87 S4 LH-Jet Engine Management Harness-what would you do?
10-16-2012, 10:09 AM
#1
Three Wheelin'
Thread Starter
87 S4 LH-Jet Engine Management Harness-what would you do?
So when i pulled the engine management harness off my 87 S4 motor, it was in fair condition but i really didn't want to just put a 25 year old harness back on a motor that will eventually have all new ECM/EZK inputs that comes with doing an intake refresh. I wanted to make a new one, but unfortunately the ECM/EZK harness has many special connectors and a TON of wiring, so i think making one from scratch is way beyond my skills (or lack therof).
With some new 2 pin, 3 pin connectors, and an MAF connector, it would probably be just fine to use. Looking at the price of a brand new one from 928 Specialists ($900 dollar range), would it be a wise decision to sell my existing harness to go towards a brand new one? I just want the motor to run perfect when i'm done with this project, and i want to eliminate the wiring harness as a possible trouble point so that there are less variables to think about when diagnosing driveability/running issues.
What would you do? When i consider the time, effort, money, and pain it would be to make one, the price of a new one isn't all that bad considering it would probably last at least another 15-20 years, and maybe more if i bought some firesleeving to go over the existing plastic sheathing. I know how sensitive EFI systems are to slightly out of spec resistances in the harness thus causing inaccurate signal voltages going into the ECM/EZK module and therefore causing inaccurate outputs.
With some new 2 pin, 3 pin connectors, and an MAF connector, it would probably be just fine to use. Looking at the price of a brand new one from 928 Specialists ($900 dollar range), would it be a wise decision to sell my existing harness to go towards a brand new one? I just want the motor to run perfect when i'm done with this project, and i want to eliminate the wiring harness as a possible trouble point so that there are less variables to think about when diagnosing driveability/running issues.
What would you do? When i consider the time, effort, money, and pain it would be to make one, the price of a new one isn't all that bad considering it would probably last at least another 15-20 years, and maybe more if i bought some firesleeving to go over the existing plastic sheathing. I know how sensitive EFI systems are to slightly out of spec resistances in the harness thus causing inaccurate signal voltages going into the ECM/EZK module and therefore causing inaccurate outputs.
10-16-2012, 01:09 PM
#6
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
When I did my TB and intake refresh I replaced the 11-pin connector on the front harness and replaced all connectors and boots on the engine harness. First time for me and yes it is a bit of a hassle to be honest, but very doable once you get the hang of it. If it is off the car still easier. In any case you will need the housings, pins, weather seals (mostly 1 mm) and boots plus the correct pliers for the job. Also some silicone paste to help get the boots on.
10-16-2012, 03:23 PM
#7
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
I think every connector is available, so it shouldn't be a big issue. If I were up to the fun of replacing all the engine-end pieces, I'd probably want to use new, later-technology conductors too. Buying cut lengths of correct-color wire gets really expensive really fast, so some economy of scale requires that you make several and sell the ones you don't use to justify doing your own.
----
I watched aircraft wiring harnesses being made at the old McDonald-Douglas factory in Long Beach many years ago now. Essentially larger-scale nail-boards were used. Challenges came when certain airframes were assembled in slightly different order. If hydraulics went in before wiring, the original wire lengths were too short. The hydraulic guys would rush in to get their plumbing in first so they wouldn't have to fuss with already-installed wiring. There's a reason why they are closing that plant.
---
I had the pleasure of working on a lot of interesting British cars over the years. None more interesting than those equipped wit Lucas-supplied harnesses. Assembled by folks who seemed to run out of certain wire colors once in a while. No worries, just do a flying twist-splice in the middle of a harness section, so the colors at one end didn't always match the colors at the other end. Plus the splice itself was not so durable. The small-production cars like Lotus were perhaps the most villainious, because their documentatiuon was sketchy at best, the wire sizes almost always too small, and loads would be added during design and assembly, forcing the use of larger fuses for the same too-small wiring.
Bottom line is that the 928 is golden compared to many interesting cars of the same period.
----
I watched aircraft wiring harnesses being made at the old McDonald-Douglas factory in Long Beach many years ago now. Essentially larger-scale nail-boards were used. Challenges came when certain airframes were assembled in slightly different order. If hydraulics went in before wiring, the original wire lengths were too short. The hydraulic guys would rush in to get their plumbing in first so they wouldn't have to fuss with already-installed wiring. There's a reason why they are closing that plant.
