Info on my '85 Camaro Z28

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(Second) ECM Swap

This project will detail the steps, parts, hints, techniques for upgrading a 1986-1989 GM TPI Engine Control Module (ECM) to a later model. The 1986-1989 TPI cars used a MAF system ('165 series ECM), while the 1990-1992 TPI cars used a MAP system ('730 series ECM).

If you're looking to upgrading a '85 TPI ECM to a later MAF system, look here.

The ECM that came in 1986-1989 TPI Fbody's and Vettes is a series 1227165 (165). The ECM is located up and behind the dash, on the passenger side of the car. (Behind where a Glove Box would be in a older pre 80s car)

The '85 and '86-'89 TPI cars use a MAF sensor inline of the intake air flow to precisely measure the air flow and adjust A/F, etc. based on that reading. 1990-1992 TPI cars switched over to a MAP system (also referred to as Speed Density) where the ECM gets a estimated air flow based on engine vacuum. The change to MAP is rumored to be based on cost reasons for GM, but for performance engine builders, the limited air flow able to pass thru the MAF is also a consideration of changing to a MAP system.

I wanted to be able to quantitatively compare the MAF-vs-MAP systems on my vehicle to have a better understand the limits of each and how my car would react/benefit from both. To easily switch between the two systems, I set out to build/adapt both ECMs, different sensors, and wiring harness differences in a convenient manner to make switching back and forth between them as simple/easy as possible. After working thru the wiring diagrams and getting much valued help from the GMECM mailing list, I came up with a solution to equip my car with both set of sensors that are different, and build an adaptor cable between my existing ECM harness ('165 wired) and the newer ('730) ECM.

Note that you do not have to build the adaptor to change systems, you can easily reuse your MAF wiring and existing knock sensor engine wiring to hook the new MAP and knock sensor to. This is a more permanent solution if you're sold on Speed Density and don't want to switch back-forth between the MAF and MAP systems like I do.

86 ECM pinout diagram                                      
92 Sensor/ECM wiring page1, page2, page3, page4, page5, page6, page7,

This is a text file that has the required connector pin changes for the conversion. They are listed in order of the '165 connector pins as well as in order of the '730 connector pins. (Note that you need an additional ECM connector for the '730 ECM)

The pin naming nomenclature is shown in the above pinout/wiring diagrams.

'165 ECM connector pin changes for 92 ECM

Many thanks go out to:
Don Broadus
John Gwynne
Bruce Plecan
Dave Zug

Parts needed:
  • MAP Sensor
  • new Knock Sensor (If you want to reuse your '165 KS, check HERE )
  • '730 ECM
  • V8 MEMCAL for '730 ( I used the AUJP base, GM part# 16151348 for $39 online at .

  • (EPROM programmer w/WINBin and 730 ECU file (or equivilent) for {min} Mag. VSS change and VATS disable. See Programming101   doc for PROM tuning guide)

  •     This is a current copy of my 730 ECU !

          A handy tool for repining GM harness connectors is the Lisle Terminal Tool, P/N 14900 and can be found here

    Adaptor parts needed:

  • old ECM or new ECM pin header
  • old harness or two for (1)24 pin and (2)32 pin harness connectors
  • Cinch Crimp on pins from D-shell connectors (Cinch P/N 030-1953-000) available from .

    Total cost for the project is ~ $150 depending on what you can get thru salvage yards and what you have to purchase new..

    Click on any image below for an enlargement (~500K) image.
    January/February 2000 (Preparation)

    Common 24/32 ECM Header connector. Desoldered from Donated ECM

    ECM Header connector next to ECM 24/32 harness for making Male/Female adaptor

    Knock sensor plug connector and '91 MAP sensor w/wires & vac tube. Pulled from junk yard

    Note!, if you decide to use your existing Knock sensor wiring, please note that the MAF system uses a Electronic Spark Control (ESC) module mounted on the firewall, which the Knock sensor wiring traverses. You will have to unplug the ESC and jumper pins C to E in the harness to complete the circuit.. The wiring diagram of the MAF system above can help with this. See HERE for additional info..

    Knock sensor plug connector and '91 MAP sensor w/wires & vac tube. Pulled from junk yard

    MAF harness plug -to- MAP sensor engine harness
    The MAF plug was made by cutting apart an old broken MAF and soldering wires to the pins. The MAP plug is available in most any Auto Store in the "HELP!" section.

