Why? Why? Why?

[randomxzero]

okay so my car starts but idle dies very slowly what could it be?
i did the HG job on it..
replaced ignition, dizzy, fuel filter, engine relay, EFI relay, Circuit relays, reset the ECU..
and the car still drops idle till it dies..
im stumped and starting to think the problem may be electrical? just wanna see what you guys think it could be and i could go check it out...

[traintech86]

any chance the cars intake is blocked off? just a shot in the dark haha hope you get it fixed!

[mr3]

A few things to check for. Fuel, spark, and air. Is your fuel pump pumping? Pull a spark plug out and hold it agains the head to see if you have spark. Thats a 2 person job. Do you have compression? A simple harbor freight compression checker will let you see if you have compression. Hope this helps at all. I just battled with this and I think I figured it out.

[randomxzero]

all new spark plugs and spark plug wires.. each cylinder is sparking..
might have low compression might need a head job but shouldnt the car stay on? and not slowly die out?

[dirocyn]

I guess you've tried turning the idle up?

If so, there are only 3 things I can think of.
1. Weak fuel pump gives it enough gas to start, but then it runs out of gas. Check the pressure with a gauge.
2. Blocked off intake/air filter. When the car runs out of air, it quits. Easy to check.
3. Plugged up exhaust. I had a muffler collapse internally, exhaust pressure puffed it out like a balloon. That was on a Chevy Blazer, not an MR2. Then a shop tried to tell me it was a bad cat. Bastiches. Anyway, if the exhaust has nowhere to go, pressure builds up and chokes your engine. Take your O2 sensor out of the manifold to make a temporary vent hole-- if it runs, you've found your problem.

[Jackstand Queen]

Try adjusting the idle speed. There's a screw underneath a rubber plug on top of the Throttle body.

Try adjusting the Throttle position sensor, if you had it off the Throttle body.

[randomxzero]

TPS is adjusted...
idle screw i have messed with and nothing :/
i can keep the car on by gassing it but if i let it on its own it dies..
im afraid it could be fuel pump but wouldnt the fuel pump just give out even when im on gas?
the car started doing this after it overheated once... it didnt wanna stay on after that so idk what else to check i am gonna replace all vaccum hoses to see and because the hoses are stale..
im wondering if a sensor might have got burned and thats what is not letting the car stay on..

[mr3]

Does this problem get better when the car is warmed up? With my car I have to rev it to 2000rpms for 2 minutes or so or it will stall out. Once it gets to the lines on the gauge it's fine.

[espguitarist33]

mr3 that sounds like its not being enriched when its cold....ever figure those vacuum lines out?

[Jackstand Queen]

I think I have it this time . . . . Vacuum Leak.

Take a propane torch, open its valve, but don't light it. Run the nozzle all around the intake bits.

If the engine responds to the propane . . . you've got your leak spotted.

[randomxzero]

alright well i'll replace all the vacuum lines after class.. they are all stale anyways so i'll see if that helps if not then i'll still be stumped

[toyotaspeed90]

check for vacuum leaks....

air able to get to the manifold after the AFM can cause problems.... if your idle is set low and you have a manifold leak, then the afm won't actually be open when you initially start.... and when the afm closes, the fuel pump kicks off after the initial prime.

I actually just had the same problem on my wifes car.... had swapped to JDM parts (and after a lot of research had to swap back)... but when I went back to AFM it ran like poop. Was missing 1 bolt on the CSI.

Also, check your timing to make sure you're on. Ensure that there are no tears in the AFM tube as well.

[randomxzero]

timing is set at 10 BDC when the terminals are jumped..
when they are not jumped timing is at 12 BDC..
i know its a dumb question bust what is CSI? Cold Start Injector?

[toyotaspeed90]

yes. Many of the bolts for things on the manifold actually go all the way through... so if there's something missing, there's a vacuum leak.... I didn't even realize this until last night.....

but if your timing is on and it'll start but dies... sound like the Fuel pump is kicking off after it's initial prime.... meaning the AFM is probably not staying as open as it should.

[randomxzero]

could a bad connection on the VSV valve cause anything to the idle?
i was lookign at the Vacuum diagram and i found the vsv hangin on by a tine little copper wire when i took it off that wire wasnt even connected to its plug..

Could that be the culprit i found the plug runs into the wiring harness

[toyotaspeed90]

i don't think that would be all that big of a deal.... I've had many aw11's missing those and they ran fine.....

[dirocyn]

Toyotaspeed90's AFM theory is a good one, but I still say you should check for exhaust blockage first because I'm the one that thought of it. O2 sensor's just attached with two little bolts, so pretty easy to check. Actually, forget that, his theory is easier to test.

To test the AFM theory, jumper Fp and +B on the check connector. Take a look at page FI-64 and 65 in the BGB and you'll see what I'm talking about. This jumper should make the pump just run. If I understand the wiring diagram correctly, you ought to be able to start the engine with those wires jumped. Mind you, I've never tried it. Anyhow, if that "fixes" the engine dying problem, take a look at the relay and at the fuel pump switch in the air flow meter--and the wiring associated with these.

[randomxzero]

so i've already switched AFM's... still did the same thing with both..
i need to check the fuel pressure..
i noticed when i was messing with the vacuum lines that the air flowing through them was really weak like almost no air at all... is that how its suppose to feel?..
sorry for the noob questions.... for i am a noob but learning as i go..

[randomxzero]

nvm got her running she stays on a little longer.. than ususal from fixing the exhaust leaks, no it seems like a vacuum leak so i gotta get on top of that

[moy407]

after 70 miles or 3 gallons of gas mine would stall. I put a bottle of heet (to soak up water) in there and it ran fine... 87 mr2