Hi, so my 87 turbo yota has been treating me good for quite some time, but now its having a problem. When I am going down the road, if I press the gas in even the slightest amount, it bogs down and starts hopping sort of. Like when I was stopped at a stop light in town, when it turned green and I tried to go, it just lurched back and forth and it took me like 20 seconds to get across the intersection (embarassing ). when I sit still and rev the RPM's, once it gets to about 2k, the RPMS just drop off even though im flooring it. It did this once before approx 5 months ago, but it fixed itself after sitting for an hour or 2. Sounds like a fuel delivery issue to me, but you guys are the experts . what do you think?

 

Check for codes, post em if you find any.

TPS - check that resistance between VTA & E2 changes smoothly with no spikes or dropouts as you slowly open & close the throttle. Make sure the values are all in range.

VAFM - check that resistance between VS & E2 changes smoothly "in a wave pattern" with no spikes or dropouts as the measuring plate is slowly opened & closed, & make sure all values in range. Check that E1 & FC (fuel pump switch) have solid continuity when vane in any position except closed.

Try jumping +B & FP in the check connector - if problem goes away, could be bad circuit opening relay, possibly bad fuel pump switch in vafm, bad ignition switch or bad connection. Troubleshooting info for COR in fsm.

Check fuel pressure, could be bad fuel pump/corroded wiring connection, clogged filter, possibly bad pressure regulator.

Check that +B has steady batt voltage when ignition on; if not, may be bad EFI relay, possibly bad ignition switch or connection.

VACUUM LEAK - check all vacuum hoses & joints with unlit propane torch & visually inspect for cracks in hoses or loose connections. Check air hose between air meter & throttle body.

TUNE UP - done one lately? If not, Denso parts recommended.

How many miles on timing chain? If over 100k, inspect chain & guides, adjust valves while you've got the cover off.

CAT okay/not clogged?

Check resistance of both circuits of ignition coil.

Check that positive terminal on ignition coil has steady batt voltage when ignition on; otherwise bad ignition switch or bad connection.

Clean up igniter ground (mounting bolts).

Verify ecu terms E01/E02 have good ground to motor & term E1 has good ground to chassis.

Could be bad ecu but that's rare.

 

Ill add distributor to that list also...start by looking for cracks.