Question about 1991 Chevrolet S-10

1 Answer

My chevy s10 failed emissions

My 1991 chevy s10 failed emissions 4.3 engine has had a new oxygen sensor spark plugs.throttle body sprayed.failed with high co and hc readings both high.any ideas?

Posted by on

  • 1 more comment 
  • Anonymous Mar 19, 2014

    failed emissions, high HC's but no check engine light to indicate why i believe the bulb is out but wondering if there is a fuse i could check as well

  • Anonymous Mar 24, 2014

    one of the spark plugs keeps getting bent

  • Anonymous Mar 24, 2014

    one spark plug keeps getting bent



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 702 Answers

Have your cat. converter checked out. I just had one of these for the same reason in my shop today.

Posted on Jul 09, 2008


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

1991 Toyota Camry running rich after cleaning the throttle body and replaced the throttle positioning sensor. Checked for vacumm leaks but cant find any

92 camry failed smog because running rich. Why? - Toyota Nation ...

Apr 26, 2012 - 15 posts - ‎9 authors
off ignition timing, and the car was running to rich. the timing i will get fixed tomorrow but the rich .... Our 93 camry le with 4 cly engine failed agin a few weeks ago, both our toyotas always fail.. they are .... 1991 Toyota MR2 V6 91 MR2 N/A Rough Idle, Running Rich, No Accelleration
10 posts
Apr 24, 2012
Celica 1991- Insane gas consumption/running rich
10 posts
Jan 24, 2011
22RE Running Rich, didn't pass smog
10 posts
Apr 25, 2010
1998 Camry 5SFE 4-cyl idle long-term fuel trim
15 posts
Sep 11, 2007
More results from

Toyota Camry running rich Questions & Answers - Fixya > Forum > Tags > running rich > Cars & Trucks > Toyota
... running rich I have a 1991 Camry that is running rich. I just replaced the O2 sensor and a new cat, oil change, new spark plugs. The car wont pass smog. it is ...

1992 Toyota Camry XLE V6 Excessive Running Rich ...

? 0:21
Aug 16, 2013 - Uploaded by StreetSports1
1992 Toyota Camry XLE V6 Excessive Running Rich ... 1997Toyota Camry V6 forward Oxygen (O2) Sensors .

Jan 11, 2016 | Toyota Cars & Trucks

1 Answer

1996. Turns over, but why doesn't it start?

Check for spark at plugs, if you have spark, spray carb cleaner into throttle body to see if she will crank up.

Oct 09, 2015 | Chevrolet S 10 Cars & Trucks

2 Answers

Why wont pass emmissions. have changed spark plugs and filter. they say my hc readings are too high and also the co readings

Any codes present? Is your car a daily driver or has it sat for extended period of time? (hence how old is your gas? ) Is this car new to you or have you had it for a while?

May 30, 2014 | 1998 Chevrolet Tahoe

1 Answer

C15001993 truck 4.3 v6 Failed Emissions HIGH CO again

Sounds like you lost O2 Control

Check fuel trim & data with professional
scanner & such

You done as far as working at home, you did all
you can

You have a rich condition (CO)

Seems as though the coolant sensor is not working &
your in open loop

Mar 05, 2013 | Chevrolet C1500 Cars & Trucks

1 Answer

I failed emissions test. The HC and CO both failed. I was told by a family member that it sounds like the catalytic converter and I wanted to know how much that would cost or estimated cost to replace

Rich fuel mixture is leaking fuel injectors,failed oxygen sensors

Need clean air filter,new spark plugs

An Exhaust Converter is only good for 12 to 14 years max then
it has to go

This is a social web site we use as you do so prices are are over the internet less labor of coarse

Mar 02, 2013 | 1997 Mercury Cougar XR7

1 Answer

200 ford expedition diagnostic code P0171

PO171- System too lean (Bank1)

Most likely a failed oxygen sensor on the passenger side,
if you never changed the front or upstream sensors at 100,000
miles, as preventative maintenance

