to the best restaurant in Nassau.

I'll bet I've caught 500 this same way in the last 12 years.

That's a #9 circle hook on the deck - if you never want to have one "get away"!
"YFT are the fastest fish in the ocean when hooked"

Attached Images

 

for something as important as injectors, I'd go factory OEM replacements.

No. Leaky injector.
What brand injector to buy? Planning to replace them all as others will fail in time. I want advice on brands to avoid. In my experience OEM is 3-10X the $ of aftermarket parts
Bought mine @~196K. You bought yours new?
what does this especially PH mean?
I’m sorry I don’t know how to connect “#9 circle hook on the deck...” to good aftermarket brand injectors.

Surely somebody makes a suitable quality replacement injector that won’t force my family into rice and beans for a month or two? I’m retrired w/4 kids, youngest is 10, living at home.

I believe an OEM injector is $132 a piece - over $800 for six?! That’s outrageous compared to other company’s OEM! In my experience Toyota OEM is 3-10X the $ of aftermarket parts. Yes some aftermarket is garbage but not all.

Somebody please help a Veteran?

I am in the OEM camp myself for electrical components like injectors and sensors. No matter the brand, even apparent OEM, you can get counterfeit injectors on Ebay so be careful. If you can afford to be without the vehicle for a while, take off all 6 and send to Witchhunter for cleaning and rebuilding.... I did this for my third gen, he rebuilt 5 and one was bad. He sold me a rebuilt used one for $35. Back in 2016, the total bill from Witchhunter was $182 (plus shipping) which included $25 for expedited service.
WitchHunter Performance - Injector Cleaning & Flow Testing Services

If you can't have the vehicle down that long, find a suitable donor vehicle in a junkyard and buy the injectors making sure they are Toyota OEM and then send them to Witchhunter. There are other Toyota vehicles that use that same injector. I have attached a pdf detailing the possible donor vehicles. If you have a pull-a-part nearby, you cna check their inventory (this site is where I got the interchange chart).
Pull-A-Part Junkyard & Auto Salvage: Find a Location Today

Checked RockAuto - I do not have experience with GB Remanufactured OEM injectors but these might be worth researching. Maybe somebody else has used them.
More Information for GB REMANUFACTURING 84212305

Attached Images

4th gen T4R V6 Fuel Injector Interchange.pdf (46.1 KB, 71 views)

Cold Misfiring Problem history by replacing all the injectors.

I expect to replace a few coil packs over the next year or so. Two are new over the previous ~18 months.

Thanks to all for your patience

Tony