1989 Chevy Corvette TPI 350. Can anyone tell me if it can be adjusted at the throttle position sensor or any way else. It has a 480 lift cam upgrade and runs really rich.well was it rich before too? before cam upgrade. 5.7L engine, 350 cubesMy answer will be, for only 1 change over stock. this car.This is TPI is really MPI(modern name) not throttle bodyit TPI ditches the MAP for funky FAM, old MAF just hate idle. speedsso you changed the flow of AIR into the engine ., fact 1.now the MAF readings are now changed.I bet the rich has simple causes. not the cam.unless the cam causes gross idle surging or huge vacuum changes foot off the throttle.Things that fail easy. (cam or no cam changed) we check fuel pressure first, and replace the stock FPR first. the FPR is way way too old to use this told. ever.fuel pressure must be at spec first . the TPS does not work like you think it is only for TIP in fast , throttle movement or WOT, not used cruising. the TPS also when say crusing you cut the trottle foot and injectors are cut dead, to save fuel. the TIP in deal is caLLED:enrich mode. then in seconds flat that mode ends and the MfP does it all .(and RPM)the TPS also signals WOT, to the PCm and that puts PCM in WOT enrich full power mode. on all EFI cars made. (02 sensors go off line AT WOT MODE)WOT = WIDE open throttle.the TPS is set for idle, position only on all TPI engines and MPIif not the PCM( ECM) gets real confused doing that wrongthis car is not some 1990 race car, with TPS only fuel injection (custom) as seen or drag cars burning nitro. no this is a STOCK PCM. (ECU/ECM),<< EFI GM OEM stock injector brain.the first rule of hot rod'ing any stock EFI systems is do no fool the PCM ! or even stock can with dead sensors or missing thermostat. or the silly fail safe thermostats. stuck opentoo rich fuel pressure not at spec (FPR bad or its hose bad?)o2 sensors bad.A bad MAF will cause too rich fueling if it sticks high. (lies)this in turn may set ECU int LIMP HOME MODE. and runs super rick. The TPS is in fact slotted. as most cars where then.this car was sold some with 2 throttle body , manifolds and TB paired and synchronizedthat you?setting the TPS wrong will cause TIP in throttle bogging,a gross throttle hesitation just off idle.due to enrich mode happening too lateTPS is set by meter voltage only1989 Chevrolet Corvettethe 1989 vette, the target is for .540 volts, but anywhere between .470-.610 is within range.0.5 volts set. simple as can be.throttle cable never set too tight, ever.. must be set lose.
https://www.corvetteforum.com/forums/c4-general-discussion/4754817-1989-throttle-position-sensor-adjustment.htmlthe PCM (ecu) has programmed at the factory fuel chart (called a map/table) but the fuel chart in the programmed EPROMis tuned for a stock engine only,this chart is indexed by MAF , ECT and RPM readings.if engine is hot it switches from the cold chart to the hot chart.the IAT is only super fine tuning sensor that corrects for errors MAF as does the O2 both. hot air is less dense than cold. modern MAF self compensates.to the MAF sensor and RPM tells the PCM how much fuel to injectif the O2 sensor is stuck at 0vdc the PCM goes super rich back then. 80 to 89exhaust leaks (cracks) cause the O2 sensor to falsely read 0vdc.sorry for the long post but this post is PURE EFI technology , old. EFI TBII tried to cover them all, (causes)It is not the TPS causing richif you used the DTC jumper at the DLC jack to see ECU false error codes DTC.youd see if the TPS fails. set wrong.the TPS set wrong causes lean for 1 to 3 seconds , slamming the throttle down fast.then the TPS signals WOT and goes RICH, as all EFI cars do then and now.on newer cars the TPI is learned key on.but not then.My first guess, (must it) is the ECU is now in LIMPHOME MODEif you see the CEL glowing running it is in LIMPif you jumper the DLC jack for diagnostic I bet it flashes out gross error codes GM OBD1 codes. do not skip doing that.
no country told, not sure if other 3.0L exist that year word wide.? me?
but my answer is for USA and maybe Canada too. AJ30 only engine.
FWD, facing the engine, hood up 1 and 2 are left, the belted side of engine
as you can see my photo shows both, answers
order and locations
the firing order is baked into the harness and PCM (fixed) via COPS
Disconnect the negative battery cable. 2. Remove the rear combination light. (See Disconnect the negative battery cable.
2. Remove the rear combination light. (See REAR COMBINATION LIGHT REMOVAL/INSTALLATION.)
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal. .)
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
1
Fastener A
2
Screw A
3
Fastener B
4
Screw B
5
Screw C
6
Rear bumper
7
Refractor
