Running Rich.

[Rich4552]

Hello everyone, So I bought my D from Maryland at sea level. I live in Utah about 4,500 elevation. The day my d got here it started right up and was idling fine (930rmp) I noticed my cat has been gutted, well I drove it around for the next week or two and put around 100 miles on it. I know its running very rich. So one day I had both boors in my garage open with my D running. As I was trying to lean it out the exhaust gas is so bad my eyes water like smoke from a camp fire.... my old D had a gutted cat but I also unplugged the 02. Ran fine and didn't smell like this at all. I don't even wanna drive it cuz it makes me smell like exhaust. Should I unplug this O2 as well and just tune off what I see? Thanks

[jawn101]

I'm not an expert on the mixture, but the idle should be more like 750rpm... if you're at 930 that's a high idle.

[Rich4552]

Hummm I've been told by many that 950 is where it should be. It even says that in the manual from dmch.

[jawn101]

Hummm I've been told by many that 950 is where it should be. It even says that in the manual from dmch.

I may be wrong. I remember being told that it should be about 750 when the engine is warm but can't find the posts to back that up.

EDIT: Check the workshop manual, section A:02:01 - Idle speed is 775 +/- 50 RPM. CO measurement should be taken at 950 but the no-load idle should be 725-825

[Rich4552]

Oh ok thanks. Will turn it down a bit.

[jawn101]

Adjusting the idle speed alone probably won't help with the rich condition/smell though, just something that leapt out at me. You may have vacuum leaks that are leading to the high idle condition. You'll want to make sure all of that is as perfect as can be before trying to adjust the mixture to compensate for the rich condition.

[deloumis]

Oh ok thanks. Will turn it down a bit.

You most likely don't need to turn down the idle, the high idle could be caused by running rich.
I can't help you on why your running rich, but others might. As stated, check for vacuum leaks, make sure all your bulk head connectors are connected properly along with the ground behind your intake manifold on the passenger side.

[sdg3205]

FV buzzing?

[Bitsyncmaster]

A working lambda system should compensate for altitude changes but it may not have been adjusted correctly when you bought it. If the lambda is working all you would need to do is set the dwell (duty cyle) of the FV after it has warmed up.

[jawn101]

A working lambda system should compensate for altitude changes but it may not have been adjusted correctly when you bought it. If the lambda is working all you would need to do is set the dwell (duty cyle) of the FV after it has warmed up.

Forgive the question (as I said, not an expert on this system!) but is this the same process as hooking a dwell meter to the orange wire to the diagnostic plug and adjusting the mixture screw, or is there another process to measure/adjust the FV?

[sdg3205]

Forgive the question (as I said, not an expert on this system!) but is this the same process as hooking a dwell meter to the orange wire to the diagnostic plug and adjusting the mixture screw, or is there another process to measure/adjust the FV?

You're correct, Jon.

IIRC, you can take the signal from the FV off the bulkhead or right at the connector too. Not sure about you, but that diagnostic plug is a pain!

[Rich4552]

FV buzzing?

I was watched a YouTube vid of my old DeLorean and it did buzz. Mine now doesn't really buzz???

[sdg3205]

Mine now doesn't really buzz???

it's audible. If you're not sure, try unplugging it at operating temperature then plugging it back in. You'll hear it stop, start or do nothing. If it is working, you'll hear it stop buzzing and the engine will idle differently.

If nothing at all happens, check your electrical.

[deloumis]

it's audible. If you're not sure, try unplugging it at operating temperature then plugging it back in. You'll hear it stop, start or do nothing. If it is working, you'll hear it stop buzzing and the engine will idle differently.

If nothing at all happens, check your electrical.

On my car, I unplug and plug, but no difference in idle. I hear it stop and start buzzing but no difference in idle. The one thing that did make a difference in my idle one time was one of my bulkhead connectors. The top nearest the back of the car, I unplugged while engine was running and made a difference in idle. I plugged and went back to normal. But then I unplugged again and no difference.

[Rich4552]

Awesome I will start checking all this out. Thanks for you time everyone.

[rdarlington]

Any resolution to this? My car runs rich too as I'm at about 7400 feet elevation in New Mexico. I had no idea till a couple weeks ago when a friend followed me up a mountain to about 9000 feet and he said his eyes were burning almost the whole way up! I never could get my idle mix set right (no swinging of the needle on the dwell meter at idle) so I just left the O2 sensor disconnected. Was this a mistake?

