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i went to recheck everything again and reset the tps. I found that as i tried setting my reading kept flickering o.l. i thought this was just me going back and forth past the idl circuit, but figured out that as i twisted the butterfly in the throttle i could duplicate the problem. Basically there is some play in the shaft of the throttle body and if i twist it a hair it goes o.l on the meter even if i have the throttle closed.
So I'm going to change the tps. It's probably has some play in it and is lifting the fingers off the resistive circuit. I bet it only causes this when i first push the throttle down and why i couldn't find it the other times I've checked the tps.
That's interesting and reminds me of a solved 22re issue on some other site that I can't find again for the life of me.
To make a long story short, someone figured out that the rod that the butterfly valve rotates on, had developed too much play and was just slightly binding against the inside of the tb. The valve would look fully closed, but was open a hair sometimes, which made consistent tps readings impossible.
Since the butterfly valve rod isn't serviceable, the repair was to use a custom-made ultra-thin spacer under all the throttle linkage springs that sit on the outside of the tb. That shifted the butterfly valve just a little to the side which allowed the valve to fully close every single time like it's supposed to.
I have had issues with a random idle when coming to a stop. Sometimes it will idle at 750, sometimes 850, sometimes 600. It's been crazy, I've tested this thing about 20 times during testing, but this was the first time it actually showed an issue. I'll try and pick one up later today and return with my results.
Yeah, still didn't fix it. I went through last night and rechecked my valves. Some were a hair loose so i adjusted them again.
i also went and cleaned every ground up, again to ensure good conductivity. After putting everything back together my idle was way higher than it was before. I had to turn the idle screw in about 2 turns and readjust the timing.
after all that it still misses, just as bad, if not worse. It damn near stalled out and had the worst back fire in the intake yet.
at this point i feel i have no choice but to check the fuel system.
i did find my new ignition wires, i did throw them in my garbage bin. But i quickly found out why i threw them away. One of them tests at 30k ohms. The max the fsm states they should be is 25k ohms, so i put them back in the garbage bin where they belong.
nah take em back out of the bin.
resistance is based on cable length. 5k ohms is not enough difference to put it in the bin.
Didnt you say they were genuine brand new leads?
You might go buy a new set and find they are exactly the same. i suggest going to the parts store with your multimeter! haha
WORST INTAKE BACKFIRE YOUVE YET SEEN
hmm
is the chain nice n tight?
if so, definately time to start looking at fuel pressure.
Relevant section of manual https://ibb.co/cvJE9b
Last edited by Thommo Thompson; 12-04-2017 at 06:29 PM.
The chain seems to be tight, unless the machine work brought it down so far that the tensioner can't do its job. Although i find this unlikely for. 020 total combined with the fact that the engine only rotates one way, which should keep the tension and timing in the correct spot. It has a new chain, guides, tensioner and oil pump. Since the tensioner is oil pressure driven (to my knowledge) and my oil pressure gauge reads ok, I'm assuming it is doing its job.
i thought of the valves sticking open as well but you would also think that my compression test/leak down test would reflect this.
i was under the impression that a lean condition could also cause an intake back fire. I could be wrong there (hell, if i knew all the answers i wouldn't be here asking for help)
i could try loosening the valves a bit to see if it changes. I had the valves and seats ground at the machine shop but did not have the guides or springs replaced. The machine shop said that it was all good. Of course I've found that a person's word doesn't mean anything anymore. I just got through arguing a 580 dollar hvac diagnosis with a company to find out on my own that it was a simple thermostat stuck. Unit is under warranty, which is the only reason i called them. Have to begin to question the word warranty now days.
Ok. I put the new ignition wires on and no change.
i took another video (dark you can't see) that allows you to hear to miss from the engine bay. If i retard the timing all the way, the engine almost stalls. If i advance it all the way it improves a lot but still stumbles (and we know i can't fix it like that anyway)
i also found that i have an exhaust leak at my header gaskets right below the o2 sensor. I put new gaskets in it and tightened it down but i just noticed it still leaks. I know that this could potentially make the ecu read lean and try to correct, but i didn't think it read the o2 on a cold motor. Maybe someone can clarify this for me.
I pieced together a vacuum gauge at work so i can check the engine vacuum. If that checks out i will order the fuel pressure gauge kit from lce to see what I'm getting there. I'll report back tomorrow morning with the vacuum reading.
ok well, a video helps a lot.
That sounds just like a carburetor fuel stumble when a carby accelerator pump is faulty. (but it can still be a vacuum leak so keep that in mind)
So on EFI engine the equivalent is the fuel pressure regulator.
I suspect yours is sticking just as vacuum is released as u press the pedal.
