A/F ratio always rich, no cross-counting. Why?

wild man · 12-11-2009, 07:39 AM

Now that the cold weather season is here (20 degrees and windy right now at 41 degrees north latitude by 76.5 degrees west longitude), I have replaced the cool spark plugs with warmer ones (hoping to get cabin heat sooner, but that doesn't seem to be happening), and replaced the oxygen sensor with a brand-spankin-new-one. And yes, it is the one meant specifically for a 951, not a universal. But my fuel economy is considerably less than ideal, there is lots of soot in my tailpipes, and I have not seen any cross-counting of the oxygen sensor voltage while driving down the road, while light on the pedal, lately. Voltage will only drop down from the 650-850mV level (average is about 730mV), when completely off of the pedal. This gives me the feeling that the engine is always running in "limp" mode, or something.

I have autothority MAF, and I just installed a blink code LED, but not seeing any codes come up. If I disconnect the TPS, idle speed drops, and the LED comes on and says on solid, until I plug the TPS back in. Is this correct?

What else could be causing this scenario? I'm starting to get sick of only seeing 80-90 miles out of a 20 dollar bill.

blown 944 · 12-11-2009, 08:55 AM

Where did you splice your AFR gauge in at?? Hopefully in the harness not the O2 wiring

Rogue_Ant · 12-11-2009, 08:55 AM

What is your coolant temp? It sounds like the car is not coming out of warm-up, open-loop.

-Rogue

blown 944 · 12-11-2009, 08:59 AM

^^^ +1 Good point.

May want to look into the temp sensor

zedsn · 12-11-2009, 04:59 PM

at $3 a gallon for 93 octane I get around your mileage on my 951S and my car is running fine. I guess it depends how many times you put your foot to the floor.

wild man · 12-12-2009, 05:26 AM

Although I now own 2 a/f gauges, none is installed yet (I need either an A-pillar gauge pod, or an under-the-radio panel that has cutouts for gauges). I am taking direct voltage measurements, using a DMM on the 2VDC scale, from near the DME (there is NO splice in the expensive 951 oxygen sensor wire). The new sensor is probably all sooted up by now, though.

With winter here now my temp gauge barely get's out of the wide white mark at the bottom of the scale. And it takes quite a while to get there from a cold start. If idling for a while it may get close to the first white line, but never past it. During the summer it does go past half-way to where the fans kick in. All of my other cars of this "breed' were just as cold-blooded in cold weather, so I don't think that is the issue.

Is there a chart of some sort where I can check coolant temp sensor resistance against a given coolant temp. I think I may have seen it in the service manual, or something.

Oh, and I was off on my estimate of fuel economy. I reset the odometer $40 ago (at $3/gal), and it had 198 on it when I sputtered up to the gas pump last night. Unfortunately, the car now starts to sputter BEFORE the low fuel light comes on. I was about a mile from the nearest gas station when I noticed it was starting to sputter. And I thought, "oh no, the low fuel light isn't even on" but it did come on about 30 seconds later. And barely touching the gas pedal, I made it to the gas station.

wild man · 07:18 AM

Here is a pic of how black my pipes are:

I apologize for taking a pic of the car while it is so dirty.

Rogue_Ant · 12-12-2009, 02:31 PM

Quote:

Originally Posted by wild man

With winter here now my temp gauge barely get's out of the wide white mark at the bottom of the scale. And it takes quite a while to get there from a cold start. If idling for a while it may get close to the first white line, but never past it. During the summer it does go past half-way to where the fans kick in. All of my other cars of this "breed' were just as cold-blooded in cold weather, so I don't think that is the issue.

Is there a chart of some sort where I can check coolant temp sensor resistance against a given coolant temp. I think I may have seen it in the service manual, or something.

I'll bet that you don't have the thermostat seal installed... My car is the same way with heating up. Your car is barely getting out of warm-up / open-loop, and probably only at idle.

You can check your coolant sensor here:

Clarks-Garage - Coolant Sensor

-Rogue

wild man · 12-13-2009, 04:25 AM

Thanks for providing the link. That must have been where I saw it, but I think there might be something similar in the service manual. It only shows 3 "data points" for the DME sensor, but that should be good enough to determine if it is providing an acceptable signal to the DME.

