Hi all, just had a reman'd 5vzfe engine put into our '98 automatic 4wd Taco w/200K, due to a hole in the piston of old engine. 2 fuel injectors were found to be clogged/failing, so those were replaced, and other 4 were cleaned/tested - those 2 bad ones were assumed to be the culprit - that they created a lean condition, which caused hole in piston at #3 cylinder, and spark plug electrode also went MIA. Mechanic dealt w/injectors, installed an AFR sensor we requested (to alert us of any potential lean condition in the future), put in reman'd engine, then emailed this update:

"I got the engine in and running, It runs great, the wide band o2 gauge looks like it is running good at idle and under acceleration, no lean condition. I am having one issue, when warm after a very short stop, 3-4 minutes it fires right up but when warm if it sits for 30 minutes it requires excessive cranking. The cold start fires right up. This indicates to me that it is loosing fuel pressure in the fuel rail slowly. Firing up good cold it has the added cold start injector but warm after 30 minutes the pressure bleeds off but the engine is still warm. I will test the fuel pressure regulator and the bleed back on the pump and get it dialed in to fix the issue."

He replaced the fuel regulator and fuel filter, and said the back pressure testing after that was good/normal. He was pretty confident the fuel pump was fine, said he had tested it. Brought Taco home yesterday. She's running beautifully, but the hestiation to start is still present on a "hot soak" (starting ~30-40 minutes after last turned off). Starts great cold, and starts great after being turned off for just a few minutes.

Here's a video of several starts last night and this morning. That first start at the beginning of the video was after shutting Taco off for ~5 minutes or less. Per the mechanic, the new AFR gauge will last longer if we turn the key to ignition, then wait (~30 seconds) for the blinking red light associated w/the gauge to stop blinking before starting Taco - apparently this allows the wire to the gauge to heat up:https://www.youtube.com/watch?v=OlQd...ature=youtu.be

Haynes manual on this topic ("Engine hard to start when hot") said 1st thing to check would be dirty air filter, so even though old filter looked only a little dirty, we put in a brand new Toyota OEM Denso air filter right before the final start in the video. The next start 1/2 hour later (last start in video) was even worse - cranked longer than the one last night. 2nd thing in manual says "fuel not reaching fuel injectors; check for a vapor lock situation, brought about by clogged fuel tank vent lines."

When dealer saw it ~1 month ago when the engine trouble started, they checked the yellow box ("may require future attention" box) next to an item that says "Fuel lines & connections/fuel tank bands/fuel tank vapor vent system hoses (damage/leaks/corrosion)." We never got to talk to them much after they looked at it, to clarify exactly they were referring to on this.

We're taking it back to the mechanic today. I mentioned to him that Haynes manual said something about vapor lock - he said they can check EVAP system, but seems unlikely cuz we'd have gotten a check engine light, which we haven't. He is leaning towards fuel pump now, cuz he said most everything else on fuel system has been replaced at this point. Please help guys. Any and all input would be GREATLY appreciated. Thank you.

 

Really? Nobody has any thoughts?

 

How/where was the AFR installed? What brand? How did this install impact the stock configuration?

All the vacuum lines in the correct places? CEL on? Even if CEL is not on it might be a good idea to check for stored codes.

Can't say I've encountered this same issue in the 5vz-fe. I can check the FSM sometime Sunday and see if it gives any guidance that may help you.

 

Has the fuel filter been changed??

Did this vehicle sit for quite a while awaiting new engine??

Lots of condensation in fuel from sitting??? Which is now in the fuel filter that was just installed.

Maybe your installer made a typo or miss spoke about the 3.4 having a cold start injector to aid cold starting unless one was added special to your engine??

For what ever reason my computer will not open videos so after all this cranking what allows the engine to start.

Your MIL does light when the key is turned on?? Not that the bulb is burned out ??

About the only thing that does not trip the MIL is fuel pressure issues.

Maybe time to hook up your scanner and get some real time data to see just what is going on.

 

Per FSM for 5vz-fe:
Difficult to Start, hot engine
1) Starter signal circuit
2) Fuel pressure control circuit
3) Fuel pump control circuit

On a stock 5vz-fe, there is no cold start injector so the installers comment is a bit confusing on that.

