norcal98

iTrader: (3)

Alright fellas, need some help here and Im running out of ideas. Apologize if this goes too long, but I want to put all the info out. Like the title says, Im having an intermittent miss out of the tailpipe that only seems to show up approximately 1500 rpms where its most notably. Prolly comes on just after 1200 rpm and can still hear it just before 2000 rpm. After that I don't hear it and I don't hear it at idle. One odd thing is, when the truck is cold and it bumps itself up to about 1200 plus rpms for warm up, I dont hear it, but as soon as I see the temp gauge start to show movement, thats when I notice it (done this a few different days to confirm). It will continue to have that low rpm miss in the tailpipe from that point on to complete operating temp and then continue to show itself in the rpm range. I don't have any surge or stumble in the motor when I hold the throttle at those rpms, or as it warms up. Just can hear it in the tailpipe and if I hold my hand in front of the pipe (as its continuing warm up, and now starting to see temp gauge move) , I can feel stereotypical larger puff on my hand when I hear it . When I drive the vehicle, I don't feel any stumble or surge and seems to pull just fine through range.

Tried a search and found two similar threads.The yotatech thread from 2016 didnt seem to finish so not sure if he fixed or what his solution was, but my truck seems to act similar.
https://www.yotatech.com/forums/f116...s-3vze-297558/

Second thread is different site, but it has a video even if poor, and my issue sounds similar to what I think he is trying to show on video. He never finished thread as well or found a solution.
http://www.toyota-4runner.org/classi...misfire-2.html

So................Here is a list of what Ive done and check off with no success to fix the miss. Hoping other people have test ideas or a fix.

- Rpm at idle (warm) is approximately 600rpms (between the 500 and 750 mark on tach and pretty steady).
-Timing is set at about 13 degrees BTDC (had it advanced a little for years with no probs till now)
- Plugs don't appear cracked or excessively wore, no large white deposits or black fouling around plug tip.
- Used a different Cap, rotor, and plugwires from a vehicle that is not having the issues to double check truck, but miss still present (I have a 4runner with 3vze as well and it doesn't have that miss)
- Took the throttle body off that same 4runner and put it on my truck, same miss was still present.
-Took the (no issue original silicone) AFM off the 4runner and put it on truck, same miss still present.
- Compression on my harbor junk gauge reads 150 plus change on all six cylinders (all cylinders about the same I figured was important part).
-Decided to check my TPS just in case with multi meter since it was out. Closed VTA -E2 in spec, 50mm gauge IDL - E-2 showed infinite (not right), 80mm guage IDL -E2 infinite, Wide open VTA - E-2 in spec. I figured that since the T.B from the 4runner didnt fix the issue it wouldn't matter, but I adjusted/turned clockwise the TPS so that the 50mm gauge showed less then infinity and less then 2.3k (much less actually) on multimeter, and 80mm gauge showed infinity. If i adjusted this wrong please let me know, but put the newly adjusted T.B back on and miss still present.
- No coolant loss and no white smoke coming out of tailpipe.
- No milk in the oil and oil looks good.
- I don't see any vaccum hoses off and using my MAPP gas torch around every part of the engine I can think of, I get no rise in RPMs.
- With truck running and soapy water, I dont see any leaks (bubbles) around exhaust manifolds or down pipe.
- *EDIT* - Forgot to mention valves were adjusted 6 months ago and within spec, I usually keep up on those since losing my first 3vze 10 years ago to burnt no.6 valve around 230k miles

Dang that was long, but just the same if you kept reading I appreciate it and looking for solutions/ tests. thanks

ksti

Have you checked each fuel injector for resistance?

norcal98

iTrader: (3)

No I havent yet, but thats probably the direction I figure I'll have to be heading. Been working graves a lot and didnt want to go that deep in the motor until I knew for sure I had the time because I need it for work.
I'll prolly do a leak down first just for giggles, but I have to drive and hour an a half one way to get a parts store with a loan a tool program.

If an injector/injectors are bad, are people having good luck with the yellow flame throwers? or just hype?

No codes by the way since I didn't mention in the first post. Distributor was in spec far as the feeler gauge and VSV seem to all check out far as resistance.

