Mark -

Right on. Very interesting about the timing light. I never would have thought of using it like that. I will be sure to use mine in the future if I suspect a bad coil pack.

You know, this sure does look like a "loading up" problem. As you've confirmed, there seems to be too much fuel in the combustion chamber at some point. Does it only seem to load up under boost? Or is it when throttle position exceeds a certain point? Closed to open loop maybe?

Does this happen when you rev it (generating boost) while the vehicle is stationary?

 

Oh, don't think about giving me credit, it was a pure accident. I clipped it on the first plug on the driver's side, didn't see the timing mark, then remembered that cylinder 1 was the first plug on the passenger side... (or the 2nd one on the drivers since it's the same coil pack). Anyway, that produced no light - and of course that just happened to be the pack that got blazing hot from the ICM failure.


It's only loading up when there's a load on the engine. I can hit redline in neutral all day long.

It doesn't seem to be throttle position related (TPS tests fine) it's more of engine load. i.e., I can coax it up to 50mph on a flat road. "coax" being defined as not getting over 2400-2800 rpm. If at any time I give it too much pedal (not necessarily smashing it to the floor) the engine just bogs terribly.

Now, if I'm doing 50mph on the flats, then hit this 11% grade I talk about, there is no way I can keep enough foot in it to maintain that speed. In fact, when I tried it tonight, I was running maybe 15mph by the top of the hill, and it's only about 1000' long. So, I dropped from 50mph-15mph in 1000'.

Ya' know though... that RPM thing comes back into play here. As I was going up the hill, I was trying to focus on what the underlying symptoms were, not just that the engine bogs.

And it _did_ seem to be RPM related. Trying to get above 2800rpm is impossible - when there's a load on the engine. Again, I can redline and "blip" it in neutral.


There's still a bit of daylight here.. Lemme run out with the camera and see if I can get a movie segment showing what's going on.

 

Okie doke...

This is about a 2meg download:
http://www.midiwall.com/4Runner/misc...yEngine_01.mpg

This is shot as I'm going up that hill. My foot starts steady on the gas, then I feather it _slightly_ to produce the symptoms.

The check engine light towards the end is a stream of misfires.

All through this there's a wonderful smell of raw fuel. There is NO fuel leak under the hood, nor in the fuel line. The fuel is raw in the tail pipe.


Thanks all

 

Maybe try another MAF Mark.

 

is it possible another coil pack got cooked at the same time as the other one?

 

maf: check, I'll dig one up...

coil pack: I thought about that, but they're all firing...


Fun huh? Never a dull moment in my world!



Thank you guys.

 

yea make sure you double check the maf...run the OBDII BR3 scanner and see what variables change greatly at the time...importantly check the maf readings....and timing...to see whats going on.

 

Have you checked that the ignition wires haven't been worn out? I had a slight roughness to my ride a few years ago due to cylinder misfires. Long story short we replaced the wires and all is well. So you all know, i am by no means a mechanic just some punk kid at Sears. Good luck.

 

OBD data's in... You guys will LOVE this...

Watching Calculated Load, Timing, Short Term Fuel Trim and Air Flow.

Cruising around 2600-2800 RPM:
Feather the throttle to make "it" happen:Note the jump in what the MAF says is airflow, and this is only a VERY small feather of the throttle. The MAF is stock and is_fine_, I can put it in another truck and it's perfect. I can put a donor MAF in my truck and it's the same result (bad stuff as above), I can put my Supra MAF back in and the truck barely idles.

Here's a new tidbit. If I have the Surpa MAF in, the truck will FAIL the "air intake cleaner test". That is, with the Supra MAF, then noting a very rough idle, then if I spray intake cleaner at the seam between the S/C and the intake manifold, on the passenger side, at the bolt just ahead of the throttle body (but down on the manifold), then the engine speed will come UP appx 200rpm and smooth out.

