P0171 After 7th Injector Install

[A.Wilson013]

Like the title states, I keep throwing a P0171 ever since I installed my 7th Injector. The 4Runner runs great, I love it, but the CEL is starting to bug me.


It first happened the morning after we put the URD kit in. [I drove it home (about 30 miles) the night before with no issues.] It was cold, so I pulled out of the garage, let it idle for ~5 minutes or so while I loaded up snowboards etc etc... Hopped back in, noticed the code. Scanned it, wasn''t too worried about it, so I turned it off and drove on.

About 30 minutes later, it came back on.

Anyway, been playing this game ever since. Hoping one day it will just stay off, but that doesn't seem to be the case.



The other day after I had turned it off; I was stopped at a stoplight. For whatever reason I was watching my Wideband and heard the motor sputter for a split second, watched the Wideband read 17.8 and the CEL come on.


So far I have cleaned the MAF (to no avail) so I replaced it with another one I had laying around (to no avail). After that I cleaned the replacement MAF (to no avail). I re-ran all of my vacuum line from the boost port (as this is the only vacuum related thing I touched for the 7th Injector) and replaced my front O2 sensor.

Any ideas guys?

 

[Dous]

Like the title states, I keep throwing a P0171 ever since I installed my 7th Injector. The 4Runner runs great, I love it, but the CEL is starting to bug me.


It first happened the morning after we put the URD kit in. [I drove it home (about 30 miles) the night before with no issues.] It was cold, so I pulled out of the garage, let it idle for ~5 minutes or so while I loaded up snowboards etc etc... Hopped back in, noticed the code. Scanned it, wasn''t too worried about it, so I turned it off and drove on.

About 30 minutes later, it came back on.

Anyway, been playing this game ever since. Hoping one day it will just stay off, but that doesn't seem to be the case.



The other day after I had turned it off; I was stopped at a stoplight. For whatever reason I was watching my Wideband and heard the motor sputter for a split second, watched the Wideband read 17.8 and the CEL come on.


So far I have cleaned the MAF (to no avail) so I replaced it with another one I had laying around (to no avail). After that I cleaned the replacement MAF (to no avail). I re-ran all of my vacuum line from the boost port (as this is the only vacuum related thing I touched for the 7th Injector) and replaced my front O2 sensor.

Any ideas guys?

Hmmm No idea, my wideband reads 14.5-ish at idle.

 

[A.Wilson013]

Hmmm No idea, my wideband reads 14.5-ish at idle.

As it should, and mine normally does as well... Other than that quick little sputter that sets off the CEL.

 

[BigFishAllDay]

P0171 = System too Lean (Bank 1)

Next time it might be a good idea to include that info... not everyone will have the list of codes handy, or know it off the top of their head.

The only electrical signals that the URD ECU is modifying at idle, or any other time, are the signals from the Crank Position Sensor to the OEM ECU, and from the Cam Position Sensor to the OEM ECU. These are timing related signals, and would result in timing issues if the URD ECU was malfunctioning.

Also, the URD 7th does not add fuel at idle. So this is not an issue of the 7th not delivering enough fuel at idle... again because it is not supposed to deliver any fuel at idle.

Because this problem occurs only at idle, I would suspect you have a fuel injector or two that is a little clogged up. The ECU will trim fuel at idle until it gets to 14.7, and a little beyond, then add some fuel back in... over and over. If you've got an injector that's a little stopped up and is just a hair off on flow, it could be giving the ECU fits with regard to keeping the AFR's balanced at idle. That's just what makes sense to me.

I had an issue with mine stumbling at idle, and stalling, when I first bought it. I ran 6 or 7 bottles of Lucas Fuel Injector cleaner through it on alternating tanks of fuel and the problem has cleared up. I would start with a good fuel injector cleaner and run it for a few tanks, then go from there.

 

[BigFishAllDay]

BTW, I'm also assuming that when you converted to the URD 7th setup, you removed the supra injectors and went back to your stock injectors.

If that's the case, that would also support it being an injector issue. They may have picked up some dirt/dust in storage, and now that you've re-installed them, you're seeing the problem. If you're still running the supra injectors with the 7th... well, you've got a whole other pile of problems.

 

[A.Wilson013]

BTW, I'm also assuming that when you converted to the URD 7th setup, you removed the supra injectors and went back to your stock injectors.

If that's the case, that would also support it being an injector issue. They may have picked up some dirt/dust in storage, and now that you've re-installed them, you're seeing the problem. If you're still running the supra injectors with the 7th... well, you've got a whole other pile of problems.

