I have a 1990 4runner 22RE mileage unknown the truck has 240000 but the guy I bought it from said the engine was replaced around 30,000 miles ago but no paperwork to prove it so I doubt it but now my problems when the engine is at operating temp and you shut it off and then restart you have give it gas it doesn't seem like it wants to start and when it does it will idle at around 500rpm and reving it doesnt help it has to be driven but only around 100 yards and then it will idle normal and the other thing when i have the headlights on and i come to a stop all the lights dim if i have the turn signal on the volt meter bounces driving and stoping with no lights on the volt meter stays close to 18 volt mark but stoping with the lights on drops close to the middle of the meter i'm thinking i might need more or better grounds but not quite sure any help would be great thanks

 

Pull the throttle off and give it a good cleaning, also be sure to clean all of the vacuum ports on it, that should help your idle, also make sure the TPS is adjusted properly. As for the voltage problem, pull your alternator off and have it tested, your lights shouldn`t dim that much.

 

Some alternators dont put out rated current below a certain rpm, its possible your low idle drops the rotating speed of the alternator enough that is not putting out enough current to supply your loads, thus causing a voltage drop (as your seeing on your gauge) and dimmer lights (effect of the voltage drop).

Not to say there isn't anything wrong with your alternator, could very well be, and having it tested should be free so you might as well. Take the battery and have that tested while your at it, although likely not your problem it doesn't hurt to know what kind of shape its in.

1. I would do a close inspection of your vaccum system, particularly the EGR system.
2. Inspect your plugs/wires/cap/rotor.
3. Cleaning my throttle body as suggest by the previous poster did wonders for my idle last week (still have an EGR issue).
4. Not sure what the idle adjustment procedure is for your engine but i'd check the FSM for that.
5. Not sure if you have a AFM or MAF but if you have a MAF i'd clean it, if you have a AFM follow FSM procedure for checking it out.
6. TPS (as stated by previous poster) check out per FSM
7. Check coolant temp sensor (there are two, you need to check the one that goes to the ECM - 2 wires, not the gauge on the dash - 1 wire) per the FSM.
8. Seafoam treatment of the intake, I don't think this does a whole lot for you but its relatively cheap and as a side bonus, I found my EGR leak during the procedure. Basicly a lot of white smoke is created in your intake and then gets pumped around the vaccum system, eventuallyit came out of the EGR leak that I hadn't been able to find for two weeks, it was super easy to find with white smoke pouring out of it.


All of the above suggestions are either free or relatively cheap (assuming you have some basic tools and multimeter) and usually solve most idle problems from what i've found searching on here (to find my own idle problem - egr I keep refering too). They'll take a while to get through but again free and effective.

 

thank you for your ideas i have done everything that you recommend in the last month except the coolant temp sensor and the sea foam i forgot one other symptom i am getting bad mpgs like 16-17 so i am now thinking maybe the O2 sensor

 

cold start injector? maybe its leaning out, thus the low idle? and the coolant temp sensor that goes to the ecu controls the cold start injector so check them both, and seafoam is allways cool

 

well that did cross my mind but if it was that it would have to be on all the time because this is happening at operating temp

 

Certainly worth checking out the O2 sensor, the FSM test seemed a bit tough and the part is spendy but if it hasn't been done they do wear out...

 

if it tickles your fancy you can just take em out and clean them...i think they have some sensor safe stuff at the parts store, take em out and spray em down and rub em up till their shiny again...

 

well my biggest problem is not knowing how it was taken care of and what had been done by the prior owner but I think everybody has that problem unless the seller is a good friend

 

Good point about cleaning the O2 sensor, I hadn't thought about that. Also, when I took mine off to clean it, i found the sensor was actually broken off!

 

well i think i might have found why i was getting horrible mpgs i took off my front skid plate to clean all the mud that it was holding and i found the vacuum line that unlocks the automatic hubs was not even hooked up so they were locked all the time i hope it didn't do any other damage but i think it explains the mpgs and also maybe more cause of the leak i'll find out tommorrow morning on my drive to work