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Discussion Starter · #21 ·
BMR, I don't know your skill level with circuitry.
I’m quite good, meaning I’m not scared of soldering larger components like the electrolytic capacitors and such. Little 1mm x 2mm surface mount components?… count me out.

For a couple years, I was buying broken iPod Nano’s on eBay, repairing them, and reselling them. But the bottom fell out of prices I could get, so I quit. I’ve got a stack of gen4’s if anyone would like one. No charge. Just PM me.

Back on topic, I think I’ll pull the ECU, open it up, and look for trouble.
 
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Discussion Starter · #22 ·
If you are not getting crazy codes for misfires, then indeed, the ECU thinks everything is good.
Thats what’s so exasperating about this! I wish it would throw a code! But if the ECU is flaky?…
Gut feeling, have you got a vacuum leak somewhere? Are all the sensors running true and reporting the correct values?
I’ve looked and looked, triple checking any that I’ve messed with, but nada. And as far as I can see, using an OBD2 monitor, all the inputs to the ECU are good, and the ECU outputs are likewise.
can I clarify (I have probably missed it), are you checking the power to the fuel pump, or the actual running of the pump? Just to be totally sure - but this is just my thought.
The bulb is connected to the same wire that powers the fuel pump. So it’s wired in parallel. If my bulb has power, so does the pump. The fuel pump is a new Denso, so I’m assuming if it’s got power, it’s running.
 

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If you know how to follow traces I would suggest to not only check the capacitors but also follow the traces to the resistors and fuses each has. If you are like me and forget what each resistors capacity is, here is a guide.


Do not just do a visual inspection. A capacitor could very well look fine but actually be internally damaged. Make sure you read what each capacitor is rated for.

You should be fine as it's not SMD.
 

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@BMR thank you for the update, I was just checking.

You could well have a circuit board issue, so as said above, have a look go for it - as you can repair stuff, you should be able to spot problems. With the age of the ECU, do check the solder, and look for cracks

Please let us know how you get on
 

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Discussion Starter · #25 · (Edited)
I got the ECU out and the PCBA removed. Using my jewelers headset with 2.75x magnification, I can’t find any bad solder joints, obviously bad caps, or any evidence of water damage. There are only 4 electrolytic caps. I may try replacing those. With age, they lose capacitance, drifting out of spec until the circuit fails.

For posterity, the electrolytic capacitors:
47uF, 50V, 105C - qty 2
220uF 10V, 105C
10uF, 50V, 105C
 
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Not sure on an ECU but with my experience with HVAC on the Celica and graphics card repair sometimes you cannot see cracked solder.

I have seen graphics cards that look perfectly fine but wouldn't work until we baked it in the oven. It was an old Alienware so me and my buddy who owned it used it for testing purposes. After essentially reflowing it it worked properly.

The 4th gen Celica HVAC panel is prone to malfunctioning and sometimes you can't see the crack but reflowing it works.

Not saying there are any cracks on the PCB, just warning that visual means little. It's all about that multimeter.

You are correct that caps can lose efficiency over time, that is due to the liquid evaporating over years of heating and cooling.

I used to repair old 80's and 90's tech all the time. Once everything went surface mount I dwindled out of it. For me the death of Radio Shack made it so I had no interest anymore however recently I have been picking it back up again. I blame youtubers such as Big Clive.
 

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Discussion Starter · #28 ·
I ordered Nichicon electrolytic capacitors on Digikey. They’re about $0.30 each, so I ordered extras. Shipping was $5 via USPS, so about $8 total. I’ve never ordered from them before, and it was surprisingly painless. Even if it doesn’t fix the problem, this is a good thing to do.

I hear ya Fox, cracked solder joints can be nearly impossible to see. I’ll do more checking with my multimeter while I wait for the caps.
 
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Discussion Starter · #29 ·
I pulled the battery to check/clean the ground cable’s attachment to the chassis. It was clean looking, but I sanded the mate surfaces just to be extra certain.

I got the cam position sensor’s resistance checked; 1117 Ω, cold. I don’t recall the spec, but I think that’s a good number? BTW, that thing is not easy to get a hand on to undo the latch and demate it!!

Lastly, I checked the timing belt to see if it’s slipped a tooth. The pic below is of the HB mark with the cam pulley on its mark. The HB notch is circled, and the zero mark on cover has a line on it. That looks a tooth off, to me. That could be the problem, eh? Although it still makes no sense the ECU never threw a misfire code.

The ECU caps arrive tomorrow, but I’m gonna set that task aside while I get the TB back where it belongs.
169455
 

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Did you rotate another full rotation to double check? Timing goes in and out of alignment and requires at least 2 full rotations. I have no idea why it does that.

If it was out of time you would have issues even at low cruising speeds such as buckling or hesitation. Like at all times.
 

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Discussion Starter · #31 ·
Yeah, the first time I got the crank pulley mark lined up, the cam pulley mark was 180 out, so I had to turn the crank another full revolution to get the cam pulley on its mark.

That’s all because the cam pulley has double the number of teeth on the crank pulley. The crank has to do 2 revs for every 1 rev of the cam.

I’ve heard from many 5S owners that being off a tooth will make it run poorly. No details on what, exactly, that means. They’ll run off two teeth, but even worse. 3 teeth off won’t run at all.

We’ll see how it runs after getting that corrected.
 

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I'm tired and my manuals are far away from me to look at. If i remember correctly if you advanced your timing it will increase lower end power and rob high end and if you retard timing it will decrease power but increase fuel economy by a little.

I have done that on a Humvee as they don't have a high end anyway, Rev limit was like 5000 lol. I did have the fastest Humvee. However it did make starting it difficult. Used to tell people that Daisy doesn't like you and will only start for me. Yes I named my Humvee Daisy. I later upgraded to an LHS (huge truck that hauls a lot of cargo) and named it Hercules.
 

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Certainly get your timing aligned, as it will really affect the performance. yes, as @foxtherouge says, the engine will run one or two teeth out, but it will be horrible.

Let us know on the ECU too
 

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BMR,

-- For what it is worth, page 4 of the attachment shows the Top Dead Center (TDC) camshaft mark and TDC crankshaft mark positions. If your Rav's camshaft and crankshaft marks are not as shown in these drawings, then the timing is significantly off. Assuming you positioned the camshaft correctly at TDC, then your photo confirms this. I agree with BigPhil555 that this apparent incorrect timing must be addressed before proceeding further.

-- To reinforce BMR's steps: When I am doing a timing belt replacement, and as it sounds like BMR understands, once I think I have the crank and cam timing set correctly, I always rotate the crankshaft exactly two revolutions in the clockwise direction, then I check to see if the crank and cam timing remains spot on. Only rotate in the clockwise direction. IIRC, rotating in the anti-clockwise direction may result in a loss of tension and slipping of the timing belt.

-- Tension must be set correctly. Doing so is a little tricky on the Rav4. If tension is not set correctly, then I expect the belt will slip and the timing could land where BMR's photo shows. Demoder's video and the service manual may be the best resources for setting the timing and tension. See www.youtube.com/watch?v=TbOr7gvqSqc

-- I do not necessarily expect codes from the incorrect timing. This is partly from observing that a bad crankshaft position sensor/reluctor assembly may cause starting/running problems and does not always throw codes.

-- Your camshaft position sensor resistance reading is right in the middle of the cold reading specifications and so is great.
 

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Discussion Starter · #36 ·
I just finished up getting the TB timing adjusted. No more bucking, and it pulls hard all the way to redline. Idle is smooth with no more stumbling.
 

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Awesome!!!!!!!!!
 

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Such a 'simple' fix, for all the trouble it's been causing you! I don't recall, but did you replace your timing belt after you got it?
 

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Discussion Starter · #40 ·
I don't recall, but did you replace your timing belt after you got it?
Yup. I bought it with a broken belt, so that’s the first thing I did. So apparently, I didn’t get the idler set tight enough.
 
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