---
I had the pleasure of working on a lot of interesting British cars over the years. None more interesting than those equipped wit Lucas-supplied harnesses. Assembled by folks who seemed to run out of certain wire colors once in a while. No worries, just do a flying twist-splice in the middle of a harness section, so the colors at one end didn't always match the colors at the other end. Plus the splice itself was not so durable. The small-production cars like Lotus were perhaps the most villainious, because their documentatiuon was sketchy at best, the wire sizes almost always too small, and loads would be added during design and assembly, forcing the use of larger fuses for the same too-small wiring.
Bottom line is that the 928 is golden compared to many interesting cars of the same period.
Trending Topics
10-17-2012, 07:44 AM
#8
Three Wheelin'
Thread Starter
Thank you for offering your opinions and advice. I really wish i could contribute more to helping other people on here as much as they help me.
To address some of the posts re: the wiring harness.
Ted; I know Carl for sure makes the front engine wiring harness that controls/runs to many of the engine bay subsystems (charging circuit, oil pressure sender, various other sensors/sending units). However this harness is for the ECM/EZK, and i don't think anybody on here or any aftermarket company such as 928MS has actually made one of these. If i was a member i would post pics of the harness, but it is damn complicated, especially near the firewall sealing boot where i see close to 100 wires of varying gauges.
Ducman; same as above, i would think the ECM/EZK harness is too complicated to reliably replicate.
John and Lizard; so should i just cut off the connectors that are shot/questionable, and find the resistance of each wire at each connector? The special 928 specific connectors luckily don't look too bad, it's mostly the ones that are exposed to the oils/heat of the motor, which happen to be mostly 2 and 3 pin ones, and the 6 pin MAF.
Bob; Your post was interesting to read. The British cars you mentioned were after all built by "Turnip farmers" as Jeremy Clarkson likes to refer to Lotus, weren't they? Lucky i don't have an old roadster eh? That would be hell to try to diagnose a problem, when your wiring diagrams say one thing but in actuality it is totally different.
To address some of the posts re: the wiring harness.
Ted; I know Carl for sure makes the front engine wiring harness that controls/runs to many of the engine bay subsystems (charging circuit, oil pressure sender, various other sensors/sending units). However this harness is for the ECM/EZK, and i don't think anybody on here or any aftermarket company such as 928MS has actually made one of these. If i was a member i would post pics of the harness, but it is damn complicated, especially near the firewall sealing boot where i see close to 100 wires of varying gauges.
Ducman; same as above, i would think the ECM/EZK harness is too complicated to reliably replicate.
John and Lizard; so should i just cut off the connectors that are shot/questionable, and find the resistance of each wire at each connector? The special 928 specific connectors luckily don't look too bad, it's mostly the ones that are exposed to the oils/heat of the motor, which happen to be mostly 2 and 3 pin ones, and the 6 pin MAF.
Bob; Your post was interesting to read. The British cars you mentioned were after all built by "Turnip farmers" as Jeremy Clarkson likes to refer to Lotus, weren't they? Lucky i don't have an old roadster eh? That would be hell to try to diagnose a problem, when your wiring diagrams say one thing but in actuality it is totally different.
10-17-2012, 02:40 PM
#9
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
...
Bob; Your post was interesting to read. The British cars you mentioned were after all built by "Turnip farmers" as Jeremy Clarkson likes to refer to Lotus, weren't they? Lucky i don't have an old roadster eh? That would be hell to try to diagnose a problem, when your wiring diagrams say one thing but in actuality it is totally different.
Bob; Your post was interesting to read. The British cars you mentioned were after all built by "Turnip farmers" as Jeremy Clarkson likes to refer to Lotus, weren't they? Lucky i don't have an old roadster eh? That would be hell to try to diagnose a problem, when your wiring diagrams say one thing but in actuality it is totally different.
As far as "lucky I don't have an old roadster eh?": Eh, no, you are not as lucky as you might be if you actually had one intact and drivable. The early cars were purpose-built hill-climbers and 'special stages' cars. Then sports-racers, and on to the GP cars using others' engines and gearboxes. On the road-going side, the philosophy that 'just good enough to finish the race is good enough' carried through nicely. No chance that they would survive a typical American's driving and maintenance and repair habits, for sure. So most didn't. Europas are quite fragile, and most ended up with the tail stuffed into the inside barriers at the hands of the average weekend racer. Early Elan road cars are a ton of fun, especially with a little extra power. The roadsters are especially fun to drive, and provided the direct inspiration for the 1.2x-scaled Mazda Miata. Those early cars were built for scrawny short Brits with tiny feet. If ypou are under 5'8", 140lbs, and have size 36 feet or smaller, you are an Elan roadster candidate. Larger need not apply.
