Engine has rough idle and lack power?

Hi, I'd start with an overall tune-up. Any trouble codes? Use a gage and check fuel pressure. If your TBI does the injector/s spray pattern look ok, engine idling? A spray pattern, doesn't mean the pressure is ok. If you have a tranny or clutch issue,

lets go over this guide

https://www.2carpros.com/articles/engine-has-low-power-output

Please run down these guides and report back.

Truck starts good idles fine ,sputters and misses under power.

Hi,

The first thing I need you to do is check for diagnostic trouble codes. Here is a link that explains how to retrieve them. You don't need a scan tool. All that is needed is a short jumper wire or even a paper clip.

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https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method


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Let me know what you find. Also, let me know if there is any smoke from the exhaust, odd smells, anything you can think of that could help me diagnose what might be happening.

Take care,
Joe

Engine Performance problem
1987 Chevy S-10 6 cyl Four Wheel Drive Manual

2.8 litre loading up on idle but has no more power after 1/4 - 1/2 throttle. the same power matted on the floor as 1/4 throttle. u can press the peddle to the floor and start backing off and from 1/2 to 1/4 throttle it makes power. it really acts like it is sort of floodin i guess, just notta lotta smoke from the tailpipe if any.

check your fuel pressure, but change your fuel filter first. It may be paritally plugged then cross A & B on the aldl and see if there is any codes. come back to the site here an dlook under obd 1 on trouble codes.

I have a 1986 Chevy S-10 Pickup truck with a 2 wheel drive V-6 Fuel injected 2.8 liter engine. It has an automatic transmission.Truck has 160,000 miles. Engine and
transmission are origional.
The truck has no pick up when in drive and performs at
about half of what you would expect power-wise on the road.
Top speed is about 55, and even then, only on a long straightaway. Start to go up hill at all, or to suddenly
accelerate from a full stop, and the engine coughs and rapid deceleration occurs.
This problem persists, and will not go away.
A professional mechanic shop is currently stumped, after having it for 10 days.
I am about to get it back because I want to get it
running. They have done no work on it.
When in Park, the engine will run very well, and when the gas pedal is held to the floor, it sounds and runs exactly like it should.
The transmission does not show any signs of trouble whatsover, and shifts in and out of all gears normally, and engages normally.
Only in Drive like I described, does the problem show itself. There is no sound from the engine indicating a bad cylander. All 6 spark plugs have been changed and correctly gapped, as well as new spark plug wires.
Distributor cap and rotor have been pulled, and inspected, are like new. While I had them off, i replaced the ignition module underneath the rotor. There are no cut or damaged wires visible under the hood, and all vacuum lines are attached and going where they should. Timing has been tested, is working fine, and is set at 15 degrees past normal settings. Lastly, old gas is not possible,it was nearly empty and then refueled with 15 gallons of non-ethanol just 4 weeks ago.
Any ideas? Thanks for reading!

I am giving you a diagnostic walk through for your situation that will go through the most likely issues causing your problem. When you get to the part about pulling trouble codes. you can go to Auto Zone or Advance Auto and they will pull them for free.
Just follow this link;

https://www.2carpros.com/articles/engine-has-low-power-output

I have a 1985 S-10 with the carburetated 2.8l v6 with 127,000 miles. The problem I have is that the engine is missing and knocking when under load. It idles fairly well but as soon as you start driving it starts missing and lacks power especially as you get to higher speeds. It is topping out at about 35 mph and starts to miss, knock, and buck. Timing is perfect at 8 degrees, new fuel filter, new fuel pump, newer plugs, wires, distributor cap, rotor, head gaskets, and intake gaskets. All spark plugs are getting spark and look fine when pulled. It also has a newer CAT and has been sea foamed. All the plugs are gapped correctly, no water in distributor, no cuts on any wires, firing order correct, no fuel leaks, fuel pump is pumping fine. I am out of ideas and with so many things being done recently im not sure what else is left.

This doesnt realy help me too much because I dont have fuel injectors, oxygen sensors, throttle position sensor, IAC valve, MAF. It has a new mechanical fuel pump so it has good pressure, the EGR valve is newer, all vacumme hoses are newer and all the ignition parts are newer. So pretty much everything on here my vehicle is not equipped with or has been very recently replaced.

Note: If it doesn't apply disregard it-

84 chevy s10 2.8 eng has gargling sounds in the carb after I start it and give it gas as well as loses power?

Check to make sure there is enough fuel pressure to it. Also, check fuel volume to it.