 

Thanks for the feedback guys. The big change since my initial post on Saturday midday is:

We started Taco up to drive her back to mechanic. She'd been sitting for ~2+ hours at that point since she was last driven/started. And that time, she BARELY started. Cranked way longer than any of the other starts in the video. Assuming that would be considered cold start, or no?

So we have:
-great starts when completely cold (sat 12 hours overnight);
-great starts when sat for 5 min or less;
-extra crank time on hot soak starts (when started ~30 min after last start)
-A LOT of extra crank time when started ~2 hours after last start - which seems to be something that is getting worse, because one of the starts in the video (Fri PM) was ~90 minutes after she was last running, and that was only a bit of extra crank time - the ~2 hour later one described here (Sat AM) was a loooong crank time

The AFR gauge is Innovate 3795 LC-1 wide band 02 sensor/gauge: http://www.innovatemotorsports.com/s...C-1_Manual.pdf
In the short time we had Taco home from mechanic (Fri PM & Sat AM), the gauge showed normal numbers each time it was driven, or at least according to what we were told, that it should never veer more than 1 point from 14.7. They said they created another hole in the exhaust to install it. Do you think this gauge could have something to do w/it? The engine and the gauge are the only variables that have changed, so seems logical that something w/one of them could be the answer.....

Vac lines are in place. No CEL. Fuel filter was changed, and in looking at it Fri night, it appeared to be perfectly installed, so no issue there. I see what you're saying about fuel sitting Wyoming - I'm thinking it had a bit of fuel in it when initially towed there mid December, then engine swap over next ~2 weeks + installation of AFR gauge and fuel filter/faulty injector replacement, then mechanic test drove ~65 miles, then he noticed the trouble w/hot soak starts, and began checking fuel system, replaced regulator. Hmm, now I wonder about that fuel that was in there..

Do you think this could be a sensor problem, like maybe the engine coolant temp sensor? My wife's got a long thread on Tacoma World she started way back when we were still trying to figure out if it was a spun rod bearing (like dealer said) or a hole in the piston. Anyway, lots of the folks on that forum are leaning towards a sensor issue, what do you guys think? Seems odd that the engine coolant temp sensor could be it though, cuz then why does it start great after 5 min, but awful after 30?

Some folks are thinking fuel pump, or leaky injector - but the injector thing seems strange, cuz all 6 were cleaned/tested, and the 2 bad ones (that caused piston hole) were replaced. Sure, even a new one could be faulty, but then also it doesn't really fit cuz why does it start beautifully when it's completely cold - if an injector was leaking for hours and hours, wouldn't that cause the same flooding effect as what's happening on a "hot soak" start, where it only sat for ~30 min?

And no, we don't have an added cold start injector (pretty sure - it's a TRD Off Road, but still don't think so, right?). I'm thinking that was just the mechanic's awkwardly worded way of saying the engine receives more fuel when it's initially started cold. That's correct, right?

Now we're leaning towards fuel pump being the culprit too. We had 2 injectors fail - at cylinders #3 and #5. Those are closest to the exhaust (hottest location of all cylinders), plus furthest away from fuel pump & regulator of all the cylinders. So seems logical if pump & regulator were slowly dying, that coupled w/those injectors being repeatedly hottest maybe led to piston hole. And now that new engine, new #3 & 5 injectors, and new regulator are in, it runs great, but that a potentially dying pump is the last piece of the puzzle to fix. Who knows, but seems like a semi logical theory...

RW, thanks for the post on what the FSM says. Would getting a scanner on it tell us if any of these items were the culprit?

 

Real time data can never hurt the more you know the better.

If it nails your problem who can say.

Back to my question with the ignition to run the Mil/CEL light is on like it should be telling you the bulb is good.

When it does start after the extended cranking the Idle Air Control valve causes the engine to idle up like it should.with no sputtering and missing that should trip the MIL

I just can`t see why the MIL is not tripping with these hard starts

I would use a scanner and see if there are stored codes and get real time data.

I know with my 3.4 engines if there is a problem they let you know.

