Running rich, cannot figure it out

[98Gate]

98 4runner with the 3.4l, I have done a lot of work lately
-Timing belt
-coils
-wires
-plugs(iridium)
-intake manifold gasket reseal
-injectors(midwest performance)
-TPS
-Crank and cam position sensors
-o2 sensors up and down stream
-coolant temp sensors(ecm and dash)
Well, I am checking data on scan tool and it I am running rich as all get out. -12 LTFT. I popped P0420 code, cleared it and hasnt come up again. Cat converter is probably going out due to the downstream fluctuating so much. I cannot for the life of me figure out why its running so rich. I am on my last leg before I take it to the shop. MAF seems in spec, I have cleaned it. My biggest concern is that it could have jumped time. It runs well, I can cruise on hw at 70 all day. Need help from the old masters in here…..

-98Gate

 

[phattyduck]

You are going to need to list the brand and source for all of those parts. Many of them are critical and many have bad aftermarket or knock-off versions for sale all over...

Also, I'm assuming you meant Motorwest Performance for the injectors? Make sure they are then 'standard flow' version, not the higher flow version meant for supercharged applications.

-Charlie

 

[98Gate]

You are going to need to list the brand and source for all of those parts. Many of them are critical and many have bad aftermarket or knock-off versions for sale all over...

Also, I'm assuming you meant Motorwest Performance for the injectors? Make sure they are then 'standard flow' version, not the higher flow version meant for supercharged applications.

-Charlie

Yes they are Motorwest stock replacements

-Plugs- Denso IK16TT(rock auto)
Wires- DENSO 6716182(rock auto)
Coils- DENSO 6731201 (rock auto)
Crank position sensor- DENSO 1961109(rock auto)
Camshaft positon sensor- Toyota 19300-62010(ordered off amazon came straight from japan)
Fuel pressure regulator-OEM 23280-62030 Toyota Fuel Pressure Regulator(bought off of Ebay, not purely sourced imo. This one is one I am sketched out about…..)
Coolant temp sensor ECT- AISIN THSAZ8001(rock auto)
TPS-toyota brand 89452-35020(came from toyota’s amazon page)
02 sensor upstream-DENSO 2344162(rock auto)
02 sensor downstream-DENSO 2344154(rock auto)

Nothing I put in is anything but toyota, denso or aisin. The only thing I can think of from those parts that would be able “sketchy” is the fuel pressure regulator. Currently LTFT sitting about -11.7 at idle. Maybe 8 or so under a load. Had it die out on me at a stoplight yesterday. The car was warmed up, was at a stoplight, went to accelerate, stumbled a bit and died. No code, started back up and ran normal. I have noticed a bit of a shudder when accelerating from a stop but its not every single time. Almost like it is running really rich after initially putting my foot on the gas. Let me know if I can give anymore info

 

[Spiker Engineering]

I had a high negative LTFT (about -12%) after putting in some aftermarket injectors. Once I put the original injectors back in (after rebuilding by Motorwest) the LTFT came back to right around 0%.

What's interesting is that my truck ran perfectly fine during that time; in other words, the ECM was able to compensate for the excess fuel by changing the trim. Sounds like in your case, that is not the case, which is a bit confusing - I would think the ECM can compensate for -11% LTFT, based on my experience. I wonder if you have several issues going on at once, one of which cannot be compensated by the ECM. Meaning that perhaps the LTFT is a red herring, and the poor idling/dying is due to something else.

 

[98Gate]

I had a high negative LTFT (about -12%) after putting in some aftermarket injectors. Once I put the original injectors back in (after rebuilding by Motorwest) the LTFT came back to right around 0%.

What's interesting is that my truck ran perfectly fine during that time; in other words, the ECM was able to compensate for the excess fuel by changing the trim. Sounds like in your case, that is not the case, which is a bit confusing - I would think the ECM can compensate for -11% LTFT, based on my experience. I wonder if you have several issues going on at once, one of which cannot be compensated by the ECM. Meaning that perhaps the LTFT is a red herring, and the poor idling/dying is due to something else.

