Bad idle/accel after spark plug change

Oh yeah, if you have a code for the throttle sensor it's most likely your problem.

 

Finally limped to a mechanic for some diagnostic help. They say throttle body needs replaced, butterfly isn’t responding properly and components are not available separately (from Toyota at least. $880. I see the part for under $500 and could attempt myself, but I’m worried about digging myself deeper. Still weird that it would crap out exactly when I changed the plugs. Oh well. Gonna sleep on it...

 

Or maybe it's just not responding correctly because the TPS isn't reporting back results that are in-spec with OEM intention?

 

I would test the throttle body myself rather then shell out $500 to confirm whether or not its the throttle body.

 

Jack, what’s the process for testing it? I agree, I’d love to do as much recon as possible before replacing. Thank you.

 

Are you sure you didn't get any anti-seize on the plug electrode?

 

If it is the throttle body, I'd personally look for a low mileage used one.

 

I agree with @rock climber
Throttle Body is really an easy item to swap out on the truck. Minimal tools needed. Shop around and see what you can find on line. JapaneseTruckDismantling.com has all sorts of Tundra parts. They have a couple throttle bodies listed right now. 125.00 ea.

take a look.

 

https://www.japanesetruckdismantling.net/

 

Yea I like that idea. I was researching some used parts as well last night. If it fixes the issues, hooray... if not, it was a less pricey gamble.

Have you used that site before? Better than something like eBay?

Thanks.

 

I’ve personally had good luck with Toyotapartsdeal.com and oempartsonline(which used to be oemgenuineparts.com)

I bought my complete suspension rebuild, knock sensor wire, plastic pieces(clips, water bottles, and interior pieces), bearings, from them after wasting money on fake Amazon bs. Prices are lower then stealership and is close to the price of parts stores knock off stuff.

 

Well, got a used throttle body from another 2000 and put it in the truck this week. The original issues went away immediately. No limp mode, good throttle response, no check engine lights. Coolant all over my driveway, but that’s just because I am idiot who can’t clamp a hose properly.

So it may have been one of the throttle sensors all along, and the connection to my spark plug change was just a coincidence.

I need to drive for a few days before I feel fully confident, but it seems we’re past the big problems. Thanks for all the help and ideas.

 

That’s why you gots to use OEM. Good fix!

 

Pretty sure it was the TPS. But may've been something else. Either way ... good job, and thanks for posting updates. It goes a long way to helping others in the future.

 

Cue the sad trumpets... the saga continues.

Tundra threw the P1120 code again and I’m back in limp mode. I suppose the good news is that I can probably rule out the entire throttle body and all sensors on it, since I just replaced it and I’m getting the same problem as before.

My latest theory is that it is an electrical connection, bad crimp, or busted brittle wire. Remember this all started when I changed the spark plugs, and perhaps some of the old wiring was damaged when I removed the ignition coil connection and shuffled the grouped harnesses around. The fact that the truck worked well at first with the new throttle body and suddenly went crazy again seems to line up with some bad electrical. Maybe?

I found another thread on here about this, and I might be able to test the wiring with a multimeter and find the point of failure. Never done this before, but maybe I can pull it off.

All good learning experiences for the future, but man I wish I could just figure this out.

 

That should not make or cause the issue he is having.
BTW Iridiums are the best damn plug by a mile over anything else.

 

I gapped the plugs to spec (.031”). The spent plugs I pulled out were over .050” - probably due to heavy wear combined with too large of a gap to begin with. I’ve considered gapping my new ones bigger just to see what happens. I’m sort of chasing anything at this point. But then I remember that the truck did drive and fire well for a bit, with these plugs and this TB, before throwing the code again.

 

As long as you don't buy on eBay or Amazon and land counterfeits. There's so many threads on this forum alone showing those two are a treasure trove of counterfeit car and bike parts. Gotta buy from a reputable seller with better control over the products sold on their site. Amazon and eBay could give 2 shits less about who is selling what. They make zero efforts to combat counterfeits, and they mix stock at the warehouses, so you can't even control what you get buying from a reputable seller on either site because - at least with Amazon - all fulfilled items from their warehouses get pulled from group bins, suppliers don't have dedicated bin space, so I've been told by folks working in fulfillment.

 

When I changed plugs in my truck right after I bought it the old ones were gapped to .071 and the truck felt no different after with new.

I agree with you saying you may have damaged a wire or connector or something. I'd look over every bit of wire for the TPS and similar sensors especially the ones near the spark plug holes

 

I believe you're on the right track by testing the related electrical components for the accelerator to be certain they are within spec before throwing money at an entire throttle body. The internal components are very durable and it's unlikely to be bad. It's possible but unlikely. I believe you're also on track by checking the related wires, connectors and pins for looseness and/or corrosion. These are the more suspect and likely culprits to your running issue.

Also, I would just leave the spark plugs gapped to Toyota's spec

 

This could be promising... found signal wire on APPS nearly severed. Very well could be the source for the P1120 code and limp mode, and it squares with the intermittent nature of the issue.

I want to splice and see if that makes a difference. Anyone know what gauge wire this might be? My guess was 20, but smallest I could find at NAPA and AZ was 18. Can’t seem to find any info/replacement on this connector. I confirmed with multimeter this is not the voltage wire or the ground so I believe it’s signal.

 

If you have a wire stripper with the gauge cutouts you could put it over the exposed wire to figure out how close you get to it before it cuts into the wire. That's typically what I do.

I have something similar to this I bought years ago...

 

I'm not near my truck or the materials needed to help you but I did want to say great job hanging in there and pokin' and proddin' with your noggin' to find that problem. We oftentimes forget the wiring and pins and connectors on the trucks are old and brittle and corroded and have seen less than better treatment and oftentimes are the root problem of running issues.

Here's to hoping it resolves your issue and thanks for coming back to update and maybe help someone else.

@BubbaW can probably point you in the right direction on acquiring that connector.

 

Curious, did you mean P2120 ?
The reason I ask is because the FSM mentions that code when related to the accel pos sensor !

Most of the bigger wires like that one are 22awg IIRC. Zooming in, that appears to be a Green w/red tracer that's messed up ? If so, that is the VPA signal that indicates the actual accelerator pedal opening angle and is used for engine control. As shown on the below drawing, it is connector A8....90980−11150

 

Wow thanks @BubbaW. Great info! Maybe I’ll just switch out that whole connector vs. the one wire. Hoping to find an OEM part that doesn’t have too long of a ship time.

The code displays P1120. I do not have the FSM, but my reader and my online searches were bringing up APPS related language. So that’s where I’ve been focusing.

 

OK, hopefully this is my final update! I replaced that connector and wiring at the APPS, and I’m back in business. No CEL, normal throttle response. It must’ve been this little stinker all along. Oh well, I’m just grateful to have the truck working again, and I learned a whole lot in the process.

Thanks again, Tundra Team.