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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.
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