[99ludelover]

Ok, here's how I have it, there are 3 different types of ECU's for 5th gens?

1. Stock....OBDII (sucks!)
2. Stock....OBDI (92-96)
2. JDM......

Now me having a 99' what options are the best? Can I order a JDM ECU and have it plug right in? Or do I get the OBDI and do the conversion (seems like a huge PIA). Or, wait till someone breaks the OBDII?

 

[smoothludey]

OBD1 is only up until 95, 96 was the first year of OBD2 although it is less 'strict' than the OBD2 in the 5gens. In the 96 OBD2 i know you can run a test pipe, with the 5gens you normally can't. I never heard of the JDM ECU working in a 5gen, i'm not so sure they're compatible. However, plenty of folks in here have successfully done the OBD1 conversion on their 5gens.

 

[vabeach_lude]

JDM ecus plug right up but I am 99% sure they are intended for 100 octane and up and might have some other miscellaneous differences.

 

[marcucci]

<font face="Verdana, Arial" size="2">Originally posted by vabeach_lude:
JDM ecus plug right up but I am 99% sure they are intended for 100 octane and up and might have some other miscellaneous differences.</font>

A JDM ECU will plug up if it's from the right model- a Type S ecu will pluginto a Type SH (ATTS) but don't expect an S Spec ECU to work on a Type SH or a Type S to work on a base model.

Type SH ECU - Type S ECU
base ECU - S Spec ECU

You'd probably be better off (cheaper) to go with an OBD1 coversion- at least that way you can still reprogram the ECU. Right now, none of the OBD2 ecus can be reprogrammed.

 

[marcucci]

Also, another note- the OBD2 ECUs don't necessarily "suck." You can work around the test pipe problem with a 10M ohm resistor in series with the sense line. You can work around the "detuning" of OBD2 by eliminating the battery backup. You can also fix the run-rich problem ALL ECUs have with an A'pexi or Field AFC.

 

[99ludelover]

Ok, well I have another question.
I have a few friends really into VW's (tattoos and all). And one has a 00' Golf TDi
diesel and on the TDi board they always talk about how they reprogram their ECU? My friend also said that 75% of the people in that board are computer nerds and soft ware writers (no flames from the nerds please, I am one myself). So does that mean that the OBDII codes in VW's have been broken and now they don't need to convert to an OBDI or earlier model? And is there any speculation on when and who is going to brake the ECU for Hondas?

 

[marcucci]

<font face="Verdana, Arial" size="2">Originally posted by 99ludelover:
- snip - So does that mean that the OBDII codes in VW's have been broken and now they don't need to convert to an OBDI or earlier model? And is there any speculation on when and who is going to brake the ECU for Hondas?</font>

The problem is not the code it's the chip. The OBD2 ECUs use a 128 pin QFP processor that has all the RAM and ROM embedded. In short, there's no easy way to get the ROM out of the chip to hack it, and nowhere to put it back into the ECU once you've done it. It's simply easier to convert to a standalone than hack the ECU. Or convert to OBD1.

Oh, yes, you're correct- they broke their code so they don't need the "downgrade" to OBD1. There are companies "reported" to be working on it, but honestly, I think they're just saying that. It's my professional opinion as a hardware designer that it would be cost prohibitive to "crack" our ECU.

 

[vabeach_lude]

<font face="Verdana, Arial" size="2">Originally posted by marcucci:
A JDM ECU will plug up if it's from the right model- a Type S ecu will pluginto a Type SH (ATTS) but don't expect an S Spec ECU to work on a Type SH or a Type S to work on a base model.

Type SH ECU - Type S ECU
base ECU - S Spec ECU

You'd probably be better off (cheaper) to go with an OBD1 coversion- at least that way you can still reprogram the ECU. Right now, none of the OBD2 ecus can be reprogrammed. </font>

Honestly, I have only worked with 4th gen JDM ecu's on USDM Preludes so I actually forgot to mention that. I should have said I dont even know how compatible 5th gen ecu's are.