I have a 99 neon dohc & am wanting to swap to a sohc. I have had nothing but problems with the dohc. Sounds fine when ideling , but when you give it the gas is noisy as a sabaru with about 250k. Put a rebuilt head with new valves, cams, put my new rocker arms, & new lash adjusters, & still sounds like ****. Just tired of dumping money into it. My question is i know i will need the computer, will i be able to use the existing wiring harness or will i need 1 from a sohc? I have found a motor with 80k for $200, just need to know about the harness. If there is anything else i need it would be appreciated. Thanks

 

Does anyone know if i will be able to use the dohc harness with the sohc engine? I have found a motor i believe is a 98 with 80k complete with altenator, power steering pump & resevoir, ac comp, intake manifold, & exhaust manifold for $200. A friends uncle has a computer from a 98 sohc for $20, i just need to know about the harness. Also plan on installing a new timing belt, rear main seal, & tranny seal before install. Anything else i should replace before install?

 

i would replace the head gasket too, just for kicks

"III. DOHC Wiring Harness
Make sure the wiring harness will work with your car. If you have a 96+ engine, you need a 96+ harness. If you don't want to buy a wiring harness, you can convert your stock SOHCharness to work the DOHC engine. It requires more work and custom wiring.

To convert a SOHC harness to DOHC, you need to change the cam positioning sensor plug, and extend the coolant temp sensor plug, it needs to be long enough to reach passenger front side of the head.Sensors may not be plug and play. You may need to buy new sensors for certain applications or use the sensor form your other motor.

If swapping DOHC to SOHC the harness will be long enough to reach.

There are some differences to some of the harnesses depending on the year:

(early 97 wiring harnesses are odd, they may have differences such as VSS, alternator, brown wire that goes to the starter, TPS, and the IAC motor all have different plugs. From what I can gather it is a Frankenstein harness between the 96 harnesses and late 97-99 harness’s)[align=left]
1995 PCM has a single plug that connects to the frame, motor, and cabin wiring harness.
1996-1999 PCM has two plugs that connect to the frame, motor, and cabin wiring harness.

1995 model year has unique plugs for almost all the sensors in the engine bay.
1996 model year is a hybrid between 95 sensors and 97-99
1997 - 1999 No changes were made to the wiring harness between these years... use all the same sensors.

1995 has a separate MAP and IAT sensor.
1996-1999 have an integrated MAP / IAT sensor.

1995-1996 use the PDC for the fan relay.
1997-1999 use a separate fan relay located just below the driver side headlight.

1995-1997 use Bosch plugs for the injectors.
1997-1999 use the USCAR square plug
The plug change happened mid year so some 97's have Bosch style some have the USCAR style.

1995-1997 use the same alternator and starter.
1998-1999 use the same alternator and starter.
They only fit the correct years harness. "


https://dodgeforum.com/forum/1st-gen-neon/154570-information-for-a-2-0-engine-swap-sohc-to-dohc.html

 

you can use your DOHC PCM, it will just give you a more agressive timing curve which will give you more POWER

 

I understand what you said about more agressive timing curve, but wont that make the car run rich. The motor is a 97 will i be able to use my 99 harness? Every junkyard i called did not have any wiring harness's.

 

The DOHC PCM will make the car run a little rich, but its up to you to decide if you wanna live with it.

You can use the 99 harness, just swap over any sensors that aren't compatible with the harness.