Just starting off at the LTFT issue, and worrying about the random stall later, where would you start? I cannot figure out the proper way to troubleshoot this if I am sort of chasing a ghost. Other than letting it get bad enough to pop a code.

-98Gate

 

[phattyduck]

I'd be a bit worried about anything from eBay or Amazon.

While you are checking fuel trims, also check coolant temperature and TPS - to make sure they are 'smooth' and make sense.

11% correction is outside of the normal range, but the ECU can do at least 20%, so you haven't run out of adjustment range.

Testing fuel pressure is a bit annoying, but might be necessary to see if the regulator you put in there is running wild... Curious why you replaced it previously?

-Charlie

 

[98Gate]

I'd be a bit worried about anything from eBay or Amazon.

While you are checking fuel trims, also check coolant temperature and TPS - to make sure they are 'smooth' and make sense.

11% correction is outside of the normal range, but the ECU can do at least 20%, so you haven't run out of adjustment range.

Testing fuel pressure is a bit annoying, but might be necessary to see if the regulator you put in there is running wild... Curious why you replaced it previously?

-Charlie

I replaced it just to sort of cover the difficulty of replacing. It was right there I was doing the intake plenum gasket reseals to stop coolant leak. Figured id do some preventative maintenance so to speak. Could I disconnect vaccum line from the manifold and see if fuel is leaking past it? Maybe that would indicate if it is bad or not? Any chance I pinched an o-ring on an injector causing a leak? Not enough to cause a misfire, but enough for excess fuel. Thanks for the help btw

-98gate

 

[phattyduck]

I replaced it just to sort of cover the difficulty of replacing. It was right there I was doing the intake plenum gasket reseals to stop coolant leak. Figured id do some preventative maintenance so to speak. Could I disconnect vaccum line from the manifold and see if fuel is leaking past it? Maybe that would indicate if it is bad or not? Any chance I pinched an o-ring on an injector causing a leak? Not enough to cause a misfire, but enough for excess fuel. Thanks for the help btw

-98gate

The regulator should be referenced to the intake tube, not the intake manifold... But that would cause high fuel trims, not low fuel trims like you are experiencing. (moving the reference to the intake manifold is done on supercharged applications, but should be kept stock for NA applications)

-Charlie

 

[98Gate]

The regulator should be referenced to the intake tube, not the intake manifold... But that would cause high fuel trims, not low fuel trims like you are experiencing. (moving the reference to the intake manifold is done on supercharged applications, but should be kept stock for NA applications)

-Charlie

I apologize, it runs into a hardline under the manifold then to the intake tube. Does this look like an OEM denso? Something about the font looks off… maybe im running a shanghai special…..

 

[98Gate]

The regulator should be referenced to the intake tube, not the intake manifold... But that would cause high fuel trims, not low fuel trims like you are experiencing. (moving the reference to the intake manifold is done on supercharged applications, but should be kept stock for NA applications)

-Charlie

Compare the font to this one…. Can anyone take a pic of one off of their truck to see if I am crazy?

 

[T4R2014]

Did the box the FPR came in look like the one pictured here? It isn't a 100% indicator but would definitely raise suspicions if yours didn't, or if the font on the packaging looks a little different.

Just a moment...

 

[98Gate]

Did the box the FPR came in look like the one pictured here? It isn't a 100% indicator but would definitely raise suspicions if yours didn't, or if the font on the packaging looks a little different.

Just a moment...

It definitely did NOT come in that kind of box. It came in a red and white “paper” box. Not that thicker cardboard. I still have the box it came in. What is the consensus here? Assuming this is a chinese part, could that be enough to jack up my fuel trims? I am not sure just how sensitive or critical that component is

-98Gate

 

[T4R2014]

It definitely did NOT come in that kind of box. It came in a red and white “paper” box. Not that thicker cardboard. I still have the box it came in. What is the consensus here? Assuming this is a chinese part, could that be enough to jack up my fuel trims? I am not sure just how sensitive or critical that component is

-98Gate

China can make good stuff, usually not when they are making counterfeits though. Yeah, I found more pics of some FPRs on sale that ship from Dubai. They have the more traditional Denso font. I think you have a fake.

