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Discussion Starter · #1 · (Edited)
Need help with my truck, this is pretty much how I bought it. Purchase a 93 Chevy Silverado 4x4 the more iv tried to get it running right the more I find out just how Much of a pain in the ass situation I’ve gotten myself into. Please correct me when/if/where I’m wrong. Might throw out some unneeded info but idefk wtf I’m doing sometimes I feel like. This is my daily driver.. It’s a 350 with 305 head (casting # lost/haven’t found where I wrote it down at yet) solenoid on starters ratted loose was the 1st pain on the road. Intake manifold ( ask if needed. I can go look. Just all the kids here this weekend) gasket leak was addressed. Still would like to swap the bolts for the proper ones (ones FOR the intake instead of using washers to accommodate the bolts heads). Exhaust manifold gasket leak occurred (again- bought a reusable gasket this time) because the PVC port was clogged I discovered when I rebuilt the TBI?? PCV clog =Inevitable seal fails? ( a couple Spark plugs, near pcvshow Similar signs that point me in that direction also. Iv replaced pvc but it still can’t handle it.. do I need a Crank case evacuation kit? Replaced Throttle position sensor. Iv got a new IAC to go in but the recent code 34 I think (egr) has me wanting to replace the MAP sensor now. I have no EGR. Or knock sensor. Both are capped/plugged. That’s how the engine was when I bought it. I’m still discovering new things. Ya it throws code 43.(knock sensor) resetting/adjusting the timing been a biotch- pretty sure it wasn’t right to begin but at this point I think code 43 is retarding the timing too much. I have no vacuum advance either. (Pull the 1 wire plug when setting base timing) but here the problem now. Distributor isn’t up to par for a normal engine (old almost shot- barely passed the test this Inexperienced self-taught “mechanic” ran on it with the Multimeter) new one has the ignition coils built right in and has a vacuum advance.. do I throw the vacuum advance in there at this point?It’ll run without the vacuum on the distributor hooked up right? If I was To port the vacuum in what line would I use do any springs need to be adjusted or swapped and would it matter with the knocks sensor code retarding the timing up to 20°? Yeah I’m pretty sure I have some internal engine work that needs to happen I’m still yet to figure out what all I need to be able to do that. Anyone suggest want to map sensor over any others or any other parts over any others for this engine. Iv been feeling around in the dark a little too much. I feel like I’m going to destroy the engine.. I can and will get pictures ASAP. Reminder- for the most part this is how the truck was when I bought it. Iv only trying to finish what someone else started
 

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My response will be bold, italic print. This is a rough brush at this point to just get started.

