Where and how many O2 / oxygen sensors in my 1990 V8 5.7L? (verifying what I see in the Chilton)

[ninety1500]

Hi everyone, I just want to double check and verify what I'm reading in the Chilton manual for this truck. I have a 1990 GMC SIERRA 1500 SLE, 4WD, 5.7L V8 TBI. I don't know the transmission that is in it (I hope I'm giving enough information here).
The manual says : "The oxygen sensor is a spark plug shaped device that is screwed into the exhaust manifold on V6 and V8 engines, and into the exhaust pipe on the 4.8L" and I just want to make sure that the factory settings should be a single O2 sensor screwed into the exhaust manifold and that it's a 1-wire sensor. Should there be any additional ones?

Thanks so much in advance!

 

[df2x4]

I'm not super familiar with the O2 sensor setups on the '88-'95 trucks so I'll let someone else answer your question, but as a general rule shop manuals like Chilton or Haynes are much less accurate and detailed than the GM factory service manuals. For example, one thing in your quote that confuses me is the reference to a 4.8L engine. To the best of my knowledge there was no 4.8L engine in these trucks, at least in the US market. It was either 4.3L (V6), 5.0L, 5.7L, 6.2/6.5L (diesel) or 7.4L.

You can download the GM factory service manuals in PDF form here for free, if you don't see the year you need in the first post keep reading. Other members have added to the collection over time.

https://www.gmt400.com/threads/88-98-service-manuals.43575/

 

[HawkDsl]

My 89 has one. Driver side exhaust manifold. Single wire. Chances are, that's all you have too.

 

[ninety1500]

I'm not super familiar with the O2 sensor setups on the '88-'95 trucks so I'll let someone else answer your question, but as a general rule shop manuals like Chilton or Haynes are much less accurate and detailed than the GM factory service manuals. For example, one thing in your quote that confuses me is the reference to a 4.8L engine. To the best of my knowledge there was no 4.8L engine in these trucks, at least in the US market. It was either 4.3L (V6), 5.0L, 5.7L, 6.2/6.5L (diesel) or 7.4L.

You can download the GM factory service manuals in PDF form here for free, if you don't see the year you need in the first post keep reading. Other members have added to the collection over time.

https://www.gmt400.com/threads/88-98-service-manuals.43575/

That was part of the reason I came here to ask, the 4.8L engine definitely seemed fishy. I searched that link previously (and just went through again to make sure) and they don't have the 1990 manual unfortunately. I would much prefer those! Thank you for linking that I think it's great information and maybe one day someone will get the 1990!

My 89 has one. Driver side exhaust manifold. Single wire. Chances are, that's all you have too.

Perfect! I think that's probably the only one also but I wanted to double check. Thank you for getting back to me with it!

This is the link to the Chilton manual if anyone is curious. It's not as good as the GM ones but it's better than nothing! https://archive.org/details/chiltonsrepairma00john

 

[someotherguy]

Oh we know the Chiltons are like comic books that aren't funny. Welcome to the forum and here's the link to a bunch of scans of the factory manuals. While there are errors in those as well, they are country miles better than any aftermarket manual.

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

Richard

 

[Schurkey]

An OBD-1 GMT400 is likely to have only one sensor.

An '88 and '89 have it in the left exhaust manifold.

By...'94 (?) the 5.7L automatic-trans vehicles had a one-wire sensor in the manifold. The manual-trans 5.7L had one heated sensor in the Y-pipe, not in the manifold.

 

[Komet]

If there's no '90, just use the '91 or whatever closest factory service manual. I use a combination of the '92, '97, and '99 manuals depending on what I'm doing.

 

[someotherguy]

By...'94 (?) the 5.7L automatic-trans vehicles had a one-wire sensor in the manifold. The manual-trans 5.7L had one heated sensor in the Y-pipe, not in the manifold.

Ya know, I've had the exact opposite observation. My '94 C2500LD 5.7/4L60E had a 3-wire O2 just ahead of the cat. My '94 C1500 5.7/NV4500 had a 1-wire O2 in the driver side manifold. Did you mistakenly get those examples backwards? The last few years of manual trans TBI stuff always seemed to me to have the 1-wire O2.

Richard

 

[ninety1500]

This is all great information and a huge help to someone that's new to this truck and engine. It seems like the 1 O2 sensor is probably the case in this truck, but I'm going to try to crawl my big butt under there and make sure I don't see anything else!

 

[Road Trip]

This is all great information and a huge help to someone that's new to this truck and engine. It seems like the 1 O2 sensor is probably the case in this truck, but I'm going to try to crawl my big butt under there and make sure I don't see anything else!

And if you have any doubt about what you are looking at, simply take a photo & post it in this thread.

Photos nearly always guarantee lots of interest/response FWIW. Photos are the unofficial currency
of this forum. :0)