 

Hi Wyoming, thanks for the reply. Not positive about the CEL bulb, but pretty sure it's good - truck is at the mechanic, so can't check right now. Hoping he puts a scanner on it and it gives us some info. I suppose it's all irrelevant speculation til then, but it's tough to put it aside - it's all we can think about, wondering what the hell it is, when we're seemingly soooo close to the end of this long crappy road of replacing the engine. Plus seems like whatever is causing the hard starts could wind up being related to whatever caused the piston hole in the first place, so super eager to find out in that regard too. We know 2 injectors failed, but to find out if their failure was caused/related to something w/other fuel system components, or EVAP system, would be great to know. Will definitely post as we hear updates. In the meantime, if anyone has any thoughts as to what to verify that the mechanic is looking at, input is appreciated. Thanks!

 

Hi guys. Oregon Taco's wife here. Brought Taco home for the 2nd time today. Mechanic found that idler air intake was stuck - they cleaned/lubed it, and started it after various time intervals yesterday and this morning, and thought hard start prob seemed resolved. Several starts at home today reveal that hard start problem seems better, but still exists a bit. Still starting instantly if shut off only a moment or so, but cranks longer than it should - not excessive, but longer than normal - if shut off for 30+ minutes.

CEL lights up when Taco is turned to accessory mode, so bulb is good, and we're still not getting a CEL light at all. Still running awesome, idling normal, accelerating normal. Mechanic assured us that fuel pressure was checked, fuel pump should therefore be OK. He did replace FPR, fuel filter, and the 2 failing injectors that were the likely culprits for the piston hole (cleaned/tested/reinstalled the other 4). They also checked vent lines and all looked fine there.

We bought a Scan Gauge II, per some advise on Taco World, and are now reading manual to see about checking engine coolant temp sensor, and whatever else we should be using this nifty tool to check right now. Input greatly appreciated - manual looks like lots of reading, and we're eager to get started without f'ing anything up! : )

Other folks have suggested cleaning throttle body, and looking for cut wires. And checking other sensors, like air intake, crank, cam position, throttle position, egr valve.

Ultimately we could take it back to mechanic again, but first want to try some basics at home, as it's a pain to drive all the way up there AND be without Taco each time. Advise? Order to do things in? Shortcuts/inside tips on checking these things? Helpful diagrams? Other things to check? Thanks guys!

 

https://www.youtube.com/watch?v=NLTx...ature=youtu.be

here's the results of using the scan gauge -we're still learning how this thing works and what the results mean - do you guys see anything funky in the results?

 

Looks pretty much how my '95 looks. My water temp runs 191-193f and normal operating range is 176-203f.

FIA at idle and even speed tends to run a little higher than ambient temp as it seems to be influenced by engine heat.

 

Thanks for the reply, RW. So what would you check next?

 

This is interesting for sure I hope you meant the idle air control IAC Valve.

Now if this was not working correct it should trip your MIL Malfunction Indicator Light.

That it did not is interesting to say the least.

 

Wyoming, yes. Idle air control valve. Should that being stuck have definitely tripped CEL? If so, any thoughts on what it means that it didn't?

I'm still wondering if fuel pump is culprit, even though mechanic said pressures looked fine. Thought about buying a fuel gauge to check at home - are they expensive/easy to use? Have heard different thoughts on fuel pumps - some say they die slowly; others say they don't get weak, they either work or don't. What do you guys think? Also, some have said it's a good idea to replace as PM when you get to 175K + (we're at 195K) - do you guys agree? Guessing it'd be a few hundred $ to have mechanic do this, so not a no brainer decision, as we're in plenty deep w/engine swap $ as it is!

Do you guys know much about AFR gauges? It's strange to me that the readings are different in two same scenarios, which puts me back to chasing a fuel issue. Mechanic told us to turn key to accessory 1st, to allow wire to gauge to heat up (will make gauge last longer he said), before starting. We've done this every time we've started, and gauge always reads ~7.4 (super rich) while light blinks. Then when light goes solid (signaling wire is warm now), normally gauge jumps up to somewhere between 19 and 21 (super lean), then gradually goes back down to ~14.7 (normal) upon starting. Just started this morning, after sitting overnight, and gauge went to ~21 when light turned solid, then down to 12 upon starting, and very slowly climbed up to ~14.7 after a moment or so. After this, I reviewed our video of same starting condition (cold start, sat overnight) from Saturday AM, and in that one, gauge did what it normally does - jumped up to ~19-21ish when light went solid, then slowly came back down to ~14.7. Maybe this means nothing, don't know. Just seems strange that in two same scenarios, readings would be different.

