I just put a rebuilt 22re in about 15k ago and since I have bought the truck it has been getting pretty bad mpg (around 15-18 if lucky). But lately this high idling problem has been getting worse. The idle speed adjustment is cranked all the way down and it still idling from 1300-1700 depending on the temperature. If I get on it the idle speed will drop and it will die, but if I don't it stays idling high. It is a very inconsistent thing so its hard to figure out what it is. Also it has significantly more power at times and sometimes it just runs like crap. Help please!

 

year?
temp change makes me think of the air valve, easy enough to take it out and check to see if its adjusted and if it works right. make sure tps is adjusted also.
try this when hot and idle is high take the air valve tube off at the intake manifold and plug it on both ends with your fingers (eliminating the air valve) should go way down, and die if your idle adjust screw screwed all the way down like you say. book says to pinch the tube but that tube is hard to pinch and old ones tend to crack. by the way, do it fast cause will get air in the engine that isnt seen by the air flow meter.

 

Its an 88, what exactly does the air valve look like? Haha, sorry I'm a newb. And to check the tps do I have to take a bunch of junk off to get to the bottom screw?

 

no problem, first the tps, to check it you just need to take the plug off. its on the right side of the t body. right now just make sure the idl(idle) is set. go here put a ohm meter on IDL and E2 (the bottom two pins) and see if it gives some resistance (supposed to be less than 2.3k ohm). if it shows infinite than adjust as the page says, if you get resistance its prob fine. not a bad idea to make sure but you do have to take the t body off.

air valve found on google, 88 looks the same. it is right under the intake manifold above the ac pump if you have one. the hose takes air right before the t body butterfly and allows more after, entering in the middle of the intake right above the t stat. it has 2 coolant lines that allow it to shut air down when warmed up

 

18 mpg isnt that bad by the way. if your air valve is not right you will burn rich and get slightly worse milage.
is the idle the same cold or hot? make sure also on the back of the air valve the connector is connected(its kind of hard to see it), that warms a coil that also shuts the air off in the valve(its a bi metal valve)

 

did some more research for you there is a good rant on this valve here

good luck

 

It idles around 1400-1700 when cold then when its warmed up its at about 1200-1400 depending on the temperature of the air. So basically air is getting in past the intake constantly and thats why its running like this correct? I just don't understand the thing where if I gas it up to 4k or so it dies when I let off the pedal. Is this because when I do that it shuts a valve with suction somewhere but then it gets stuck open again and idles high? Because that seems to make sense.

 

sounds like the air valve is working but not adjusted..or not closing enough when warm. you should never run with the idle screw all the way closed. i think it dies because your computer is confused, as there is too much air bypassing, and therefore your idle is too high.

be aware there are other things that could cause high idle (straight out of the book)
- your fuel pressure regulator could be too high (faulty) check with a fuel pressure gauge should be 38-44psi - i dont think this is your problem
- cold start injector is leaking
- injectors leaking
- vacuum leaks

just have to trouble shoot down to the prob.
i really think it is something going on with the air valve, close it off like i said once warm and if nothing happens thats NOT your prob, but if rpms drop than its stuck open

 

Alright, I'll do that right now. IS it bad for it to run it like that? Because I have been for a while now... but I'm driving 400 miles over thanksgiving so I'm hoping I can get it taken care of by then.

 

no not going to fry anything running like that

 

15 -> 18mpg is not bad at all. Mine gets that around town, when it was new I got 22mpg but that was 20yrs ago. Best ever was a hyper-mile drive of 30mpg one time when money was tight (engine off - coasting downhill).

Try seafoam; It helped my daughters truck with her idle problems. Uses it regularly and has no issues now.

Cleanliness is next to godliness; clean first before replacing parts

 

Try seafoam; It helped my daughters truck with her idle problems. Uses it regularly and has no issues now.

What do I seafoam? Just in the gas?

 

Seafoam is a product. You start the engine and draw some from the can into the PCV hose or some other hose per directions. Shut engine off and add the remaining according to directions.

It works and has good reviews.

http://www.seafoamsales.com/

 

water is cheaper than seafoam and does the same thing. sounds weird but use a squirt gun in the intake for a good steam clean. i really dont think this is going to solve anything for him though.
how many miles does your truck have?

 

I used that water down the intake trick in the 80's. LOL
Geez we even used it for detonation prevention, with a water tank and washer pump, today they mix it with Alky for turbo cars.

But the steam only comes after combustion, not before so yes the exhaust ports got steam cleaned, but not the intake side of things. So you are left with chemicals, and more chemicals and elbow grease.
Yes he could pull the TB and do it manually with a spray can of solvent too. But after a couple of seafoam treatments she dodged that chore.

My daughters truck has 130k and mine blew at 336k. Windowed the block on both sides when #4 connecting rod failed.

 

good point, i have used seafoam before, i like seeing the black crap fly out the tailpipe. quite satisfying