    Crimp pins (AMP) used in RS232,etc. connectors hooked to harness connector wires

    Close up of Crimp pins

    Close up of Crimp pins, some already heat-shrink covered

    24 and 32 pin connectors modified and slipped onto header

    All three (24,32 and 32) connectors modified and slipped onto header

    Long taped-off wires in foreground will hook to new MAP and Knock Sensors.

    All three (24,32 and 32) connectors modified and slipped onto header

    Long taped-off wires in foreground will hook to new MAP and Knock Sensors.

    '730 ECM pluged into harness.

    (labeled, but not soldered to pin header)

    '730 and '165 MEMCALs.

    '730 (lower) from L4 Cav, '165 from v8.

    '730 V8 MEMCAL.

    Knock Sensor circuit board built onto MEMCAL.

    '730 (and '165) modified V8 MEMCAL.

    low-profile ZIF into solded socket.

    '92 5.7L Knock Sensor from Autozone

    Knock Sensor w/ junkyard harness conn.

    Junkyard MAP mounted on cowl

    Junkyard MAP mounted on cowl

    1/4" Vacuum port Y'd for MAP hookup

    "Trailer Hitch"

    wiring harness pulled thru firewall for MAP hookup to adaptor cable

    ECM header with adaptor pins soldered on

    ECM header with adaptor pins soldered on

    ECM header with hot glue support casing

    ECM header with hot glue support casing


    New (Second) knock sensor installed into drivers side of block

    Knock sensor wire routed into CTS harness

    MAP and second knock sensor wired into engine-bay and down/thru firewall

    Black plastic conduit used for all wiring for clean look.

    '730 ECM hooked to adaptor cable and onto "OEM" harness

    I started the car and gathered an initial ALDL scan to check sensors,etc. The car ran very poorly and the data showed it running VERY rich with the stock '92 5.7l calibration. I have enough preliminary data to start zoning in the EPROM. The ALDL data (after warmup) from the RPMs, MAP, O2 from the first start can be seen here
    The adaptor was then unhooked and the '165 ECM reattached to prove they can be swapped easily. The ALDL data from the subsequent MAF is shown here .

    A basic EPROM image and road test data will be forthcoming..

    3-1/2" aluminum tube replacing MAF sensor

    Cut from 3-1/2" diameter aluminum jar, 6" long. Painted "stealth" black

    3-1/2" aluminum tube replacing MAF sensor

    Cut from 3-1/2" diameter aluminum jar, 6" long. Painted "stealth" black
    MAF hookup wire can be seen on thermostat housing

    The first test of the season was run at Cecil County Dragway on March 4, 2000. The 7 runs were recorded as:

          1    (MAP)    13.098@105       (let car shift to OD)
          2    (MAP)    13.095@105       (let car shift to OD)
             3    (MAF)    12.941@105       (kept car in 3rd to 5600rpm)
             4    (MAF)    13.071@103       (let car shift to OD)
             5    (MAF)    12.927@106       (kept car in 3rd to 5800rpm)
          6    (MAP)    13.063@105       (kept car in 3rd to 5800rpm)
          7    (MAP)    13.050@105       (kept car in 3rd to 5600rpm)

    *note: all the runs had 60' times between 1.812 and 1.860 and so I feel are warranted for comparison..

    The Bins used for the tests are a AUJP (Runs 1,2)   , AUJP (Run 6)   , AUJP (Run 7)   variant used in the '730, and a ARAP   variant used in the '165.

    *NOTE! - The MAP (AUJP) bins were created with a buggy editor and are not correct in at least injector constant. They should not be used/copied into any vehicle and only shown here for comparison!

    My latest up-to-date MAP Bin can usually be found here

    Diacom snapshots of the RPM,air flow,O2 for the best MAP   and MAF   runs..

    Diacom snapshots of the RPM,Spark Adv (TDC relative),Knock retard for the best MAP   and MAF   runs..

    The MAP system runs very strong now. The above tests were with an early (in tuning) MAP chip that barely had the fueling stable and had no spark advance tuning done. I've since tuned it much better and the MAP setup is running at and above the level of the MAF setup..
    I will soon be building a cold-air intake for it that is much more difficult to do with a MAF system...