Deciphering Fuel Enrichment Relay Setup

[CriticalB]

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.

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[David T]

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!

[CriticalB]

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.

[FABombjoy]

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.

[NckT]

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.

[CriticalB]

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.

[CriticalB]

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.

[David T]

It makes no sense that the O2 sensor would get wired into the cold start system. In fact, if you put 12 volts on the O2 sensor you probably can damage it. Or the Lambda ECU. In fact, if you wire it up the wrong way you can damage the Thermo-Time switch. Refer to D:04:15 in your Workshop Manual for tests to make sure the Lambda ECU is functioning correctly by grounding the O2 sensor line, disconnecting it, and applying 1.5 volts to it. I can't tell you if your wiring diagram is good to use until I can see it. Or I can send you one. I will look up the muffler #'s when I get a chance. Refer to D:04:12 for the Lambda wiring and D:04:06 for the cold start system. My guess is the PO was looking for a way to force more fuel into the motor by trying to run the cold start valve. You have some clean-up work to do. First try to get the cold start system and the Lambda system back to stock. Then make sure everything else is OK.

[David T]

I have not been able to find the muffler #. It is a pretty generic one. The approximate dimensions are 8" W X 13" L X 4 1/4" T. The inlet and outlet are 2". The inlet is centered and the outlet is to one side. You must add a hanger so all of the weight is not hanging on the turbo housing. As I said, you should be looking for cats, not mufflers. Might also need exhaust tips to dress up the exhaust. Any exhaust shop should be able to match something up.

[CriticalB]

Thanks for the muffler info, though based on the recommendation I may save up for cats.

I took the cold start valve off the relay circuit and retired everything according to the diagram on my first post. Seemed to be running much better when I took it on a few errands last night. I can easily get to 4-5 lbs of boost. I don't think the turbos quite sound like they used to, but it does feel like power has returned.

There is a basic AF gauge that has been wired to power, but the signal wire was never connected to anything. It always showed one bright green LED at full rich. I clipped it to the O2 sensor and at first thought it wasn't on at all, but it was actually just really dim...barely visible. If you look closely you can see a few LEDs bouncing around on the lean side. I don't think the signal wire would affect brightness of the LEDs, so does anyone think it might just be a faulty guage? Is it possible the system is running really lean? I'm not super concerned about this, but thought I'd mention it in case it might be relevant.

What does concern me is what happened today. I decided to drive about 20 miles to the office. There was a little idle hunting after startup, but after it warmed up it stopped hunting and would idle a little high (1000) at stops. On the way home, same thing with the idle hunting while warming up, but about halfway home it would stall whenever returning to idle. Come to a stop, stall. Shift to neutral while coasting, stall. It would restart easily with a little throttle applied (although it usually starts right up without pumping the gas) but as soon as I released the throttle it would bottom out.

It was a looong drive home in stop and go traffic but I made it, and it actually would hold idle again by the time I reached my neighborhood. Once it cooled a bit, it would start normally and idled fine. I checked vacuum lines, checked microswitch adjustment, wiggled wires, etc. the idle hunting stopped, so I took it around the block and after 2 miles it started stalling at idle again. Made it home but I'm not sure where to look next.

[NckT]

It's too lean.

[David T]

It could be too lean but do you really trust the O2 sensor? It could be contaminated and isn't putting out enough voltage for the gauge to get a good reading. I would try a new O2 sensor. BTW, it doesn't have a heater in it so it takes a while for it to start outputting a voltage.

[CriticalB]

Too lean crossed my mind, given the gauge reading, but I don't really trust the gauge since it came with the car and I'd never seen it actually working. I searched for symptoms of running too lean, but surprisingly couldn't find much. The O2 sensor is relatively new from Autozone, but could be bad. I've driven it as much as 30 min without seeing a reading on the gauge, so think it's warmed up enough to supply a signal. It has been connected but hasnt been installed in the bung until last weekend. I'm willing to spend $20 and try a new one. I ordered a dwell meter earlier today to see if I need to adjust the mixture, but I've read enough on here to know I need to verify several other system components are in order first.

I also ordered new silicone vac lines just to be thorough, as I'm also trying to get the vacuum system back to the island turbo specs. I don't have a vacuum delay valve (ordered that too) and instead of the hose that would connect to it, the CPR is capped off on that side.

