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Chevrolet S-10 ZR5 4x4 Crew Cab
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Discussion Starter · #1 · (Edited)
Hello!

My truck has been throwing some mixed signals this year. At first she was giving me a P0301, so I changed all the electrical components (sparks along with the wires, distributor rotor and distributor cap). I also installed a new fuel pump and the air intake is in perfect condition (clean filter, MAF and throttle). I scan the obd2 after the new stuff was installed and she gave me a P0304, to later give me a P0300 to a P0303 and this has been the most consistent of all the code readings. That P0303 has been there for months now and I'm beginning to think I have to replace the Piston Rings. I'm not an expert I just think they went bad cause in my mind I replaced all the basic components (air, fuel and electricity) to make the engine work so it has to be something besides that, right?
I will be replacing the fuel injectors to the AC Delco 217-3028 to see if MAYBE the fuel injector for Cylinder 3 has gone bad and it's not receiving the fuel it needs, hence the misfire. If that has nothing to do with misfires then I'm sorry for my ignorance, I'm kinda desperate.

What do you think is causing that P0300/P0303 misfire?

Thanks in advance for the replies.
 

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Been there Done it
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Do a compression check. Sounds like the truck is getting tired. No HVAC and missing. Miles on it?
Did you use all original equipment plugs, wires, cap? S-10s are touchy about that.
Could be bad injectors. Those new style aren't infallible.
Those misfires can be hard to find. The new fuel pump could be weak. Do a fuel pressure test. Cat could be clogged. Wear on the distributor gear. Faulty sensors happen. Bad rings is rare under 200K, but not impossible.
 
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Hello!

My truck has been throwing some mixed signals this year. At first she was giving me a P0301, so I changed all the electrical components (sparks along with the wires, rotor cap and distributor). I also installed a new fuel pump and the air intake is in perfect condition (clean filter, MAF and throttle). I scan the obd2 after the new stuff was installed and she gave me a P0304, to later give me a P0300 to a P0303 and this has been the most consistent of all the code readings. That P0303 has been there for months now and I'm beginning to think I have to replace the Piston Rings. I'm not an expert I just think they went bad cause in my mind I replaced all the basic components (air, fuel and electricity) to make the engine work so it has to be something besides that, right?
I will be replacing the fuel injectors to the AC Delco 217-3028 to see if MAYBE the fuel injector for Cylinder 3 has gone bad and it's not receiving the fuel it needs, hence the misfire. If that has nothing to do with misfires then I'm sorry for my ignorance, I'm kinda desperate.

What do you think is causing that P0300/P0303 misfire?

Thanks in advance for the replies.
I have a 1996 s10 4.3 liter. Had a p0303 code for months. Replaced plugs wires cap rotor coil. It ended up being my spider injectors. The plug had a broken pin. Replaced the spider now it runs like new.
 

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I'd think that if rings were that bad, you'd have blowby out the wazoo. Pull the oil fill plug before you start it and see how much crankcase air is blowing out. If it's a good bit, do a compression and/or leakdown test.
I'd doubt that the rings are the problem unless it's had a lot of dirt run through the engine.
 

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DILLIGAF
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Do a compression check or a vacuum check. Mine had a valve stuck open and I got the multiple misfire code. I did like you and changed plugs cap rotor and wires, even the fuel spider. Then I did what I should have to start with. I did a vacuum check and it was all over the place so I did a compression test and found the bad cylinder. My conclusion was after putting Seafoam in the vacuum system it broke loose a piece of carbon and it got stuck in the valve guide. Once the valve got stuck of slowed down the piston bent it. The picture (bore scope) is the valve stuck open.
345581
 

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Chevrolet S-10 ZR5 4x4 Crew Cab
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Discussion Starter · #7 ·
So, I did a compression test after installing a new fuel spider and it's giving me around 75 psi (10 cranks). It's either a valve or the rings at this point. Will update as soon as I can.

Thanks for your replies, I'm so glad to have this community as active as it is.
 

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Discussion Starter · #11 ·
This has gone places I'd never thought of going...

So, misfire is still on, like I said before, it has a new upgraded fuel spider (ACDelco 217-3028 GM Original Equipment Fuel Injector) with it came the intake manifold gaskets so that's new too and today I installed the fuel filter (ACDelco Fuel Filter GF645) and am still getting the misfire. The only thing left before I leave the truck in a machine shop is to change the alternator (which is old) and the distributor to have all electrical components changed at 100%.

Now to the opening sentence; I took the truck for a spin, after driving 47 miles (75 km), let her sit for around 7 hours, I start her up, all normal so I start my journey and curiously after a slight bump on the road the ABS light came on along with the E-Brake light and the speed indicator went dead. Truck was running ok, tho. I get home, let her be for a week. Start it up again for errand and she is stuck with the ABS light on along with intermittent E-Brake light. I'll post a video so you can see what I'm talking about.