 

[98Gate]

China can make good stuff, usually not when they are making counterfeits though. Yeah, I found more pics of some FPRs on sale that ship from Dubai. They have the more traditional Denso font. I think you have a fake.

I agree… that partsouq one looks legit. Might just go with that one. I appreciate the insight. Something about the denso logo just looked….. off. Welp get to have another fun go at getting the manifold off. Ill let yall know if that fixes it

-98Gate

 

[phattyduck]

Assuming this is a chinese part, could that be enough to jack up my fuel trims? I am not sure just how sensitive or critical that component is

-98Gate

Oh Jesus, yes. It is a MAJOR component for fuel trims. Take this as a lesson though - on a Toyota, it is rarely a good idea to swap out a working OEM part 'while you are in there" - it just introduces risks.

I haven't heard of a FPR failing on a 5VZ...

As a point of reference, when you supercharge the engine, you move the FPR reference to a vacuum/boost reference. This causes ~+10% fuel trims at idle, reducing to around 0 at atmospheric pressure into the engine - and then (hopefully obviously), extra fuel for the injectors under boost.

-Charlie

 

[98Gate]

Oh Jesus, yes. It is a MAJOR component for fuel trims. Take this as a lesson though - on a Toyota, it is rarely a good idea to swap out a working OEM part 'while you are in there" - it just introduces risks.

I haven't heard of a FPR failing on a 5VZ...

As a point of reference, when you supercharge the engine, you move the FPR reference to a vacuum/boost reference. This causes ~+10% fuel trims at idle, reducing to around 0 at atmospheric pressure into the engine - and then (hopefully obviously), extra fuel for the injectors under boost.

-Charlie

Oh you bet I learned my lesson on that. The old “don’t fix what ain’t broke”. I hate to admit it, but on my old 4runner, I give it the best I can put into it(except ebay china crap apparently lol). I took my dang drivers test in this thing. Been through many girlfriends riding up front and many dogs riding in the back. I appreciate all the help and if yall are ever around central Alabama, send me a message and id be happy to meet up and catch a beer with you gentleman. FPR is gonna be at the stealership tomorrow so I should be able to give results to yall in the upcoming week…. Fingers crossed

-98Gate

 

[98Gate]

Update

New FPR is in…. and while I definitely had a fake one installed before, the new one isnt performing much better. Data showing still around -11 LTFT, I will put a picture of the data from my drive today. I am just stumped and tired of firing the parts cannon. Calling on all of the gurus in here for help….. she does drive just fine, I just want to know what the heck is going on.

-98Gate

 

[T4R2014]

Hmm. I'd still call it progress. Funnily enough I just had Motorwest Injectors installed on my 1998 Limited. And it just threw a P0420 code. Gonna check my fuel trims.

 

[T4R2014]

As luck may have it, my LTFT was at -10.9%. I've got a recently installed JDM engine and I had Motorwest injectors put in. Now, I might have fouled O2 sensors from the previous engine's coolant consumption, and I also do have a bit of an exhaust leak, so I wouldn't let my situation completely throw you off That said, I did come across this thread.

Just a moment...

 

[98Gate]

As luck may have it, my LTFT was at -10.9%. I've got a recently installed JDM engine and I had Motorwest injectors put in. Now, I might have fouled O2 sensors from the previous engine's coolant consumption, and I also do have a bit of an exhaust leak, so I wouldn't let my situation completely throw you off That said, I did come across this thread.

Just a moment...

I am pretty sure I have a small exhaust leak too, either at the headers or crossover pipe. It definitely could be throwing off the O2 sensor but -11 is pretty dang rich. Mine is running rich as can be at idle and deaccelerating and braking. Under a load trims are great. I might take one for the team and rebuild the old injectors. Before that im gonna hook up the shop vac to the exhaust and spray the headers and crossover pipe for leaks….

-98Gate