No start/spark issue
06-27-2022, 12:00 PM
#16
Drifting
Thread Starter
I think this was done successfully when I was trying to implement VEMS. I'll take another look at the schematics.
On 85 schematics, w22 goes to XIV 87, which is the starter relay on an 85.
On 89 schematics, w22 goes to XXV 30, which is LH.
For whatever reason, this pin was pulled and taped off during the VEMS experiment, but I can't find any reason in my notes or in any threads where I was seeking help in converting the 85 CE panel to accept the 89 harness.
I believe this was the only change made to my CE panel or harness.
On 85 schematics, w22 goes to XIV 87, which is the starter relay on an 85.
On 89 schematics, w22 goes to XXV 30, which is LH.
For whatever reason, this pin was pulled and taped off during the VEMS experiment, but I can't find any reason in my notes or in any threads where I was seeking help in converting the 85 CE panel to accept the 89 harness.
I believe this was the only change made to my CE panel or harness.
Last edited by Brett Jenkins; 06-27-2022 at 02:44 PM.
06-27-2022, 03:06 PM
#17
Rennlist Member
Brett,
When alayzing a system I find is usefu to prepare a single line diagram from all the component sinvovled rather than try to work with the wiring diagrams that jump around all over the place with terminal numbers etc etc and if you are not getting the continuity and signals expected then you have to analyse why especially on a mongrel like this as Hans rightly suggests.
I was under the impression you had this system working and then modified it to VEMS but maybe you simply took it from 85 spec to VEMS. Either way you need to ensure the wiring is correct or you have no chance of making the thing work assuming it has never been functional to start with with stoick 89 wiring. The earler 87 LH abnd EZK make no difference to functionality as I am aware- they are all fully interchageable evne though there are some internal differences year to year. All 87 on LH units for sure are innterchangeable and I have fired up mymotor with EZK from 89, 90 and 92 models.
When alayzing a system I find is usefu to prepare a single line diagram from all the component sinvovled rather than try to work with the wiring diagrams that jump around all over the place with terminal numbers etc etc and if you are not getting the continuity and signals expected then you have to analyse why especially on a mongrel like this as Hans rightly suggests.
I was under the impression you had this system working and then modified it to VEMS but maybe you simply took it from 85 spec to VEMS. Either way you need to ensure the wiring is correct or you have no chance of making the thing work assuming it has never been functional to start with with stoick 89 wiring. The earler 87 LH abnd EZK make no difference to functionality as I am aware- they are all fully interchageable evne though there are some internal differences year to year. All 87 on LH units for sure are innterchangeable and I have fired up mymotor with EZK from 89, 90 and 92 models.
06-27-2022, 03:18 PM
#19
Drifting
Thread Starter
When I bought the car several years ago, it had an 85 engine (mostly, S4 intake, heads, etc). It used 85 CE panel and 85 wiring harness.
When I replaced the 85 engine with the 89 S4 engine, I believe the only wiring modification was pulling the W connector pin W22, for reasons I don't remember. This allowed the car to fire up and run (horribly) with VEMS. This was with no MAF and an aftermarket TPS was used. I replaced that TPS with an OEM unit before ditching the VEMS.
Looking through my notes, conversations with Colin J and Peep from Vems, the difference between W22 on an 85 and 89 is that 12v isn't required to be constant on an 85, only present during cranking, but it is expected to be constant on S4. I tested voltage on W22 key off and cranking and got nothing, so that might be my issue. I am troubleshooting that now.
On an 85, it looks like W22 pulls 12v from the 14 pin connector under the hood, controlled by starter relay XIV 87, then goes to LH 4.
On an 89, it looks like W22 pulls 12v straight from the battery, controlled by relay XXV 30, via U12/direct from battery. I see the ignition monitoring circuit is in the mix here, also.
?
