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'00 4 Cyl. Auto Camry LE
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935 Posts
thank you for your response.
yes it uses an electric tb. Before getting the volt meter out, etc I happen to have an extra working oem throttle body I have not used before. if it's indeed a TPS issue, replacing the throttle body with a known good throttle body should fix the issue, right?
-If- the issue is with the TPS (or other electronics) in the Throttle Body - then Yes, replacing w/ the extra working oem throttle body should fix the issue.

As a "parts swap" test: it won't cost you anything, and will either confirm / or deny the (electronic throttle body) is the issue. Recommend making sure you have any TB -> to manifold / plenum gaskets needed, prior to doing the TB swap.
 

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2009 Camry SE I4
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35 Posts
I had a problem with the engine jerking, it was the engine mounts.
I doubt it would affect rpm if it was mounts, but do you recall if your RPM would go up and down rapidly while the jerking happened? almost as if you were rapidly revving the throttle in & out?
 

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2009 Camry SE I4
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35 Posts
-If- the issue is with the TPS (or other electronics) in the Throttle Body - then Yes, replacing w/ the extra working oem throttle body should fix the issue.

As a "parts swap" test: it won't cost you anything, and will either confirm / or deny the (electronic throttle body) is the issue. Recommend making sure you have any TB -> to manifold / plenum gaskets needed, prior to doing the TB swap.
Okay, CamryFL - I will swap the TB sometime later today. The current throttle body is a cheap aftermarket I bought 2-3 years ago off Amazon for $50 to apply and test a "grooved" throttle-body modification (https://gadgetmangroove.com/). Now I wish I had just bought a used Toyota OEM TB off ebay.

Shouldn't be a problem installing. I have an extra gasket somewhere, but the current TB gasket should fine to reuse w/ a little silicone grease. The only PIA I find with the replacing throttle-body is trying to minimize the amount of coolant that leaks out when disconnecting the two coolant-lines from the TB.

Regardless, after I swap swap the TB, I'll do an ecu-reset, test-drive and report back here with the results.

By the way - do you happen to know how long an average toyota TPS/TB lasts? And - do you know if it's typical for a TPS to go bad and Not trigger a CEL code?

Thanks again.
 

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2009 Camry SE I4
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35 Posts
I really hope not. No other apparent issues. AT fluid is clean. All the shifts are smooth. all other driving operation seems fine, but who knows. If changing the TPS does nothing, I may have to start looking in that direction...
 

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'00 4 Cyl. Auto Camry LE
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935 Posts
By the way - do you happen to know how long an average toyota TPS/TB lasts? And - do you know if it's typical for a TPS to go bad and Not trigger a CEL code?
It's quite possible Artbuc1. There may be a mechanical issue. Q/A'ing the TB / Accelerator pedal to (eliminate) those as possible causes, would then point in that direction.
Doing the TB / Accelerator Pedal Q/A first was the path I followed here when diagnosing a TB issue, in any case.

WesK711: I do not have direct experience w/ your particular vehicle. With that said, I would expect the "average" electronic factory OEM TB assembly to last as long as any other, namely 10-15 years / the average life expectancy of the vehicle. No, it is not "typical" for a bad electronic TB assembly not to trigger a CEL code.

With that said: the electronic Throttle Body assembly is a complex component, having the duty of metering air intake to the engine, via multiple sensor inputs, relying on an electronic actuator (motor) to adjust air intake, as commanded from both the driver (accelerator pedal) and engine computer (PCM) to maximize fuel economy.

It has been my own experience on Ford vehicles (2005-2010) that the PCM is 'biased' when detecting -> generating TPS / Throttle Body assembly DTC codes: it requires a (2 trip) issue detection before generating -> and storing a DTC code. I have no idea what the Toyota DTC trip detection logic or strategy is in regards to this, but if similar: it may explain it, see below.

Both the TPS sensor and, the Accelerator Pedal sensor(s) both fall under the "category" of an electronic "switch" / a potentiometer. Switches, Relays, Motors, electronic components in general have a rated duty-cycle ("life-cycle"), and eventually fail. If either the TPS sensor, or the Accelerator Pedal sensor(s) are "intermittent" / on their way out - then Yes, you will not "see" a DTC code from the failing sensor ("switch"), as the PCM will be constantly input with valid / erroneous data from the sensor: and attempt to compensate -> "self correct" the issue.

In short, a "flaky" / failing TPS sensor, or Accelerator Pedal sensor may / or may -not- generate a DTC code, in my experience.

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Also, ensuring good Primary electrical power to all vehicle systems is a valuable "up-front" Primary Diagnostic.

All DTC testing, (and values expected) are predicated on primary electrical components (Battery, Terminals, Cables, Ground points, Charging system) being in good condition - something that many service manuals don't explicitly state, up-front. Taking a few minutes to visually inspect / clean / test voltage as needed to make sure everything is in good order, can only help w/ your diagnostic testing.

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You mention the TB was "modded", which may explain the (+3) LTFT value you state - if- the PCM is commanding extra fuel due to increased air, via the mod. IF YOU MODIFIED any other system ( PCV, EGR, etc.) I would recommend RESETTING those mods. also: for the purpose of Diagnostics / testing.

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Again, above is based on my own experience here. I am not trying to 'remote diagnose' your issue: only relay information that you may find useful to apply to your particular situation. ... Hope the info. helps.
 

