1987 -1988 ECU ?

Dave In Indy · 08-30-2009, 05:54 PM

I have a known good ECU for a 1988, and our 1987 MR2 was giving a code 6 for a bad ECU. I swapped the known good one in and I got a code 2 and a check engine light. That code is a O2 code, so my question is are the 2 ECUs not compatible, or is it a bad O2?

mr3 · 08-30-2009, 06:23 PM

They are interchangeable as far as I know. Clear the code, it may be stored in the ECU. Once it's cleared it should be back to normal.

Dave In Indy · 08-30-2009, 09:04 PM

Isn't there a little different EGR system or vacuum system on them? I can't remember what the difference between the years was.

mr3 · 08-30-2009, 09:41 PM

I'm pretty sure the most changes were from 86 to 87. I'm not 100% sure so I'll just let someone else chime in but it will work. I ran an 88 on my 87 for a while just to make sure it worked and everything checked out fine so I got rid of it.

Jackstand Queen · 08-31-2009, 12:42 AM

There was a change in the dizzie in 1988, and they went with a 4 wire O2 sensor I think. Also I think the ignitors changed in 88 also.

So these changes would make swapping ECUs across these years not a good idea.

Papo J · 08-31-2009, 08:23 AM

The NA distributors are all the same except for the high comp engines, the main changes were the 4 wire O2 sensor, location of the EGR pipe and high impedance injectors which do not need the resistor box. From what I've seen, most if not all 87s had the early componnents and electronics.
BTW, a code 6 is for the RPM signal which comes from the distributor and igniter, it is not necessarily a bad ECU code.

Dave In Indy · 08-31-2009, 09:19 AM

I thought the code six was an ecu. What you are ssying makes more sense. The car gets a rough idle once it warms up and will occasionally die at a stop light.

Papo J · 08-31-2009, 12:15 PM

If you have access to a spare igniter, swap yours out with a known good one and see if it runs better. Every code 6 I've seen has been caused by a bad igniter.

Dave In Indy · 08-31-2009, 12:41 PM

Thanks, I'll have to swap out the spare on I have and see what happens.

08-30-2009, 05:54 PM	#1 (permalink)
Dave In Indy Some Skills Join Date: Jun 2009 Posts: 61 Thanks: 1 Thanked 3 Times in 3 Posts iTrader Rating: (0/0% )	1987 -1988 ECU ? I have a known good ECU for a 1988, and our 1987 MR2 was giving a code 6 for a bad ECU. I swapped the known good one in and I got a code 2 and a check engine light. That code is a O2 code, so my question is are the 2 ECUs not compatible, or is it a bad O2?

08-31-2009, 12:42 AM	#5 (permalink)
Jackstand Queen Cage Fighter Join Date: May 2008 Posts: 840 Thanks: 75 Thanked 64 Times in 60 Posts iTrader Rating: (1/100% )	The pre 88 an the 88 and later There was a change in the dizzie in 1988, and they went with a 4 wire O2 sensor I think. Also I think the ignitors changed in 88 also. So these changes would make swapping ECUs across these years not a good idea.

08-31-2009, 08:23 AM	#6 (permalink)
Papo J 6SPD GTE Join Date: Sep 2006 Posts: 591 Thanks: 2 Thanked 50 Times in 49 Posts iTrader Rating: (0/0% )	The NA distributors are all the same except for the high comp engines, the main changes were the 4 wire O2 sensor, location of the EGR pipe and high impedance injectors which do not need the resistor box. From what I've seen, most if not all 87s had the early componnents and electronics. BTW, a code 6 is for the RPM signal which comes from the distributor and igniter, it is not necessarily a bad ECU code. Last edited by Papo J; 08-31-2009 at 08:29 AM..

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08-30-2009, 06:23 PM	#2 (permalink)
mr3 unskilled Join Date: Jun 2008 Location: Plymouth Mtg, Pa Posts: 2,408 Thanks: 24 Thanked 98 Times in 93 Posts iTrader Rating: (7/100% )	They are interchangeable as far as I know. Clear the code, it may be stored in the ECU. Once it's cleared it should be back to normal.

08-30-2009, 09:04 PM	#3 (permalink)
Dave In Indy Some Skills Join Date: Jun 2009 Posts: 61 Thanks: 1 Thanked 3 Times in 3 Posts iTrader Rating: (0/0% )	Isn't there a little different EGR system or vacuum system on them? I can't remember what the difference between the years was.

08-30-2009, 09:41 PM	#4 (permalink)
mr3 unskilled Join Date: Jun 2008 Location: Plymouth Mtg, Pa Posts: 2,408 Thanks: 24 Thanked 98 Times in 93 Posts iTrader Rating: (7/100% )	I'm pretty sure the most changes were from 86 to 87. I'm not 100% sure so I'll just let someone else chime in but it will work. I ran an 88 on my 87 for a while just to make sure it worked and everything checked out fine so I got rid of it.

08-31-2009, 09:19 AM	#7 (permalink)
Dave In Indy Some Skills Join Date: Jun 2009 Posts: 61 Thanks: 1 Thanked 3 Times in 3 Posts iTrader Rating: (0/0% )	I thought the code six was an ecu. What you are ssying makes more sense. The car gets a rough idle once it warms up and will occasionally die at a stop light.

08-31-2009, 12:15 PM	#8 (permalink)
Papo J 6SPD GTE Join Date: Sep 2006 Posts: 591 Thanks: 2 Thanked 50 Times in 49 Posts iTrader Rating: (0/0% )	If you have access to a spare igniter, swap yours out with a known good one and see if it runs better. Every code 6 I've seen has been caused by a bad igniter.

08-31-2009, 12:41 PM	#9 (permalink)
Dave In Indy Some Skills Join Date: Jun 2009 Posts: 61 Thanks: 1 Thanked 3 Times in 3 Posts iTrader Rating: (0/0% )	Thanks, I'll have to swap out the spare on I have and see what happens.