So, since this is an 85 CE panel, I should see 12v on W22 only when cranking. During cranking, I only see .05V on W22. A continuity check between W22 and the jump post of the 14 pin connector shows continuity. Any ideas why only .05V on W22. Do I need to wire 12v directly to W22 for it to work with an 89 harness? In a different thread, Greg Brown said."The '85 to '87 relay board conversion is pretty straightforward. You have to add a relay and do some rewiring." but I never got clarification on this or figured it out myself. AS best as I can discern from the 85 and 89 wiring diagrams, something changed as far as the XXV LH relay and the XIV starter relay.
When I replaced the 85 engine with the 89 S4 engine, I believe the only wiring modification was pulling the W connector pin W22, for reasons I don't remember. This allowed the car to fire up and run (horribly) with VEMS. This was with no MAF and an aftermarket TPS was used. I replaced that TPS with an OEM unit before ditching the VEMS.
Looking through my notes, conversations with Colin J and Peep from Vems, the difference between W22 on an 85 and 89 is that 12v isn't required to be constant on an 85, only present during cranking, but it is expected to be constant on S4. I tested voltage on W22 key off and cranking and got nothing, so that might be my issue. I am troubleshooting that now.
On an 85, it looks like W22 pulls 12v from the 14 pin connector under the hood, controlled by starter relay XIV 87, then goes to LH 4.
On an 89, it looks like W22 pulls 12v straight from the battery, controlled by relay XXV 30, via U12/direct from battery. I see the ignition monitoring circuit is in the mix here, also.
?
So, since this is an 85 CE panel, I should see 12v on W22 only when cranking. During cranking, I only see .05V on W22. A continuity check between W22 and the jump post of the 14 pin connector shows continuity. Any ideas why only .05V on W22. Do I need to wire 12v directly to W22 for it to work with an 89 harness? In a different thread, Greg Brown said."The '85 to '87 relay board conversion is pretty straightforward. You have to add a relay and do some rewiring." but I never got clarification on this or figured it out myself. AS best as I can discern from the 85 and 89 wiring diagrams, something changed as far as the XXV LH relay and the XIV starter relay.
Last edited by Brett Jenkins; 06-27-2022 at 04:43 PM.
06-27-2022, 05:05 PM
#20
Former Sponsor
I've done several of these conversions, in both early cars and '85/'86 cars.
Each one has required some alteration of wires at the relay board.
Obviously, the 12 pin connectors on the '87on loom need to be changed for use on the 10 pin '85 relay board, which sounds like you've done.
I've got notes, somewhere, but as I recall, the '85/'86 relays trigger differently than the '87on relays and some changes need to be made on the relay board, itself.
Each one has required some alteration of wires at the relay board.
Obviously, the 12 pin connectors on the '87on loom need to be changed for use on the 10 pin '85 relay board, which sounds like you've done.
I've got notes, somewhere, but as I recall, the '85/'86 relays trigger differently than the '87on relays and some changes need to be made on the relay board, itself.
07-11-2022, 09:10 PM
#22
Drifting
Thread Starter
I noticed something weird during my daily troubleshooting session. This car has always primed the fuel pump when the key is turned on. It did it with the old engine and stock computers and it did it with this 89 engine/harness and it did with VEMS. Something seems to have happened/changed during my intake R&R to fix the vacuum issue, which included replacing the TPS. It did start up right before that and hasn't sparked/started since then. Also, the fuel pump no longer primes with key on, with VEMS or with S4 LH/EZK. The fuel pump does run during cranking though. What I noticed today was that for a second after I pull the EZK connector, the fuel pump runs/primes, every time. I am not sure what that means, though, as far as what is getting triggered when EZK is detached and why it does't happen with EZK attached. If I just turn on the key with the EZK unplugged, the fuel pump does not prime. Side not, is it harmful to detach/attach the ezk connector with key on? Any thoughts?
When I get time this week, I plan on digging into 2 wiring diagrams and figuring out all the triggers so I know if I need any more modifications to the CE panel and/or connectors.
When I get time this week, I plan on digging into 2 wiring diagrams and figuring out all the triggers so I know if I need any more modifications to the CE panel and/or connectors.