millenniumtree
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| posted on 5/6/07 at 02:01 AM |
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The 'What else is wrong with my engine?' blog.
I'm not sure what is going on here, but I've compiled a short list of symptoms. Maybe someone on here can help diagnose what is going
on...
Toyota 22R motor (Hilux/Pickup/4Runner, Celica) - Carbureted.
 
Engine Bay
I just put a shiny new fuel pump on and the engine is running much better, but!
It runs pretty well when started cold, but after starting the engine up warm (after driving for a bit)...
1) It idles high (but the high idle cam is NOT engaged)
2) It is very sluggish when the gas pedal is pressed lightly (almost wants to die), but gets slightly better if you press it harder, though still a
bit sluggish.
3) Unplugging the Mixture Control valve hose to let fresh air into the intake manifold, actually LOWERS the idle (seems to idle almost normally!) If
you plug the hole or plug the MC valve back in, it goes back into an erratic high idle.
4) The hot air intake is closed, so it's sucking regular cold air
5) The choke heater system is functional (I've watched the choke open slowly when started cold and the heater body heats up)
Why would letting more fresh air into the manifold lower the idle?? I'm totally confused! Please help!
[Edited on 5/6/07 by millenniumtree]
[Edited on 7/6/07 by millenniumtree]
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millenniumtree
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| posted on 5/6/07 at 12:43 PM |
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quote:
Originally posted by robocog
letting more air in lowering the idle speed /could/ mean mixture is already weak due to an exhisting air leak? or not enough fuel flowing(or low flaot
bowl level??)= not enough juice to support the air going in?
...
either way sounds like not enough juice or too mch air to me
Too much air? Then why does opening a hole into the intake manifold (which sucks air like crazy) lower the idle? If there was too much air, then
sucking MORE fresh air should make it die, not go back to a normal low idle... Maybe I'm missing something? I don't fully understand all
the principles going on here...
Also, I forgot to mention that the float level is quite high - barely within the sight glass, way above the two marks.
I have compiled a list of things to check, based on research with the service manual - a lot of this doesn't make sense to me, but I'll
check them anyway.
1) Secondary throttle plate gummed up and isn't closing properly
2) Bad auxiliary acceleration pump diaphram or pump operating all the time
3) Bad fuel cut solenoid
4) EGR valve may be full of carbon and sticking open?
5) Vacuum leaks in a 'hot' system somewhere
I'll go down the list in that order and see what I find.
Anyone have a similar problem that you have solved? I want to resolve this before I get a tune-up next weekend because I don't want them to
have to do much more than tune the mixture.
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millenniumtree
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| posted on 5/6/07 at 05:23 PM |
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Come to think of it, the brakes are rather soft, so the booster may have a leak or be completely blown... That might account for a leak, but would it
explain the fact that everything runs just peachy when started cold, and the problem only shows up when I turn the engine off and start it again
hot??
I'm tempted to just disconnect each emissions system one at a time until the problem goes away. If I didn't have to remove that bloody huge
air cleaner every time I worked on it, it'd make things a bit easier.
There appears to be a very badly installed aftermarket cruise control system as well - and I think they tapped a line into the brake booster vacuum
hose! I guess I'll rip that out while I'm in there.
You can see the orange tape and zip ties they used to connect something to the hose here...
 
Brake Booster Detail
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millenniumtree
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| posted on 7/6/07 at 03:11 AM |
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Oi. What else is wrong with this engine??
Today, I pulled the vacuum hose off the Auxiliary Acceleration Pump (AAP) and the hose had fuel in it! So the diaphram in the pump is perforated! I
disconnected and plugged the vacuum hose and it started up sweet and ran (idle still high even after disengaging the fast idle and getting up to
temp)
I pulled the MC valve hose off the intake manifold and it revved HIGHER this time, so maybe the AAP was having an excess of fuel sucked through it by
the high vacuum and lowering the vacuum temporarily cured it.
I shut it down but then it wouldn't start at all, with or witout the AAP. I think because the heated choke was still wide open from having just
been run up to temperature a minute before, so it wasn't enriching like it was supposed to.
Or maybe it was vapor lock??
I'll check the EGR for cloggedness tomorrow and see if I can locate the fuel vent lines to see if they're clogged too.
This is turning into a 'what's wrong with my donor' blog.
[Edited on 7/6/07 by millenniumtree]
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