2009 Kia Sedona 3.8 - No Throttle Response (Brief, Intermittent), No CEL, No Codes

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Jul 7, 2014
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Winnipeg MB CA
This is Jr's van. We've swapped vans for their holiday, as our Grand Caravan is in better shape and has working A/C, and I've been doing a bit of work on theirs.

So far, I've changed out the front rotors (which got rid of the pulsation in the brake pedal), and replaced all four stabilizer-bar end links (also successful, the ride is much quieter now).

Unfortunately, a new problem has cropped up - I was driving the van this afternoon, and at one point it lost power. I wondered if my foot had slipped off the accelerator pedal, and thought no more about it. It was good the rest of the way home.

This evening, it happened again, several times. The engine would simply quit responding to throttle inputs for several seconds. At one point I pulled onto the shoulder and put the 4-ways on, waited for traffic to clear, and then pulled out again. Things were normal again, but only for a few minutes. This is a really dangerous problem - imagine trying to make a LH turn through a gap in opposing traffic, and having the throttle cut out as you start the turn.

This has not triggered the CEL or set a code yet.

I've checked a Hyundai-Kia forum, and watched a few YouTube videos - I think without exception, the symptoms are similar, but there is a CEL and associated code.

We bought the van in 2016. A couple of months later, on a long road trip, it went into limp mode. I found that disconnecting the battery would restore proper operation. Unfortunately, I can't remember if it set a code at that time. The problem got increasingly more frequent over the next week or so.

Research at the time indicated a bad TPS, which Kia recalled in the U.S. but not Canada. :mad:

I was unable to buy a TPS separately (had not discovered Rock Auto yet), but did buy a rebuilt throttle body (with TPS included).

So now nine years later I think it's the same root cause - a bad TPS.

I see that R.A. does sell the TPS separately, and am tempted to try that first. (The throttle body is considerably more expensive.)

Any thoughts on this from anyone? Thanks.
 
Sounds like it might need a throttle body cleaning, if you do it pull whats needed to access the opening and turn the ignition on, but don't start it. Put a stick on the throttle in the cab and jamb it into the front of the seat. It should be at 80% to 100% open and DO NOT force the blade open and closed with your hand with power off or on. It is very easy to smoke the positioning system in the throttle body. I use throttle body cleaner and a thin "Menard's" auto microfiber fresh towel soaked in TB fluid( available by the plastic gas tanks and auto shop rags in most Menard's) . After spraying it out at first. I stick my fingers into the TB with the rag and don't forget to clean the backside of the throttle blade and the edges. Don't for get to spray in the 2 to 3mm hole that is by the closed blade area. That would be my start.

Next, would be to clean one of the two fuel metering systems your car would have, (It's up to you to find what your car has ) both with the mass airflow spray so it is comparable with these sensitive sensors. Not carb cleaner. MAF (mass air flow sensor, and MAP (manifold absolute pressure sensor).

https://www.amazon.com/CRC-Sensor-Cleaner-Throttle-Air-Intake/dp/B0CYZFHFRM/ref=sr_1_1?crid=2CZLJ0ERLKNDD&dib=eyJ2IjoiMSJ9.4XO5PSluHUsOvymd5eR1-ph59yh-3WniaOQZDRjjTVbJ2vPP0i2fe4p5hxzH6cIw1GgQFRDc9Y6yWc21cA2UymuzrkwQ5l08LMk1U6_rfaTZsEMJwRf7FKVqknznDoSH0ChRiu9aY5E5Gfxh-Eg1vguLbt41aLBP6hHwy3u4GegZtBrqPvQdYepfjt2IekOMKQ8y3rFLjyTTzjUYgQ9iqzkiaOQTiBRKw-CD3ylYHpo.ivevq0r4c4htKYU6XwxGfVnHyLiYMArlMWq6x23hyG0&dib_tag=se&keywords=CRC+05111+MAF+Mass+Air+Flow+Sensor+&+Throttle+Body+Intake+Cleaner+Twin+Pack+Kit&qid=1755917573&sprefix=crc+05111+maf+mass+air+flow+sensor+&+throttle+body+intake+cleaner+twin+pack+kit,aps,995&sr=8-1

.
 
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Weird that it hasn't set a code if it's happened a few times. (at least pending)
I would believe that your thinking is probably correct on this. It probably is related to the TPS.
With that said, the accelerator pedal could cause the same symptoms if it's acting a little wonky. (After all, it is a pedal position sensor.)
I don't think it's a common issue like the TPS, but all things must be considered.
 
Is it a cable linkage or a drive by wire throttle?
Drive-by-wire, so unfortunately, while working under the hood I can't blip the throttle.

I also realized I can't easily check the TPS (to see if it drops down to idle position) with my Scan gauge - it's in my van, which is way across the country right now.
 
What are you using to scan for codes? OBDFusion is a great app. I lets you log data that can be analyzed in excel. I'm suspecting the fuel pump and/or filter are the cause.
 
If you have an analog DVOM you should be able to watch the TPS signal steadily increase as somebody pushes down on the pedal. Any jumps or strange movements would indicate a potential issue with the sensor. Of course this is a lot easier with a cable-operated throttle, the pedal position sensor complicates things, as @HemiBenny notes, as it can cause the same issue.
 
On my 03 Saturn with GM v6 (Bosch drive by wire throttle body) the position sensor slowly started wearing out producing a lot of random behavior - although it did set some codes occasionally. They don't sell the sensor separately but I was able to find a closeout complete assembly for 90 bucks on Rockauto and everything ran well after changeout.
 