As always, I appreciate your response.

In regards to the injectors, I did NOT change them back out for the stock ones. I left the Supra Injectors in with the thought, "Prior to the 7th Injector they ran just fine in closed loop, why wouldn't they now?" With them in, the base tune from URD is very close to perfect in open loop, and closed loop runs just fine as well...

Back to the issue: The problem does not only occur at idle. I was just at idle in the 2 examples that I gave. The first day it happened, the CEL stayed off all day until I was on my way home back from the mountain. This time I was cruising at 55mph down the highway. I have literally turned this code off probably a dozen times... It just pops back up randomly, it seems.

I did a quick search via Google and found that the problem is quite common in Camrys/Corollas... They describe what I think to be the same split second hesitation at the time of the code.

 

[BigFishAllDay]

So now that you've clarified your problem... here's what I think:

The Toyota ECU controls the injectors and the AFRs by varying the length of the injector pulses... in milliseconds.

The Toyota ECU is programmed to assume that for X milliseconds of injector pulse, the combustion chamber will recieve X amount of fuel.

When you change the flow rate of the injectors, you change the ratio of fuel injected/millisecond.

With the Supra injectors installed, the ECU assumes it is X:X, but it is actually X:Y. This is where your old URD setup came into play. It acted as an intermediary to correct the ratio when necessary. When the engine needed X:Y or X:Z or X:whatever, it allowed it, but when the engine needed X:X it ensured that correction occured as well.

Now you have removed that intermediary from the system. All you've got is an ECU that thinks the fuel injected/millisecond is X:X, when in reality it is X:Y. There is no longer any ability to correct the ratio for when the engine actually needs X:X.

When the ECU in your truck is backing fuel, it is not able to back it at the proper rate. It thinks it's reducing the fuel at X:X ratio, but in reality it's reducing it by X:Y. Because the Supra injectors have a higher flow rate, the flow of fuel increases at a faster rate when the injector pulse is lengthened, but also decreases at a fast rate when the pulse is shortened.

The truck is trying to lean out the ratio to get to stoich at various times in closed loop, but it's reducing the fuel at too fast a rate and overshooting it's intended setpoint...... because you have changed the ratio and eliminated the correction factor. This results in you bumping the high limit of AFR's that triggers the trouble code.

The stock ECU cannot run those injectors. You need to go back to stock injectors w/the URD 7th setup.

 

[A.Wilson013]

So now that you've clarified your problem... here's what I think:

The Toyota ECU controls the injectors and the AFRs by varying the length of the injector pulses... in milliseconds.

The Toyota ECU is programmed to assume that for X milliseconds of injector pulse, the combustion chamber will recieve X amount of fuel.

When you change the flow rate of the injectors, you change the ratio of fuel injected/millisecond.

With the Supra injectors installed, the ECU assumes it is X:X, but it is actually X:Y. This is where your old URD setup came into play. It acted as an intermediary to correct the ratio when necessary. When the engine needed X:Y or X:Z or X:whatever, it allowed it, but when the engine needed X:X it ensured that correction occured as well.

Now you have removed that intermediary from the system. All you've got is an ECU that thinks the fuel injected/millisecond is X:X, when in reality it is X:Y. There is no longer any ability to correct the ratio for when the engine actually needs X:X.

When the ECU in your truck is backing fuel, it is not able to back it at the proper rate. It thinks it's reducing the fuel at X:X ratio, but in reality it's reducing it by X:Y. Because the Supra injectors have a higher flow rate, the flow of fuel increases at a faster rate when the injector pulse is lengthened, but also decreases at a fast rate when the pulse is shortened.

The truck is trying to lean out the ratio to get to stoich at various times in closed loop, but it's reducing the fuel at too fast a rate and overshooting it's intended setpoint...... because you have changed the ratio and eliminated the correction factor. This results in you bumping the high limit of AFR's that triggers the trouble code.

The stock ECU cannot run those injectors. You need to go back to stock injectors w/the URD 7th setup.

You're the man. I'll throw in the stock ones next weekend and let you know if you were right. =p

Thanks again!

 

[ocman40]

So now that you've clarified your problem... here's what I think:

The Toyota ECU controls the injectors and the AFRs by varying the length of the injector pulses... in milliseconds.

The Toyota ECU is programmed to assume that for X milliseconds of injector pulse, the combustion chamber will recieve X amount of fuel.

When you change the flow rate of the injectors, you change the ratio of fuel injected/millisecond.