My temp did rise above the first line (to mid-point) the other night, after I was sitting in the drive-through line at KFC for about 20 minutes. And I assume the seal you are referring to is the thermostat O-ring. I've never had the T-stat housing off on the 951, so I can't really say if the seal is there, or not. I'm not really too hip on getting into it, because the last time I had a T-stat out on on the 924S (a good number of years ago), I remember it being quite a pain to get at with the snap-ring pliers, due to fit/space issues.

It's currently running about 18-35 degrees around here. The last time I saw closed-loop operation while driving, it was in the mid 50's. Is it possible that I contaminated the (used) TPS that I installed when I changed plugs and O2 sensor, since I have not-yet rebuilt the throttle body?

I'm still not sure if the blink-code LED is acting correctly, either. I have yet to see it blinking. If there are any codes, they should "reveal" themselves if the engine is run continuously at over 1500rpm for more than 30sec (after warm-up), and then dropped to idle, right? And, is the LED supposed to be on continuously whenever the TPS is not connected?

Rogue_Ant · 12-13-2009, 02:21 PM

Quote:

Originally Posted by wild man

My temp did rise above the first line (to mid-point) the other night, after I was sitting in the drive-through line at KFC for about 20 minutes. And I assume the seal you are referring to is the thermostat O-ring. I've never had the T-stat housing off on the 951, so I can't really say if the seal is there, or not. I'm not really too hip on getting into it, because the last time I had a T-stat out on on the 924S (a good number of years ago), I remember it being quite a pain to get at with the snap-ring pliers, due to fit/space issues.

It's currently running about 18-35 degrees around here. The last time I saw closed-loop operation while driving, it was in the mid 50's. Is it possible that I contaminated the (used) TPS that I installed when I changed plugs and O2 sensor, since I have not-yet rebuilt the throttle body?

I'm still not sure if the blink-code LED is acting correctly, either. I have yet to see it blinking. If there are any codes, they should "reveal" themselves if the engine is run continuously at over 1500rpm for more than 30sec (after warm-up), and then dropped to idle, right? And, is the LED supposed to be on continuously whenever the TPS is not connected?

There would not be any blink codes for warm-up stuff...

The TPS most likely would not keep the DME from going to closed-loop, unless it is telling the KLR that you are above ~60% throttle.

The best way to deal with the snap-ring, is to get a pair of 90degree angle needle-nose pliers and file the ends to work with the snap-ring. Makes changing the snap-ring easy. And as I mentioned you are missing the seal/O-ring, which is why you car is only heating up when there is no real airflow to the radiator (sitting in the drive-through line).

-Rogue

wild man · 12-13-2009, 04:21 PM

I think I only had 45 degree angle tips on the snap ring pliers. You sound pretty confident about this, so I will go to 1 of my "people" who is a mechanic, and has good (snap-on brand) tools, and have him check it , or even replace it with a new one, even if it does have one in it.

Should I just say effit, and get a new T-stat for him to put in? They do provide a new O-ring with a new 'stat, right?

Rogue_Ant · 12-13-2009, 04:47 PM

If your friend has Snap-On stuff, he is not going to want to take a file to the pliers (which you have to do, to get it to fit into the snap-ring)... I know, all my tools are Snap-On as well. Just get a cheapo pair from Autozone, and use a file on them.

I would replace the T-stat at the same time.

-Rogue

wild man · 12-13-2009, 08:45 PM

Hmmm, the resistance of the potentiometer section of the last TPS that was in it was off-base due to oil contamination. The one I replaced it with might be suffering from the same fate, since I haven't rebuilt the TB yet. Looks like I need to put that on my list of things to check.

I think I'm just going to replace the 'stat and seal with a new one. Do the new ones (like duralast) come with a new seal? It's been so long since I had one out, that I can't recall if they are the style that uses an O-ring, or outside grommet type seal. Now I'm thinking that's the style it is. Oh well, doesn't matter, if I replace with new.

Rogue_Ant · 12-14-2009, 10:01 AM

It is a couple of O-rings, IIRC. Here is the part and seals from Pelican:

Click Me

-Rogue

wild man · 12-16-2009, 02:41 PM

It's 1 o-ring, I think. But last couple of days it seems to be OK with heat, but it has been (slightly) warmer outside. And got 104 miles out of last $20 worth of fuel, in cold, around town driving. But haven't been monitoring A/F voltage though. I guess it's good enough for now, as I'm not too hip on doing any work on it until the weather gets warmer.