dbittle

And look at the E1 measurements. Definitely something odd going on there too.

Co_94_PU

iTrader: (-1)

B+ and E1 route thru the oxygen sensors on 2nd gen TCCS systems, junction I15...


Worth mentioning if you've got exhaust leaks under the body your o2 readings are junk. The way the sensor works it expects clean fresh air to compare the exhaust with and if you're spewing exhaust under the body (near the sensor) you can't really trust the sensor output. The way the zirconium sensor works is it compares the exhaust flow with a small port on the sensor. This bias gets squewed if the o2 external.port is dirty, blocked, or exposed to exhaust flow.

maxvp01

Hm this is good information. I may need to get a temporary straight pipe. Currently have holes all over from the catalytic converter end to tailpipe.

For the infinity reading between +B and E1, I am a little confused on why the resisters factor in from the VAFM sensor. It looks like the +B and E1 meet at the VAFM switch according to my diagram. I am no expert at wiring diagrams and could be completely wrong, but here’s a picture highlighting the +B wire (yellow marking) and the E1 wire (red marking).

2ToyGuy

Those are all grounds.
When the switch in the VAFM closes, IE has air flowing through it, it applies a ground to the COR main, or "run", coil. The B+ is +12VDC from the battery, present on one side of the COR main coil, when the key is ON. When the VAFM applies the ground through it's switch, it allows the COR to remain energized, allowing the fuel pump to operate. When the engine stops, for whatever reason, the VAFM switch opens, removing the ground from the COR main coil, shutting down the fuel pump. If it's due to an accident, and the key remains in the ON position, the fuel pump will still shut down, even though B+ is still on one side of the COR's main coil. No ground, no complete path for current flow, no energizing of the coil, no fuel pump.

Does this explain it? About as clear as a good Moly-b grease?
Pat☺

maxvp01

That explains it better, but I am still confused on how I am suppose to get anything besides out of limits for the +B and E1 spec. I confirmed the wires have continuity to the VAFM sensor, my +B wire has about 106 ohms to the connector at the VAFM, and my E1 has 0.003 ohms to the connector at the VAFM.

I tested the +B through the circuit opening relay aswell.

When looking at the wiring diagram there is a switch in the VAFM that is suppose to connect these wires together as Pat states above. But with the computer disconnected that switch does not close (even with Key On). That would explain my OL reading, that is the only place I found on the wiring diagram.

EDIT: also when doing the voltage tests to ecu, the +B - E1 gave me the correct reading of battery voltage.

When looking at my other wire where I got OL, which was Ne- E1, I do not see where these two wires touch either as Ne goes straight to the ecu.

2ToyGuy

The B+ wire is reading through the coil of the COR, reading from the ECU connector to the VAFM connector, thus giving the 106 ohm reading. E1 is direct to ground, not through a coil or anything, thus, 0 phms.
You can easily test the switch in the VAFM. Ohm across the two terminals of the VAFM plug the wires from the switch go to. When the vane of the VAFM is closed all the way, it should read Infinity ohms, when the vane is open, even slightly, it should read 0 ohms.

It's really a very simple circuit.
Pat☺

Co_94_PU

iTrader: (-1)

NE comes out of the distributor through the igniter, these likely have a filter. You OL is probably a fluke or it would be throwing a code and not running at all if NE was open. It might be an intermittent open, which explains some misfires.

I was actually looking at E2 , when i mentioned the resistors, which is sensor ground. E1 and E2 only meet inside the ecu.

Not sure off the top of my head where that ground wire attaches, wouldn't be a bad idea to clean it and make sure it's tight.

STJ concerns me, that's grounding the cold start.

​​​VTA could be a typo, check the voltage as you sweep it from closed to open. It shouldn't max out before the throttle stops moving.

VS looks kinda like book errors.

maxvp01

I did a compression test today, results are as follows:
Cylinder 1- 174.0 psi
Cylinder 2- 164.5 psi
Cylinder 3- 168.5 psi
Cylinder 4- 151.5 psi
Cylinder 5- 169.0 psi
Cylinder 6- 168.5 psi

I will do the ECM voltage test again when I get a chance and post every single result. I figure this will tell me better than the resistance test If the ECU is receiving everything it should.



When pulling spark plugs to do the compression test, I noticed they are half fouled now on all 6.. The only thing I have done differently that I can thing of is advancing the timing quite a bit by feel/sound (do not have a timing light at the time to see the exact degree.) Timing is over 14 degrees advanced I know for a fact.



