Tbi swap build thread

[cjracing15]

Well I would re-trace the wires to see what they are doing.

A-10 is a brown wire from the ecm, and B-10 is a org wire with a blk strip on it. let me know what you find, I am just staring my swap as you can see.

[skidder111]

OK Thanks, man. I will check it out. Will check back here tomorrow.

[rfmaster]

Originally Posted by cjracing15

Well I would re-trace the wires to see what they are doing.

A-10 is a brown wire from the ecm, and B-10 is a org wire with a blk strip on it. let me know what you find, I am just staring my swap as you can see.

P/N line Orange/black wire is grounded by a P/N switch when in park or neutral position. P/N switch ECM input is used by ECM to compensate idle speed when additional engine loads (AC, PS pressure, etc) are present while in drive and within idle speed range. ECM commands IAC to add additional 50 to 75 RPM over commanded idle speed under such conditions. In your case (manual tranny) leave p/n wire open (i.e always in 'drive')

VSS is extremely important for complete EFI operation. It is unfortunate that many omit VSS during conversion. In your case, having 4 speed manual, it is imperative to have a functioning VSS. Since you have 1227747 ECM you'll need to have 2-pulse square pulse VSS inline unit. These are readily available (JTR, others). VSS provides vehicle speed to ECM which uses this input to accurately set fuel mixture and timing. One common problem with absent VSS and manual tranny is a severe drive train jerking during deceleration. This due to inability of ECM, which uses TPS, MAP and VSS inputs, to enter DE/DFCO mode (Deceleration Enleanment / Deceleration Fuel Cut Off).

When the ECM detects a sudden drop in throttle position and engine load, it reduces the injector pulse width while continuing to monitor engine load and vehicle speed. The purpose of DE is to produce a lean fuel mixture by reducing the amount of fuel gong to the engine. DE mode conditions are determined by ECM on a continuous bases provided that 1) Vehicle speed is above XXMPH (this depends on EPROM calibration value), 2) engine load decrease is below a limit value (this parameter also depends on EPROM calibration value), and 3) Filtered %TPS drop is <1%.

The difference between DE and DFCO parameters is that DFCO parameters are based on fixed values stored in EPROM. The DFCO fuel mode is entered after moderate to heavy acceleration then followed by abruptly releasing the accelerator. Usually ECM will transition into DE prior to entering into DFCO mode as the deceleration continues. Interestingly enough operating conditions may or may not cause ECM to command DE exit by itself. However when ECM enters DFCO mode DE is automatically disabled. Usually DFCO is a 'long' term (self resetting) duration event - coasting down hill in gear for example.

Both DE and DFCO are used for emission control, (keeps CATS from being burned up due to excess fuel during deceleration), but the two will effect drive train and exhaust longevity. There are many other ECM controlled parameters that are derived from VSS input.

//RF