Need help with my truck, this is pretty much how I bought it. Purchase a 93 Chevy Silverado 4x4 the more iv tried to get it running right the more I find out just how Much of a pain in the ass situation I’ve gotten myself into. Please correct me when/if/where I’m wrong. Might throw out some unneeded info but idefk wtf I’m doing sometimes I feel like. This is my daily driver.. It’s a 350 with 305 head (casting # lost/haven’t found where I wrote it down at yet) solenoid on starters ratted loose was the 1st pain on the road. Intake manifold ( ask if needed. I can go look. Just all the kids here this weekend) gasket leak was addressed. Still would like to swap the bolts for the proper ones (ones FOR the intake instead of using washers to accommodate the bolts heads). Washers are a good idea, the intake is aluminum which is softer material than the steel bolt, washers between the bolt head an aluminum prevent damage to the aluminum when torquing the bolts. Exhaust manifold gasket leak occurred (again- bought a reusable gasket this time) An exhaust manifold leak also allows air entry to the exhaust, the O2 sensor will read this as a lean mixture where the computer will command more fuel to correct the AFR. because the PVC port was clogged I discovered when I rebuilt the TBI?? PCV clog =Inevitable seal fails? Not likely a cause to effect, the PCV is drawing blow by from the crankcase, if not doing that crankcase pressure will escape elsewhere either by hose to the air cleaner or past gasket sealing the engine interior (valve cover, oil pan, grommets or crank seals no effect on in cylinder gaskets or seals nor the exhaust exhaust system. ( a couple Spark plugs, near pcvshow Similar signs that point me in that direction also. Iv replaced pvc but it still can’t handle it.. do I need a Crank case evacuation kit? These engines have a reputation for eating cam lobes and lifters this will oil foul the spark pugs on the affected cylinders. A PCV valve replacement should be sufficient if that was needed that’s the magic part the rest is tubing and grommets. Replaced Throttle position sensor. Iv got a new IAC to go in but the recent code 34 I think (egr) If you have an exhaust leak it is likely you’ll see an EGR code as well. has me wanting to replace the MAP sensor now. I have no EGR. Here too if the EGR is not functional you’ll get an EGR code there are a couple types GM used you need a maintenance manual to ID what this has. Or knock sensor. Both are capped/plugged. These functions do not go away in a computer logic sense because they are physically thwarted by some means, the computer is testing for them by presence and function effect on the engine. That’s how the engine was when I bought it. I’m still discovering new things. Ya it throws code 43.(knock sensor) resetting/adjusting the timing been a biotch- pretty sure it wasn’t right to begin but at this point I think code 43 is retarding the timing too much. Yes it is, this is an anti-detonation function to protect the engine from damage. I have no vacuum advance either. The computer does all the advance work, there is no vacuum advance as such, it gets that info from the Manifold Absolute Pressure (MAP) sensor that also feeds the fuel schedule through another logical process. (Pull the 1 wire plug when setting base timing) but here the problem now. Distributor isn’t up to par for a normal engine (old almost shot- barely passed the test this Inexperienced self-taught “mechanic” ran on it with the Multimeter) new one has the ignition coils built right in and has a vacuum advance.. do I throw the vacuum advance in there at this point?It’ll run without the vacuum on the distributor hooked up right? The factory distributor, if present, does not use and cannot use a conventional vacuum advance, you need to figure out what you got. The factory computer driven distributor is a small cap with external E core coil. The cap base has a raised cut out that clears a pretty large connector no other GM distributor has this. If I was To port the vacuum in what line would I use do any springs need to be adjusted or swapped and would it matter with the knocks sensor code retarding the timing up to 20°? If this is an original TBI distributor there are no springs, if someone substituted a pre computer distributor you’re F’ed as the computer is looking for a tach signal from the distributor as a main component to determining both ignition advance and injector fuel schedule. The computer’s three main reference points are engine RPM, intake manifold vacuum they call Manifold Absolute Pressure via the MAP sensor and throttle position via the Throttle Position Sensor (TPS). and t Yeah I’m pretty sure I have some internal engine work that needs to happen I’m still yet to figure out what all I need to be able to do that. Anyone suggest want to map sensor over any others or any other parts over any others for this engine. Iv been feeling around in the dark a little too much. I feel like I’m going to destroy the engine.. I can and will get pictures ASAP. Reminder- for the most part this is how the truck was when I bought it. Iv only trying to finish what someone else started You have a huge project on your hands, it’s obvious some hack went at this with less than zero understanding of how it works, there is no relationship of how TBI functions to any knowledge about carburetors. While your there you need to check the block casting number to see if this is a 350 with 305 heads or if it’s a 305 period, that alone if this is a 305 for what had been a 350 will screw up the computer in terms of what it is programmed for versus what it is trying to operate. The computer programming is very specific, it is not one size fits all, you can’t just make changes on a ‘cause, I wanna basis like a carbureted engine. This get worse as time marches into the future. My recommendation to the home tuner is not to buy anything newer than 1986. That’s the last GM carburetor, Ford about 1983 or 84 is it, Chrysler products don’t even rate my list as suitable purchases.

You gotta a tough row to hoe ahead of you if you don’t need to SMOG the least expensive route out short of scrapping it is to convert to a carb, the down side of that is if this is an electronically controlled automatic like a 4l60E or 4L80E there is another level of computer complication to be dealt with. As of now you are between a rock and a hard place that will test your mechanical and electrical skills to the edges of the envelope.

