'87 350 TBI questions

[Sailor]

Hello All,

So I've been having problems with my TBI when going downhill. When I am coasting downhill without touching the throttle, if I slow enough, it will stall, and if I clutch in to downshift it will stall. Only after the engine is warm (don't know temp as gauges don't work) will it idle properly at 650/700rpm. Overall, it feels a little sluggish so I'm thinking fuel pump or tps?

 

[GNERGY]

Your IAC idle air control valve could be dirty or sticking, or be bad.
Tarey

 

[4X4HIGH]

Was this vehicle originally an auto trans that was swapped to a manual? If so did you have a new chip made for the manual trans so the ECM knows when to adjust the IAC for load/no load?

 

[Sailor]

It was not an auto. I'm not too concerned about the idle, it's the stalling downhill issue I'm more worried about. Someone said to turn the distributor cap a little bit to fix this. I'm thinking not.

 

[dyeager535]

What happens when it's not warm?

Good visual inspection of the engine bay. Connectors, wires, hoses. How about tune...good plugs, wires, cap and rotor?

I'm thinking you've got a vacuum leak though. That would be the second thing I'd do after a GOOD visual inspection...go through ALL the vacuum lines and see if any are bad. If questionable, replace.

Got any Autozones or other places that have a scantool that you can use? I'd want to make sure that the coolant temp sensor, throttle position sensor, and vehicle speed are working correctly/reflected correctly at the ECM as well if you

 

[Sailor]

When it's cold it'll still stall downhill. I've got a doozy short hill right before a stop sign so I try not to downshift too far down the hill.

I'll check around the hoses and see. I've looked before and nothing is obvious to me.

 

[oldstonewall33]

is your engine light on? if so try this: If you look at the plug thing under the dash.. the black on.. yep thats it. now turn on ur ignition without starting. take a paperclip and jump the top far right two IE: [ g|f|e|d|c|b|a ] so that would be stick a paperclip in terminal B and A, now your check engine light will flash 1 time, pause and flash twice. this means ur goign into diagnostic mode. it will do that 2 or 3 times and if your have an error code running through the ECU it will flash. Count the number of flashes before the pause. that is the first number. then count the number of flashes after the pause. thats the second number. look up on google the trouble shooting codes or look in a haynes or chilton, and wala!

just some food for thought.