Need help with DTC 44/64

A few weeks back I did a lot of work to my 94 Roadmaster wagon. Car ran fine as always but needed a new radiator, engine oil cooler hoses, etc. I got it all done except for two things I wanted to do, which were to install an Innovative Wiring headlight harness and two new O2 sensors. the car ran fine after all the work. The next weekend I installed the wiring harness (which I think is totally unrelated but including it for information) but I didn't complete the job because I don't like the way it hooks directly to the battery and want to re-engineer that. Then I went on to install the driver side O2 sensor but not the other because I didn't have the proper tools to reach the other one. As soon as I started the car it ran fine until it went into closed loop, then it ran in closed loop for maybe two minutes and threw a code 44 (lean left bank). My scanner showed zero volts on the left O2 and everything normal on the right side. I should add that these O2 sensors are Delphi sensors that are supposed to be the replacement for original but don't look anything like the old ones. These have kind of a tin can looking tip and the wire colors are different plus there is no external ground wire. I figured it might be a bad sensor so I installed the other new one and got exactly the same result - lean left bank, normal right bank. The next weekend I got the tool and installed the passenger side, figuring maybe it was mismatched sensors. Now I have a code 64 as well (lean right side). You can see the voltage on each side starting at about .9 cold, then they both gradually get lower. After the car goes in to closed loop they get really low. The injector pulse width is very high and my long term fuel trims are pegged at 160. It is improving slightly, as I am getting more than zero volts at least. All other readings look normal, air intake temp, etc. At the same time the second sensor was installed, a really good oil leak developed at the back of the engine. I assume it was from the intake manifold and my theory was that maybe I had an intake leak all along and the old sensors didn't detect it. That doesn't seem likely because the car ran too well. Today I went to the AC/Delco store and asked to see the proper sensor for my car. The one they showed me looked exactly like the ones I put in. I tried to find the source of the leak and it had stopped completely. I'm sure it will start up again but I'm not too sure anymore that the leak has anything to do with the sensor issue. Should I drive it and let it get used to the new sensors or is there another explanation for this. I'm pulling my hair out. Anybody see this before?

Have ypu put the original sensors back in to see what it does?GM has changed something in the new sensors that is throwing those codes,haw about a set of aftermarket O2 sensors?

dwardo wrote:

I should add that these O2 sensors are Delphi sensors that are supposed to be the replacement for original but don't look anything like the old ones. These have kind of a tin can looking tip and the wire colors are different plus there is no external ground wire.

Sounds like they are not the right sensors, or at least, that the exhaust system is not adequately grounded to the PCM ground.

It is entirely possible that someone at Delphi goofed at some point in the past when transcribing a part number. Stranger things have happened. Now, throw us a bone here: pictures or part numbers or something!

buickwagon wrote:

dwardo wrote:

I should add that these O2 sensors are Delphi sensors that are supposed to be the replacement for original but don't look anything like the old ones. These have kind of a tin can looking tip and the wire colors are different plus there is no external ground wire.  

Sounds like they are not the right sensors, or at least, that the exhaust system is not adequately grounded to the PCM ground.

It is entirely possible that someone at Delphi goofed at some point in the past when transcribing a part number. Stranger things have happened. Now, throw us a bone here: pictures or part numbers or something!

Dwayne,what the hell did I just say with slightly different wording? [/quote]

So, how is the exhaust grounded to the PCM? That's an intriguing thought. I have a FSM but maybe somebody just knows.

You suggested someone at GM changed the design, which to me implies a deliberate change. I am suggesting someone at Delphi screwed up. But either way, we both are thinking the problem is the new sensors -- hell, the PCM is basically screaming that the sensors are wrong.

I just had a look at the pictures @ rockauto and every O2 sensor listed for the 94 RM has 4 wires. The wires are different colours or in a different order, but every one has 4 wires. That will be a ground for the sensor, a separate ground for the heater, power to the heater and the signal wire. By the sounds of it, the replacement sensors he was given only have 3 wires. My guess would be that the new sensor has a common ground for signal and heater. They might be made to work if the grounds were connected in the car harness, assuming that the other wires are all in the right order. One would have to meter the old and new sensors to figure out the wire order.

Ok, I see dwardo added a question while I was typing.

Basically, through the ground wire(s). Of which, I gather one is missing? In a single-wire sensor (such as the TBI cars use), the O2 sensor relies on a metal to metal connection through the exhaust to the block to the engine ground to the battery. A two wire sensor adds a ground wire, a 3 wire sensor adds a heater and a common ground and a 4 wire sensor has separate grounds for heater and signal. 5 wire sensors are a completely different technology.

buickwagon wrote:

hell, the PCM is basically screaming that the sensors are wrong.

I,ve never heard a pcm do that,...

phantom 309 wrote:

buickwagon wrote:

hell, the PCM is basically screaming that the sensors are wrong.  

I,ve never heard a pcm do that,...

You need stock exhaust to hear it.

