Throttle body not closing

We have an 88 4Runner 22re with manual. It would idle high at about 2k when we got it, found that to be the throttle body not closing all the way. First we cleaned the throttle body by taking it off, that didn’t do anything, so we put a slightly larger/stronger spring on the throttle attached to the body. That fixed the stuck idle at 2k and isles closer to 1k. It isn’t fully closing still, it can be forced fully closed still and idle seven lower, has anyone had this problem with a throttle body? Is it just a bad throttle body?

It then got a bad fuel pump, so we changed the pump and filter. Timing was also 30 degrees advanced so after the fuel pump instal we took it to a buddy to get it timed, and then drove it back. Everything seemed fine for a bit, until later on that day we drove it and it couldn’t go past 50mph, also now noticing hard starts and having to throttle it slightly to stay started when cold. And also now noticing maybe it bogging down when going into first gear.

thanks for the help!

 

Bad? Yes, technically. It may just be dirty.

You can try spraying it with some carb cleaner, on both sides, to get both bearing surfaces where the flapper valve rides. Then, a little drop of oil, or graphite, to each side to ensure it's free.

You DID verify the throttle cable isn't either too tight, or sticky, not allowing the throttle body to let the valve go closed all the way? Easy enough to check. Disconnect it, and press and release the gas pedal. The return spring on the gas pedal should be enough to let it go all the way back to idle, if it's not sticking. If it is sticky, the throttle cable can be fairly easily replaced with a new one, or taken loose and lubricated.
Pretty obvious if it not adjusted correctly, too. Just LOOK at it when the gas pedal is not pressed. There should be just a little slack to it where it connects to the throttle body.

Replacing the return spring with a stronger one is a pretty common "thing". If nothing else, it gives you more control over the throttle performance with the truck not in gear. Otherwise, it seems like you breathe near the gas pedal and you redline the engine! At least it does on mine...

Good luck!
Pat☺

 

Ok I’ll clean it up some more tomorrow morning, when I cleaned it, I mainly focused on the surface area, I’ll try and make sure the bearings are clean and lubed as well. Yes we have checked the throttle cable itself, it moves freely and engine still idles high with throttle cable removed.

Any thoughts on engine not being able to go past 40-50mph. We replaced fuel pump, filter and then got it timed. Tmrw we are going to test the fuel pressure at the pump then if that’s good, move to testing fuel at engine and cleaning gas lines and injectors. If everything gas related checks out, correct fuel pressure, and cleaning injectors, then the only thing I can think of is setting timing back to 30 degrees advanced and seeing if it runs how it did before, being able to get past 40-50mph and not bogging in first gear.

What could cause an engine to not run right with stock 5 degree advanced timing vs 30 degree advanced? This is my cousins truck, he took it to his buddy to get timing set to 5 degrees advanced, I wasn’t there when they set the timing, and we took it to smog shop and they said timing was 10 degrees advanced. Is there something that could of been overlooked or not done properly when setting the timing? Anything that I could visually take apart and check as I don’t have a timing light. His buddy said it was set 5degree advanced, but smog shop showed me it was still at 10 so it just has me thinking about how he set the timing...

 

Is that +5° WITH, or without, the test jumper in? If it's with, then that's what the book specifies. If it's without, then it's 1/2 the advancement the book calls out. A very quick, easy to check condition. You do need a tachometer, NOT the integral, factory supplied one, but even a Harbour Freight cheapie will do the job fine. Make sure the idle is set to 800 RPM, with the test jumper in. Then check the timing with a timing light.
Again, HF can be you best friend with this. Inexpensive. Most auto parts stores will have a cheapie too. You don't need anything fancy with these older trucks. They're also darn handy to have if you want to check if you have a bad spark plug wire coming off the distributor. Just clip the pickup cable to the plug wire, near the plug. If it flashes, good wire. No flash, bad wire. Or distributor cap. I've gotten a cap from the store with a hairline crack, causing bad spark.
With the test jumper in, +5. Then pull the test jumper, and recheck it. +12.
Only set the timing with the test jumper in. The ECM takes care of things after that. Without the test jumper, +12 at idle, is what the book calls out. If the guy that did it set it to +5 without the jumper in, AT IDLE, problem found.

All that checks good, check the distributor pickup ohm readings. Also, check the distributor pickup's gap. How-to, and what all these tests should indicate are readily available in the book. Get the book! Even the PDF version will do the trick. I can post the correct pages for the distributor pickup's check, if you need, but I very strongly suggest getting it for yourself. You'll need it sooner or later, no question.

Check for anything in the throat causing it to stick. After a long life, it can easily get a small chunk of something kinda glued in the throat, or even just a carbon buildup, causing the stickiness you're seeing. Remember, the gunk can be on the back of the flapper as well as the front.

While you're "doing" to the TB, checking the o-ring on the idle speed screw. After all these years, they can go bad. Easy to replace, and readily available for cheap at most auto parts stores. Make sure you're checking the idle adjust screw, btw, not the screw that covers it. Not that I've ever done that...ahem...

Just make sure that before you take the idle adjust screw out, you screw it all the way down, counting how many turns, 1/2 turns, whatever, it takes. That way you can easily return it to the original setting when you re-install it. Once you know it's proper adjustment, take it out and check it's o-ring for cracks, missing chunks, etc etc.
When you install it again, with or without a new o-ring, rub a thin layer of Vaseline on it. That not only helps it last much longer, it helps it seal better. Works on all o-rings, or other rubber parts that may be getting questionable.

Easy place to check the fuel pressure is at the cold start injector. Just put a gauge on it, either temporary or permanent. You'll get the system pressure in a place that's easy to see wherever you're working in the engine bay.
Bear in mind that you can NOT reuse the crush washers. You pull one out, toss it. It's now bad. Be a good idea to get a number of replacements in all the sizes (I think 2, might be more). Don't forget, like a guy in the forums says, when you're down to your last one, it will leap out of your hand and vanish into the engine someplace, or under the truck, and just...vanish. Never fails.

Check the injectors. If they're dirty or clogged, you could very well see this trouble. Same with clogged fuel lines. It's not just fuel pressure you need to have, but flow volume as well. Easy to check. Pull the return line from the pressure regulator at th back of the fuel rail, and put a fuel line on it, leading into a graduated container. I can't recall right off what it should be. Check the Yota-tech forums for it. it's in there.

If the injectors are clogged, replace them, or send them out to get refurbished. Don't forget to replace the rubber o-rings on them before installing them, and lube the rubber with fuel.

I gotta go. Lets us know how things go!
Pat☺