This is all pictures of the same spark plug.

Also found a ECU on ebay for a steal that I ordered, figured i’d never see one that cheap again in my life so I went ahead and got it, that’s the last thing that hasn’t been tried. Should be here by the end of the week.

I will find my engine grounds and clean all of those off with a wire brush/wheel

Also to the knock sensor comment- I did replace the pigtail, but did not replace knock sensor. I figured if the knock sensor was sending a bad signal the motor would be very retarded in timing and throw a code for it

dbittle

Good result on the compression test. I think if one of the cams was off a tooth, they would be a lot more all over the map. That takes us back to the emission system, where you had some strange readouts. Man, I really hope that new ECU fixes it for you! Its almost either that or a harness issue. Did you have a chance to do the check where you held your hand at the end of the tailpipe? It's just curiosity, since one cylinder had less compression, if it makes a little "poof" in the exhaust when it fires.

maxvp01

Did not feel any “poofing” that I could tell from my hand being there.

Today when I was coming home from school I shifted from 4th to neutral as I was coming to a stop light and the truck stalled out. It has almost stalled out before because a few times before all of the warning lights showed up then disappeared once the RPMs came back up.

When I got home I was blipping the throttle at different RPMs and if I blip it at 2,000 rpms that is the worst, it will drop right down to about 200-300rpm and the voltage gauge will bounce and drop then pick back up. It all bounces in the “safe zone” of the gauge.

Also when Idling at the stop light I noticed my idle is now around 500-600 rpm, occasionally the voltage gauge would bounce then too. Truck still lopes and surges at idle. It was a damp rainy day today too if that would affect anything.

EDIT: starting to think my TPS adjustment went out of spec. will pull throttle body off and check/readjust according to FSM if needed.

dbittle

Hmmm. Hopefully the new ECM clears it up and you also have some wiring faults to chase down. Those could be more apparent in damp weather, possibly. On the long and winding road of chasing this problem, did you ever check or replace the ignitor?

maxvp01

I think the ECM will narrow down this gremlin of a problem quite a bit. *hopefully*

Its also a used OEM ECM, it was working when pulled out of the truck it was from. It’s from a 89 XtraCab, 4x4, 3vze, M/T. Mine is exactly the same so we will see what happens

So I have tried swapping a junkyard igniter and coil with the one that came on the truck, didn’t feel a noticeable difference right away so I swapped it back. I just swapped out the coil/igniter combined piece with the junkyard one instead of doing just one or the other.

maxvp01

Lots of new information i discovered today:

So ECU came in the mail today, didn’t change anything. (big surprise.. not)

Next I checked fuel pressure, 38psi when at idle. Fuel pressure goes up when throttle increases. Also disconnected fuel pressure regulator vacuum hose- pressure increases.

THEN i turned off the car and fuel pressure instantly drops to 0, not even slowly falls.. So a huge leak is somewhere such as the check in the fuel pump.. I remembered I have also changed the injector connectors. So I checked which wires I hooked up to the harness and cross referenced with wiring diagram. Sure enough I wired the injectors up backwards.

The circuit is switched by ground, and has constant power. It might be possible depending on how the injectors are wired internally that they are always open, and get switched closed, which would cause a very rich condition on ALL cylinders, and would explain why the fuel pressure drops instantly. I highly doubt this is the case because it’s just a coil of wire in a solenoid but it worth crossing off the list.





I was able to borrow a scope today and I used that to look at the injector pulse width. I first got my old AFM out and set it to the factory notch, the pulse width was 4ms





So then I set it full rich (10+ clicks) and the pulse width increased. (increased a lot more than the lean scope picture)

Then I set it full lean (10+ clicks) and the pulse width shortened (picture below)





So this does tell me the ECM is compensating or at the very least communicating with the AFM.

Next I unplugged the ECT and watched the pulse width. I got a few resistors out, one was 250 ohms to simulate operating temperature, one was 50 ohms to try and simulate a lean condition.

I plugged the 250 ohms into the connector and checked voltage with my meter. I read about 2V (from resistor on the connector to battery ground). This tells me the voltage is changing from 5v to what it needs to be and the ECT is truly sending a reading. The pulse width did not change from adding this resistor.

Next I added the 50ohm resistor, that did not change the pulse width at all.