[David T]

Well, you are correct in trying to get back to "stock" configuration as far as the Island Turbo set-up is concerned. The CPR may have been disconnected/modified so as to give an additional bit of fuel. It may not function correctly so check it with a pressure gauge as the car warms up once you get it reconnected. I would also confirm timing and advance to make sure it was modified for the Island set-up. Many of the Island cars were modified over and above what the documentation said in order to get more fuel out of the K-Jet system. Some also tried water/meth injection to get more boost with the stock pistons. if you go with cats you don't want to run too rich, you will burn them up.

[CriticalB]

I got a dwell meter this weekend, set it to 4 cyl, and hooked it up. With the engine off, it read 87. With the engine on and warmed up, it pretty much just sat on 58. I swapped in a new O2 sensor and no change. I read somewhere that if it doesn't bounce around, the O2 sensor is disconnected. I now have the ECU/O2 on the relay i mentioned at the start of this thread, so to rule that out I removed it and connected the O2 sensor straight to the ECU; still no change. I did some reading on here and cleaned the contacts on the ground near the RH intake runner near the FV, and that didn't make any difference either.

Should I suspect the lambda ECU might be bad or is there something else I should rule out first? I'll also note that the A/F meter behavior didn't change with the new O2 sensor. The LEDs are still very dim and read in the lean range.

Also, in reading up on the ECU, it seems there's a silver (101068) and a black one (110067). Mine is silver, but what's the difference?

In the meantime, everything seems to be running fine again. I'm not planning to change anything while I'm waiting on new silicone vacuum hoses and injector seals to come in at which point I'll start ruling stuff out from the valley up.

[David T]

You need to figure out why you aren't getting into "Closed Loop". Doubtful the ECU is bad, more likely it isn't getting a good O2 signal or the ground is not good. The O2 signal is very low voltage so any problems getting it to the ECU (or the ground) and the ECU can't "see" it. Probably why the A/F meter isn't working right either.

[CriticalB]

Problem solved! Well, the most recent problem anyway...

I've probably noticed this a dozen times and never though anything of it. There was an old vampire tap on the SHIELDED O2 sensor wire running to the ECU. I popped it off, massaged the wire and 'bandaged' it with some electrical tape. Now the A/F gauge is working perfectly and I'm getting ~40-44 on the digital dwell meter. Idle sounds good and car is running well. I'm guessing someone tried to tap the AF meter here instead of closer to the O2 sensor, it didn't work, and that's why i found the signal wire tucked under the dash.

[NckT]

We call them scotch-locks. ... and I HATE them

Well done in sorting the problem out. I hope it runs nice now :)

[David T]

You need to wire up the A/F gauge correctly so it can work. Small problem now that the motor is running better. You should go over the whole "system" wire by wire as to what was modified and how for the Island Turbo set-up and try to get it working as it should.

[CriticalB]

Quick update to close the loop - it’s been a busy few weeks but I finally had time to sort everything out and install a new fuel pump while I was at it. For some reason or another I was getting suspicious that I was losing fuel pressure shortly after my last post. I know the accumulator was replaced by the previous owner, so I decided to take a look at the fuel pump and found there was no pump cover and the boot was filled with gas or water...or water that smelled like gas. I wicked it out with a rag, but decided to just replace the pump as it was original and the electrical contacts were rusted beyond repair. While I was waiting on that, I decided to dig into the valley to install my new silicone vacuum hoses. It wasn’t too bad down there but I did need a new heater pipe and a few new hoses. Took the plunge on a new water pump too, again b/c I figured the original was on borrowed time. Got everything back together last weekend, including the new fuel pump. The old vac lines were pretty brittle in the valley and I must have had a leak somewhere b/c the car now idles better than ever. I now have the vac lines routed according to the turbo manual. Even though the idle sounded good and the dwell was between 35-45, I noticed the engine stuttered on acceleration up to 25k rpms in all gears. Double checked everything - wires, injectors, plugs, fuel pump hoses and connections. Ultimately, an ever so slight adjustment to the mixture seems to have cleared things up.

For now, everything seems good - fingers crossed things stay that way!

[Flash66]

Hey critical, what manual are you using for turbo routing? Thanks!

