S10 4.3l won't accelerate

[paragonbuilder]

So I've got this S10 that is boggling my mind. When I bought it I replaced the spider injectors, ignition control module, MAF, rotor,cap,wires,plugs, and it ran decent for a couple months. One morning I went to start it and it fired right up and purred like a kitten. When I hit the gas it fell on its face, I couldn't even move the truck.
This is the third time I'm attempting to fix it and I'm tired of throwing parts at it.
It's now got another new MAF, TPS, idle control. Nothing I do seems to change it. Pull any sensor and it might sputter for a second or stall. But will start right back up and act the same. I tested the MAP, it's modulating 0-5v with a mighty vac. Put a flat gasket over the egr to plug it.
Idles perfect, touch the gas and instant bog. I thought fuel pump but I've got 60psi at idle. Tried spraying ether in intake while operating throttle, nada.
My mind is blown. Lol. What am I missing.

I pulled the cap today and saw a little corrosion so I cleaned it up, no different.
I'm going to pull the plugs tomorrow and see if anything looks fishy.

Any ideas?

 

[e.fisher26]

Clogged cats?



-•------------------------------------------------------------

Just a home owner that likes the older better made machines

Craftsman 3.7 x2
Husqvarna 36

 

[Stihlbro]

What year s10?

 

[RIDE-RED 350r]

4.3 is a great engine, but they are notorious for eating cap and rotor much more frequently than anything else on earth. I have literally done them once a year or more, sometimes less than 5k miles between changes. While the symptom is usually no-start, I did notice hard starting and sometimes stumbling idle at times before total failure.

I might try another cap and rotor. It may not be your fix, but it's not that expensive and at least can eliminate it as the cause. Never know.

 

[jmssaws]

Is it on limp?
What year?

 

[Brush Ape]

Spraying ether in that intake means spraying it all over the outside of them new CMPI spiders. Your gonna have a fire boss and probably melt them multi port injectors.

 

[paragonbuilder]

Clogged cats?



-•------------------------------------------------------------

Just a home owner that likes the older better made machines

Craftsman 3.7 x2
Husqvarna 36

Overnight? Maybe...

 

[paragonbuilder]

What year s10?

1999

 

[paragonbuilder]

4.3 is a great engine, but they are notorious for eating cap and rotor much more frequently than anything else on earth. I have literally done them once a year or more, sometimes less than 5k miles between changes. While the symptom is usually no-start, I did notice hard starting and sometimes stumbling idle at times before total failure.

I might try another cap and rotor. It may not be your fix, but it's not that expensive and at least can eliminate it as the cause. Never know.

I'll try that... Is there a better one?

 

[paragonbuilder]

Is it on limp?
What year?

Not sure if 1999 has limp mode.
Cleared codes after pulling sensors, nothing comes back.

 

[paragonbuilder]

Spraying ether in that intake means spraying it all over the outside of them new CMPI spiders. Your gonna have a fire boss and probably melt them multi port injectors.

Well I won't do that again... Thanks for the tip!

 

[Motorhead]

Sounds like valves

 

[paragonbuilder]

Sounds like valves

??? Explain?

 

[RIDE-RED 350r]

I'll try that... Is there a better one?

I don't think so on the "better" cap and rotor...

But I do recall reading a GM service bulletin about the issue. It involved wrapping the AC condenser line that passes directly over the top of the distributor in foam, like a water noodle or bar pad on dirt bike handle bars to prevent the condensation from that line dripping onto the dizzy causing issues. The other part of the service bulletin stated that the screen in the vent in the bottom of the dizzy under the rotor should be removed as it would corrode and prevent proper ventilation of the dizzy thereby causing premature corrosion of the cap and rotor contacts resulting in failure of those components.

 

[Motorhead]

If the valves aren't sealing properly you won't have any power under a load.Do a compression check. How many miles are on the motor?

 

[RIDE-RED 350r]

I should add that many times the contacts in my bad caps and rotors did not visually look all that bad at all. I swore just a quick little bit of cleanup would be the fix. No Sir, new cap and rotor was the fix...

