SOLVED! Post 2853 Leaking Injectors, Dealer Techs Rock! Extended Cranking after Engine Swap 3.4L 5vz

according to the article it sounds like if air was escaping out of the positive crank case valve, then our piston rings are leaking. and if air was coming out of the exhaust pipe, then the exhaust valves are leaking. am I reading this correctly? @noahpete only displayed air escaping from one of the other spark plug holes, but he also said: "In the cases of the cylinders that are above 5% air can be heard in the intake plenum through the throttle body. Air in the intake manifold/throttle body indicates air is getting past the intake valves." which tells me the leak is intake valves only? I wonder what would the average mileage be for a vehicle that showed a 30% leak down? I wonder if that same vehicle would display the same type of hard starting symptoms we are having after sitting hot for a short period of time?

 

yea, air through the crankcase indicates poor piston sealing, via the intake, intake valves, and most likely, via the exhaust due to burn't exhaust valves. I have a leakdown tester...and 30% leak on one cylinder basically points to a dead cylinder.

 

So if the cylinder was perfectly sealed there would theoretically be 0% leak down. The 5% that is normal and what can be seen on a brand new engine is air leaking past the ring set and into the crankcase. So there is always a little air heard going into the crankcase you just have to determine if the percentage is high and rule out intake and exhaust to confirm rings. There is also potential for cyl leak into cooling system but that would show up with bubbles in the coolant (with the cap off) during the test. none found

 

...researching new engine=hot start issue

 

You are correct...the "normal" leak path is past the rings into the crankcase. That is known as blowby and is handled by the crankcase ventilation system. Leakage into the intake or more likely the exhaust points to poorly sealing valves and exhaust leaks are the most common since those valves are exposed to high heat. If there is a bad cylinder head gasket or a crack into the cooling system, them you would see bubbles in the radiator.

What takes interpretation is the AMOUNT of leakage and is it indicative of further issues to be investigated. And personally, I think the heads of this engine should come off for inspection. I would like to see the condition of the valves, valves seats and guides. If the clearance is good and the valve is still leaking, we have sealing issues.

Howard

 

if someone were going look to buy a first gen v6 taco with the 3.4L today, how would you check for hot start issues?

besides the typical frame rust and everything else to check, whats the short version of making sure there is no hot start issue I could do at car lots

 

When I was looking for vacuum at the fuel pressure regulator on the Tacoma I found that there was no vacuum in the line to it at idle. I traced the line and it goes to the intake tube before the throttle plate resulting in no vacuum source. I went on to research this unusual phenomenon and found that Toyota uses two types of fuel pressure regulators referenced to "manifold vacuum" or "atmospheric pressure." Here is all the info I could find about atmospheric pressure referenced fuel pressure regulators. This is from Toyota technical training and is for educational purposes only.


ENGINE CONTROL SYSTEMS I


Course 852


The pressure regulator maintains fuel pressure in the rail at a specified value. This value will vary in relation to either manifold vacuum or atmospheric pressure, depending on model.




Atmospheric Modulated Pressure Regulator

The atmospheric modulated pressure regulator changes fuel pressure in relationship to atmospheric pressure. A hose is connected from the pressure regulator to the air intake hose between the air filter and throttle plate.

A combination of spring pressure and atmospheric pressure determines fuel pressure. One example is a climb from low to high elevation, where a decrease in atmospheric pressure on the diaphragm results in lower fuel pressure.

This could be why we see a constant fuel pressure of 57psi at all times when driving. No change even if quick rev while idling. 57psi seems like it might be a bit high or might not? The FSM test is completely wrong, it described removing the reference line to the fpr and noting a change this will just not happen if it is referenced to atmosphere. So yea ... good morning

 

@noahpete, thanks for that last post, lots of great info and it's all stuff I found very interesting. So you are saying we have the atmospheric modulated pressure regulator, correct? As opposed to the manifold vacuum type, right?

Here's my dumb questions - are the two types interchangeable? Is it possible we need the other kind? Is it possible we have a faulty one that needs replacing?

 

I removed my atmosphere/vent line from the intake tube to regulator when I built my "sanitized" intake tube out of stainless exhaust tubing. This was also accompanied by installing the Cali emissions "mini header" due to a cracked oem cast manifold. Another note is that I am without the cat converter as someone else found that they needed it more than me one night at work. The truck picked up seat of the pant power and it also changed it's exhaust note at about 2000-2100 rpms as I row thru the lower gears. A cleaner picked up sound, for lack of a better explanation. The end of the atmosphere/vent line is covered in a single thin layer of open cell foam, just to keep the heavy road crap from climbing up that line and plugging it off, as it needs to vent the regulator.

Climbed up to about 5900 feet a few weekends ago and didn't note a huge loss of power or combustion instability, not anything out of the ordinary to cause concern. Situation normal for that altitude. This is with a 3RZ 2.7 4 cyl.

 

Buy the extended warranty if it's offered is one. 2nd would be to take it for a longer than normal test drive with the salesmen, trying to replicate that situation.

 

http://www.aa1car.com/library/fuel_injection_toyota.htm

I really like this article. I've come back to it so many times in the past 4 months for different reasons every time. Lots of easy to read info about toyota fuel systems.

At the bottom of the article, it talks about the cold start injector. Some might remember how when we were first told about the hot start issue on 1/2, it was described to us in an email like this:

"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. Sorry for the delay, I was hoping to have it back to you today, I was short handed today as one of my techs want in. Like I said the engine runs great and sounds great, we will get this issue figured out."