With the Supra injectors installed, the ECU assumes it is X:X, but it is actually X:Y. This is where your old URD setup came into play. It acted as an intermediary to correct the ratio when necessary. When the engine needed X:Y or X:Z or X:whatever, it allowed it, but when the engine needed X:X it ensured that correction occured as well.

Now you have removed that intermediary from the system. All you've got is an ECU that thinks the fuel injected/millisecond is X:X, when in reality it is X:Y. There is no longer any ability to correct the ratio for when the engine actually needs X:X.

When the ECU in your truck is backing fuel, it is not able to back it at the proper rate. It thinks it's reducing the fuel at X:X ratio, but in reality it's reducing it by X:Y. Because the Supra injectors have a higher flow rate, the flow of fuel increases at a faster rate when the injector pulse is lengthened, but also decreases at a fast rate when the pulse is shortened.

The truck is trying to lean out the ratio to get to stoich at various times in closed loop, but it's reducing the fuel at too fast a rate and overshooting it's intended setpoint...... because you have changed the ratio and eliminated the correction factor. This results in you bumping the high limit of AFR's that triggers the trouble code.

The stock ECU cannot run those injectors. You need to go back to stock injectors w/the URD 7th setup.

Awesome explanation. Things always have to make sense in my mind when Im working issues and this makes perfect sense.

 

[Travolous]

I'm sure you are, but you do run 93 octane right? Not 91, not 89 with octane booster, 93!

I was forced to put 89 octane in my (now Dous's) supercharged 7th setup upon which I put octane booster just to be safe. I threw the p171 as well. I immediately put 93 in and cleared the code. Never came back on.

 

[Hepar]

Sure sounds like a lot of trouble to me...

 

[A.Wilson013]

I'm sure you are, but you do run 93 octane right? Not 91, not 89 with octane booster, 93!

I was forced to put 89 octane in my (now Dous's) supercharged 7th setup upon which I put octane booster just to be safe. I threw the p171 as well. I immediately put 93 in and cleared the code. Never came back on.

I run whatever the highest is my local Chevron has... I don't think it's 93, but it's good fuel.

I am sure BFAD is right. I need to just stop being lazy and swap injectors like I should have the night we put the 7th in.

 

[Hepar]

<iframe width="480" height="360" src="http://www.youtube.com/embed/k3pltmw6cmI" frameborder="0" allowfullscreen></iframe>


OK, sorry for posting nothing productive. Last one, I promise.

 

[BigFishAllDay]

I'm sure you are, but you do run 93 octane right? Not 91, not 89 with octane booster, 93!

I was forced to put 89 octane in my (now Dous's) supercharged 7th setup upon which I put octane booster just to be safe. I threw the p171 as well. I immediately put 93 in and cleared the code. Never came back on.

Just for everyone's information here: The Octane Rating of the fuel has absolutely NOTHING to do with AFR's (lean/rich conditions).

The Octane Rating of fuel is simply a measure of the ability of a given fuel to resist pre-ignition (detonation, ping, whatever you want to call it).

Running lean (and the associated high AFR's) are a result of a lack of fuel.

Pre-ignition occurs due to heat and cylinder pressure. By adding a supercharger to a stock engine, you increase both heat and cyl. pressure, and thereby increase the tendency of the fuel to ignite before the spark plug fires. Using a higher octane fuel counteracts these conditions, and reduces this tendency as much as possible.

The 7th injector adds fuel before the supercharger, which has the effect of cooling the intake charge (picture a mister in your face on a hot summer afternoon). This reduces the amount of heat added by the supercharger, and reduces pre-ignition.

If your AFR's are outside of the normal range (ie. above 14.7 in closed loop, or above 12.0 in open loop) that has nothing to do with the Octane Rating of the fuel you are using. It has to do with the amount of fuel being injected into the combustion chambers.

The only way the two are related is in the fact that high AFR's increase heat in the combustion chamber (because leaner mixtures burn hotter), and the increased heat further increases the chance of pre-ignition. This relationship presents another reason to use fuel with the highest octane rating available in forced induction applications. If your engine does run lean, the high octane fuel provides the benefit of protecting your engine from pre-ignition during the lean running condition. It will not FIX the lean condition.

 

[A.Wilson013]

So now that you've clarified your problem... here's what I think:

The Toyota ECU controls the injectors and the AFRs by varying the length of the injector pulses... in milliseconds.

The Toyota ECU is programmed to assume that for X milliseconds of injector pulse, the combustion chamber will recieve X amount of fuel.

When you change the flow rate of the injectors, you change the ratio of fuel injected/millisecond.

