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Discussion Starter #1
hey guys,

1996 GQ TI wagon TB42 EFI . Converted from auto to manual.
No power above 80klms an hour.

Been told it is because the computer needs to be changed to a manual computer.

Can anyone confirm this or comment on what the problem could be?

thanks
 

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Someone will know more than me about this, but I think you need to put a diode somewhere on the wiring for the auto trans computer. to "trick" the ECU into thinking you still have an auto. Sorry not more help, but it might give you somewhere to look. All I know is, it can be done without changing computers.

Mark
 

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well towed the boat with it last night. (4.6m tinny) yeh something is really wrong.
a n/a diesel would go better.
have to keep going down gears just to move.
not getting hot or using excessive fuel. will try get a manual computer to try.

thanks
 

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I'll do some research for you as soon as I get chance. You shouldn't need to spend the dollars on a manual ECU, just trick the ECU as said in case it's looking for a trans signal. Did you remove the auto trans computer when you did the manual swap? Or is it still there and sending a signal to the ECU?

While not the same, the EFI systems seem to be fairly similar between RB30E and TB42E due to being similar eras of technology. I run an auto RB30ET ECU on my manaul RB30 and the only difference (Bobby will probably correct me here:p) between manual and auto were rpm points for deceleration fuel cutoff. Timing and fuel maps are the same. The wire for the ECU trans signal is just bundled up, not fed a signal and not earthed on mine.
 

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Did you change final ? what manual gear box did you convert for TB or TD ? If you converted to TB manual box and final remain 3.9 it it too high gear ratio.My friend converted auto to TD manual box with 3.9 final ,AT ECU,255/85R16 33.3inch is no problem .

Edit: neutral signal from trans mission control idol state .
 

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The auto ecu was removed when auto came out. It got a tb manual box put in. It has heaps of power and revs thru the rev range till getting upto 80kms/h after that theres a lack of power. Completely useless for towing and need to find the fault as very frustrating. Changed plugs, leads, dizzy cap, coil and anything else I could think of. Any ideas would be helpful
 

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can u put a scan tool on it
done a couple hundred rb conversions and never had problems running and auto engine ecu
but never touched a tb42 so not sure what could be wrong
does it go hard until an exact km or does power slowly drop off
pull the plug of the speed sensor on gbox and go for a drive
u wont have a speedo but this will also not give ecu speed signal
see if it helps
but I recon maybe some sensor for the motor got disconnected maybe
so get a scan tool and scan the engine ecu and see if u get any codes not related to the auto
 

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Thanks Bobby, it goes hard in all gears and goes thru the rev range upto 4k. But its seems to lose power as the speed builds upto 100k/h. It sits at 2200revs @ 100k but loses power on any hills and put pedel down to flat to floor (only alittle bit of pedel range left, about 1") ill try your suggestions to see how I go.
 

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Well, scanned ecu with scan tool and came up with NO results. Unfortunately it shows no error codes. So back to square 1.... Still lacking power from 80kms up wards. Confused, as it goes hard in lower gears and no delay thru the rev range. Looked for anything disconnected or lose, including vacuum lines. All good there. Any ideas what to do now.to.solve the problem?
 

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Just a thought, it's not something stupid like a blocked fuel filter is it? You might be dropping fuel pressure at the rail in the same amount of time it takes you to get to 80km/h.
 

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Thanks for the idea but I had replaced fuel filter, rotor, dizzy cap, leads, spark plugs and coil. Checked timing, just cant seem to find whats causing the lack of power problem
 
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