Down on power after car wash (P0172) ?

[thegipper]

So yesterday I took my truck through the car wash and when I was leaving, I noticed that it seemed sluggish. I had to stop at wal mart after the wash and when I was pulling into the parking lot, it actually died (it's never died on me before).

I coasted into a spot and popped the hood. Checked everything over (oil, coolant, tranny fluid, leaks, etc) and it all looked fine.

I decided to see if it would start back up and she fired back up like normal. After shopping it again started right back up and seemed fine in the parking lot. On my way home though it again felt "down on power". It doesn't buck or anything but as it revs out, you can feel it almost "surging".

Looked it over at home and nothing stands out. Decided to clean the MAF, replace the air filter and I cleaned the throttle body. Also checked tranny fluid condition/level, both perfect. Battery terminals are tight, it's charging like it should.

Took it for another spin and it again was feeling sluggish and down on power, especially noticeable in higher revs. I hit up some back roads and decided to floor it from a stop and see what it did. To my surprise, it revved out like normal and felt likes its normal slow self (no lack of "power" and no feeling of surging).

I figured everything was back to normal.

I took it to work today to see if it was still fixed and it again felt sluggish at first but later in my drive (only 12 miles to work) it felt normal again.

Spark plugs are only a couple years old (going to check them tonight anyway). Wires are old AF.

No CEL

I've never really had any engine issues other than the blowing the head gasket on the original engine (my 97 truck has an engine from a 99, been in there for a couple years now). The engine sounds great, idles great, no funny noises, revs up great in park but when its under a load, at higher rpm, the sluggishness happens.

Any ideas what I should be checking? Clogged cat? Water got into something it shouldn't have?

 

[plcfcng]

Thanks for all the info. I would check with a Vac gauge if it is low it could indicate one of two things a clogged cat or maybe a timing jump. To check the cat you can take it to a muffler shop they can drill a small hole and do a gas sample I think about 30 dollars or pull the front O2 sensor and drive it around the block to see if power improves. For the timing jump pull the cover and check timing marks. After that resistance check on the plug wires while your there a spark plug reading and a compression test. Other item to look at TPS .:car:

 

[thegipper]

I know you can check a clogged cat also with an IR temp gun (measure temp before and after the cat). Timing belt/WP/tensioner etc were all done with the engine swap, I'll check and see if everything still lines up.

What's the procedure for checking the TPS?

Fuel filter is original because I was never able to remove it (tried flare nut wrench but wouldn't budge, afraid it's going to strip).

Doubt it's a compression or timing issue since the problem is intermittent.

 

[gamefreakgc]

That's a head scratcher... my best guess is that water got in somewhere it wasn't supposed to. Perhaps the hood drains backed up and water spilled into the top end of the engine bay? Any obvious water stains on something sensitive? My first thought was moisture under the distributor cap but then I remembered what kind of car we are talking about lol. Plugs and wires look clean with no water intrusion? Really grasping at straws here, I'm not aware of any engine part that will act up if it gets wet, unless there's a wire shorting out.

 

[spartacus]

I know you can check a clogged cat also with an IR temp gun (measure temp before and after the cat). Timing belt/WP/tensioner etc were all done with the engine swap, I'll check and see if everything still lines up.

What's the procedure for checking the TPS?

Fuel filter is original because I was never able to remove it (tried flare nut wrench but wouldn't budge, afraid it's going to strip).

Doubt it's a compression or timing issue since the problem is intermittent.

testing the tps

 

[tgreenwood75]

My bet is on the old plug wires. Even if it doesn't feel 100% like a conventional misfire, mine did the exact same when it got wet until I replaced the wires. Every time I did an automatic wash, drove through a really deep puddle, or drove on flooded roads it would misfire until one day on a highway during a storm it got to the point of demobilizing the vehicle and causing it to die. Swapped the plug wires and was good to go.

 

[thegipper]

I'll order some wires just because mine are who knows how old and maybe it is the problem.

Also, I pulled all of the plugs and they all looked fine minus some were semi loose. Also, a couple had oil on them (looks like I need to do a VC job soon).

And finally, although I don't have a CEL, I checked for pending codes and sure enough, I have a P0172.

I think I should start there. So what causes that code?

Thanks guys.

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[RandyBobandy]

Mine had those symptoms for a long time, mostly up steep hills, and would occasionally feel like I was driving over a rumble strip when accelerating, took it maybe 3k miles to even throw a code because it was so intermittent, turned out I had a single bad coil pack, that would only cause trouble when it got warm, since it tested within spec when cold. Maybe some water got in somewhere and pushed a questionable wire or coil pack over the edge, usually a miss caused by a small amount of water will go away as the water evaporates.

My extremely unprofessional opinion is drive it until it throws a code or displays another symptom and go from there

Edit: I just noticed you had a code, I’d check your maf sensor, and maybe replace your o2 sensors, I think Toyota recommends replacing those every 60k anyway but someone correct me if I’m wrong

 

[thegipper]

I have an ultra gauge and other scan tools, let me know what I should display if that helps with trouble shooting the code.

I have this setup on my ultra gauge so far. At first, short term fuel trim was at - 20 at idle, after awhile, it settled around 0 (+/-). Not sure what that means.