In experimenting with the motor, there seems to be a direct correlation to the pair valve being active and not getting that miss at the rpm range. I'm thinking that may also be why I don't see/hear the miss when its warming up? Not sure what that means yet exactly with regard to a solution, but an interesting observation.

norcal98

iTrader: (3)

Wasnt able to get a hold of a leak down tester, none of the parts store seem to carry them or even sell them.

Did test injector, resistance came in right at about 14. Decided to do a test on injector flow with jars. All seemed to spray the jet pretty consistent and they measured out nearly identical in 15 seconds tested 3 times. The only thing I need to confirm is the amount that it should have been?

EG2-226 of the FSM says 45-55cm/15sec. I didn't have a measuring device for cm, but the little cups for cough syrup would give me ML. So I had a little over the 2.5ml line, Im thinking with what little was still left in the jar plus what was over the line then its probably about 3ml in 15 seconds.

My question I need to confirm, is the FSM telling me I need 45-55cm of fuel in 15 seconds for each injector? (seems like a lot as it would be 45ml or over 9 teaspoons for every 15 seconds per injector). If thats the case, then I am way lean and it must be my problem.

Unless the FSM is saying 45cm divided by 15 should equal the number I get in my measuring cup? i.e. 45cm/15 = 3ml which would mean Im right in the area I need to be. Im more inclined to think thats it, just because how consistent the injectors were to each other, but don't want to assume just because they are consistent. If the injectors are within spec (even if lower end which Im okay with cause the motor runs rich) then it checks that off, but still doesn't help me know what the problem is.

Thanks to anybody who may know the answer.

scope103

Hmm. This sounds like a math problem.

45cubic cm is 45ml. 45ml in 15 seconds is 180ml/min = . 10800ml/hour = 10800ml/hour * .033 oz/ml = 356 oz/hour = 356 oz/hour / 128oz/gal = 2.8 gal/hour

I can get about 20mpg at 60mph (flat road, cruise ctl.,...) or about 3 gal/hour. We each have 6 injectors so that's about 0.5 gal/hour/injector.

So if my injectors can put out 45ml in 15 seconds open, then at cruising my injectors are open about 1/5.6 = 18% of the time. This sounds about right to me.

9 teaspoons is only 1 1/2 oz. Which doesn't sound very much to me.

So what's up? The first question I had was: How did you hook up your test? The manual http://web.archive.org/web/201311071...90injector.pdf shows a lot of SST (Special Service Tool) plumbing. With specialized threaded fittings to connect to the fuel line, pressure regulator, and the injector. Did you do all that? Or did you invent a very clever work around using rubber hose and hose clamps?

So if your test fixture is good, why are you getting such low flow? If you're getting the same 3ml/15 seconds on all 6 injectors, then it almost certainly has to be low fuel pressure. Use some of that inventive genius to hook up a pressure gauge. (or put it all back together and set up something like this with a commercial fuel pressure tester)

norcal98

iTrader: (3)

I wish I was that cleaver to invent a way to get around all the SST stuff needed. Now that I look at your post above, I think I realize why my numbers are off. When I look at the FSM test again and see it asks for direct power to the injector, that must mean it get a constant stream and not a pulse? That would change how much fuel it puts out in 15 seconds if thats the case.

I used this method I found on a search
https://www.yotatech.com/forums/f116...s-home-239660/

I guess all that really tells me is each injector is firing (which is good) and how much fuel each one is putting out in 15 seconds of cranking the motor (whatever pulse rate). I took the fuel that was in the individual jar under each injector and measured each out separately and why I said they were putting out the same. About 2.5ml. So at this point I don't see the FSM numbers matching up unless when you put direct power from a battery to an injector, it will pulse automatically?. I don't know enough about injectors to know for sure, but I would guess that's not the case?

Im starting to lean more toward a valve issue. Scope - When I remove the rubber air line from metal line at the front of the manifold that connects to the resonator at the AFM, I can hear the gurgle from the PAIR valve, I don't seem to hear or see the miss (if I watch the tailpipe on a real cold morning) as long as it gurgles. As the engine warms, the pair valve gurgle stops based on temp, when that happens the miss will show itself. The pair valve adds air correct? I'm not sure why adding of air from that makes the miss seem to disappear/appear, but there seems to be some correlation between the two. Of course correlation doesn't mean causation so I may be barking up the wrong tree.