RW, does the data we posted from Scan Gauge II tell us that this is definitely not a sensor issue? Meaning, all sensors are definitely correctly installed and showing normal readings?

 

I don't get it. 319 views and only 2 guys replied? Bummer. RW & Wyoming, wheredya go?

To refresh your memories, mechanic cleaned/lubed/reinstalled our IAC valve on Monday. Since then, we've had a couple of good warm starts, but for the most part the warm starts are still ˟˟˟˟ty. Still fires up fast/beautiful when very cold or very hot. RPMs lope every once in a while, and Taco idles pretty low - got as low as 494 on Scan Gauge last night just sitting in driveway letting her run.

We're now contemplating replacing the fuel pump, even though mechanic has assured us multiple times that pressures were good on fuel system, just based on quite a few others saying it fixed their similar problem, plus others saying its good PM at this mileage (195K) - what do you think?

We're also contemplating replacing the IAC valve. Some folks gave us instructions on how to test it's function, so we'll try to do that next, hoping tonight, but since no garage and just started raining, we'll see........

Which of those would you guys try first? Have you ever replaced a fuel pump yourselves? Mechanic said can be done either way, but for our truck they'd drop the tank (not the bed). Others have advised pros and cons of each method. Your thoughts? Contemplating attempting this ourselves in a gravel driveway, to save a few $$$ in labor.....we're in deep enough for the engine cost right now, and still have a short laundry list of $$$ items to do (wheel bearing, shocks/struts, rack & pinion).......

Mechanic strongly suspects IAC valve is the culprit, not fuel pump, based on how thoroughly they said they checked our fuel system, as well as saying they never ever see fuel pumps die on Toyota trucks & SUVs, and that's really the only vehicles they deal with. Do you guys hear of many fuel pumps dying on V6 Tacos? Does the description of our problem sound like fuel pump could be the culprit?

After learning more about how IAC valve functions and its location under the hood, it would certainly make sense to think of it failing and contributing to the lean condition we had at #3, coupled with faulty injectors and higher temps due to proximity to exhaust. So that, plus the low idling and occasional idling lopes, and the mechanic's thoughts make us lean towards that as the 1st part to throw money at.

But a dying fuel pump seems like it could fit with this whole picture too........thoughts? Please? Where did everybody go on Yotatech, or is my thread just super lame or what?

 

Sometimes the real world gets in the way. 30 hours in 2 days tends to make me tired anymore not like when I was young.

The problem that bothers me is your not getting the MIL lighting with the varying idle conditions.Now if this shop does Toyota vehicles are they not familiar with the OBD11 system and what are there thoughts on the MIL not tripping??

Are they old school and only deal with the older vehicles??OBD1

both my 3.4 engines trip the P0505 code the second it detects a different then normal pattern

Without a code to point you in the correct direction you can be looking in the wrong area.

About the only thing that kills fuel pumps is running the tank below quarter tank all the time .

I would not want to drop a tank to change a fuel pump so much easier to damage things that way .

I have cut holes in the bed I have unbolted the bed and moved it back far enough to get to the fuel pump bracket .

If you want to change the pump just because go far it??

Did something get pinched or damaged during the engine swap?? Who can really say.

Non Toyota sensors used ??

 

Wyoming, thank you so much for the reply. Here's the update -

Took to mechanic today, had them test IAC valve by the FSM rec' method.

Tested fine.

They found some dirt in line to charcoal canister, blew it out. Told me to take it home and see if it made a difference, as we are reluctant to throw $ at parts without some confirmation that they are failing, and they don't know WTF else could still be causing hard warm starts.

Hard warm start as I was leaving there, which unfortunately senior mechanics didn't hear, but another one did. Talked to senior mechanics, who then offered to install a used IAC valve to see if any difference over the weekend, then make more decisions from there.

RPMs were more normal (much higher) on the way home (~30 miles), and also more normal sitting parked in driveway upon arriving home. Was really super duper encouraged by this.

Then, super hard warm start ~30 min after arriving home. ˟˟˟˟!

What would you do next?

