Smoke after chaging injectors, P0172

[AndreiR]

I just changed all six injectors (followed this good write up) on my 99 4runner, 3.4. Took it for a test ride. The idle is rough, got some nasty smoke from under the hood. The scanned code is P0172 (System Too Rich Bank 1). What went wrong? Please help. Thank you!

 

[gamefreakgc]

A few things to try:

Remove the EFI Relay in the fuse block in the engine (this won't make a difference if you had the battery terminal off as you worked on changing the injectors).

Wait a bit, you may have had excess fuel in the system and it'll burn off as the engine gets hot.

Did you go with any sort of aftermarket brands, or put used injectors in that were not flow tested?

 

[AndreiR]

A few things to try:

Remove the EFI Relay in the fuse block in the engine (this won't make a difference if you had the battery terminal off as you worked on changing the injectors).

Wait a bit, you may have had excess fuel in the system and it'll burn off as the engine gets hot.

Did you go with any sort of aftermarket brands, or put used injectors in that were not flow tested?

Thanks gamefreakgc for your reply!
I did have the battery terminal off while working on it.

The injectors I got are GENUINE OEM DENSO FUEL INJECTOR SET, from eBay -- supposedly new.

Is it possible some injector didn't sit well in its socket? I think I tighten the fuel injector rail bolts down very well.

Last night the smoke was so nasty, and a smell of gas was present, I'm afraid to start it up now. But you are suggesting that after it was sitting over night, the excess gas evaporated?

 

[gamefreakgc]

Yeah, those look decent enough. Look to be refurbished used ones, which is pretty common and usually work ok. Just to cover the bases here, you have no fuel leaks right? No fuel smell if you turn the key over but not crank the engine?

And yes, excess fuel in the exhaust or engine would evaporate overnight so if that were the case it would run much better if you try it again.

If you can manage it without tearing down the engine again, check the resistance of the injectors with a multimeter. Should be 13.8k ohms with a multimeter (set at 20k).

Last but not least, are you sure all your hoses are connected back up correctly? If you accidentally swapped a hose or two it'll run real bad like you are experiencing. Did you take any pictures before hand to compare it to? If not you can google "5VZ-FE vacuum diagram" and go to images, should be enough there to double check.

I accidentally swapped the fuel return hose with another the first time I worked on my 4Runner (oops). My picture I took make it look like it went the other way around. Then I looked real hard and realized the hose was connected to a HARD LINE and wondered, why would a vacuum hose be routed like that?

 

[AndreiR]

Yeah, those look decent enough. Look to be refurbished used ones, which is pretty common and usually work ok. Just to cover the bases here, you have no fuel leaks right? No fuel smell if you turn the key over but not crank the engine?

And yes, excess fuel in the exhaust or engine would evaporate overnight so if that were the case it would run much better if you try it again.

If you can manage it without tearing down the engine again, check the resistance of the injectors with a multimeter. Should be 13.8k ohms with a multimeter (set at 20k).

Last but not least, are you sure all your hoses are connected back up correctly? If you accidentally swapped a hose or two it'll run real bad like you are experiencing. Did you take any pictures before hand to compare it to? If not you can google "5VZ-FE vacuum diagram" and go to images, should be enough there to double check.

I accidentally swapped the fuel return hose with another the first time I worked on my 4Runner (oops). My picture I took make it look like it went the other way around. Then I looked real hard and realized the hose was connected to a HARD LINE and wondered, why would a vacuum hose be routed like that?

I just went out and started it up. And now in a day light I see gas gushing badly from the top of the injector #3 (middle passenger side). I guess I have to take off the top part of the intake manifold. Would it be safe to drive a hundred yards to my garage?

 

[gamefreakgc]

Yeah it won't blow up on that short of distance

Chances are your o-ring gaskets on the injectors didn't seat correctly. When you install them before completely torqueing down the fuel rails you should be able to rotate the injectors freely. If not the o-ring is messed up. It's a one time deal too, now that it's misshaped it'll likely leak again. I would pick up some new ones and replace.

I attached a few pages from the FSM that might help, has torque values as well. By the way, you're not supposed to re-use the copper crush washers on the fuel rail, not sure if you did or not. Would hate for you to patch it all up again just to leak somewhere else.

 

[AndreiR]

Yeah it won't blow up on that short of distance

Chances are your o-ring gaskets on the injectors didn't seat correctly. When you install them before completely torqueing down the fuel rails you should be able to rotate the injectors freely. If not the o-ring is messed up. It's a one time deal too, now that it's misshaped it'll likely leak again. I would pick up some new ones and replace.

I attached a few pages from the FSM that might help, has torque values as well. By the way, you're not supposed to re-use the copper crush washers on the fuel rail, not sure if you did or not. Would hate for you to patch it all up again just to leak somewhere else.

