Rough Idle, weird stall, diagnosing fuel system...HELP!

Hey all, so after some struggling, some shop diagnosis and some replacement pieces I've decided to start a thread to see if y'all smarties have any ideas on what my next move should be.

Truck is a 2000, V6 Manual with 215,xxx.

Been having some weird issues over the past 6 months. Truck started to bog down under load, like accelerating from a stop needed ages of time to get to speed. Once accelerating it would do so in kind what ill call a chugging maner, like almost bucking forward as in VROOM...vroom..VROOM..vroom..VROOM. This was alleviated greatly when I had the PCV valve+ gasket, spark plugs, coil packs all replaced. My thinking stronger spark doing better dealing with strange fuel/air mix.

Since then it has felt much better overall, the chugging is still there but close to unnoticeable. Then it started dying at idle. I could watch the idle drop from 1500 down to 1000 then 500 then 250 starting to die. When this happens at a stop, I can rev it back up slowly, but it bogs down at 1500 in 1st just barely being kept alive for maybe 30 second by my right foot, then as if the "clog" (that can't be an issue right?) clears itself it revs right up again and is back to running around that 80% strength. I have heard a few strange pops when it does this, not loud backfires, but a strange POP POP in front of the passenger seat.

Shop diagnosed it to be MAF. Swapped that no change. Swapped upstream O2. No change. Swapped Fuel Filter, no change.

Next thoughts, Dying Fuel pump?
Leaking/old Injector?
Vacuum leak? What's the best way to find a vacuum leak without smoke?

I had a P0171 code last week, so I've been going down that list.

Thoughts? Ideas? Bring me and beer for my troubles??

Cheers y'all, anything helps!

 

Use an unlit propane torch or starting fluid to find vacuum leaks with engine idling.
RPMs will increase when sprayed on leak.

 

Does your truck hit a "wall" in ever gear?? My truck does almost the same thing but my a/c stops blowing cold, I loose complete connection with the ecu threw my obd port. But it only does it when it wants to. Most when its warm and I cut it off then start it back, or if I leave the key on. Sometimes it won't do it for weeks other times everyday other times everytime I drive it. Idk whats wrong with it and forum has no clue either. Hopefully you figure it out cause my issue has ruined the motor in my truck.

 

Any chance your catalytic converter is plugged up? Some muffler shops can test for plugged converter. Worth a shot.

 

Duct tape a fuel pressure gauge to the windshield and go for a drive

 

I don't have a cat on my truck anymore. But its backed fires so much and so hard when it starts missing it cracked the exhaust manifold.

 

Ouch! Backfiring means the fuel isn't getting burned in the cylinders. Double check the coils and plugs

camshaft timing is also a concern

 

What would make it do it so randomly and intermittent? A ground or a loose connection?? But like I said itll go weeks at times without doing it.

 

super intermittent problems can be hard to find.

Who put the plugs/coils in? What brand are they? Are all the vacuum lines plugged in?

 

I changed both. And it does seem to be. I got a manual off of Emanuelonline.com and went over all the basic stuff like that when it first started it. I should check over it again now. But one more question what doors/windows interchange on the first gens??

 

Not sure what you're asking about doors and windows..

Did you replace the ignition wires too? Look for cracks or signs of arcing on the spark plug boots

 

Do all first gen tacoma doors fit one another? Or is it certain years of the first generation that will swap out. Can I take a drive side window from a 99 tacoma and put it in a 96 tacoma? Hopefully that makes better sense.

And I also changed the wires, the rotor button and cap but not the distributor. It has a small oil leak around that seal when I did change it. And when it misses it blows oil like crazy and I couldn't figure out where from untill just now. Thank you lol

 

Oops I thought I was talking to Dusty with the V6.

@lowered_TACO start your own thread so we don't get confused

 

@b_r_o i have hopefully o dang hmy bad I was just thinking. Dang I done hijacked his post. My bad @DustyT22

 

HAhaha No worries lowered! I have an ultra gauge, maybe i can run fuel pressure on that sucker and take a look. My issue is also equally intermittent, but it does seem to do it more if i have already driven somewhere, say like 20 minutes. Then stop for 20, then upon starting it back up it will bog down.

Read one thread that mentioned leaky injectors in this case, as in injector is dripping gas while you stop so a cylinder is overloaded when you start again?

 

So it definitely seems like we have almost the same problem. I have noticed my truck does it more often if I have stuff under my seat or in the bed of my truck. Have you noticed anything like that??

 

Not really my truck just does it on days that end in Y, and when I put my right shoe on first....lol

I just read through this whole thread 1st Gen 3.4 Vacuum Hose Thread | Tacoma World and am gonna tackle hoses next. Rubber that's old enough to buy a beer probably isn't doing a perfect job anymore!

 

Maybe plugged injector(s)
I have had success in the past on different vehicles dropping the injectors in an ultrasonic cleaner with 50/50 Simple Green mix. Soak for a couple hours, then run through a few cycles. Spray down with carb/brake cleaner and reinstall. Harbor Freight has a good ultrasonic cleaner, I've had for almost 10 years no problem.

Other one to check I hadn't seen anyone comment on is compression. Low compression can cause loss of power, and make it real tough to run smooth at idle if the compression between different cylinders varies widely. If it's compression, I'd start by doing either a water-wash or seafoam through the intake while the engine is hot. That would take care of low compression if the cause was valves not sealing up real tight. Quick, easy, and cheap

If low compression, and due to rings, then your best bet would be to get those cleaned up. Without taking the engine apart, you're left with chemistry options. If not already running synthetic oil, switch to a good one with high detergency like Castrol Edge. You could even go with one of the newer diesel engine oils, look for the SAE 10W-30 "API CK-4" version.