[David T]

Quick update to close the loop - it’s been a busy few weeks but I finally had time to sort everything out and install a new fuel pump while I was at it. For some reason or another I was getting suspicious that I was losing fuel pressure shortly after my last post. I know the accumulator was replaced by the previous owner, so I decided to take a look at the fuel pump and found there was no pump cover and the boot was filled with gas or water...or water that smelled like gas. I wicked it out with a rag, but decided to just replace the pump as it was original and the electrical contacts were rusted beyond repair. While I was waiting on that, I decided to dig into the valley to install my new silicone vacuum hoses. It wasn’t too bad down there but I did need a new heater pipe and a few new hoses. Took the plunge on a new water pump too, again b/c I figured the original was on borrowed time. Got everything back together last weekend, including the new fuel pump. The old vac lines were pretty brittle in the valley and I must have had a leak somewhere b/c the car now idles better than ever. I now have the vac lines routed according to the turbo manual. Even though the idle sounded good and the dwell was between 35-45, I noticed the engine stuttered on acceleration up to 25k rpms in all gears. Double checked everything - wires, injectors, plugs, fuel pump hoses and connections. Ultimately, an ever so slight adjustment to the mixture seems to have cleared things up.

For now, everything seems good - fingers crossed things stay that way!

It's OK to run a bit richer because of the Turbo kit. In fact, under boost you may find you run lean so there are modifications that can be done to "trick" the CPR into giving more fuel under boost. While you are checking things, check the base timing and the mechanical and vacuum advance. Use the highest octane fuel you can find too. NEVER let the motor have detonation during boost. It won't take much to blow the pistons! Make sure you never exceed 5# boost. Adjust each wastegate actuator if necessary.

[Flash66]

Hey David, Can you elaborate on the CPR "trick"for me? I'm installing a newly rebuilt BAE Rajay including an upgraded Turbonetics modern wastegate with a #5 spring installed. The diaphragm was bad in the original Rajay wastegate so I had to find another solution. I have the pin 11 or Lambda trick with WOT or Hobbs, but curious about what you've mentioned. Sorry to hijack but may be beneficial knowledge to both of us. Thanks!

[CriticalB]

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.

[David T]

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.

[FABombjoy]

You're running the stock O2 sensor, right? You won't get much useful data from that anyway. Narrowband gauges just let you know if you're teeter-tottering around 14.7:1 AFR and not much else.

You do want to be richer under boost but you don't want to be excessive. K-Jet can deliver a ton of fuel and you can easily see AFRs lower than 10:1.

David is alluding to a method where you use the control pressure regulator to enrich under boost. Inside the CPR is a diaphragm and a vacuum chamber on each side. If that diaphragm moves up, control pressure is increased and the mixture leans. If it moves down, control pressure is reduced and the mixture richens.

Legend Industries proposed a system using vacuum switches & vents to pressurize the appropriate port under boost and then bleed the pressure out of the chamber when off boost. This was done to preserve the warm-up enrichment function as well. Plumbing gets complex when you're trying to double-duty the WUR to give both cold enrichment and boost enrichment.

I had a UTCIS-PT which allowed programmable changes to control pressure. I don't recommend it. It doesn't correctly handle warm-up on our cars no matter what the company tells you.
If you want to keep K-jet but would like to log & program it, there is the FrankenCIS. This is the ultimate K-jet solution as you could actually see what the fueling looks like under load and make changes as needed.

[CriticalB]

For the gauges use a pod and attach it to the "A" pillar. Then you can see them.

But then I'd have a pair of 2 in holes in my knee pad...I wonder if there are any gauges out there that use Bluetooth to display a virtual pod on an app on your phone? Far less permanent and more customizable...

[Flash66]

But then I'd have a pair of 2 in holes in my knee pad...I wonder if there are any gauges out there that use Bluetooth to display a virtual pod on an app on your phone? Far less permanent and more customizable...

I'm in the boat with you! There's the "Torque" app that will do this for boost and AF but only for OBD2.

[FABombjoy]

There are multiple wifi or bluetooth systems available but nothing plug & play.

I previously used an LC-1 / AuxBox combo to log AFR, RPM, lambda d/c, and MAP. Those have a BT solution.

14point7 iDash

AEM X-wifi

FrankenCIS + Microsquirt would get you the standard Megasquirt-compatible adapters and anything that works with CANBus

I have an internal BT module in my MS3X box. Also currently running digital WBO2 and vac/boost gauges (placed on top of the center console) but plan on replacing them with CANBus gauges so I can change the displays to different sensors.

[David T]

But then I'd have a pair of 2 in holes in my knee pad...I wonder if there are any gauges out there that use Bluetooth to display a virtual pod on an app on your phone? Far less permanent and more customizable...

Well, you could just put some round covers over the holes, try to repair and recover it, or get another kneepad. Putting the gauges into a double-pod IS the way to go.

[Flash66]

I've been trying to get a hold of the folks that make the frankenCIS to no avail. I'd like to stay with the KJet for now as my fuel system is 100%. Just would love to be able to tune it for the turbo!