Wiring issues???

[dei4ever03]

First off, I am new to posting on these things. I have a 1991 eclipse that i have done a transmission swap from auto to manual. as well as the ecu and some wiring for reverse lights and power(as if the auto trans is in park to start the engine)..

got the car up and running. but its running pretty rich. I am getting error codes from the ecu. they are 13(intake air temp sensor) 21 (engine coolant temperature sensor) and 25(Barometric pressure sensor)

i've checked all the voltages and so on from the shop manual the sensors are good (although i did replace the coolant sensor) and the voltage measurements from the harness were good.

so does anyone have any ideas on why my ecu will keep coming up with these codes? even after you disconnect the battery.

 

[GTM]

...

i've checked all the voltages and so on from the shop manual the sensors are good (although i did replace the coolant sensor) and the voltage measurements from the harness were good.

so does anyone have any ideas on why my ecu will keep coming up with these codes? even after you disconnect the battery.

I can only hazard a guess the answers are to be found in the automatic tranny swap to manual tranny. You may get lucky and find someone who has done this and encountered some of the problems you have but I'm afraid it will be nothing more than grunt work of sorting out what you connected to where. Most people who attempt what you have done realize they are on their own for the conventional diagnosis and solution does not apply.

Most important will be the misidentification of what you thought was a ground was in fact part of the bulb check and similar posting circuits.

Perhaps if you tried a different approach and included auto to manual tranny swap in the subject you would have better luck.

Anyone know who has been here and done that??

Cheers,
GTM

 

[dei4ever03]

I do appreciate the reply, although i did no modifications to these circuits. they all involved jumping a couple wirings at the auto transmission electrical plug. and the reverse lamp circuit got put to the manual transmission back up sensor.

These sensors that I am getting the error codes on have not been messed with, and were working before. the only difference now would be the ecu's. i have seen a pin diagram for AN ecu, i don't believe there was a difference between the auto/manual ecu's

please anyone, any ideas?

 

[LunarEclips]

auto and manuel ecu's are different. I'm sorry to say that i have never done the swap, but you certainly sound like you have ecu wires mixed up in those specific areas... I know you say you have not changed the wires to your ecu, but you will have jump wires around on your ecu. I was reading a thread about it somewhere here on dsmtuners, so you might want to do a search. Good luck and let us know how it turns out.

 

[steve]

Do you get the same errors if you put the old automatic ECU in the car?

Steve

 

[dei4ever03]

I'm dissapointed to say, that i no longer have the automatic ecu in hand. it was sold.

I do know the ecu's are different, the manual is programmed to control the bigger fuel injectors. but the pin outs ... ?

i will be talking to a dealership monday, to find out much the manual wiring harness costs.

as a used one is 15-16 years old and all dryed up and cracked from age/weather anyways.

 

[steve]

I do know the ecu's are different, the manual is programmed to control the bigger fuel injectors. but the pin outs ... ?

Are identical.

i will be talking to a dealership monday, to find out much the manual wiring harness costs. :cry

More than your car is worth.

What I was trying to get at was this could easily be a problem with the ECU rather than the wiring. Swapping a known good ECU would be the first step to isolating the problem.

Steve

 

[dei4ever03]

Thanks for the suggestions! I have a remanufactured ecu coming this wednesday. If it turns out my ecu isnt bad, I'll just return it

I will let you know what happens either way. I do appreciate the help.

 

[GTM]

...
What I was trying to get at was this could easily be a problem with the ECU rather than the wiring. Swapping a known good ECU would be the first step to isolating the problem.

Steve

For my edification are there sensors and controls on the auto which must fit one condition and not another?? For example, it cannot be indicating being in both 1st and drive at the same time or torque converter lock at 5mph etc.

I was thinking by him jumpering switches etc. it may be receiving conflicting info for which if it loads up the ECU resorting to taking default conditions X times it then goes into overload and can't cope. Or if it's supposed to be reading a value it sees a complete open or shorted circuit.

I too remember seeing a thread maybe a year+ ago about changing pins at the ECU but that's about all. Cant remember who the protagonists were or why.

I'm at a loss here and wondering why he would have to rewire the reverse lights?? I don't know if they are part of the bulb check circuit. There are too many what iffs for me to help without having the resources and knowing how he handled each condition.

Cheers,
GTM

 

[dei4ever03]

GTM..
i meant by rewiring the reverse.. origingally its going to the autotransmission plug, now its wired to the backup sensor on the manual transmission.

 

[steve]

The ECU doesn't communicate with the transmission except for the safety interlock for idle speed control. DSM's have a TCU on automatic cars the controls the trans. It shares inputs with the ECU for sensors like the TPS, Vehicle Speed Sensor, etc.

The difference between the automatic turbo ECU and the manual turbo ECU is due to the engine differences. The auto engine gets milder cams, smaller injectors and a smaller turbo. The programming in the ECU is set up for these differences. If one was to upgrade the car and retain the stock automatic ECU the car would still operate but run richer due to the ECU thinking it was using 390cc injectors (@ 43.5 psi) when in fact the injectors were 450cc (corrected to 411cc @ 36 psi)

The reason I suggested swapping the old ECU in was because the new manual ECU is a unknown. Since capacitor leakage is so common and can cause thses error codes it's smart to see if another ECU gives the exact same errors before spending more time chasing wiring problems that may be ghosts.

Steve

 

[dei4ever03]

i did not mention that when i did this swap, i parted out the engine in the car (because it was for the auto transmission with the differences I knew, and you have spoke of.)

I then bought a JDM engine, same thing except for the cyclone intake. It also came with the 5-speed transmission, transfer case, and the 16g turbo. this is why i purchased an ecu from a manual transmision gsx on ebay(mdq166262), and i was told it was working

my sensors are getting the right voltages to them, and giving the right resistances back, i have done all the tests my shop manual suggests. this does lead to the ecu being possibly bad. I guess I will only know once it comes in.

 

[dei4ever03]

just an update:

the new ecu did it, the codes are gone

just wish you could trust some people in the world... if a parts working or not.

 

[steve]

Glad to hear that was the problem. I'm not too surprised.

Steve

 

[GTM]

just an update:
the new ecu did it, the codes are gone
just wish you could trust some people in the world... if a parts working or not.

Kudos to Steve for the solution on what could have been a nightmare.

As I keep saying, it's hard to get good help any more. Finding a professional in this industry is difficult at best whether it's parts staff or the guy twisting wrenches.

Good luck on your project and the dogged effort to get it done.

Cheers,
GTM