This test is telling me the ECU is not receiving this voltage for some reason. I am getting the 5V from the THW wire but I do not think it is going through due to the E2 wire.





Tomorrow I plan on putting a resistor in the 5V pin of the connector and running a jumper from the other end of the resistor directly to the E2 pin of the ECU and see what happens.

I also plan on pulling the plugs and jumping FP and B+ to put a boroscope in the hole to see if the injectors are stuck open or leaking. (highly doubt this is the case but it is something I havnt not crossed off the list yet.

I will update with the results

EDIT: Should also note the O2 sensor remained pegged at 0.9V during all these tests.

Also Tested TPS and the OEM one I found was out of spec and would not fall within specs so I went back to the Beck and Arnly TPS. Checked it 4 times and it is well within spec.

Truck now bucks less when cold, shifts a little better, and accelerates better. So that’s one problem solved.

dbittle

+1 on the boroscope idea and its good news you got some benefit from the TPS replacement. I was crossing my fingers for you on the computer being the problem, but at least now you have a good spare. Tracking down the internal fuel leak will be another big step forward picking apart your problem.

maxvp01

I used a boroscope and pressurized the fuel rail- no leaking fuel coming into the cylinders at all.

I also jumped the 5V reference from the ECT connector directly to the E2 pin on the ECU with a 260 ohm resistor, no difference.

When I was looking closer at the connector, the wires were in rough shape. There was maybe half of the strands left on both of the wires at the base of connector. Also when I would wiggle wires at connector, occasionally it would cause the engine to change RPM then pick back up. Anyways I bought a new connector and soldered it on. It feels like a slight power increase afterwards, also have been told it can increase MPG slightly.

Truck is still rich after this.

Starting to think that possibly the aftermarket “csperformance injectors” are the problem. When I bought the injectors they offered me a free upgrade to the newer style denso injectors with matched flow rate and all that. It’s possible they did not flow match them at all, or they sent me the wrong ones and gave me them for a 5VZ.

I don’t really have any good way to rule these out. I still have my old injectors but they are in ROUGH shape except my one beck arnly reman. My friend wanted to help with my rebuild so I had him put the wiring harness on the engine.. he noticed the injector connectors were broken so he put weather strip adhesive on them all and glued them together.. I might be able to salvage 3 and hope they aren’t the clogged ones.

Thinking if I put 3 of my old injectors on one bank and keep 3 new ones on the other I could drive it around and check the plugs after 30-50 miles, and compare them.

The only thing that makes me think it’s not the injectors, is that there is no code saying it’s rich, meaning the computer hasn’t compensated all the way. This makes me think it could still be wiring too.

dbittle

Howdy yotatech 3vze brother!. You still have the issue of the fuel pressure instantly going to 0 when you shut off the engine though. If it isn't leaking out of the injectors or cold start injectors, it has to be going the other way back through the fuel pump check valve. Let's run that problem to ground and eliminate it. You may have as many as 4 contributors (TPS (already fixed), fuel pressure going to 0, frayed wiring harness with possible opens and shorts, and then maybe the injectors flowing above spec). Personally, I would take them on in that order and eliminate each before I moved on to the next.

wallytoo

iTrader: (1)

even if the fuel pump check valve has failed, it should not affect performance while the engine is running. it might marginally affect starting performance by delaying it for a second or two. i have somewhere in the vicinity of 40K miles on my 22re fuel pump, the whole time with a failed check valve (faulty out of the box). but after changing the pump 7 or 8 times in about 18 months (long story), i didn't care, as long as the pump still pumped.

i do have a permanently mounted fuel pressure gauge at the csi, so i know that while the truck is running, it has the correct fuel pressure. the non-functioning check valve doesn't affect that.

maxvp01

Im just going to be leaving my pump as is for now until I get time to drop the tank again. Extremely disappointed in the quality of the pump I got. Next time will be putting an OEM in.

As for the the list mentioned by dbittle:
-TPS is within spec
-Fuel pump check ball is bad, but pressure is within spec (just have to prime pump a couple times before I crank)
-Wiring needs to be completely ruled out- I will be working on this and trying to rule it out

wallytoo

iTrader: (1)

as long as the fuel pressure is within the specification, the pump is adequate even if it won't maintain pressure after shutdown.

Co_94_PU

iTrader: (-1)

Don't forget the exhaust leaks.