The fuel pressure is critical. Have you been able to watch it while you drive?
The 18:1 thing is what I'm hung up on. I spent time driving around with my Wideband and I kept adjusting what the Innovate controller was telling the Lambda-Sond. If I was getting 18:1 or higher under load the car would be undriveable. My car idles best at around 12.5:1 AFR, but you can smell unburnt fuel at that level so I run it around 14:1.
If you have good fuel pressure and the fuel pressure is not giving issues while driving, I wouldn't focus on the relay. If you don't have good fuel pressure, then you would need to sort that out.
If you have good fuel pressure, and you don't have an engine miss, your cam isn't installed incorrectly, your AFR is 18:1 and you also don't have an exhaust leak contaminating the AFR reading, you should suspect the Lambda Sond or the fuel distributor. It's easier to troubleshoot the fuel distributor in my opinion, it has no electronics in it. That's why I recommended pulling the plug on the Lambda Sond for testing.
I'm telling you this based upon my experience while trying to chase down fuel problems on my 1978 K-Jet car. I'm definitely not pulling this out of my rear.
I bypassed the fuel pump relay and wired in my own relay.
I replaced both fuel pumps.
I ran new wire to the under car fuel pump and installed a dedicated relay for it, when I discovered that there was a significant voltage drop at the pump.
I installed a voltage booster in the trunk and wired it into the in tank fuel pump so that I could overdrive the in tank pump and observe the behavior. I did this after I discovered quite a large voltage drop in the rear of the vehicle as well. I delivered up to 18v to this fuel pump during testing, and I could audibly hear the pump running harder.
I installed 2 different fuel pumps in the tank until I found one that worked well (the higher volume IPD pump worked great). I attribute this issue to the fact that you can't buy the original high pressure Volvo pump anymore, and the replacement pump that I got along with the first in tank pump gave me "cavitation" sounds in the fuel system and a performance issue after the car had been running for a while. The overdriven pump proved that the in tank pump wasn't delivering what the high pressure pump needed, at that point I found a higher volume in tank pump.
I replaced the rubber fuel line from the tank to the fuel pump.
I replaced the fuel filter.
I replaced the injectors and injector seals.
I purchased a kit to check my fuel pressure (and tested it).
I replaced the fuel pressure accumulator because it leaked.
I replaced all of the normal stuff like plugs/wires/cap, etc.
I replaced the O2 sensor, first with a normal narrow band, then with an Innovate Wideband and controller.
Make 100% sure you fuel pressure doesn't drop while driving or under a load. Your AFR should not be at 18:1 at idle. My car would barely idle at 18:1, if at all while in gear.
Check your compression, just to rule it out. It's easy to check. The plugs are easy to remove.
Check your cam timing.
Thanks for checking it out! I have not done it yet but I do have the relay. I will probably get that done tomorrow, while I'm waiting for my new relay and other parts.
Guess I will check out ebay for a dwell meter, I asked around and I don't know anyone who owns one.
I have a dwell meter, but I didn't use it. In my opinion, the fuel distributor needs to be set so that the O2 sensor will have plenty of leeway to make adjustments to be on the lean and rich side of the spectrum. I have not been able to tune the fuel trim screw to a position that works well at idle with and without the Lambda-Sond plugged in. Ultimately you will need to have it tuned so that it works well with the Lambda Sond. I believe the purpose of the dwell reading is to get you right in this ball park, but it's not black magic. If you have a Wideband, you are already ahead of the curve because you can actually have an accurate view of the rich lean swings. The only thing I don't have is the C0 meter.