Bogie
 

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Well, The distributor you should have there should be a small cap HEI with external coil
The distributor should have 2 connectors. One with 2 wires that connects to the Ignition coil and
The other connector should have 4 wires and that goes to the ECM/PCM
If you have a throttle body injection system it should have said above described distributor. Period. Nothing else will work. Without it , the ECM will throw a code , or 2. At that point nothing else you do will help.
Set your base timing with the Tan/Brn wire unplugged at the connector with engine fully warmed up.
The connector is likely under the cover for the firewall fuse connector next to the AC box, under the hood, or under the passenger side carpet below the heater box
Check the vacuum supply to your MAP sensor.It should be manifold vacuum.
Check to be sure the EGR doesnt leak . Pull it off, check the gasket, check its passageway to be sure it seals, and check the diaphram to be sure it holds vacuum. As long as the gasket is good and the passage will seal on its own, put it on, leave it unhooked for now.
Ohm out the coolant sensor to be sure its close to spec
You can also unplug the knock sensor to eliminate it from jacking the timing around, at least to try and get some of the mess sorted out. If the Knock sensor is actually retarding the timing , it may be the engine is knocking due to higher compression from the puny 305 heads raising the CR too high.




It sounds like you bought a very wrecklessly assembled mess.
 

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I should note that there are guys here that can help you through this. But this is an adventure in time and money so one of the first things is to get a read on whether the bottom end is any good to spend money and time on. This being a daily driver is going to requiring what you want or can to do, then carving it up in weekend long chunks.

At this point it is very F’ed up, if it drives then drive it don’t waste time and money chasing codes, your going to see them, leave them be an work with us to plan a route out of these problems. I’ve done a number of these from TBI and TPI to carb conversions and own one myself as my daily driver which is an S15 the GMC version of the Chevy S10 with a 350 stuffed in it. As I said in my previous bolded, italic response if this has a stick gearbox or a 700R4/4L60 with no suffix of E it is a lot simpler. The computer operated 4L60E or 4L80E are messier to do as you have to leave the computer so the truck is sort of half computer pregnant but with a throttle position sensor applied to a carburetor is a can do effort. These computer operated automatics are quickly identifiable by a big wire harness (nearly the size of your wrist) that plugs in to the tranny on the passenger side. My guess this being a 3/4qtr ton 4x4 if an automatic behind a 350 it is a 4L80E which is a damn sturdy transmission.

As LATech points and is something I forgot (octogenarian problem) yes the 305 has a very small combustion chamber which bolted over a 350 pumps the compression ratio to sky high. Until that gets fixed your better off not having any advance, yeah it’ll run like crap, guzzle gas like a drunk sailor in a Tijuana bar but it should stay under the ping limit. You can’t run this long like this as the excess fuel will kill the rings, so we need to get on it ASAP.

Bogie
 

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1993 chevy Silverado 4x4
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Discussion Starter · #6 ·
My response will be bold, italic print. This is a rough brush at this point to just get started.




You gotta a tough row to hoe ahead of you if you don’t need to SMOG the least expensive route out short of scrapping it is to convert to a carb, the down side of that is if this is an electronically controlled automatic like a 4l60E or 4L80E there is another level of computer complication to be dealt with. As of now you are between a rock and a hard place that will test your mechanical and electrical skills to the edges of the envelope.

Bogie
I believe it’s 4l60e transmission
 

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Discussion Starter · #7 ·
Does it have driveability issues?
Maybe we can start there, seeing it is your only ride to work/daily driver.
lately it likes to idle really rough at stop lights. I stick it in Neutral an it seems to smooth out a little but half the time when the light turns green and I stick it back in drive to take off it does regardless of how “well” it was just idling in neutral.. other then that it’s seem a to be a late shift. Not so late after replaying coolant temp sensor (the 2 wire guy not the 1 wire one) it really started shifting better after I discover/distrusted 6 of the wires running down to the transmission and splices in new lines. I’m self taught everything so ya it’s been a struggle
 