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2009 Camry SE I4
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35 Posts
Swapping the TB seemed to improve the issue [make it better]. The jerking doesn't seem as prominent, although it's still present, but only when I really try to replicate it (giving a lot of unnecessary throttle at once). Still getting a +3 LTFT ; wondering if there's possibly a small vac leak in the intake manifold.

No problem I appreciate any/all input you have.
 

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'00 4 Cyl. Auto Camry LE
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935 Posts
A positive LTFT / and vehicle 'bucking' under full load, without throwing -any- DTC codes ...

-If- you are confident Fuel Delivery is as expected ( Fuel Pressure, and Volume ) -

Would have me suspect of an (exhaust system restriction) / a partially collapsed -> failing Cat. Converter, if here.
 

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'93 LE Wagon V6 '94 LE I4
'93 V6 wagon, '94 I4
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900 Posts
WOT would mitigate a vac leak. If you have a Bernzomatic torch, you can unscrew the flame head and slip a piece of hose over the pipe. With the torch about half and the car running, put the end of the hose anywhere you suspect a vacuum leak. If there is a leak, the engine speed will increase when it sucks in the propane instead of just air. I've done this in the past and it works. Your call.
 

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2009 Camry SE I4
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35 Posts
Can the same thing be done with carb/choke cleaner?

Also, based on the fact that this doesn't happen during wot, would this rule out a clogged cat?
 

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'93 LE Wagon V6 '94 LE I4
'93 V6 wagon, '94 I4
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900 Posts
Can the same thing be done with carb/choke cleaner?

Also, based on the fact that this doesn't happen during wot, would this rule out a clogged cat?
Yes, on the carb cleaner. My experience is mostly pre-cat, but I would think a clogged cat would make things worse, not better, at WOT.
 

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2009 Camry SE I4
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35 Posts
Thanks, going to take out the whole intake manifold anyway to inspect for cracks etc. Have a fresh gasket ive been meaning to put on anyway
 

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2009 Camry SE I4
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Okay, so I was not able to remove the intake-manifold - as in take it completely out to inspect - as originally planned. It would not fit by pulling up and out since it's situated behind the engine block if you're facing the hood, I wouldn't have to take apart a whole lot of the car that time wouldn't permit me, just to get it out. However, I did manage to clean out lots of gunk at the tips of the headers, entrances to the combustion chambers as well as replace the intake-manifold gasket.

This seems to have stabilized the fuel trim. While driving if I let my foot off the gas (idle) the LTFT/STFT both revert to 0.0 whereas before LTFT would remain +3ish indicating a slight lean condition. Perhaps there was a slight vacuum leak I wasn't able to detect with the carb spray...

The original issue of bucking under sudden high-throttle is whole-hardheartedly less apparent after the gasket replacement. Once again, this does not happen if I floor it (WOT from stop or in motion). If I floor it, it takes off smoothly without bucking, runs through each gear up to 6000rpm until reaching OD. However, if I'm stopped or already moving and go from 0% throttle and then suddenly to anywhere between 20% - 90% throttle it will start to buck as soon as it hits ~4000 rpm (albeit, the bucking is much less now - perhaps due to the new intake gasket).

It also doesn't matter if I keep the gearbox set in 1, 2, 3, 4 or D as I've tested. The effect seems to be solely based on demanding too much throttle too fast.

Once again, there have been no CELs. After this last replacement of the intake-manifold gasket, I did give it a full ECU-reset (positive and negative disconnected w/ alligator clips connecting negative & positive terminals, key in RUN, for a good hour, etc) so anything happening right now in the next 50 miles, good or bad, could just be a part of the relearning procedure.

I don't really have a need to demand that much load from the engine at once; it accelerates optimally by just being a little smoother/patient with the throttle, but I am just trying to figure out if this is a sign of something starting to go bad and can/should be corrected (now) before it gets worse...?

Thank you all for your help and input by the way. I sincerely appreciate it. I will continue reporting back here with whatever I try/test and whether or not I resolve the issue.

-Wes
 

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'00 4 Cyl. Auto Camry LE
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935 Posts
Was glad to read cleaning the Intake Manifold afforded improvement. If your model / gen Camry has "additional" (variable) Intake runner features within the manifold - that is also something I would investigate -> consider cleaning, if present on your vehicle.

Although an exhaust system restriction will exhibit the behavior I described previously: checking for this is usually the 'last in the line' diagnostic: much like considering a failing ECM is the 'last in line' diagnostic for DTC issue investigation in the diagnostic tree.

Given what you found inside the Intake manifold, I would again consider checking the PCV and EGR systems, replacing the PCV Valve if due, and consider doing a check / diagnostic on the O2 or Wide-Band A/F sensor, as it is most directly responsible for Fuel Trim when running at operating temp. / in closed-loop mode.

Depending on age / condition of the O2 or Wide-Band A/F sensor, it is entirely possible it is "lazy", or contaminated internally w/ whatever was collecting inside the Intake manifold, affecting operation. Best to do a proper diagnostic w/ an OBDII scanner, observing sensor readings, etc. before making the call on replacement. Hope this feedback helps.
 

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2009 Camry SE I4
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35 Posts
The wide-band sensor has at least 50,000 miles on it; I'm just going to replace it since they're quite cheap right now and ruling that out would at least allow some progress. Thanks.
 
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