Thanks a lot gamefreakgc! The PDF also makes clear many things. Darn it -- I should've had it before I started the whole project. One thing I'm kind of proud of is that I put all other things together -- next time it will be much easier. I guess I'll leave the truck where it is until I get new o-ring gaskets (as you suggested) and new copper crush washers for the fuel rails (you are right -- I used the old ones).

 

[gamefreakgc]

Hey no worries, it how we learn right? I'm no mechanic, I learned things the hard way by trial and error. But with the right tools and a good manual you can tackle pretty much any job on a vehicle. Plus the 5VZ-FE is a very easy and forgiving engine to work on.

No offense, but that write up you linked wasn't very good. Left out way too much important info. The pictures are nice, but that is about it. The fact that he didn't cover up his intake manifold is the tell-tale sign, you don't want to know what happens if you drop a bolt or washer down there and can't/forget to get it out.

Best of luck to ya Andrei.

 

[AndreiR]

Hey no worries, it how we learn right? I'm no mechanic, I learned things the hard way by trial and error. But with the right tools and a good manual you can tackle pretty much any job on a vehicle. Plus the 5VZ-FE is a very easy and forgiving engine to work on.

No offense, but that write up you linked wasn't very good. Left out way too much important info. The pictures are nice, but that is about it. The fact that he didn't cover up his intake manifold is the tell-tale sign, you don't want to know what happens if you drop a bolt or washer down there and can't/forget to get it out.

Best of luck to ya Andrei.

Thanks Jerod for your encouragement!

You are right about that write up, but it's the best I could find, including a couple of videos on YouTube -- those are even worse (even though I appreciate people's effort). But there were some useful tips in the comments down below the pictures, some suggesting to cover the intake manifold, so I did. In my case any info is welcome.

Again, thanks a lot, and I will report my progress later. :hatsoff:

 

[AndreiR]

Update -- saga continues...

Hi all! I'm back with the updates.
Got a new set of o-ring gaskets and crush washers for the fuel rail, installed everything -- this time correctly.

All worked well for a while, then CEL went on again. The reading this time was:
P0130: O2 Sensor Circuit (Bank 1 Sensor 1)
P0133: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)

Cleared it off, drove for a while, then CEL came on again, with reading the code:
P0171: System too Lean (Bank 1)

Somebody suggested (on this forum) to clean or replace MAF sensor. So I cleaned the Mass Air Flow Sensor following this instructional video -- with Q-tip and alcohol:
https://www.youtube.com/watch?v=sXXs-MK7u-0

Drove again. This time - no CEL. But the codes still show (refreshed):
P0171: System too Lean (Bank 1)
P0130: O2 Sensor Circuit (Bank 1 Sensor 1)
P0133: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)

The idle and acceleration feel fine, except for a slight shivers running through at a regular interval (like human breathing) while idling in Neutral.

So now I have: all new spark plugs, all new injectors, cleaned MAF sensor.

What would be the next logical step to address the above code readings? From what I was reading around the oxygen sensor could be at fault. Bank 1 Sensor 1 would be one on the passenger side, upstream (before cat. converter)?

 

[gamefreakgc]

Yes, that's correct about the O2 sensor.

Try this first: unplug the EFI fuse and relay (both just pull out) in the engine bay fuse box. They will be labeled in the lid. I can't remember which one actually resets the fuel trims. It's a good thing to do whenever working on the fuel or air intake system since it'll reset faster.

If that doesn't clear it up then replace the front O2 sensor with a DENSO unit. RockAuto.com has one for $47ish dollars, depending on which one you need. That's the OEM part and cheaper than anywhere else you'll find online or at an auto parts store.

 

[AndreiR]

Yes, that's correct about the O2 sensor.

Try this first: unplug the EFI fuse and relay (both just pull out) in the engine bay fuse box. They will be labeled in the lid. I can't remember which one actually resets the fuel trims. It's a good thing to do whenever working on the fuel or air intake system since it'll reset faster.

If that doesn't clear it up then replace the front O2 sensor with a DENSO unit. RockAuto.com has one for $47ish dollars, depending on which one you need. That's the OEM part and cheaper than anywhere else you'll find online or at an auto parts store.

So you think so too, great! Thanks for suggesting to "unplug the EFI fuse and relay". I'll try that first and report back.

I also found this Denso 234-4162 Oxygen Sensor on Amazon for $47, free shipping.

 

[19963.4lsr5]

I got my bank 1 denso on Amazon too. Great price.

 

[AndreiR]

fixed!

Just wanted to follow up with an update.

The 02 sensor replacement fixed the situation. No CEL and the engine runs nice and smooth. I didn't have a chance to notice gas mileage improvement, but I hope to see it at the next pump.

Thank you all who helped me with this problem and have a nice rest of the week!!! :thumb::thumb: