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Don't spend more time on the EGR system, Jeff.

One fairly definitive way to check the EGR Valve is to apply vacuum to the side port while idling. The engine should then die.



By applying vacuum, the valve opens to allow exhaust back into intake through the EGR pipe.

Well, you don't have a vacuum pump. Instead, you can push on the diaphragm manually, as in:


So, while idling, if you push on the diaphragm manually, which opens the valve, the engine should also die.

Thus, if you pull the side tubing (red x), or even cover the side port, there should be nothing that can affect the diaphragm to open the valve, and the EGR system shouldn't be activated at all.

305360


If you are still not convinced, you can cover up (e.g., with a piece of folded aluminum foil) the opening that goes from the EGR Valve to intake (blue line). Then even when you push on the diaphragm, the engine should still be running.

 

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'00 4 Cyl. Auto Camry LE
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Aloha and Good Morning, CFL...

Thanks for the thoughts. I suppose what confounds me the most is how well the engine will rev when in park in the driveway, yet stutter under load in gear. Some of the issues seem to me that they would be present in park as well, i.e. fuel quality issues, bad injector, plugs/wires. I would expect them to manifest their faults when reving in the driveway also. The timing issue does intrigue me. I've read somewhere that this engine has a "static" belt tensioner and that over time the belt may stretch and then timing is off. I've done 3 different timing belt/chain projects in the past and in each of them if the timing was off by even 1 tooth, it was apparent from the outset in trying to start the car, so the belt thing seems less likely a culprit. I also read something about valves getting out of clearance and needing to be reshimmed; this is where the water goes from under my chin to over my nose, lol. Not the clearance/shimming, I got that no problem, but more how the valves being out of clearance might manifest under load but not in driveway. With the fact that when my engine is cold the low idle is smooth but warm engine low idle is rough, I'm still thinking I'm missing something in the vacuum/EGR concept. Our O'Reilly's here doesn't have a rental vacuum test kit/gauge and my neighbor who does have one is gone atm, so I haven't done vacuum tests yet like I'd like to.

I found this link and will be attempting more tests. Sure wish the car would throw me a CEL code.


Mahalo and Aloha,
Jeff
Good morning Jeff,

Best answer I can give, re: why it free-rev's in Park, without any load, vs. stumbles in Drive, is weak spark, or lean Air/Fuel mix causing the issue.

Yes, as part of verifying static Timing, the physical condition of the Timing Belt s/b examined also, for (1) complete revolution of motor. Looking for any belt degrading / damaged or missing teeth on the Belt.

re: EGR - If you think it should be Q/A'd fully before proceeding further, then do it. Andy's got you covered w/ that, learning as well here.

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^^ Weak spark will cause stumble under load, which is why I recommended completing the tune-up (wires, plugs), as you noted improvement after coil replacement. I can't tell you if a wire or plug was affected from any coil issue. A bad plug is uncommon, but not rare. A wire affected by weak or failing coil is not rare, either.

^^ Your Fuel Pressure test reading of 36 PSI, with engine running, is "borderline" too low. That's my opinion, based on experience here. With multiple vehicles.
Anything 35 PSI or under, expect driveability issues where normal PSI range is 40 / 42 / or above Whether it's the FPR, Pump, or piping issue somewhere in-between ... dunno. What I can tell you is a 25 y/o Fuel Pump "doesn't owe anyone anything". It's provided good service: and may want to retire. From above: a weak Fuel Pump will cause a lean Air/Fuel mix when the vehicle is operating under load.

You stated the issue is worse at operating temp / closed-loop mode. -If- the issue -only presents- @ operating temp., then suspect a sensor issue. O2 Sensor, and TPS would be suspect, as you have already replaced the ECT sensor. But as a Sanity Check, review all sensors, wiring, and connectors, just to be sure.

If -not- Ignition, and not Fuel, and not exhaust system blockage ... after all is said and done, then I would suspect ECM. ISB mentioned that above.

Good luck w/ the repair, hope the feedback is helpful to you.
 

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Discussion Starter #43
Aloha and Thank You,

That is some outstanding words of wisdom. At this point repairs are on hold due to Hurricane Douglas approaching the islands. I'll return to wrenching after it passes. Thank you again for things to consider and fix.

