bearfoot990

So recently my 87' 4runner has been acting strange at first i thought it was electrical so i replace the cap rotor plugs and wires but that didnt fix it. So heres the symptoms at low rpms it sputters and kinda cuts out unless i stomp on the gas then once it gets to 2500 or so (guessing since i have no tach) it stops. any ideas whats going on?

Windsor

EFI? check for vacuum leak.

Spence1016

that sounds more like a fuel delivery problem than electrical. Try checking/replacing fuel filter, fuel pump, injectors. Has it been sitting for a long time?

bearfoot990

its my daily driver, it sat for about 3 days over the holidays but thats it. and yeah 22re EFI. yeah thats kinda what ive been thinking is fuel delivery or a vacuum somewhere the question is... where?

bigt

or afm.. causing fuel pump.. or ignitor/coil

any hard starting when cold?

bearfoot990

Nope it starts just fine just runs funky.

bearfoot990

oh it idles at a really low rpm as well

Windsor

Generally fuel delivery problems get worse at higher RPMs.

Vacuum leaks, OTOH, really show during low RPMs because the leak could equal the amount of air passing your AFM. Also, most ECUs built around this time use pre-built maps for idle and WOT, so the O2 sensor is out of play. At higher RPMs, most of your air is coming through the AFM and the closed-loop mode of the ECU can compensate for the minor offset.

First off do a visual check of everything after the AFM. Get a flashlight and mirror and look on the bottomside of the piping and vacuum tubing. The obvious places to look are at joints and bends.

If you find something, you can verify with a tiny shot of WD/40 or starter fluid while idling -- if the idle improves, you found it.

If you can't find anything, then do the WD/40 or starter fluid test anyway, picking key locations again (especially blind spots that you couldn't get a mirror into).