After setting 15 years ,replaced everthing fuel system, car starts right up but when you hev the engine Antu suggestions, the tack pegs over high, replaced ecm and when the engine tries ti return to idle it revs back up on its own? Any suggestions? Thanks in advance.

Try replacing the tach filter. Thats the little silvered colored cap with a wire attached that sits near the distributor. That will fix the tach problem. As for the idle racing that could be a big vacuum leak or a defective TPS sensor.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 10-04-2024).]

quote Originally posted by Wayne Renninger: After setting 15 years ,replaced everthing fuel system, car starts right up but when you hev the engine Antu suggestions, the tack pegs over high, replaced ecm and when the engine tries ti return to idle it revs back up on its own? Any suggestions? Thanks in advance.

the revving back up is the iac over compensating due to a vaccum leak. block everything off and start from there

quote Originally posted by cartercarbaficionado: the revving back up is the iac over compensating due to a vaccum leak. block everything off and start from there

If possible, try to rent, borrow or build a smoke machine. That will easily tell you where any leaks are coming from.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "