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Thread: Deciphering Fuel Enrichment Relay Setup

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  1. #1
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    Deciphering Fuel Enrichment Relay Setup

    Up until yesterday my DeLorean has been running pretty well. At least well enough that I haven't been poking around much lately. One thing my to-do list was get some mufflers installed and have a bung added so I could re-install the O2 sensor. (I discovered after purchasing the old sensor had been cut out of the exhaust and zip-tied to the frame. It's an island twin turbo, and on the way to the muffler shop I know the turbo was working - I could easily hear it spinning up.

    They didn't have any mufflers that would fit, but they did weld in a bung with a plug. This quieted things down a bit and on the way home I was listening more to the difference in the exhaust noise than paying attention to the turbos. When I got home I installed the new O2 sensor after the exhaust cooled down. I simply swapped it with the old one and spliced it to the wire running through the frame into the lambda ECU. The first thing I expected to see was the AF gauge next to the boost gauge react, but when that didn't happen, I found it looks like the gauge is wired to power, but the signal wire wasn't connected to anything.

    On the way to get some extra wire to hook the AF gauge I realized the turbos were no longer kicking in. In fact, the boost gauge is around -20 at idle, as usual, but under load won't pass 0. Previously it would get to around 3-4 and I'd hear the turbos spin up. I checked all the vacuum hoses, and all the clamps on the the turbo setup and couldn't find any leaks. Well, I did look inside the cubby in the engine bay and found nothing was connected to the carbon canister. I plugged everything back in but it didn't make any difference. I looked all around where the bung was welded and couldn't find anything that would've been disturbed.

    Question #1 is: what is happening? If it's a vac leak, why do I still show -20 on the boost gauge?

    In researching, I pulled out the turbo install guide looking for anything that might help. I went to check the hobbes switch was connected properly according to the docs and found it was different. Based on the install docs, I expected to find 2 hobbes switches between the ECU and O2 sensor. Instead I have one that's wired up to a relay and the O2 sensor isn't part of the circuit. I have a lot of paperwork passed down from POs and found a diagram and some notes related to a fuel enrichment relay mod - pics attached. The O2 sensor is noted, but I'm not sure from reading this where I'd need to wire it in.

    So question #2: How reliable does this setup look - is it worth trying to get back to this, or should I try to get back to the stock setup? How likely is this to have anything to do with loss of turbo functionality since it appears the O2 sensor hasn't been wired in all along.

    IMG_6218.jpgIMG_6219.jpgIMG_6220.jpgIMG_6223.jpgIMG_6227.jpg

  2. #2
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    It was originally done with 2 switches but it is easily done with one and a relay. Doesn't matter as long as you hook it up right. The turbos are operated purely on manifold vacuum. Hooking up the O2 sensor should not have had any effect on boost. Check the hoses to the actuators, maybe they were disturbed when the shop did the bung. The switches and relay are so the A/F meter can use the same O2 sensor and under boost force full enrichment using the WOT circuit. The mufflers are nothing special but if you are going through the trouble of adding mufflers, the later kits used catalytic convertors to reduce the noise and clean up the exhaust. More expensive but cleaner. The muffler is a Walker, I can look up the # if you need it. I can also send you some wiring layouts if you need. Make sure all of the air hoses are in good condition with no leaks and the clamps are all on tight. Verify the timing and advance. Double-check the boost is limited to 5# on both actuators and that they move freely. Good idea to also check the turbo air output for any signs of oil once in a while. Use synthetic oil and change it often. When the Island Turbo kit is working correctly it is a BLAST!
    David Teitelbaum

  3. #3
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    That's good to know. So if I leave the relay in, I'll need to wire in the O2 sensor according to the PO's diagram. The only difference seems to be the connection to the ECU / O2 sensor is currently spliced into the Blue/Black wire on the harness for the cold start valve. If I'm reading the factory wiring diagram correctly, that traces back to either the thermo time switch or the hot start relay. So that means the hobbs switch is dictating whether this circuit is active - what sense does that make?

    I think the air hoses look good, and I checked the actuators this morning - they seem to be in good shape.

    If you could provide that part number for the muffler, I'd really appreciate it. If I were to go with cats rather than mufflers, were those specific to the turbo kit, or would 'stock' cats be sufficient?

    I think the air hoses look good, and I checked the actuators this morning - they seem to be in good shape.

  4. #4
    '82 T3 FABombjoy's Avatar
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    A couple of quick things:

    The actuators are for the wastegates, which are used to control max pressure. Disconnecting them would only serve to create more boost. I'm thinking the flappers are stuck open and the turbos are being bypassed. You should be able to move them by hand or run 4-6 psi into the actuators and see them move. If you disconnect the arms the flappers should open easily. Google photos of "internal wastegate" for reference as they're almost all the same.

    Also, if interested, you can remove the relay entirely from the Island enrichment scheme and use a single hobbs switch that connects ground to the K-Jetronic terminal 11. Same effect without disturbing the O2 sensor wiring.
    Luke S :: 10270 :: 82 Grey 5-Speed :: Single Watercooled T3 .60/.48 :: Borla Exhaust :: MSD Ignition :: MS3X Fully SFI Odd-fire EFI :: DevilsOwn Methanol Injection

  5. #5
    Senior Member NckT's Avatar
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    If it was working fine before, why not just connect the o2 sensor direct to the afr gauge direct and leave the existing method of fuel enrichment intact ? The addition of the oxygen sensor may be trying to lean out the autumnal fueling causing the engine to run not as good as before.
    RIP Rob van de Veer Top bloke

    I say Sir, I must be mad, one loves fixing K-Jet !

    Make sure there's plenty in the tank for the weekend chaps....

  6. #6
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    Quote Originally Posted by NckT View Post
    If it was working fine before, why not just connect the o2 sensor direct to the afr gauge direct and leave the existing method of fuel enrichment intact ? The addition of the oxygen sensor may be trying to lean out the autumnal fueling causing the engine to run not as good as before.
    Well the goal is definitely to get it working again, but I guess while I'm figuring that out I'm trying to understand why some things I find along the way are different from the norm and whether that's good or bad.

  7. #7
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    Quote Originally Posted by FABombjoy View Post
    A couple of quick things:

    The actuators are for the wastegates, which are used to control max pressure. Disconnecting them would only serve to create more boost. I'm thinking the flappers are stuck open and the turbos are being bypassed. You should be able to move them by hand or run 4-6 psi into the actuators and see them move. If you disconnect the arms the flappers should open easily. Google photos of "internal wastegate" for reference as they're almost all the same.

    Also, if interested, you can remove the relay entirely from the Island enrichment scheme and use a single hobbs switch that connects ground to the K-Jetronic terminal 11. Same effect without disturbing the O2 sensor wiring.
    I disconnected the actuators this morning and the flappers were swinging easily, and the actuators weren't seized. Don't know if they are adjusted correctly, maybe I'll look up how to calibrate them. I suppose it's possible they Got knocked out of whack or something though that seems unlikely.

  8. #8
    Senior Member Flash66's Avatar
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    Hey critical, what manual are you using for turbo routing? Thanks!

  9. #9
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    Quote Originally Posted by Flash66 View Post
    Hey critical, what manual are you using for turbo routing? Thanks!
    There's a guide here in the resources section for the Island twin turbo kit, which is what I have. It calls for the removal of the vacuum solenoid and redirection of the hose connected to the left intake runner to go to throttle body adapter that replaces the w pipe. Then the tap on the intake runner is connected to the vacuum advance on the distributor. A PO had done several modifications. The warm up regulator was capped on one side with no vacuum delay valve. No idea what that was supposed to achieve. Both the WUR hose and solenoid hose from under the intake manifold from were capped. So to fix all that I installed all new silicone vacuum hoses according to the stock setup, then made the modifications from the turbo guide. For peace of mind I labeled the hoses from the thermal control valve, which has saved me several headaches. There was also a fuel enrichment relay that, according to some notes that were passed along with the car, would disengage the O2 sensor and trigger open loop when boost was detected. However, someone had modified that to activate the CSV under boost, so I switched that back as well. I also got the boost and a/f gauges working, as it appeared some of those changes above had left them non-functional. Oh, and I did confirm the wastegates are set to 4- 5#. Hard to tell exactly as the gauges are mounted on the left knee pad and when you're hitting boost it's not a good time to crane your neck around the steering wheel to watch your gauges. I've given serious thought to rigging up a go-pro to get a good look at what's happening on those gauges later.

  10. #10
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    PM me with your e-mail address and I can send you what I have. For the gauges use a pod and attach it to the "A" pillar. Then you can see them.
    David Teitelbaum

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