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Discussion Starter · #8 ·
Well, The distributor you should have there should be a small cap HEI with external coil
The distributor should have 2 connectors. One with 2 wires that connects to the Ignition coil and
The other connector should have 4 wires and that goes to the ECM/PCM
If you have a throttle body injection system it should have said above described distributor. Period. Nothing else will work. Without it , the ECM will throw a code , or 2. At that point nothing else you do will help.
Set your base timing with the Tan/Brn wire unplugged at the connector with engine fully warmed up.
The connector is likely under the cover for the firewall fuse connector next to the AC box, under the hood, or under the passenger side carpet below the heater box
Check the vacuum supply to your MAP sensor.It should be manifold vacuum.
Check to be sure the EGR doesnt leak . Pull it off, check the gasket, check its passageway to be sure it seals, and check the diaphram to be sure it holds vacuum. As long as the gasket is good and the passage will seal on its own, put it on, leave it unhooked for now.
Ohm out the coolant sensor to be sure its close to spec
You can also unplug the knock sensor to eliminate it from jacking the timing around, at least to try and get some of the mess sorted out. If the Knock sensor is actually retarding the timing , it may be the engine is knocking due to higher compression from the puny 305 heads raising the CR too high.




It sounds like you bought a very wrecklessly assembled mess. Yea it is throttle body (220). Tan/brown wire is Conveniently located near the distributor on this one. I’d rather the need for the convenience not be there tho haha. What do you mean by manifold pressure exactly? I wondering about the MAP failing just because some things on the engine i suspect may be as old as iam (30s). I will definitely check for that leak around egr but tbh every time I try to find one, I don’t. Wouldn’t be nice to pin point tho because it’s felt like a vacuum leak. Especially since I recently realized/discovered the pcv (for lack of better terms) sucks/isn’t up to par (haha) on top of (Literally and figuratively) the valve covers being “cheap pos” as it was put yesterday so there went another also $20 hopefully we’ll spent on cork gasket for the valve covers. Also no knock sensor.. you could Say it’s already unplugged it’s just I bought the factory service manual and it described the PCM as testing the knocks sensor and throwing the code if it doesn’t test back as operational so it sounded like if I throw one in iv just gotta bypass it and figure out how to throw 5v of ac back at the pcm to make it think it tested as operational.. Please keep in mind I am self taught and for all I know I’m way off base
Reckley assembled is accurately put. Your Description of the distributor is accurate
 

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Discussion Starter · #9 ·
Not even sure if I’m replying right now.. that last reply looks different haha.. posting on here was put on my todo list right above work on truck already
 

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Discussion Starter · #10 ·
My response will be bold, italic print. This is a rough brush at this point to just get started.




You gotta a tough row to hoe ahead of you if you don’t need to SMOG the least expensive route out short of scrapping it is to convert to a carb, the down side of that is if this is an electronically controlled automatic like a 4l60E or 4L80E there is another level of computer complication to be dealt with. As of now you are between a rock and a hard place that will test your mechanical and electrical skills to the edges of the envelope.

Bogie
Converting to carb has been recommended before. I like the idea. I’d rather not destroy the engine. It as far as what step to take.. my knowledge is limited to what iv stumbled upon as far as this trucks engines goes. I REALLY like the idea of closing the hood and not gaf but I can’t find tape put over the dash lights and the speaks are a little inconsistent so it’s hard to muffle sounds sometimes. Got to the point i forgot I had a radio
 

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Discussion Starter · #11 ·
Oh ya. And iv only replaced something after i troubleshoot it and do whatever test I can find to run before I make sure I’m even looking in the right place. That’s why iv replaced TPS(might of gotten it wet?) Coolant sensor Tested around 20degrees colder then actually temp (inferred thermometer). Rebuild tbi (1 injector pod sounds noisy every since- like it has a miss on one of it spark plugs -Figuratively speaking of course) - I have spent a good deal of time learning/bonding with this engine. Wasn’t ever this fascinated with engine before
 

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I should note that there are guys here that can help you through this. But this is an adventure in time and money so one of the first things is to get a read on whether the bottom end is any good to spend money and time on. This being a daily driver is going to requiring what you want or can to do, then carving it up in weekend long chunks.

At this point it is very F’ed up, if it drives then drive it don’t waste time and money chasing codes, your going to see them, leave them be an work with us to plan a route out of these problems. I’ve done a number of these from TBI and TPI to carb conversions and own one myself as my daily driver which is an S15 the GMC version of the Chevy S10 with a 350 stuffed in it. As I said in my previous bolded, italic response if this has a stick gearbox or a 700R4/4L60 with no suffix of E it is a lot simpler. The computer operated 4L60E or 4L80E are messier to do as you have to leave the computer so the truck is sort of half computer pregnant but with a throttle position sensor applied to a carburetor is a can do effort. These computer operated automatics are quickly identifiable by a big wire harness (nearly the size of your wrist) that plugs in to the tranny on the passenger side. My guess this being a 3/4qtr ton 4x4 if an automatic behind a 350 it is a 4L80E which is a damn sturdy transmission.