That bolded part - I remember when I first posted about this, everyone told me we don't have an added cold start injector. So we assumed that was just a typo, because how could the person that just installed our engine not realize that? So here's my "out there" theory for the day - could he somehow have hooked something up incorrectly because he thought we did have that? I know, probably doesn't make sense.........figured I'd put it out there anyway - nothing to lose, right?

 

All that has been mentioned in this thread several times and even discussed in a T4R thread you recently linked to.

A rehash, all V6 1st gen Tacos use the non modulated, vent to atmosphere FPR. The only exception is very early engines, I believe the same ones that had EGR systems.
Are the 2 interchangeable? Good question, never fooled with the early ones. They very well could be the same, one used with vacuum modulated by the ECM thru a VSV or just run at the "fixed" fuel pressure with no modulation at all outside of altitude (like yours). All fuel delivery in your engine is decided by the ECM and achieved by its control of the injectors. Hence all the discussions we have had on the relevant sensor inputs to the ECM. Crank, cam, ECT and even the "STA" starter signal play a part in "starting" fuel delivery.

Back in the day Gadget of URD (Taco fuel system expert) fooled around with raising fuel pressure to help supercharged engines. One method was to stick and fasten a rod into the OEM FPR depressing the diaphragm (see noahpetes diagram) achieving the opposite of vacuum resulting in higher pressure. The Taco FPR has the hose connection going straight in from the top not at 90deg like the generic FPR in noahpetes diagram.

The FSM is in fact wrong when it describes the vacuum modulation of the FPR. I believe the entire section is an artifact from the early FSM mistakenly compiled into the later ones.
Quite a number of FPR's get mistakenly changed out due to this. As good as they are (the best), I find errors in the FSM on a nearly weekly basis.

 

That was me, it was my first clue that the "engine builders" (good or bad) were confused or just plain something else with respect to diagnostics.
It would be near impossible for something to be "hooked up wrong" at this point because so many folks have inspected things. Also the physical "installation" is just not that complex.

I keep asking where the residual fuel pressure bleed off is going.

 

but that's just it, I am unsure of the exact situation I am trying to replicate.

am I getting it fully warmed up then wait 30 minutes? or an hour? then try restarting it?

it seams people with this issue seam to do it at different times and not every time.

 

Make whoever you buy it from sign something that says you'll receive a full refund if you note a hot start issue within the first xx days of owning it. Or ask them if you can drive the car for a weekend, or better yet a week, even if they want a rental fee - at least then you'd know. Because you're right, I've seen people report different time intervals, different heat factors, etc, impacting how their hot start behaves. You can always try to duplicate by test driving, but there's no guarantee you'll aggravate it exactly the right way if it DOES have a hot start problem and you only get one crack at pissing it off enough to display it in front of you. Good luck Keakar!

 

I remember that like yesterday DP. That was when we started bickering about the quality of Haynes vs. Chilton vs. FSM, because we posted that pic of a cold start injector out of Haynes, thinking that we DID have one ("we'll show him!"), then after the fact realized the Haynes photo was of a 93/94 T100 V6 and we were completely wrong That was right around the time that I realized you "aren't just some guy on the internet" and that you "don't make this stuff up" - you actually know your stuff

Is it possible the engine they put in used to have a cold start injector, and they just removed it and now the engine is confused?

FWIW, I called parts and asked all about different FPRs. They said with our VIN, we'd use 23280-62030. He said that part was used on 5vz Tacos from Jan 95 through Sept 00. It was also used on 96-02 4 Runners, 94-98 T 100s, and some early 2000's Tundras with 5vz. Then in 2001, Toyota updated to FPR 23280-75020. He said 2001-2004 Tacos could use either the old one or the updated one, but I think he was saying Toyota kind of recc' the updated one during that time? Not completely sure.

 

I got yelled at for reading my phone while on vacation.

First pic of one boring stretch of I-75. Alligator alley. About half way across the bottom of the state.

 

Glad you made it! Just tell your friends to sign up on TW also, then you can all be on your phones together!

 

well now I feel like a turtle in the middle of the highway, I need a v6 but im afraid of what might happen in my attempt to get there.

I found a great one in perfect condition inside and out with very low miles on it but it doesn't have power windows or locks and it has no cruise control, all things I view as a must haves but I have to live without if I want this truck.

not sure if I should keep looking ??????

it would cost around $300 to add just the cruise only with aftermarket brand, OEM parts are discontinued for first gens.

I can made do without power windows and locks but not having cruise is like not having a steering wheel the way I feel about it

 

See, you remember more of this stuff than you think.
The jury is still out on if that's good for our brains or not.

No on the cold start injector. No place to put one or wiring to connect to it on your engine.

When I run 23280-62030 on Toyota dealership sites (without VIN#) I get all years/models with the 5VZ. When I run 23280-75020 I get the same thing but for the 2RZ and 3RZ 4 cylinder engines. When I do the same on aftermarket sites such as RockAuto I get the same results.

noahpete
It would be interesting to see just what effect atmospheric pressure actually has on the FPR, I have a hunch it's not much and not really a "designed in function". Just speculation there and could be all wrong but it would be nice to know.
So, the difference in atmospheric pressure between sea level and 10,000 feet is 4.6 psi. That equates to around 9.3 Hg vacuum. Assuming you folks are near seal level, apply that amount of vacuum to the FPR and see just how much fuel pressure change results.