(Video:)

Today I disconnected the battery to see if that would reset the computer but no dice. I'll also share that I recently changed both front wheel hubs with the Duralast Wheel Bearing/Hub Assembly DL513124HD which came with the ABS cable attached. The ABS light went off as soon as I installed those new hubs but now it's back and with a vengance (e-brake light and dead speed indicator). The truck won't change gears or will do randomly. It looks like some sort of limp mode but I don't know if these S10s had one. I also checked the connections, fuses and read for ABS codes and all looked normal, no codes came up. I haven't checked the REAR ABS sensors, that's on the list.

She is somewhat undrivable now.

What are your guesses?

As always; thanks in advance, this has been an adventure for me and I hope it'll help people in the future.
 

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DILLIGAF
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My ABS bugged the piss out of me. I changed the sensors and that didn't help. I unplugged the speed sensor on the transmission and plugged it back it. That worked temporarily. I unplugged the ABS module and took the bulb of the dash circuit board with a soldering iron. I don't miss the ABS either. I've read that the S10's develop issues with the ABS module with age.
 

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The dash weirdness is probably a bad ground. Check the grounds on the back of the block and the firewall.

If you really had 75 psi on a compression test, then I kinda doubt that the truck would be running. That's way too low. Instead, I think you didn't do the test properly. Pull all the spark plugs and then test one cylinder at a time with the fuel pump fuse pulled and the throttle butterfly propped wide open. Report back with updated compression values for each cylinder.

Lift the distributor up and examine the drive gear all the way around. If you see heavy wear on it, replace it and solve your misfire.
 

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2004 Avalanche. 2001 V6 Extended Cab ZQ8.
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This has gone places I'd never thought of going...

So, misfire is still on, like I said before, it has a new upgraded fuel spider (ACDelco 217-3028 GM Original Equipment Fuel Injector) with it came the intake manifold gaskets so that's new too and today I installed the fuel filter (ACDelco Fuel Filter GF645) and am still getting the misfire. The only thing left before I leave the truck in a machine shop is to change the alternator (which is old) and the distributor to have all electrical components changed at 100%.

Now to the opening sentence; I took the truck for a spin, after driving 47 miles (75 km), let her sit for around 7 hours, I start her up, all normal so I start my journey and curiously after a slight bump on the road the ABS light came on along with the E-Brake light and the speed indicator went dead. Truck was running ok, tho. I get home, let her be for a week. Start it up again for errand and she is stuck with the ABS light on along with intermittent E-Brake light. I'll post a video so you can see what I'm talking about.

(Video:)

Today I disconnected the battery to see if that would reset the computer but no dice. I'll also share that I recently changed both front wheel hubs with the Duralast Wheel Bearing/Hub Assembly DL513124HD which came with the ABS cable attached. The ABS light went off as soon as I installed those new hubs but now it's back and with a vengance (e-brake light and dead speed indicator). The truck won't change gears or will do randomly. It looks like some sort of limp mode but I don't know if these S10s had one. I also checked the connections, fuses and read for ABS codes and all looked normal, no codes came up. I haven't checked the REAR ABS sensors, that's on the list.

She is somewhat undrivable now.

What are your guesses?

As always; thanks in advance, this has been an adventure for me and I hope it'll help people in the future.

The ABS issue is pretty common on these trucks. Well pretty common on and GM with this module. So there is a large relay, and 2 large plugs that can have cracks in the solder joints. The pic below is from my truck, if you look where the barcode sticker is you will see the 5 pins from the relay, and there are 4 pins at the bottom, and 4 more at the top that are the high power wires from the truck, and to the pump motor. Removing the module from the truck is easy, there are 4 T20 bolts holding it on, and 3 plugs. After you remove that you will need to remove 6 small T8 screws that hold the lid on. Use a dedicated T8 driver and not a 1/4" bit, there isn't enough room for the bit driver. After you get those 6 little buggers out you will need to take a sharp exacto knife and carefully cut the RTV that has the top glued to the bottom. Just make little cuts all the way around till you can easily pry the lid off. DO NOT FORCE IT OFF! There are a couple places where there is some now dried heatsink compound that will have to give up it's grip first. Also sometimes the RTV gets on the circuit board which will need to be carefully cut off. Once opened you can reflow those solder joints and that will fix the issue 99% of the time, if you have the communication with module codes.


347000
 

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2004 Avalanche. 2001 V6 Extended Cab ZQ8.
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I just watched your video. Do you have any VSS codes? I would love to see the signal for that. With your speedo jumping like that it tells me that the VSS could be bad, or a bad ground for it's circuit which could throw the computer into a fit with it trying to figure out what's going on. It may be time for a higher level scanner. Also please recheck the Compression, all 6 plugs out and throttle wide open. 75lbs is good compression for a Model T, not for an S10
 
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