If I stuff a rag in that general area, there's no change. If I isolate that area by wrapping up everything else around it, I still get the idle speed increase. All the bolts are torqued down, the seam is straight, the intake gasket looks perfect.

Now, me being the pessimist, I think this is looking like a cranked intake manifold, or a cracked casing on the SC. That might make sense in the form of "at appx 2600-2800 rpm, the engine is running such that any crack will be exacerbated by the vibrations, thus opening it up to unmetered air".

But, if that were true, then why does OBD show such a massive increase in flow? Isn't that number straight from the MAF itself? And, why would the "air intake cleaner test" _pass_ with a stock MAF in there?

 

like the good book always says...

Replace ecm....

THat is VERY odd if all the sensors work fine then why would that happen?

The load itself comes from TPS and MAF....so something is up...in the end it could very well be the ecu!

 

I'll poke around and see if I can find one Johnny - thank you.

I'm still concerned though by the results of the intake cleaner spray test. That doesn't seem right.

I have to say though, that once I saw the MAF spike and the load skyrocket, I knew what was really happening (well, I THINK I know). Gotta be the ECU dumping a boatload of fuel and flooding the engine. That'd explain the fuel smell, raw fuel in the tail pipe, and of course the potentially blown cat.


Oh, my radiator's cracked too... Right at the lower hose connection. Anyone wanna take a guess on what'll be next? dang...

 

Dang sorry you are having such a time getting it up and running again.


Hey did you ever get the Dyno run done a few months ago? I never saw a thread for it but i was gone for a few weeks there...

 

yeah.. Gregg (Greedy) and I went; we had VERY disappointing numbers (supposedly I was only putting 199hp to the ground).

We had a conversation about how the dyno operator was driving (he was feathering the throttle ABOVE 3200 to stop it from downshifting) and Gregg found a another dyno place.

I went with him the next week, got the operator to drive it like _we_ think an auto should be driven (flat out, let the tranny create the torque by downshifting) and Gregg's numbers came up by about 30hp, but that's STILL below where he was running motnhs ago with less boost. I didn't run that day.

We both learned some interesting tidbits from the dyno operator that day, and went back to put them to good use. We both picked up some seat-of-the-pants power and response, and were looking to head back to the dyno soon. My trouble started shortly thereafter, and I'm not sure if Gregg went back.

Bottom line right now in regards to power.. I think I'm about 100hp below where I should be; Gregg's at least 50hp below. What's weird is that our A/FR's are flat 12.5's through the pulls, which would tend to indicate that there's no room to feed more fuel, in order to generate more power.

VERY weird.

We've had a couple of indications from people that based on my 9.5psi, and Gregg up at 10, then we should NOT be expecting more power. My point back has been "I dun't buy it", there are a couple of very "famous" cases of 300hp at the wheels with LESS motor than I have.

People retort with "well, it's the tune". If that were true, then where should I be tuning my fuel at? 12.5, 12. 11.5? I'm NOT gonna get my missing 100hp out of moving from a 12.5->11.5 tune.


Anwyay.. rant & hijack off.

 

Hmm, that is strange. I have heard of people running these with 500hp+ pretty easy and with all the work you have done you would think you have a lot more than 200hp! Stock they have what 125hp at the wheels? I agree that just doesn't sound right. and what is even stranger is that both of you were below what you should be. are the tails of 500hp just a myth?

I know that next year i am going to get a SC with all the other goddies to go with it (hence why i have to wait a year ro save up the $$) and try to brake the 300hp mark. Be sure to keep us posted on that once you get this fixed.

And looking at you latest problem that has me stumped that the cleaner test passes with the stock maf but fails with the supra maf. i have NO idea what would be causing that. either there is a break in the seal or not, the MAF should not change that.

 

Well, I dunno about 500rwhp being "easy", I mean, at that level you're talking about twin turbos, 30+psi of boost, custom pistons, etc... There are only a handful of people running that kind of power on this block.

There are many people in the 300rwhp range, all with dyno sheets. Soemthing's up - just dunno what.