As LATech points and is something I forgot (octogenarian problem) yes the 305 has a very small combustion chamber which bolted over a 350 pumps the compression ratio to sky high. Until that gets fixed your better off not having any advance, yeah it’ll run like crap, guzzle gas like a drunk sailor in a Tijuana bar but it should stay under the ping limit. You can’t run this long like this as the excess fuel will kill the rings, so we need to get on it ASAP.

Bogie
Like Bogie said. Just drive it.
Unless its has some serious drivability issues. Just drove it....
 

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Just drive it.
Thats rich.

Dude comes on here , with a truck that wont Idle at a light , dies when he puts it in gear, and sometimes shifts late and the answer he gets is "Just drive it"

Wow. I thought we were better mechanics than that. :(
 

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Just drive it.
Thats rich.

Dude comes on here , with a truck that wont Idle at a light , dies when he puts it in gear, and sometimes shifts late and the answer he gets is "Just drive it"

Wow. I thought we were better mechanics than that. :(
Just drive it.
Thats rich.

Dude comes on here , with a truck that wont Idle at a light , dies when he puts it in gear, and sometimes shifts late and the answer he gets is "Just drive it"

Wow. I thought we were better mechanics than that. :(
Sorry Bro.
Desperate is in the title.
Daily driver is also in there.
He doesn't have many other options right now considering tomorrow is monday, and the man needs to work tomorrow.

There is a wealth of knowledge around here, but desperate times call for desperate measures...
 

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That is why GOOD advice would be paramount here.
Walking OP through some good basic solid diagnostic routines to help him find the right place to look

And if you look at the post you took that quote from you will see it is full of good recommendations on what to check.
You just took the one statement from the whole paragraph that was ..... say.....the truth.
Read the whole post .

I see you did not post anything other than "just drive it"

Do you have any suggestions on what OP should be checking?
After all, its much easier to diagnose an engine that runs , instead of taking it all apart and looking at things you dont knw anything about.
 

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Wasnt sure where you were headed with all that.

But more important is we ARE good mechanics here and I am sure you have skills to help the OP
I find sometimes it best to focus on one thread and dig in a little . Sometimes I just float around and read and dont post.
But OP seems to get it and is responding at every post thrown hos way. Not just a one post wonder.Pretty cool right there.

From the post OP put up, he understands quite a bit about testing and DVOM s and such. He should be able to Iron it out with our help. Even if he just puts together a solid plan for next weekend ya know?
 

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I think OP shuld do a compression test tomorrow after work just to see how healthy the engine is and how high the cranking pressure are.That would give some insight to the CR
The 305 heads may not be hurting as much as we are thinking.
 

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Yes on compression test. This should find if the compression is off the map, and should give us an idea if the bottom end is in good enough condition to even mess with.

The OP needs to for sure ID the trans. This link should help, we’re at a place where guesses are of no help. For converting to a carb this is really inconsequential the fact that it’s an electronically controlled automatic means the computer stays but it’s range of control will be reduced to the transmission. For a carb that will mean the TPS sensor kit has to be installed as this is the key to modulation for either the 60E or 80E transmission.


We also need to know what distributor is being used. Sounds like some sort of HEI. The absence of vacuum advance sounds odd, don’t know if this is a lack of vacuum connection or lack of the diaphragm assembly. The standalone HEI distributor needs a switched from the ignition key separate 12 volt source independent from the computer. The computer cannot effect the timing of this type distributor, if the OP is seeing a 20 degree retard at idle then the distributor is not timed correctly to the crank. With no tach signal the TBI computer isn’t getting the basic data it needs to fuel this correctly independent of what ever it would like to do with ignition timing. Problem here will be for the OP to chase the wiring, who knows what the builder of this did. He needs to get a decent manual with wire diagrams to figure these things out.

Bogie
 
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