Check the carb as it is getting too much gas. The float may be out of adjustment letting more fuel into the system. you should have a rochester carb on it.With the float out of adjustment the girgling sound is the excessive fuel that is left over when the intake valve closes and from the heat. The lack of power is the engine running too rich. Another thing that can do something like you are saying is the timing so have it checked but do think it is the carb float.

Have changed spark plugs and wires, fuel filter, fuel line, cleaned carbuerator, changed air cleaner, oil change, doesn't know why it keeps bogging down and cutting off going down the road around 40 mph and up

Have you checked the carburator base gasket? It should have a heat grid in it and when this grid goes bad or melts down the truck won't run very good. So with the air cleaner off have a flashlight and upen the throttle and look down inside and see if it has a heat grid and if so does it look either burnt or missing some of the grid?

Yeah we've replaced that first

ok good eliminates that then. Next question have you checked the cat?

I let a friend look at my engine and he said a vacuum line was disconnected. It fixed the choke problem as it was a cold start in the mornings and the choke would never idle down. But when I get on the hwy and try to accelerate it's like I am letting off the gas and it will not over 30-40 mph and it surges causing it to jerk back and forth real bad. Sometimes when I let it cool down and drive it again it does not do it, but it seems to have gotten worse. I think this guy sabotaged my vehicle. I have had it for about 9 months and never had any problems until he messed with it. Please help me. Can you send me a diagram of vacuum lines in a 83 S10 Blazer 4wd 2.8 LTR engine 5 speed manual transmission? thanks

Welcome to 2CarPros.

I attached 3 pictures below of the vacuum system. They are for federal emissions. California is different, so if that is where you are located, let me know.

Now, when the engine is warm, remove the top of the air filter housing. Is the choke open or closed? Also, some of these had a vacuum pull off for the choke, I need to see yours to know if it does. If you can upload a pic of it, that would help me.

Last, confirm that the vacuum advance on the distributor isn't disconnected.

Let me know if any of this helps and what you find.

Joe

I don't know where any of that stuff your asking me about is, but I took some pictures fr you. I push on the gas and it just wont go. No power at all.

There are several of the vacuum hoses there. However, have you checked to see if there is a blockage in the exhaust? If it is plugged or partially plugged, you will lose power.

Take a look through these links:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Joe

I found out it is the automatic choke. Worn parts are causing the choke plate to stay closed if I am not mistaken. A friend did some adjustments and for 2 days I thought my troubles were resolved but the first time I drove it on the hwy at a faster speed it started bucking and surging again exactly like before. I am am sending a photo of the things that aren't working right. First photo is so you can see carburetor and second one is what isn't working properly.

When I went to the parts store and as for an automatic choke the lady handed me a choke thermostat. I don't think that's the problem. the items that I circled in the photo are the items that are not moving when the accelerator is pushed. those parts allow though choke plate to open and close and when I accelerate. those parts don't move at all. When I move then manually they just flop around rather loosely and barley open and close the choke plate.

Hi,

I looked again at the pictures you sent. The item appears to be the vacuum pull off for the choke. Do me a favor. First confirm there is a vacuum supply to them. If there is, see if the pull off holds vacuum.

Let me know.

Joe

Wow! It is fixed. I went to a local parts store and bought a fuel filter for $2.99 and a friend put it in for me. took it for a test drive. no more bucking! Thanks for all the help and advice guys. I am so stoked! Brenda M Coquille, Oregon

Wow!!! That's great news. I'm glad to hear you got it fixed. Let us know if you have questions in the future.

Take care,
Joe

Can you please tell me where the idle control screw would be located in my 1983 Chev S10 Blazer...thanks guys! Brenda Merritt

I need you to take a picture of the main throttle lever for me to see. There are different designs. Curb idle is usually controlled by the vacuum stepper. If I recall (and it's been awhile), the vacuum controller screws in and out to adjust the idle speed.

Let me know.

Joe

I know that there is a screw missing on a metal plate that's right by the idle adjustment screw, but i don't know what it is for. Here are the photos I have of the carburetor. Let me know if this is what you needed. The small item circled near the idle adjustment screw is where I am pretty sure a small bolt/screw is missing because there is a clip on the metal plate where the hole is to keep the screw from coming out. hope this helps Thanks, Brenda M

Hi Brenda,

I copied one of your pictures and circled what I believe to be the idle control motor. There should be a threaded bolt coming from the opposite side that pushes against the throttle lever. You should be able to extend that bolt to increase idle speed. I also noticed that there is no electrical connector attached to it. Did you just have it disconnected while working on it?

Let me know
Joe