The original sensors are 4 wires. One of them attaches to the outside of the body of the sensor and is apparently a ground. The wire color is pink or tan. I can't tell, I just looked at it in bad light. The new sensors are 4 wires but all wires go directly into the inside of the sensor. As far as I can tell, the original sensors have been unavailable for a long time so SOMEBODY has used the new-style sensors, assuming they are the correct ones. I'm really stumped on this. I am going to do a basic check tomorrow to make sure all the exhaust manifold bolts are tight as well as intake manifold. When I bought the car 3 or 4 years ago I did that and found the rear exhaust manifold bolts were loose but not broken and the intake manifold bolts were all very tight. I don't really think that's my answer. I'm hoping to hear from someone who has had the same problem. Ugh. "Never f**k with a running piece" is good advice. My motto is "If it ain't broke, fix it til it is".

dwardo wrote:

I am going to do a basic check tomorrow to make sure all the exhaust manifold bolts are tight as well as intake manifold. When I bought the car 3 or 4 years ago I did that and found the rear exhaust manifold bolts were loose but not broken and the intake manifold bolts were all very tight. I don't really think that's my answer.

If you mean to ensure an electrical ground, you would be wasting your time. That sensor is not grounded to the case, it's grounded through a wire. Two wires, one for the heater and one for the sensor. Get out an ohmmeter and compare the new sensors with the old. Get out your FSM, figure out which two wires are the heater and which two are the sensor by comparing the wire colours at the plug with the wire colours going into the sensor. The heater wires should show a constant resistance between them. Now switch the ohmeter to volts, hold the sensor in a vise, and measure the voltage between the two sensor wires while heating the sensor with a propane torch. You should see voltage when heated that rapidly changes as you pull the torch away. If the new sensors behave properly, then the wires are in the right order. If they don't then the wires are probably in the wrong order.

Go get the Bosch sensors and be done. That's what I have used and no issues. Look like original, work like original, and you can pick up almost anywhere

You're the first person I have seen in twenty years that has suggested a Bosch O2 for a B body. The universally accepted opinion is that AC Delco O2s are the only good choice. I use Bosch... on VW.

My aim in checking the bolts is just to make sure there are no leaks. I did look at a Bosch sensor at the auto store and it looked a lot more like mine than the Delphi did. Still different wire arrangement. I agree that most everyone has said that AC sensors are the way to go and my policy on this car has been to use nothing but OEM parts. However, GM did obviously change the sensors. I think I'll go buy one Bosch sensor and put it on the easy side. If it fixes that side I'll do the other.

Maybe a stupid remark, why not put back the old sensors. The car ran fine, as you stated....
Pete

"You're the first person I have seen in twenty years that has suggested a Bosch O2 for a B body. The universally accepted opinion is that AC Delco O2s are the only good choice. I use Bosch... on VW."

Well when you follow the heard, you usually turn into ground beef. I like the free range.
I don't know who or why that is the opinion, but I have been using Bosch 02 sensors in everything, no issues yet.

As for the wire arrangement, what are you talking about? My Bosch sensors were pre-wired with Oem connectors. Take out old, put in new and no worries

Dutch Pete wrote:

Maybe a stupid remark, why not put back the old sensors. The car ran fine, as you stated....
Pete

I don't car who you are,. thats funny right there,..

ROTFLMAO!!

Keep fixing it till its broke,..

OK. I put a Bosch sensor on the left side and disconnected/reconnected the battery. The result appears to be that the Bosch side is working now. My IPW stayed around 3 and my ST fuel trim is actually lower at 118. After replacing the left side, the right side actually started out at zero volts and came up to normal a bit later, I guess when it got warm enough. After it ran for a while the left side started doing the same old thing, declining volts gradually. Wound up with a left side IPW of 6 ot 7 while the right side stayed at 3. LT fuel trim on right side pegged at 160 again. So ... it appears the Delphi sensors are not a replacement for our cars, or I got the wrong ones, or I just got two bad sensors. Tomorrow I will get another Bosch. ALSO ... I found that when the AIR pump is commanded off there is still some air flowing into the hose, thus perhaps into the manifolds. I don't think that's normal. I tried plugging the hose and air cleaner and removed the relay but I got a DTS 26. I thought the OBD1 cars didn't care if you disconnect the air pump. Can somebody tell me if air going into the hose is normal with the pump off?

Yup, that pretty much confirms that the O2 sensors are not the right ones. Could be a manufacturing error or could be a clerical error in the listing. I would still very much like to know the Delphi part number of the sensors you installed.

Part of the air pump disable procedure is to plug the hose. The air pump disable TSB only applies to the 95 and 96 cars, and I think perhaps only for the US models -- it's not available for my Canadian 95 anyway. So you will get the DTS 26 code if you unplug the relay. I think unplugging the air pump itself is not detected though.

buickwagon wrote:

So you will get the DTS 26 code if you unplug the relay. I think unplugging the air pump itself is not detected though.

True,....

OK guys, I'm sorry for taking so long to get back to this thread. The Delphi sensors I bought were p/n ES20317. I put another Bosch sensor on the other side and now the car runs like a beast. I disabled the Air pump and plugged everything while I was at it, and cleaned the MAF. Now I'm dealing with oil leaks. One that has reappeared since the weather got cold is the steering box. I've been using p/s fluid with leak inhibitors ever since I got the car with good success but it may have reached the point where it needs to be replaced. There were a couple poplice car steering boxes on Ebay a while back, I think they were Cardone. Anybody got an opinion on that?