O2 sensors are who knows how old.

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[thegipper]

Oh and I have a spare of basically every part on the truck (I have a parts truck) so I can replace any suspect items with the spares I have.

I'm starting to think it had nothing to do with the car wash (just a coincidence).

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[LittleCaesar]

Based upon those fuel trim numbers, you are having excess fuel dumping into a cylinder, probably from a failing injector, though if the O2 sensors are original, they need to be changed. If it starts acting up again, pull the plugs and see if any smell like gas.

Any weird smells from the exhaust.?

I would guess that the wash is just pure chance, though check the driver’s side electrical connections, including battery, are dry. No washing of the engine bay I take it.

 

[MaineRunna]

I have an ultra gauge and other scan tools, let me know what I should display if that helps with trouble shooting the code.

I have this setup on my ultra gauge so far. At first, short term fuel trim was at - 20 at idle, after awhile, it settled around 0 (+/-). Not sure what that means.

O2 sensors are who knows how old.

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P0172 means system rich. Those fuel trim numbers mean the ECM is trying to take away fuel. (lean out the fuel trim/mixture) I'd say something happened to your MAF during the car wash or maybe it's a coincidence and it needs an O2 sensor, or it has a leaking/dribbling fuel injector. You also may be dumping raw fuel out the exhaust due to a bad ignition wire, coil or coil boot that got wet during the wash. The coil boots are replaceable, Just replaced a set of original ones this morning on a 20 y/o runner due to a misfire at start up that sometimes caused a backfire and a total lack of driveability.

 

[thegipper]

I inspected the wires/coils/ connectors all "looked" OK.

I'm leaning towards bad MAF or O2 sensors at this point. I'm going to swap the MAF tomorrow after work with the spare I have.

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[19963.4lsr5]

I inspected the wires/coils/ connectors all "looked" OK.

I'm leaning towards bad MAF or O2 sensors at this point. I'm going to swap the MAF tomorrow after work with the spare I have.

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It’s a good place to start. The LTFT is the number to watch not the STFT. And -10 on our rigs is abnormal.


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[thegipper]

Based upon those fuel trim numbers, you are having excess fuel dumping into a cylinder, probably from a failing injector, though if the O2 sensors are original, they need to be changed. If it starts acting up again, pull the plugs and see if any smell like gas.

Any weird smells from the exhaust.?

I would guess that the wash is just pure chance, though check the driver’s side electrical connections, including battery, are dry. No washing of the engine bay I take it.

I did notice that the exhaust smells gassy which only further confirms it's running super rich.

Does the P0172 code distinguish what bank (1,3,5 vs 2,4,6)? I thought I read it means that bank 1 (1,3,5) is running rich.

I ordered both the upstream and downstream o2 sensors today (Denso), even if they aren't the problem, they're possibly 23 years old.

 

[19963.4lsr5]

I did notice that the exhaust smells gassy which only further confirms it's running super rich.

Does the P0172 code distinguish what bank (1,3,5 vs 2,4,6)? I thought I read it means that bank 1 (1,3,5) is running rich.

I ordered both the upstream and downstream o2 sensors today (Denso), even if they aren't the problem, they're possibly 23 years old.

Bank 1 means all 6 cylinders collectively. If there was a O2 sensor fir each cylinder bank before going into the Cat then we would have a bank 1 and bank 2.

So, whatever is happening is that it thinks it needs to reduce the fuel mapping by 10 percent (-10 LTFT).

What speed were you driving at or was it at idle? At idle it will pull fumes off the EVAP and you will see a negative number.


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[ambush]

Hi

I can try to add as well. My 99 has a GASSY + exhausty smell and the power is not consistent. I have new wires + plugs as well. No CELs.
Further investigation, I can see the manifold/header gaskets need to be replaced as well as fuel injector o-rings (thanks to the gas smell in the cabin).
I have yet to tackle it as I just bought 2 more 3rd gens and they have my attention. (pictures coming soon!!!)

I hope that kinda helps on other places to check.

 

[thegipper]

Bank 1 means all 6 cylinders collectively. If there was a O2 sensor fir each cylinder bank before going into the Cat then we would have a bank 1 and bank 2.

So, whatever is happening is that it thinks it needs to reduce the fuel mapping by 10 percent (-10 LTFT).

What speed were you driving at or was it at idle? At idle it will pull fumes off the EVAP and you will see a negative number.


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Those numbers were at idle after the initial startup but after a minute or two, the STFT settled around zero (+/- 3%).

It definitely runs the worst at startup for the first 5 minutes or so, after it is warmed up, it runs completely normal.

If I shut it off and let it sit for 30 minutes or so, the roughness returns.

 

[19963.4lsr5]

Those numbers were at idle after the initial startup but after a minute or two, the STFT settled around zero (+/- 3%).

It definitely runs the worst at startup for the first 5 minutes or so, after it is warmed up, it runs completely normal.

If I shut it off and let it sit for 30 minutes or so, the roughness returns.

What is the LTFT driving down the road?


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[thegipper]

What is the LTFT driving down the road?


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I'll have to check that and report back.