I spent some time talking to my local guru ("D") last night and he had a simple explanation.. The engine's creating a huge intake vacuum, and with the stock MAF there's enough of a restriction at the neck that it's pulling air through whatever this leak is. With the Supra MAF, then that restriction is reduced, so air can get in more freely the "normal" way.


I picked up a donor ECU last night... I'll give that a shot next. New ideas from D also included wiring harness issues in general; torsional load on the harness (would explain the RPM threshold); injector wiring hacks (I have the clips for the larger injectors wired in parallel with stock); piggyback wiring failing (piggyback's disconnected, but there could still be issues in the wiring).

He's pretty convinced that this is NOT an internal problem. Given that it engine idles smooth, runs fine up to 2600rpm under load, and through redline at idle, there's nothing wrong inside.

Pretty confusing to say the least.


Oh, something new in the pot... My oil cooler/heater (bottom of the block by the pan, driver's side) is leaking. Hopefully that'll just be a tweak with a 24mm socket, if I can get a socket in there.

 

I agree that its not a engine problem, this sounds completely electrical...im still looking at the ecu being the problem. If you have replaced the maf several times then the only thing really in its way is the ecu.

Have you tried to hook the smt6 back up and read the voltage coming from the maf?


Man a rad and oil cooler leak as well...dang...

I just got a critter in the pass side valve cover.....

 

Johnny, are you saying I should really be trying to THINK through this problem and keep in mind ALL of th diagnostic tools I have at my disposal?

Silly you..

(nope, I totally didn't think about that... thank you!)


Oh, the tranny's leaking too, but I think it's just from being overfilled after the re-assembly. It looks like it's from the inspection plate where you get to the TC bolts. I HOPE it's just that fluid got pushed into there and it's draining out. I'm 97% sure that I torqued the crap out of the TC bolts when I put it back together.


WEEEEEEEEEEEEE!!!! Brothers in pain!

 

Heh, im still in the same boat too Midiwall. Im completly stumped on what to do next. Heres is what ive done.

Changed the front O2.

Got a different FTC.

Changed out the MAF.

Got a new TPS.

All this and i still run lean. The exact opposite of the problems yours having. I can still drive mine w/o it bogging down. (I dont drive it saying its drivable still) But is sounds like someone dropped a large bag of marbles in the intake. and AFR's go all the way up to 18.

Im almost getting to the point of getting a new ECU aswell, but im afraid to call and ask the price of them. Do you know by chance?

If it makes you feel any better, My oil pan is leaking, axle seals are leaking and the rear diff is leaking.

 

Hehe Mark....check it out to see if the MAF is going nuts which cause the ECU to go nuts...if the maf gives you a nice reading yet the ecu is going haywire...then yea you have a bad ecu...

I too got a tranny leak...my fault..i used a non toyota gasket when i put the valve body in....its getting worse now. Other then that just that odd noise...which i have to look at when i get back from my trip this weekend (tacoma stays at home now)...


Good luck hope we can figure this out! I got a source for ecus...i dunno if he still has a couple but maybe...

SteveO,
That really sucks...its hard to help out perfectly i im not there This may be a pain in the ass but did you check your fuel pressure?

 

Mark;

Not clear as to why you have eliminated timing (under load).

Also, still trying to understand this:

Cruising around 2600-2800 RPM:
Load: 16%
Timing: +15*
Short Term Fuel: -3.9%
MAF: 1.29 lb/min

Feather the throttle to make "it" happen:
Load: 97%
Timing: -2.9*
Short Term Fuel: +10.7%
MAF: 10.37 lb/min

Is that not saying that the timing retards under load? Sorry if I'm not getting this, mostly trying to follow along here.

In any event, take it easy on your truck.. no point in breaking something else while trying to fix it. (my platitude of the day...)

Speaking from the world of electronics... Upon rare occasions the initial problem causes another problem. This can make troubleshooting "confusing".