OBD1 converted to OBD2 (problems)

[twolf1 0]

My friend recently converted my 93 reg OBD1 to an OBD2 engine due to original being knackered.

All went well with the conversion untill we realised there was no where to fit the chip key transponder box thing. Because of this we had to put the original wiring loom (OBD1) on the new engine (OBD2).

Because of this the new ECU (OBD2) couldnt be fitted as it wont work without the new loom, chip key etc....

At the mo the car is working on the old ecu (OBD1) but am worried that some problems may be brewing.

can anyone help as I still have the new ecy and loom if anyone knows how to fit this.

Any help would be appreciated as its kinda outa our league

Appreciated :^)

[cabrioman 6]

if ur changing from obd 1 - 2 then you need to replace the loom from the fuse board out, intake mani, throllte body, rad fans, lamda probe, maf, fan controler module (under the expansion bottle) and get the imoblizer removed from the ecu which united motorsport can do for you ...

[twolf1 0]

Shit, quite a bit more work needed then.

How come the engine works/runs on the old ecu...

Is it dangerous driving it as it seems to run fine?

[Rikki 2]

So your not running obd2 your runnin obd1 with a later engine.......which is identical to an early one! On Board Diagnostics is what it stands for its the management not the engine!!

[twolf1 0]

the engine is quite different - the original is 93 L reg and the new one is P reg 96/97. Looks like the new one doesnt have an idle control valve.

All the Loom from the original fits the later engine. Just worried if running the ECU from the OBD1 engine is bad or can I keep it as it is as it seems to be running fine

(dont really understand cars enough)

[UnitedMotorsport 55]

I think we need to know some specifics here!

• What inlet manifold/Throttle body has been used? OBD1 or 2?

• What main engine management loom (from fuse board to engine/ECU) has been used? OBD1 or 2?

• The little loom on the engine (Goes from round multiplug to injectors etc.) Which has been used OBD1 or 2?

If the answer to the 3 above questions is all OBD1 then you have no problems.

Just to clear a few things up:

An ENGINE being a block and head with no ancillaries : OBD1 and OBD2 engines are the same thing. Just because you fit an OBD2 ENGINE to an OBD1 car doesnt mean that you need to fit the OBD2 ECU. It also means that your car is still OBD1

OBD stands for On Board Diagnostics.-This is a function of the ECU and has nothing to do with the physical ENGINE that is fitted.

The inlet manifold and throttle body are not the same between an OBD1 and OBD2 setup.

[twolf1 0]

ur an absolute STAR x made it sounds very simple to understand

I have left the throttle body on the new engine as it was (so better add the old throttle body back on to the engine) It was ideling very high. I take it it is a universal fitting

Main engine management loom was left OBD1

Little loom was kept OBD1

Thats brill - so as long as I put the original throttle body back on then all is fine with the engine

[twolf1 0]

Out of interest - why does the original throttle body have to go back on the new(er) engine

is it controlled by the obd2 ecu so as i have the obd1 ecu on there it needs the original throttle body to control it?

(sorry if i sound dunb, but we all go to start somewhere)

[Rikki 2]

You just use the main block from the late car....im runnin an early 2.9 in my 98 car.....you use all tb inlet everythin from your existing car!

[UnitedMotorsport 55]

Out of interest - why does the original throttle body have to go back on the new(er) engine

is it controlled by the obd2 ecu so as i have the obd1 ecu on there it needs the original throttle body to control it?

(sorry if i sound dunb' date=' but we all go to start somewhere)

[/quote']

To put the OBD1 throttle body back on your engine, you will also have to change the inlet manifold, as the throttle bodys have a different bolt pattern.The OBD1 manifold also has the port for the Idle control valve.

On an OBD2 setup, the ECU controls the throtle body, and on the OBD1 it doesnt.

[twolf1 0]

brill - i will change this this weekend (hopefully its easy to change?)

By the way, the engine is now running very rich and ideling very high (I now can assume the high idle/fuel mix is because of the wrong throttle body and making the car idle way higher than expected)

[twolf1 0]

Just wanted to say thanks for the advice on changing over the throttle body and manifold - Done this last night, only took about an hour and engine is running like it always was again.

No ideling on 20000, no black smoke coming from exhaust. Very happy again

Wudnt of been able to do it without the advice, was seriously scratching my head for ages tryna work out what was wrong with emmissions and idle.

As I said, thanks