-Bob


Hello everyone, So I bought my D from Maryland at sea level. I live in Utah about 4,500 elevation. The day my d got here it started right up and was idling fine (930rmp) I noticed my cat has been gutted, well I drove it around for the next week or two and put around 100 miles on it. I know its running very rich. So one day I had both boors in my garage open with my D running. As I was trying to lean it out the exhaust gas is so bad my eyes water like smoke from a camp fire.... my old D had a gutted cat but I also unplugged the 02. Ran fine and didn't smell like this at all. I don't even wanna drive it cuz it makes me smell like exhaust. Should I unplug this O2 as well and just tune off what I see? Thanks

[Bitsyncmaster]

Any resolution to this? My car runs rich too as I'm at about 7400 feet elevation in New Mexico. I had no idea till a couple weeks ago when a friend followed me up a mountain to about 9000 feet and he said his eyes were burning almost the whole way up! I never could get my idle mix set right (no swinging of the needle on the dwell meter at idle) so I just left the O2 sensor disconnected. Was this a mistake?

-Bob

If your going to be driving with large altitude changes, I think you need to get your lambda system working. You would adjust it where you do most of your driving. I'm not sure how much the lambda can vary the mixture with altitude and keep it running at 1.00 lambda. My guess would be 5000 feet would not be a problem.

[Rich]

Confirming that the K-Jet will compensate for elevation changes as Dave says.

Our D lives near sea level but on any of our trips in it over the years up as high at 6,500ft elevation there has never been an idle, starting or mixture problem. No tweaks required ever since it came from the factory.


A working lambda system should compensate for altitude changes but it may not have been adjusted correctly when you bought it. If the lambda is working all you would need to do is set the dwell (duty cyle) of the FV after it has warmed up.

[rdarlington]

I've heard of a high altitude mod for the car but can't really find anything. Is this something documented in the workshop manual? Anything more than just adjusting idle mix for the altitude?

-Bob

[David T]

I've heard of a high altitude mod for the car but can't really find anything. Is this something documented in the workshop manual? Anything more than just adjusting idle mix for the altitude?

-Bob

If the car spends most of it's time at high elevations you set the mixture at the higher level. The infamous hot start relay was supposed to be for high altitudes but was discovered to be unnecessary and never used (the white plug by the relays behind the passenger seat). If you are running rich and your O2 sensor is disconnected you need to get it connected (and probably replaced,) get the mixture set and in doing so probably find and fix the reason it was disconnected in the first place. Most likely because the Lambda system was not running. Does your frequency valve buzz?

[rdarlington]

Okay, new data. I went out and jacked up the car to re-connect that O2 sensor and lo and behold, it was connected the whole time. Fine. I go for a 10 minute drive, come back and hookup my dwell meter. It's right there mid scale and not budging. Hit the switch at the end of the throttle travel and it buzzes louder and the needle swings to the right. Let go, it comes back to mid scale and won't budge.

I turned the idle mix screw almost a 1/4 turn CCW to lean it out a bit (multiple slow steps, checking each time), but at no point did I see that needle move.

Now the oil light comes on when I hit the clutch and let off the gas real fast. The RPMs bounce very low and then back up. A little lower than what I'm used to. I even stalled it on the way into the garage which is unusual for me. Hooked up dwell meter. Nothing budging.

Old video, but it shows the position of the needle that I saw today and how I have it hooked up:

https://www.youtube.com/watch?v=cpNB1eRktzM

Next step, test the lambda computer I guess? Ground and then +1.5 volts on the O2 sensor lead and watch for needle swings?

-Bob

[jamesvnz]

try a new OXYGEN sensor bosch 11032 they are not very much on amazon

its on the left lower engine in from the back left wheel and a black wire runs out it
my d ran better after a new one and was no longer running ritch

[Bitsyncmaster]

With your new data, It does sound like your lambda system is working but you need a new O2 sensor. Then adjust the mixture (it should be bouncing around after warmup).

You may need to adjust your curb idle and idle switch screws to reduce idle hunt after the mixture is correct.

[rdarlington]

Was afraid of that. I will buy the new one vs playing roulette with another from DMCH (yep, the one I have is "new" from last June.).

-Bob

[David T]

Was afraid of that. I will buy the new one vs playing roulette with another from DMCH (yep, the one I have is "new" from last June.).

-Bob

It doesn't matter how new it is, if you are running rich enough to make your eyes tear it is probably contaminated and needs to be replaced.

[rdarlington]

Clearly I'm not cut out for this. New sensor came in yesterday, got it in today without any trouble. I had my idle mix set lean to start with from two days ago. Went out for a 10 minute warmup drive and back to the driveway. Adjust, close hole, watch needle, rinse repeat. Just sitting as if I'm open loop. At some point I was able to get the needle to swing around. It went up, back to the middle, and then down to the left. Okay. Turn a little more to the right (rich) and it does the same. Based on a lower duty cycle I'm assuming it's trying to lean my mix so I turn back to the left. Same. Keep going, plugging and checking every little bit I turn, and then it sits mid scale not moving. I was reving the engine between tests for about 10-15 seconds at a time.

