Engine Swap Everything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.

2.8 to 350 Wiring issues

Thread Tools
 
Search this Thread
 
Old May 21, 2009 | 04:54 PM
  #1  
88onfire's Avatar
Thread Starter
Junior Member
 
Joined: Jun 2008
Posts: 30
Likes: 0
From: Lee's Summit, MO
Car: '88 Firebird
Engine: 350 (340 Est. HP)
Transmission: Turbo 350 (1800 Stall Convertor)
Axle/Gears: 3.42 Posi/28 Spline/Alum Diff Cover
2.8 to 350 Wiring issues

We have gotten the 350 into the car (Former MPFI 2.8 V6), and everything attached. We hooked up what little wiring we needed that was in the car to the 350 (dizzy, alternator ect.) We have "made" a hook up for the temp gauge and adapted the 2.8 oil pressure sending unit to the engine. We have not cut any wires at all. When the engine was finished, it ran like a mother on the test stand, but it has only ran for 30 seconds one time since its been in the car. The lead tech at the dealership said all of the unhooked senors still leading into the ECM are confusing the computer and keeping the car from running. He also said that we would basically have to rewire the car and gauges. Does anyone know when the last year was for a fully carbed firebird? We were thinking we could use the harness in place of a full rewire.

Any help would be greatly appreciated.
Thanks (I know that was a long read)
Reply
Old May 21, 2009 | 05:19 PM
  #2  
Wrenchp's Avatar
Junior Member
 
Joined: Apr 2008
Posts: 79
Likes: 0
From: Casper WY
Car: 1988 RS Camaro
Engine: Undetermined
Transmission: TH400
Axle/Gears: Stock
Re: 2.8 to 350 Wiring issues

Wait, aren't you putting a carbed 350 in this car?
Reply
Old May 21, 2009 | 06:37 PM
  #3  
five7kid's Avatar
Moderator
25 Year Member
iTrader: (14)
 
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Originally Posted by 88onfire
When the engine was finished, it ran like a mother on the test stand, but it has only ran for 30 seconds one time since its been in the car.
So, what is it lacking - fuel, compression, spark?

Originally Posted by 88onfire
The lead tech at the dealership said all of the unhooked senors still leading into the ECM are confusing the computer and keeping the car from running. He also said that we would basically have to rewire the car and gauges.
Other than lengthening and reterminating some wires,

Originally Posted by 88onfire
Does anyone know when the last year was for a fully carbed firebird? We were thinking we could use the harness in place of a full rewire.
1987.

All you need is the stuff that goes to the firewall bulkhead connector in the back driver side corner of the engine compartment. From your V6 harness, you need the ignition power wire (went to the coil), tach wire (if so equipped - also went to the coil), oil pressure gauge sender, temp gauge sender, alternator wires (will probably need to lengthen). You could get that harness from any V8 car, but one that has the alternator in the same place as your engine would make it easier. '82-'87 V8 carb'd would be the best choice, most likely.

You may need to rewire the fuel pump relay if you remove the ECM.

Something tells me you have a mechanical fuel pump on the engine, and the in-tank electric isn't running (and you didn't do anything to accommodate the in-tank electric).
Reply
Old May 22, 2009 | 01:15 PM
  #4  
88onfire's Avatar
Thread Starter
Junior Member
 
Joined: Jun 2008
Posts: 30
Likes: 0
From: Lee's Summit, MO
Car: '88 Firebird
Engine: 350 (340 Est. HP)
Transmission: Turbo 350 (1800 Stall Convertor)
Axle/Gears: 3.42 Posi/28 Spline/Alum Diff Cover
Re: 2.8 to 350 Wiring issues

Wrenchp - We have a carbed 350 on the car

five7kid- Forgot to mention we have an inline fuel pump with regulator...old in tank pump has been removed and the pickup has been extended down. It is also hooked up and pumping plenty of fuel. We are getting fuel, compression and spark. Im going to talk to my dad and see if we cant try to look over the wiring again. Thanks
Reply
Old May 22, 2009 | 08:04 PM
  #5  
Curtisyz54's Avatar
Member
iTrader: (5)
 
Joined: Jul 2008
Posts: 254
Likes: 0
From: Michigan, West Bloomfield
Car: 84 z28, 86 irocz
Engine: LS6, 305 TPI
Transmission: TH350, T56
Axle/Gears: 3.73, 4.10
Re: 2.8 to 350 Wiring issues

Originally Posted by 88onfire
Wrenchp - We have a carbed 350 on the car

five7kid- Forgot to mention we have an inline fuel pump with regulator...old in tank pump has been removed and the pickup has been extended down. It is also hooked up and pumping plenty of fuel. We are getting fuel, compression and spark. Im going to talk to my dad and see if we cant try to look over the wiring again. Thanks

if u ahve a carbed 350 in the car. The old ecm shouldnt even be in the car. and if it was you have nothing to hook it to. meaning the ecm isnt causing any problems, unless you have a really bad wiring mess.
Reply
Old May 26, 2009 | 12:26 PM
  #6  
88onfire's Avatar
Thread Starter
Junior Member
 
Joined: Jun 2008
Posts: 30
Likes: 0
From: Lee's Summit, MO
Car: '88 Firebird
Engine: 350 (340 Est. HP)
Transmission: Turbo 350 (1800 Stall Convertor)
Axle/Gears: 3.42 Posi/28 Spline/Alum Diff Cover
Re: 2.8 to 350 Wiring issues

We looked at it again and it appeared to be the hot wire for the HEI. We were getting spark sometimes, but not all the time. We rewired the dizzy and we were able to drive it for the first time sunday, and it doesn't have any brakes. (First time car has moved under it's own power in over a year, previous owner thought it would be fun to go mudding)
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
theshackle
Tech / General Engine
4
Sep 17, 2020 08:26 AM
Jake_92RS
Tech / General Engine
8
Jan 28, 2020 10:37 PM
Infested
Tech / General Engine
3
May 22, 2018 11:56 PM
Fronzizzle
Electronics
3
Aug 17, 2015 02:52 PM
86Base
TPI
14
Aug 8, 2015 01:34 PM




All times are GMT -5. The time now is 06:11 PM.