With the Supra injectors installed, the ECU assumes it is X:X, but it is actually X:Y. This is where your old URD setup came into play. It acted as an intermediary to correct the ratio when necessary. When the engine needed X:Y or X:Z or X:whatever, it allowed it, but when the engine needed X:X it ensured that correction occured as well.

Now you have removed that intermediary from the system. All you've got is an ECU that thinks the fuel injected/millisecond is X:X, when in reality it is X:Y. There is no longer any ability to correct the ratio for when the engine actually needs X:X.

When the ECU in your truck is backing fuel, it is not able to back it at the proper rate. It thinks it's reducing the fuel at X:X ratio, but in reality it's reducing it by X:Y. Because the Supra injectors have a higher flow rate, the flow of fuel increases at a faster rate when the injector pulse is lengthened, but also decreases at a fast rate when the pulse is shortened.

The truck is trying to lean out the ratio to get to stoich at various times in closed loop, but it's reducing the fuel at too fast a rate and overshooting it's intended setpoint...... because you have changed the ratio and eliminated the correction factor. This results in you bumping the high limit of AFR's that triggers the trouble code.

The stock ECU cannot run those injectors. You need to go back to stock injectors w/the URD 7th setup.

Man, I was SURE you were right.

Anyway, put the 5vz injectors in yesterday and thought I was good! Drove 80 miles with no CEL, only for it to turn on today on my way to go snowboarding. I turned it off, and it came back on about 20 miles later.

Seems the problem was not my injectors =(





So back to square 1, I suppose.

FULL STORY

1. Pulled into my buddies shop with no CEL to speak of other than an occasional (once a month or so) p0420

2. Took out the URD MAF/Timing Calibrator.

3. Installed the URD 5VZ 7th Injector Kit

4. Get a p0171 the next day, and on.

 

[SliderNH]

I suggest checking the throttle body gasket. Here's why:

I did the 2nd gen install a month ago. At the same time I installed but didn't hook up the 7th injector. 7th wasn't hooked up because the wiring harness i got from Gadget (the plug and play 'bridge' that leaves the stock wiring harness alone) was wired wrong - so it was literally straight up SC'd, no fuel management system at all. I got the lean code, I was convinced it was because the 7th wasn't hooked up. I sent the wiring harness back to URD to get fixed, and I called Gadget to let him know, and pick his brain about the lean code. He told me point-blank, the 7th injector won't prevent/ or cause a lean code. He said it was one of two things, and needed to be fixed BEFORE hooking up the 7th (hooking up the 7th to cure the lean code would be like putting a bandaid on a stab wound).

Drum roll.....

So the two likely culprits: 1. A vaccume leak from one of the vaccume lines. or 2. A leak in the throttle body gasket. To address #1 i put inch-worm hose clamps on all my vaccume lines. Reset the ECU, lean code came back 20 miles later - as usual. So to adress #2 i took off the TRD paper throttle body gasket that I installed with the SC, and put the stock metal one back on. Reset the ECU, CEL never came back on. badabing! TB gasket. So now that I knew where the problem was coming from I had to figure out why. I put a new TRD gasket on this past friday, and didn't use the gasket sealer, STILL NO CEL! So heres where I went wrong, I think....With the initial installation - I may have installed the TRD gasket backwards (what Gadget suggested the problem was from), but I'm 99% sure I installed it the right way. I attribute it to putting liquid gasket sealer on the paper gasket. My question for you is: Did you use gasket sealer on your paper TRD throttle body Gasket?

 

[A.Wilson013]

To answer your question, no, I did not use any sort of sealant.

I will order a new gasket and report back.

 

[A.Wilson013]

Well, LCE wants me to pay $14 to UPS to ship a gasket, so I just went to Autozone and got some gasket material and made my own.

So far no codes, but I'll report back tomorrow.

Thanks for the original idea, SliderNH.

 

[BigFishAllDay]

I wanted to reply earlier, but today was a busy one.

SliderNH has offered a good suggestion, so I guess we'll wait and see how it pans out...

but...

Regardless of whether or not it solved your problem w/the P0171 lean code, changing back to the stock injectors was/is the correct thing to do if you are going to run the URD 7th setup... or any setup where you do not have a fuel controller dedicated to managing the larger injectors.

 

[SliderNH]

Well, LCE wants me to pay $14 to UPS to ship a gasket, so I just went to Autozone and got some gasket material and made my own.

So far no codes, but I'll report back tomorrow.

Thanks for the original idea, SliderNH.

I had no idea how sensitive the TB was before running into my problem. Making your own gasket is a good idea, Hope it works. let us know!