For a while there I thought I was making progress as I saw the needle swinging back and forth as it went up to the top of the scale and then back down to the left and sat. Damn this car. I have no idea if I was on the right track or not. This is the most I've seen that needle do without me pushing the switch by the throttle. I swear this thing is toying with me. Maybe time to sell it and get out of the DeLorean business. It's funny how something so darn simple is so damn frustrating to me.

-Bob

[David T]

Clearly I'm not cut out for this. New sensor came in yesterday, got it in today without any trouble. I had my idle mix set lean to start with from two days ago. Went out for a 10 minute warmup drive and back to the driveway. Adjust, close hole, watch needle, rinse repeat. Just sitting as if I'm open loop. At some point I was able to get the needle to swing around. It went up, back to the middle, and then down to the left. Okay. Turn a little more to the right (rich) and it does the same. Based on a lower duty cycle I'm assuming it's trying to lean my mix so I turn back to the left. Same. Keep going, plugging and checking every little bit I turn, and then it sits mid scale not moving. I was reving the engine between tests for about 10-15 seconds at a time.

For a while there I thought I was making progress as I saw the needle swinging back and forth as it went up to the top of the scale and then back down to the left and sat. Damn this car. I have no idea if I was on the right track or not. This is the most I've seen that needle do without me pushing the switch by the throttle. I swear this thing is toying with me. Maybe time to sell it and get out of the DeLorean business. It's funny how something so darn simple is so damn frustrating to me.

-Bob

The mixture screw is VERY sensitive. a 1/4 turn and you can be WAY off. Maybe the way to go is to start over and set the mixture so it is just cracking open the injectors. Adjust in 1/16 or less increments. Don't try adjusting until the fans have kicked on and go off at least once so you KNOW the motor is fully warmed up.

[rdarlington]

The mixture screw is VERY sensitive. a 1/4 turn and you can be WAY off. Maybe the way to go is to start over and set the mixture so it is just cracking open the injectors. Adjust in 1/16 or less increments. Don't try adjusting until the fans have kicked on and go off at least once so you KNOW the motor is fully warmed up.

Yeah, my adjustments were very small. 1/16th turn at the very most. Really I was going for as tiny a change as humanly possible with my little allen wrench. I was warmed up. Fans kicked on a couple times in that 20 minutes I was out there killing yet another O2 sensor. This was after driving for a bit.

Would a better way to go about this be using some kind of sealing diaphragm over the hole for the adjustment screw? I'm not sure *how* I'd do this, but making the adjustment while air is leaking in, then pulling the wrench so even more air leaks in, then plugging it seems like a pretty crazy way to do it, although I'm sure it works for everyone else but me.

BTW, while I had the hole uncovered, I could see the needle swinging up to compensate for the extra air so I thought I was on the right track but damn this car hates me.

-Bob

[David T]

Yeah, my adjustments were very small. 1/16th turn at the very most. Really I was going for as tiny a change as humanly possible with my little allen wrench. I was warmed up. Fans kicked on a couple times in that 20 minutes I was out there killing yet another O2 sensor. This was after driving for a bit.

Would a better way to go about this be using some kind of sealing diaphragm over the hole for the adjustment screw? I'm not sure *how* I'd do this, but making the adjustment while air is leaking in, then pulling the wrench so even more air leaks in, then plugging it seems like a pretty crazy way to do it, although I'm sure it works for everyone else but me.

BTW, while I had the hole uncovered, I could see the needle swinging up to compensate for the extra air so I thought I was on the right track but damn this car hates me.

-Bob

As the O2 sensor gets old and/or contaminated you will see less and less "swing". You might also have bad/dirty connections on the O2 wire to the Lambda ECU. Try grounding the wire and applying 1.5 volts to it as per D:04:15 to make sure the Lambda system is functioning properly without the O2 sensor. I have had some limited success "cleaning" an O2 sensor by heating it up with an Oxy-Acetalyne torch to burn off the contaminants. Seems to work for a while at least. Something to try before buying another one. It doesn't take much running at too rich to foul them up. Remember, the O2 sensor signal is VERY small. A bad connection is enough to kill the signal.

[Bitsyncmaster]

When I have seen it hard to set and hold a dwell, the problem was a plugged up CAT. There still could be other problems (ECU, bad injector, bad FV, etc). If you were running rich, it's likely your CAT is damaged.

[rdarlington]

Bah. Damn car.

Don't get me wrong, I love it, it just hates me.

My plan of action is to check the injectors, replace the rubber seals for them (ordered and on the way), and get a test pipe to replace the cat for testing. Will check in after killing another sensor in a month or so. Bah.

-Bob