To answer your question, these guys work only on Toyota trucks & SUVs, but primarily do engine swaps. They do other stuff too, but mostly engines. And yes, I think a lot of their customers have 22REs and other older trucks, but I think a good amount of their business is swapping our engine type (5vzfe) into trucks that have 3.0, etc, so I believe (can't say 100%, but pretty confident) they have plenty of experience dealing w/our engine type. We really haven't talked with mechanic specifically very much about the fact that we're not getting a CEL, other than when I proposed possible vapor lock, and they said not likely cuz no CEL, but they'd check for vapor lock anyway.

Things they've already checked/replaced:

Fuel Pressure Regulator
Cleaned/tested injectors; replaced 2 faulty ones assumed to cause piston hole
Tested coil packs
Cleaned MAF/intake air temp sensor
Checked engine coolant temp sensor
Thoroughly inspected our fuel system pressures via fuel pressure leakdown test - said PSI drop was within spec
Tested IAC valve, it was fine; replaced w/used one anyway just in case
Inspected all vac lines and hoses to rule out vapor lock/leaks
Have assured me more than once that all sensors were properly swapped over and checked

Please, any insight would be so much appreciated. We're in nearly $6K now w/new engine and a bunch of other necessary crap that went with it, yet still having issues. Could care less that it takes a few extra seconds to crank on warm starts, but obviously the fear is that seemingly harmless thing leading to disaster. Please, input, please. Can't just keep whipping out the plastic - at some point it has to get paid back. Starting to consider throwing in the towel/cutting our losses and selling it, after all this. It's driving us batty.

PS: Thanks for the insight about best/easiest method to replace fuel pump - we may very well need it in the near future. We rarely let it drop to below 1/4 tank, and mechanic seems extremely confident it's not that, yet it's tough to know what else to suspect at this point.

 

It comes down to this when you are getting different idle speeds from what the ECM is used to seeing it will trip the MIL



I can only think of someplace there is a electrical connection that is being effected by the heat from the engine

Are all the grounds clean and tight ??

The one for the ECM is so important and the fact it goes into the aluminum manifold it is so easy to be corroded causing problems . Sometimes you can`t see the corrosion with your eyes.

These are just out of the box ideas strange things I have encountered over the years.

another random thought ground cables worn and tired .

For what ever reason the starter bearings get tight after sitting for 30 minutes or so drawing system power away from the ECM during cranking causing the no start condition .

Being on the other side of the country makes it rough to troubleshoot.

I need to try something on my engine to see if it does what I think about something.

 

Thanks Wyoming. Our Scan Gauge is definitely telling us we're not getting any codes. Do you think this means our computer or wiring harness is ˟˟˟˟ up? Thinking about taking it to a Toyota dealer and asking for their best tech to do diagnostic inspection. We'd love to test/inspect simple stuff ourselves, but have a gravel driveway that's constantly getting soaked with Oregon rains (no garage), plus we're nervous about f'ing something up now that new engine is in, and potentially screwing up our warranty as a result. I believe our mechanics are skilled/knowledgeable, but we've been back 2x now to have them investigate the hard warm starts issue, and they are still scratching their heads.

We do have this new info - don't know if it means anything, but I'd really appreciate your input on it if you have any -

The IAT (intake air temp) readings on Scan Gauge is typically in the 40s when we have a good cold start, which makes sense cuz temp outside will be right around the same, and I assume engine is receiving extra fuel, due to being cold.

But then IAT will jump up to ~80-100 F ~20-30 min later, and that's when the hard start happens.

WT (engine coolant temp) values on SC seem consistently normal - it starts ~50 F on a cold start, then gradually climbs to ~200 F in a seemingly normal period of time.

Does it seem normal that IAT goes up to 80-100 F in 20 min while truck is just sitting there? I know IAT goes down when driving, due to more airflow coming in (right?), therefore I assume the opposite is true, that when you're sitting w/engine running, the engine's heat coupled with the lack of airflow should either make IAT rise or stay put, right? But should it go up that much that quickly?

 

IAT readings are fine.

If it is open or shorted the readings are like minus 40F and like 248 F

What kind of voltage are you getting at the battery??

With all this cranking and testing are you keeping the battery charged??

Have you pulled and looked at the plugs??

More after I eat before I pass out I forget to eat some times