Do both sides,clear codes & if they come back, check for vacuum leaks

Do spark plugs every 3 years, as well as fuel & air filter

Spray throttle body inlet with CRC Throttle Body Cleaner

Spray MAF Sensor with CRC MAF Cleaner

Check Fuel Pressure a rail port with a gauge (38# to 42# )

Nov 18, 2012 | 2002 Ford Expedition

2 Answers


mccartlidge. are you serious?? high HC is the result of a headgasket problem??? do everyone a favor and dont give advice when you clearly dont know a damned thing about emissions. as far as solutions to your high HC output, someone else mentioned the possibility of a worn out cat along with carb problems and or a simple air fuel adjustment. this car if i remember correctly has a feedback carb which means it has an oxygen sensor and a mixture control solenoid on the car to fine tune the air fuel mixture. it is not uncommon to have a oxygen sensor not functioning at all or out of normal calibrated range. easy test for oxygen sensor(single wire oxygen sensor ) is to hook up a voltmeter at 0 to 1 volt range(positive lead to oxygen sensor wire, negative lead to any good ground source) and watch the voltage. a perfectly working system the signal should look like a wave constantly rising and falling from .9v-.1v. test at 2500 rpm as well as at idle on a hot engine.if the oxygen sensor doesnt rise and fall, add fuel(spray small amount of carb spray) into carb while at idle or high rpm and the oxyen sensor should go full rich(approx .8-1v) that is point 8(.8v) not eight volts. you will usually see a reading of .9v . if the oxygen sensor doesnt put out a rich reading than its no good. on the other end you can remove a vacuum line(brake booster hose, half way removed as to not stall the engine) the oxygen sensor should go lean which means around .1 volts. if the oxygen sensor does not respond correctly replace it. beyond that, the engine first and foremost has to run on all cylinders to run clean and efficient. if it has a missfire or dead hole that will cause high HC along with high CO as unburnt fuel is going out the tail pipe. i could go on and on about possibilities but figured i would give you a couple basics to go on. Good luck.

Aug 12, 2012 | Chevrolet Chevy Cars & Trucks

1 Answer

High emisions new cat new sensor


High emission are often consequence of engine problems. In that case the new cat converter or exhaust and new oxygen sensors will not help.

High emission from engine occurs because of many different reasons, main causes are:

Electronic injection problems:

Do an OBDII scan to find out if there are error codes. If there are no codes check injectors sensors in the air intake (MAF and IAC), check vacuum for leaks. Clean throttle body. Check EGR, IAC, PCV systems.

Engine internal problems:

Do a compression test to find problems associated with engine faults (eg.piston rings, head gasket, valves).

Also make sure that spark plug, fuel and air filter have been replaced. Make sure that there is no misfire or distribution problem.



Sep 20, 2011 | 1998 Ford Escort

2 Answers

Have an 87 chevy s10 pickup truck with a 2.3 v6 engine. Fuel pump, distributor cap, wires, plugs, and filter have all benn replaced. Still truck will only start after you spray ether in the throttle...

check the spark plug gaps and make sure their set to 25th ,do this first then if still not starting then look at the autochoke ,this is an old vehicle and so it should have a sensor that turns the autochoke on like a temperature sensor in the head for the gauge but iam not familar with this american vehicle to be able to tell you sorry

Jan 24, 2011 | 1987 Chevrolet S-10 Pickup

2 Answers

L failed # i on the emisions test which is the HC l put new spark plugs in and had the throddle body cleaned and oil changed the reading is supposed to be 57 i had 128 took it in after spark plugs and...

Your engine is still running rich, inspect all your vacuum lines and your fuel pressure regulator. A bad fuel pressure regulator can cause your engine to run rich and is there any check engine light on???
Thank you for suing Fixya and keep me posted, be glad to help you get your car running 100% again soon

Mar 29, 2010 | 1991 Chevrolet Camaro

Not finding what you are looking for?
1991 Chevrolet S-10 Logo

1,433 people viewed this question

Ask a Question

Usually answered in minutes!

Top Chevrolet Experts


Level 3 Expert

78267 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Ronny Bennett Sr.
Ronny Bennett Sr.

Level 3 Expert

6927 Answers

Are you a Chevrolet Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides