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98 engine and harness into 99 body

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Old Nov 29, 2007 | 01:35 PM
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Default 98 engine and harness into 99 body

i have a 98 trans am engine and harness that i am swapping into a 99 Formula. has anyone done this (98 to 99) and could anyone tell me what the differences are between them.there are sum connectors on the passenger side kick panel.now the promblem lies is the 98 ecu harness has three plugs and the 99 body has two plugs.i repinned the fuel and ignition plugs so the car runs,and runs pretty good. but whats with the gauges?

so the story is,do i mess around with repinning everything to get the gauges to work? or swap out the gauge cluster from the 98.

has neone done this and if so would appreciate a experienced hand.thanx!!
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Old Nov 29, 2007 | 06:54 PM
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Originally Posted by the duke
i have a 98 trans am engine and harness that i am swapping into a 99 Formula. has anyone done this (98 to 99) and could anyone tell me what the differences are between them.there are sum connectors on the passenger side kick panel.now the promblem lies is the 98 ecu harness has three plugs and the 99 body has two plugs.i repinned the fuel and ignition plugs so the car runs,and runs pretty good. but whats with the gauges?

so the story is,do i mess around with repinning everything to get the gauges to work? or swap out the gauge cluster from the 98.

has neone done this and if so would appreciate a experienced hand.thanx!!
I highly recomend you dont do this, the 98 PCM/Harness is a major step down in performance and tuning capability, along with you will have to backwards swap the guage cluster/gas tank fuel pumps etc to ever get your fuel guage to work

Get yourself a 99 PCM and harness. it would be cheaper to buy a 99 pcm and harness then all the stuff youd have to buy to make the 98 work, and youd still be stuck with the bastard 98 PCM.
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Old Nov 29, 2007 | 07:02 PM
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Originally Posted by Eurospec2
I highly recomend you dont do this, the 98 PCM/Harness is a major step down in performance and tuning capability, along with you will have to backwards swap the guage cluster/gas tank fuel pumps etc to ever get your fuel guage to work

Get yourself a 99 PCM and harness. it would be cheaper to buy a 99 pcm and harness then all the stuff youd have to buy to make the 98 work, and youd still be stuck with the bastard 98 PCM.
I agree, dont go backwards. Do you have the original 99 harness?
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Old Nov 30, 2007 | 12:57 PM
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ok, can a 99 pcm and harness work on a 98 motor, or what kind of changes? sensors?
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Old Nov 30, 2007 | 02:41 PM
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the temp sensor is different, don't know about any others. the 99 PCM will need to be programmed for the larger 98 injectors(28 in 98, 26 in 99), but that is simple for any tuner
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