4A-GE ECU conversion

**Blackers** · 25-08-2006, 10:57 PM

I have converted my 88kw AE86 ECU to a 100kw AE 92 ECU, we changed the dizzy, fitted the knock sensor and air temp probe and changed the injectors from green top to yellow top. I fitted the correct MAP sensor that came with the ECU but we are now having dramas with the car running rough and only driving on light throttle, heavy throttle applications cause it to run like it's either very lean or very rich (like a pig really) but I haven't put a mixture meter on it to find out how lean/rich. The only fault code I have is 42 which is a road speed sensor fault, nothing else comes up. I have checked the resistance of the injectors, they are the 13.5 ohm units. We changed injectors as the car ran way too rich with the green tops in, the only 100kw parts not fitted are the coil and ignitor. I have been told that the ECU has come from an AE92 SX seca with the 100kw motor, I have the same motor fitted to the car in question (my AE 86) and it has the small port head and standard 100kw inlet manifold and throttle body. Ideas anyone? Will pay beer to the person who can solve the mystery.
Cheers
Blackers

**slide86** · 25-08-2006, 11:42 PM

check the adjustment of the TPS? this maybe out of whack

**Vios-GT_07** · 26-08-2006, 03:55 AM

doesn't the 100KW ecu come with an AFM rather than a MAP sensor?

road speed sensor? does that point toward yoru speedometer or a speed's input to your ECU? that has to be significant.. also any issue with ABS?

okay now u've lost me... so your car has a 100KW motor, but has a 86KW ECU..? then u're changing that ECU to a 100KW ECU??

**Blackers** · 26-08-2006, 01:15 PM

I got given a 100kw engine from an AE92, no wiring harness though. I had an AE86 86kw factory harness and ECU etc, the original 4AC wasn't up to the task so the 100kw went in. I recently aquired a 100kw ECU and MAP sensor from what I was told was an AE92 (member name is Bayka) but didn't think to get the coil and ignitor. The ECU has a PIM pin which is for the MAP sensor signal and this has been wired accordingly. AE86 doesn't have ABS, well at least mine doesn't and I know that the AE92 uses road speed signal for fuel economy and idle control circuts, hence my car hunting when you pull up to the lights initially. I believe that some of the earlier 100kw engines were MAP sensor rather than AFM but I am not sure. Will try the TPS and see if it helps.

**parrot** · 26-08-2006, 09:19 PM

What flow are these yellow injectors? I would put the green tops back in as the ECU fuel map will match them.

**Grega** · 27-08-2006, 02:01 AM

if u disconnect the MAP sensor does anything change?
ie: disconnect it ; start car ; see if it behaves the same way?

**Blackers** · 01-09-2006, 02:34 AM

Disconnecting the MAP sensor brings up a code and the car will run but not as well. The yellow injectors are 213cc units, the green ones make the car run very rich which given that I believe they are 260cc items would make sense. I have reset the TPS as per the manual, no difference to the performance or lack thereof in this case. I still suspect the coil and ignitor could be an issue but am having trouble tracking 1 down at the right price atm. Have been thru and checked things like air temp sensor resistance and set the timing as per the manual, I even measured the resistance of the MAP sensor against the old one and it appears to be the same. Going to have a lack of hair shortly as I am pulling it all out and I'm getting tired of riding the bike around!

**Grega** · 01-09-2006, 05:24 AM

OK. so MAP is OK
an ae92 SX should be running green injectors.
two things
try disconnecting the cold start injector - i wonder if this is leaking or dribbling perhaps?
which air temp sensor do you have? is it a big blue thing that sits on the side of the airbox?

**c2888** · 01-09-2006, 07:37 AM

new spark plugs?
new fuel filter?
steady fuel pressure?
Timing set correctly? 10 deg btdc with t and e1 pinned

Dan

**Blackers** · 01-09-2006, 09:29 PM

Can't remember what colour the air temp sensor is and I have unfortunately had to go to a site for work (Heavy duty plant mechanic with the WA CAT dealer) so won't be able to play cars til I get back. Will post with more updates once I'm home again, thanks for the tips so far.

**Cuzzo** · 02-09-2006, 09:10 AM

im thinking timing. Have you put the dizzy in correctly? Lined up the dots/lines on the dizzy to the eninges indicators? At TDC?

**Blackers** · 18-09-2006, 04:31 PM

Got back on Saturday night and had a play with the car yesterday, discovered the E21 and VF wires are around the wrong way after starting from scratch and tracing all the wiring 1 at a time. Car seems to be running alot better so I put the green injectors back in. Not alot of difference between the yellow and green in terms of performance but it idles better with the green ones. Still seems a little doughy top end compared to the old ecu but has much nicer low end/midrange and this could be masking the fact that it's going just as hard but cause it's fatter down low I don't notice it as much. Going to drink copious quantities of beer to a) Get over the car issue and b) I now remember why I hate working on minesites! Thanks to all those with ideas, not sure why it works now but it does so I'm going to leave it at that.
Cheers
Blackers

**Grega** · 18-09-2006, 05:11 PM

good work mate.

**roadsailing** · 18-09-2006, 06:27 PM

how are you controlling TVIS?

**Blackers** · 18-09-2006, 11:12 PM

The engine does not have TVIS, I originally modded a 100kw inlet manifold to fit the car ie changed the throttle body from 1 end to the other as I didn't have the standard AE86 inlet manifold. I have my own TIG and was able to get the end faced at work to allow me to put the TB on after I welded a plate to the manifold which I put a big hole in and drilled/tapped the mount holes for the TB, seems to work ok.

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