Richard123

You can also test with a multi-meter on the pressure switch (wires disconnected). If black-brown make on the first press of the brakes, then you have no volume in the accumulator (or a ton of air in the brake lines!). If they don't make, then you have a corroded or weak set of contacts in the pressure switch. As discussed, it should take several presses of the brakes to get black-brown to make (turn on pump) and then several more to get black-white to un-make (activate anti-lock light and get ABS computer to run the pump every time you hit the brakes).

Ah, fair enough. I thought your issue was the long time for loop closing. For interest though, has your exhaust back pressure valve been removed? I had one instance where the car would not run closed loop, occurring after I washed the engine seeking the source of an oil leak. It would sit and idle, but not take any fuel. Threatened to stall every time I touched the throttle. I let it cool to get it home, and replaced the O2 sensor with one of those Bosch 13030's. My O2 4-wire connector is long gone and a couple of the single connectors were more than dodgy, so I suspect getting the wires wet caused the issue though I can't confirm as the issue never reappeared. I'm betting your new O2 sensor cleans up your issue.

Robin, From the graphs, it seems that your issue is the same as mine. Your O2 sensor was hot (near max output) well before the ECU closed the loop. After the loop closed, your O2 sensor "wobbles" just fine, lol. So I don't suspect a bad O2 sensor. Yours is a 1995, so it came factory with the exhaust back pressure valve and throttle jack which were intended to allow the cars to go closed loop quicker, correct? And can I assume they have been removed? Mine are removed from my 1994 S4, and I am wondering if the 1200 rpm cold idle isn't throwing the ECU off, as it is expecting the throttle jack to produce a much higher cold "warm up" idle?? Might that anomaly cause the ECU to abandon the standard map and decide to wait for a specific coolant temperature before closing the loop? Just a theory, but if your EPBV and throttle jack have been removed, it may make some sense. I might test it by hooking up the throttle jack again and going with a 2400 rpm (or such) cold idle just to see what it will do.

I think I know this one. The O2 signal climbs from about 0.45 volts when cold up to about 0.9 volts when hot. The high reading is because the voltage output is higher when there is no oxygen (rich). Once it goes closed loop the ECU leans the mixture (less gas) until voltage drops (it senses oxygen), then immediately richens mixture until the voltage increases, then leans it, etc. The signal wobble is produced by leaning out every time the O2 reads high, and richening every time the O2 reads low. It's best to watch on an analogue voltmeter, the needle acts like a metronome! My issue is that I have a nice hot O2 sensor putting out a solid 0.9V and an ECU that is reluctant to close the loop, so certainly something else is at play. I'm pretty sure engine temps plays a part in my car, but not in others' Esprits and I don't know why.

Does anybody have any idea what all causes the ECU to go closed loop and if it can be manipulated?? My 1994 S4 used to close the loop in about 45 seconds but is now waiting about 4 minutes for a coolant temperature of 56.8C to be achieved. I put in a new O2 sensor (13030) and checked the 12V heater circuit, no codes thrown, drives fine though it idles up (say 2000 rpm) when rolling clutch in, then idles back down (1200 rpm) when the car stops, until warm. The O2 sensor still hits approximately 0.9V by 45 seconds. I tried the battery disconnect to no avail. I will try resetting the BLM's via Freescan, but figured maybe this was a familiar thing? (The car has never had the exhaust backpressure valve since I've owned it, and I've blanked off the throttle jack, so neither function.)

Best few dollars I spent was for the fitting to tee a pressure gauge into the oil line at the turbo. There is still that feeling of trepidation when you see the needle in the red, or the flicker of the red light as you first rev it up, but at least you know what you have. There is something to be done to solve this in 2018. of course. Buy a 2018 Lotus. They don't do it. Else, add it to the "Esprit experience".

Before you start buying parts, pump it empty (40 presses), leave it for a few minutes to dissipate, then turn the key to pump it all back up again. See if you get back to 5 or 6 presses.

OK, so rich mixture on all 4 cylinders. See the other thread in this section about fuel pressure regulator. Pull the vacuum line off it and see if it stinks of fuel, internal diaphragm might have blown so it might be leaking raw fuel into the manifold.

Sounds like you got a bad cylinder. Pull a plug at idle and see if one isn't contributing. A dead cylinder will pass plenty of unburnt fuel.

There is a very slight offset inwards. Measured from a straightedge to the bolting surface, was 1cm less on the front side than the rear side. (So 0.5cm from dead centered.) Maximum diameter of rim (outer edge) is 39cm.

Found it. Mine was fastened down under a couple of hoses, not easy to see. The +tive looked good, but the ground that went to the far side of bracket seemed loose. Fished for it with a screwdriver and snugged it up. Boost gauge back to normal, owner back to happy. (It's all this good living I've been doing. Give a few bucks to a homeless guy, and see how it pays out?!?!?)

So it's the thing with the hose and two red tagged wires running to it? I didn't see it when I was there, but once I saw the MAP sensor and the plastic hose running to it, I stopped looking! Thanks so much Ian, I really appreciate it. (Crossed fingers for a loose wire!)

Ah, so they are separate, which explains why the car seemed unaffected. So the device I found (above RH fuel tank) is the MAP sensor. Where might one find this gauge transducer? Clearly somewhere with ease of access and likely a commonly available and inexpensive part I assume?

My boost gauge never did zero, it always read a needles width up, but going down freeway yesterday it really started to act up. It would jump up to 0.5bar for no reason, then drop back. When I did dig in for some boost, it would over-read substantially. All the while the car ran fine and seemed unbothered by its antics. Am I right to assume the gauge gets it's signal from the sensor behind the carpeted right hand engine bay side cover? And that is also the sensor that gives the ECU it's information? So a quick Freescan should tell me if the sensor is failing? Since the car ran fine, is it safe to assume it's a gauge problem? If so, any ideas? The other gauges were fine. You think the gauge itself? Grounds? Anybody else have this issue?

On my 1994 S4 the spare is a 175/70R14.