10-17-2012, 03:08 PM
#10
Pro
Join Date: Jan 2005
Location: Centennial, WY
Posts: 612
Likes: 0
Received 0 Likes
on
0 Posts
Jet engine management???
When I started working in the Pratt and Whitney Aircraft Engineering Department in 1961 after getting my degrees the only electrical stuff on an engine was an exciter wired through braided cable to an exciter (like a spark plug). We dared not even speak about electronic stuff as this was considered too unreliable. All controls were hydromechanical. Oh for the good ol' days.
When I started working in the Pratt and Whitney Aircraft Engineering Department in 1961 after getting my degrees the only electrical stuff on an engine was an exciter wired through braided cable to an exciter (like a spark plug). We dared not even speak about electronic stuff as this was considered too unreliable. All controls were hydromechanical. Oh for the good ol' days.
10-17-2012, 08:25 PM
#11
Three Wheelin'
Thread Starter
Mechanical actuation/engagement/injection is deffinitely more reliable. Just look at diesels, they usually outlast the body of any domestic truck/car by a lot.
Bob; What's your opinion on Jags from the 80's-90's in terms of their electrical systems? I heard that Jags (or at least the original non-Ford ones) were notorious for having an electrical system that was just thrown together in the "it works, good enough" fashion. After the 928 or even during, if i get a high paying job, i would love to get an XJS. I constantly fantasize about driving through the local country roads listening to classical music in a comfy luxurious XJS. Ahh.
Bob; What's your opinion on Jags from the 80's-90's in terms of their electrical systems? I heard that Jags (or at least the original non-Ford ones) were notorious for having an electrical system that was just thrown together in the "it works, good enough" fashion. After the 928 or even during, if i get a high paying job, i would love to get an XJS. I constantly fantasize about driving through the local country roads listening to classical music in a comfy luxurious XJS. Ahh.
10-17-2012, 09:20 PM
#12
Rennlist Member
At the risk of dating myself........
Anything British with the name "Lucas" attached to the electrical system......
Run Away....
or replace at your leisure......
Anything British with the name "Lucas" attached to the electrical system......
Run Away....
or replace at your leisure......
10-17-2012, 09:23 PM
#13
Rennlist Member
And,
Mechanical actuation/engagement/injection is deffinitely more reliable. Just look at diesels, they usually outlast the body of any domestic truck/car by a lot.
Bob; What's your opinion on Jags from the 80's-90's in terms of their electrical systems? I heard that Jags (or at least the original non-Ford ones) were notorious for having an electrical system that was just thrown together in the "it works, good enough" fashion. After the 928 or even during, if i get a high paying job, i would love to get an XJS. I constantly fantasize about driving through the local country roads listening to classical music in a comfy luxurious XJS. Ahh.
Bob; What's your opinion on Jags from the 80's-90's in terms of their electrical systems? I heard that Jags (or at least the original non-Ford ones) were notorious for having an electrical system that was just thrown together in the "it works, good enough" fashion. After the 928 or even during, if i get a high paying job, i would love to get an XJS. I constantly fantasize about driving through the local country roads listening to classical music in a comfy luxurious XJS. Ahh.
Actually had a friend years ago who could afford a stable...(NSX, '67 Vette, etc. etc. ad nauseum...
Always drove his XJS rag...his absolute favorite.....
10-17-2012, 09:25 PM
#14
Rennlist Member
Yes
At your age, fantasies are normal....
Don't worry, most will pass....
Don't worry, most will pass....
Mechanical actuation/engagement/injection is deffinitely more reliable. Just look at diesels, they usually outlast the body of any domestic truck/car by a lot.
Bob; What's your opinion on Jags from the 80's-90's in terms of their electrical systems? I heard that Jags (or at least the original non-Ford ones) were notorious for having an electrical system that was just thrown together in the "it works, good enough" fashion. After the 928 or even during, if i get a high paying job, i would love to get an XJS. I constantly fantasize about driving through the local country roads listening to classical music in a comfy luxurious XJS. Ahh.
Bob; What's your opinion on Jags from the 80's-90's in terms of their electrical systems? I heard that Jags (or at least the original non-Ford ones) were notorious for having an electrical system that was just thrown together in the "it works, good enough" fashion. After the 928 or even during, if i get a high paying job, i would love to get an XJS. I constantly fantasize about driving through the local country roads listening to classical music in a comfy luxurious XJS. Ahh.
10-17-2012, 09:39 PM
#15
Nordschleife Master