This presses home my constant complaint about car manufacturers back in this era, they couldn't just bight the bullet and make everything electric or leave everything mechanical. With a vacuum operated fuel pressure sensor, and everythign else electronic, there is a mix of mechanical and electrical controls which makes diagnosis so hard and makes the number of failure points much larger.
There is no fuel rail pressure sensor in this engine is there?
There is a fuel pressure regulator on the rail, but it's mechanical. Later year 22re's have a vsv on the valve cover that controls the regulator, but you can delete it and the fpr still works fine.
I have the fpu vsv in mine, it just bypasses vacuum to raise pressure during warm engine starts i think. I bypassed it at one point for testing but have it reconnected now.
I'm leaning on a fuel issue now as well but im doing this vacuum check just to be sure. It will help eliminate vacuum as a cause anyway.
I'll check fuel pressure as soon as i get the time and money to buy the gauge kit. Is not much but I've had some financial stuff this month that ate my budget (and i bought that tps)
When you pinch the fuel return, all you are doing is enriching the mixture. Which could be "solving" a whole bunch of problems that don't have anything to do with the FPR.
So before you mess with the FPR, get a pressure gauge and test it. My guess is that it is at spec, and something else is leaning out the engine.
I know when i jump my fuel pump it sounds like i have good flow. I do not know what voltage I'm getting to it though.
i already have to seat out and access to the pump so I'll check to make sure i have good voltage to the pump when running and that is not dropping out. I will also pull it out and visually inspect it. This truck has sat for 2 years prior to me getting it, i drove it a year then parked it for another while i worked on it. It has sat for pretty much the last 4 years with occasional use.
I'll have to wait on the fuel pressure gauge until my bank account improves. It is Christmas time after all
... I'll have to wait on the fuel pressure gauge until my bank account improves. It is Christmas time after all
All the more reason to avoid replacing parts until you're pretty sure they are bad.
Until the 25th, you can do a good check on the Fuel system by pulling the return line, replace with 6mm (1/4") clear vinyl hose, and run into a suitable container. Run the pump with B+, FP and you should get about 1/2 liter/minute on the return line. That does NOT test the actual pressure the FPR is setting, but it does test a lot of other things in the fuel system.
And in this shopping season, it doesn't cost anything (unless you have to buy the vinyl hose. It does't even cost gas; just pour it back in the tank.)
All the more reason to avoid replacing parts until you're pretty sure they are bad.
Until the 25th, you can do a good check on the Fuel system by pulling the return line, replace with 6mm (1/4") clear vinyl hose, and run into a suitable container. Run the pump with B+, FP and you should get about 1/2 liter/minute on the return line. That does NOT test the actual pressure the FPR is setting, but it does test a lot of other things in the fuel system.
And in this shopping season, it doesn't cost anything (unless you have to buy the vinyl hose. It does't even cost gas; just pour it back in the tank.)
that's a good idea, i have another if you care to share your opinion.
if i were to take a pressure gauge (which i have) and hook it into the end of that line on the return side (blocking it essentially) then would that not tell me if my pump will put out enough pressure. obviously this will also not tell me if the fpr is doing its job, but i think it would tell me if my fuel pump is. Assuming I'm correct in that with no vacuum on the fpr i should get full flow from the fpr on the return side.
Testing the regulator by pinching the return line does give us some useful info tho. The fact that it smoothness things out on revving suggests fuel is the problem.
If there was a large vacuum leak, pinching the regulator line would likely result in surging, but it sounds as if it just helped smooth out the power down low.
Now the fact that we haven't had any indications of power problems up high, suggests to me its more likely the regulator than the pump. As a failing pump, usually cannot supply enough fuel when you kick it in the guts, and your symptoms have only talked about just coming off the throttle, and your video suggests it as a hesitation only at that rpm range.
Saying that, a failing electric fuel pump failure is just as common on older cars because DC motors like nice unrestricted 13.5 volts with good amps. Corrosion in wires, or the contacts of fuel pump relays, can cause the power to become erratic, or simply restrict the voltage which causes the current sucked by the motor to go up to compensate. This overheats the windings and causes them to become more resistive over time.
to quote another source:
"If the motor draws constant current then the resistor will drop a constant voltage and the motor will run at a fixed (lower) speed. However the motor will draw more current when starting up and as the load increases, causing higher voltage drop and reducing speed even more. If it is driving something whose loading increases as speed increases (eg. a propeller) the speed will eventually stabilize, but if the load is variable then speed regulation will be poor."
So a marginal alternator, or a bad electrical contact, or an old fuel pump relay, can cause the pump to fail.
and a sticking regulator woudl explain any black/brown smoke you see when revving the engine, as when you let go of the throttle, the regulator should close up, but it may be sticking open keeping it rich.
12-02-2017, 11:15 AM