Mahalo and Aloha,
Jegg
 

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Discussion Starter #44
Aloha and Good Morning Everybody,

Back to wrenching .... First question of the day is exactly how many O2 sensors? Two or more? I have what appear to be 2 sensors on the exhaust manifold in the engine compartment. One is higher on the manifold and it is a single wire with 2 12mm nuts/bolts. The lower one is a 2 wire, single 22mm(?) screw in mounting. I assume there is also one under the car on the exhaust.

My fuel pressure "analysis" was based on ... Fuel Pressure and Volume Testing - Toyota Engine Control Systems

So ... new wires and plugs will be done ... will attempt the O2s ... and then if that don't work, the FP after that.

Mahalo and Aloha,
Jeff
 

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'00 4 Cyl. Auto Camry LE
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Good Afternoon,

Ok, Cool. Should be straightforward then. Top O2 sensor, (closest to motor), is the Primary, or B1S1 sensor. B1S1 is the sensor directly responsible for fuel trim / adjustment @ the ECM.

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I am going to recommend that you go "out of order" on the Diagnostics at this point - the fact that you have not seen a single MIL / CEL light to-date, is "too odd" for coincidence.

With engine cold / sitting overnight, recommend unplugging the ECT sensor, starting the vehicle and bringing up to operating temp., the disconnected sensor "should" throw a code 22 on the CEL. If you don't see a flashing CEL after bringing the vehicle up to operating temp. w/ the ECT disconnected, then something's up with either the CEL indicator lamp, or ECM.

In short, confirm ECM ( Malfunction Code ) reporting functionality, before investing more time & $$$ ... in various parts.

* Tune up parts excepted: I would still (order, if needed and) replace wires / plugs, complete the Ignition tune-up / Q/A and confirm, or eliminate, Ignition as source of issue, if here.
 

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Discussion Starter #48
Ok, can and will do. So the single wire sensor, yes? The CEL light does function, early on in this adventure I had unplugged some sensors when engine running, I think MAP and TPS can't remember exactly, and then the CEL flashed some codes, but I will go ahead and do as you have suggested with the ECT. Question ... What should I expect a "normal" engine to do if the O2's are disconnected?

Update ... ooops forgot to send this message before I went to do the procedure, lol. But boy she didn't like that at all. Unplugged ECT and it started poorly and idled roughly from the get go and CEL lit up. Turned off, plugged ECT back in and started, no CEL and idled fine. Turned off, didn't get up to temp.


Mahalo and Aloha,
Jeff
 

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'00 4 Cyl. Auto Camry LE
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Hi Jeff,

I would expect it to do exactly as what happened. But not as fast. :)

Good that the ECM is "yelling at you, when required" - I would proceed forward, as you see fit, would concentrate only on the B1S1 O2 sensor first: the secondary (B1S2) sensor is for Cat. Converter health reporting only: not used for Fuel Trim / engine adjustment by the ECM, this is FYI.
 

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Discussion Starter #50
Hi Jeff,

I would expect it to do exactly as what happened. But not as fast. :)

Good that the ECM is "yelling at you, when required" - I would proceed forward, as you see fit, would concentrate only on the B1S1 O2 sensor first: the secondary (B1S2) sensor is for Cat. Converter health reporting only: not used for Fuel Trim / engine adjustment by the ECM, this is FYI.
Ok, I will proceed with upstream O2. Good about downstream not being an issue, having problems with using a 7/8" crowfoot ... seems to want to round the edges, stopped before significant damage.
 

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Discussion Starter #51
Aloha and Good Day Gentlemen .... and mostly ... Good Bye !!! .... This thread is DONE !!!!! 😍

Changed the plugs, wires and upstream O2 sensor and the girl is back and running like before. I can't thank you all enough for your time, consideration, patience, thoughts, advice and tips. CFL ... thanks for staying with me the whole time. Andy, thank you as well for your input. Insightbrewery ..... if I'd done the O2 like you said 2 weeks ago ... well I would've saved some money, LOL. Next guy you try to help, maybe yell at him louder so he'll listen better than I did. I may have to go to all the "lack of power under acceleration" threads and pay your advice forward. O2, O2, O2 !!!

Anyway, thanks again to all of you, great gang you got here. Anybody good on Jeep Grand Cherokee Dana Axle 30 Front Differential repair? ... LOL 🙃

Mahalo and Aloha, everyone take care,
Jeff
 
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