I've ordered a TPS locally - it will be available Monday. The TPS is cheap (C$30), and there's enough of a spread between it and the TB to justify gambling on just replacing it (the TPS).

I'll try to dig up my ancient (2005) ScanGauge (the one that looks like a Heathkit) and look for erratic readings from the TPS.
 
If you have an analog DVOM you should be able to watch the TPS signal steadily increase as somebody pushes down on the pedal. Any jumps or strange movements would indicate a potential issue with the sensor. Of course this is a lot easier with a cable-operated throttle, the pedal position sensor complicates things, as @HemiBenny notes, as it can cause the same issue.
My ancient ScanGauge won't connect (communication-wise).

I may break out the ancient Radio Shack (Micronta?) analog multimeter and test the TPS's resistance, if I can enlist a helper. The problem is intermittent, so unless the test shows gaps or jumps it won't be conclusive. That is, a good linear resistance slope doesn't mean the TPS will provide same the next time I drive.
 
What are you using to scan for codes? OBDFusion is a great app. I lets you log data that can be analyzed in excel. I'm suspecting the fuel pump and/or filter are the cause.
I'm using a cheap little Chinese scanner friends bought me. It's good within its limited capability.
 
Sounds like it might need a throttle body cleaning, if you do it pull whats needed to access the opening and turn the ignition on, but don't start it. Put a stick on the throttle in the cab and jamb it into the front of the seat. It should be at 80% to 100% open and DO NOT force the blade open and closed with your hand with power off or on. It is very easy to smoke the positioning system in the throttle body. I use throttle body cleaner and a thin "Menard's" auto microfiber fresh towel soaked in TB fluid( available by the plastic gas tanks and auto shop rags in most Menard's) . After spraying it out at first. I stick my fingers into the TB with the rag and don't forget to clean the backside of the throttle blade and the edges. Don't for get to spray in the 2 to 3mm hole that is by the closed blade area. That would be my start.

Next, would be to clean one of the two fuel metering systems your car would have, (It's up to you to find what your car has ) both with the mass airflow spray so it is comparable with these sensitive sensors. Not carb cleaner. MAF (mass air flow sensor, and MAP (manifold absolute pressure sensor).

https://www.amazon.com/CRC-Sensor-Cleaner-Throttle-Air-Intake/dp/B0CYZFHFRM/ref=sr_1_1?crid=2CZLJ0ERLKNDD&dib=eyJ2IjoiMSJ9.4XO5PSluHUsOvymd5eR1-ph59yh-3WniaOQZDRjjTVbJ2vPP0i2fe4p5hxzH6cIw1GgQFRDc9Y6yWc21cA2UymuzrkwQ5l08LMk1U6_rfaTZsEMJwRf7FKVqknznDoSH0ChRiu9aY5E5Gfxh-Eg1vguLbt41aLBP6hHwy3u4GegZtBrqPvQdYepfjt2IekOMKQ8y3rFLjyTTzjUYgQ9iqzkiaOQTiBRKw-CD3ylYHpo.ivevq0r4c4htKYU6XwxGfVnHyLiYMArlMWq6x23hyG0&dib_tag=se&keywords=CRC+05111+MAF+Mass+Air+Flow+Sensor+&+Throttle+Body+Intake+Cleaner+Twin+Pack+Kit&qid=1755917573&sprefix=crc+05111+maf+mass+air+flow+sensor+&+throttle+body+intake+cleaner+twin+pack+kit,aps,995&sr=8-1

.
Thanks, I opened the throttle plate partway as you suggested (ignition in the ON position but with the engine off, and accelerator pedal depressed with a wood brace against the driver's seat), and sprayed in a generous amount of throttle-body cleaner.

Let it sit for a few minutes, and then started the engine. The engine took a few seconds to start, and chugged a bit before picking up and running fine.

Did it help? If the problem doesn't return, yes. (Intermittent problems are so annoying!)

It was probably due anyway!
 
What are you using to scan for codes? OBDFusion is a great app. I lets you log data that can be analyzed in excel. I'm suspecting the fuel pump and/or filter are the cause.
Here's a photo of the code reader's box.
20250824_083204.webp

It does read fuel trims, which is helpful.
 
Well, the inexpensive shot fired from the parts cannon appears to have hit the bull's eye - I installed the new TPS, and the van behaved well on a test drive.

The scariest part was removing the three M4 bolts (T20 heads) that secure the TPS to the throttle body. They did come out OK. I cleaned them up with a wire brush on the bench grinder, and reinstalled them with some anti-seize.
 
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Well, the inexpensive shot fired from the parts cannon appears to have hit the bull's eye - I installed the new TPS, and the van behaved well on a test drive.

The scariest part was removing the three M5 bolts (T20 heads) that secure the TPS to the throttle body. They did come out OK. I cleaned them up with a wire brush on the bench grinder, and reinstalled them with some anti-seize.
Glad it worked out, had something similar but a little different years ago with our Isuzu Ascender. It just randomly died and then would comeback to life. Very similar situations as you'd be driving or turning and nothing, then be back on a few seconds later, very scary. Ours was a broken negative terminal inside the battery. Glad yours was just a tps.
 
Well, the inexpensive shot fired from the parts cannon appears to have hit the bull's eye - I installed the new TPS, and the van behaved well on a test drive.

The scariest part was removing the three M4 bolts (T20 heads) that secure the TPS to the throttle body. They did come out OK. I cleaned them up with a wire brush on the bench grinder, and reinstalled them with some anti-seize.
M4 is dumb, that's equivalent to a #8 machine screw (5/32")
 
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