Anyhow, I found the GM service bulletin. It pertains to the full size trucks, but should still apply to the 4.3 powered S-10 and Blazers as well:

Poor Engine Performance-Misfire, Rough Idle, Stalls, Engine Cranks but Does Not Run, SES/Check Engine Light On, DTC P0300 Set (Inspect Distributor Ignition(DI) System Components, Replace as Necessary) #05-06-04-007 - (Jan 28, 2005)

2001-2003 Chevrolet Silverado Models

2001-2003 GMC Sierra Models

with 4.3L Gas Engine (VINs W, X -- RPOs L35, LU3)

Condition
Some customers may comment on poor engine performance and the Service Engine Soon/Check Engine light being illuminated. Upon investigation, the technician may find DTC P0300 set.

Cause
This condition may be due to high levels of internal corrosion in the distributor, causing misfire, rough idle, stall and Engine Cranks But Does Not Run. This corrosion is attributed to a lack of airflow internal to the cap caused by the vent screens being clogged with debris.

Correction
Important: It has been determined on the Sierra and Silverado applications with the 4.3L engine that the A/C accumulator line is routed directly above the distributor area and condensation from that line can aggravate the corrosion condition. For these vehicles, install the foam sleeve, P/N 15190971, to the A/C line. Cut a slit in the sleeve and secure to the line using tie-straps.


Remove the vent screens and inspect the internal components of the Distributor Ignition System using the procedure listed below. If the distributor base has to be replaced, the vent screens will also have to be removed on the new distributor. If there is evidence of this internal corrosion, replace the affected component. Refer to the appropriate procedure in the Engine Controls sub-section of the applicable Service Manual.

Important: All of these inspections can be done on-vehicle.


1. Inspect the distributor cap. You may notice a white residue on the cap walls. For higher mileage occurrences, the interior of the cap may have changed to medium brown in color.
2. Inspect the distributor rotor. You may notice the presence of black streaks on the plastic surface. More typical evidence would be visible green spots on the copper surface of the rotor segment.
3. Inspect the distributor base. You may notice high levels of surface rust on the distributor shaft or surface contamination on the sensor hold down screws.



4. Inspect the distributor vent screens (1). If the vent screens are present, remove them by using a plastic-handled, long blade awl or pick (2). Insert into the airflow vent screens and pop them out. Refer to the figure for removal procedure. If the vent screens have been removed from the base of the distributor, then check the airflow inlets for being clogged with debris.

 

[paragonbuilder]

If the valves aren't sealing properly you won't have any power under a load.Do a compression check. How many miles are on the motor?

150k
Trick ran fine when I shut it off, then in the morning nothing but idle...
I can comp test. Good thinking.

 

[paragonbuilder]

I don't think so on the "better" cap and rotor...

But I do recall reading a GM service bulletin about the issue. It involved wrapping the AC condenser line that passes directly over the top of the distributor in foam, like a water noodle or bar pad on dirt bike handle bars to prevent the condensation from that line dripping onto the dizzy causing issues. The other part of the service bulletin stated that the screen in the vent in the bottom of the dizzy under the rotor should be removed as it would corrode and prevent proper ventilation of the dizzy thereby causing premature corrosion of the cap and rotor contacts resulting in failure of those components.

Didn't know there was a vent... Cool!
I'll look.

 

[RIDE-RED 350r]

150k
Trick ran fine when I shut it off, then in the morning nothing but idle...
I can comp test. Good thinking.

My cap and rotor problems came on quick like that too, fine one day, no start the next. Initially it would sputter and try, but then just crank. I suppose I flooded it cranking it.

The second time around with that particular truck I refused to believe the cap and rotor were bad again as I had just changed them a few months prior and only having a one mile commute I only put about 2K miles on since the cap and rotor swap. I did plug wires and the coil figuring for sure it just couldn't be the cap and rotor again already. I was wrong. LOL!

 

[Mastermind]

Check the distributor drive gear for wear. I had a 4.3 that did damn near the same thing.