I'm going to be home for a week and am going to try to get some maintenance done on my 99 s10 4.3L. There are two problems I'm going to be addressing.
1. Coolant leak. The thing has had a coolant leak for as long as I can remember. Hadn't been a problem until I was bad and had forgotten to refill the tank and the truck started to overheat. I have never been able to smell any coolant coming out or see any dripping. It's not a real fast leak but enough to cause me problems. I've heard some people talk about the intake manifold gasket going bad. Anyone ever heard of this and if I hook a pressure gauge up to the radiator cap, do you think I'll be able to see it coming out around there?
OTHER PROBLEM
2. Misfire. For Christmas I got a OBDII scanner. It plugs in and then you use your smartphone as the computer (the app is called Torque). It runs over bluetooth and is really pretty cool. My truck didn't have a checkengine light on, but I was running some tests and it is saying my truck is misfiring. Some days I can really feel the misfire, and other days unless you are really paying attention, you wouldn't know its there. Where do I even start looking to try and correct the misfire? My dad and I were talking and we are sure neither one of us have ever replaced the timing chain, so at 220,000 miles, that should probably be done regardless, but would that be enough to cause all the misfires? What else should I be looking at. Here's a picture of the code my phone threw at me.
Thanks for any help
Enganeer said
Mar 10, 2014
To find where the misfire is occurring, you can try using a spray bottle to mist water vapor in the engine bay in a unlit garage. You should be able to hear and maybe even see the spark. Check the coil also, a friends truck with the 4.3L had a coil that was grounding itself when it was slightly humid and cool. I had some wires that looked good but had pin hole tears in the insulation.
SteveS said
Mar 10, 2014
Chris P (67ss) is the one to ask on the codes your throwing. To me when they're talking about "minimum voltage error reading" they are talking about the O2 sensors
-- Edited by SteveS on Monday 10th of March 2014 12:50:11 PM
67ss said
Mar 10, 2014
You are looking at what is called Mode 6 data. It is like reading greek but I can tell you a few things about the perameters with X on them. The two TID 07's relate to EGR tests. One seems to indicate the EGR is not opening off idle and the other something related to EGR decel test which again sounds like it is not seeing EGR flow. Could have a stuck EGR valve which could make it idle rough. Pull it off and check to see if the pintle inside of it moves freely with a small pocket screwdriver.
The TIC 0C relates to catalytic converter efficiency for bank 1 side of the engine. Could be setting that do to misfire concerns.
Coolant leak is probably intake gaskets or water pump. I would try to pressure test it and see if you can find the drip like you were saying. Sometimes the coolant can leak into the engine and you might see it in the oil.
SteveS said
Mar 10, 2014
67ss wrote:
You are looking at what is called Mode 6 data. It is like reading greek but I can tell you a few things about the perameters with X on them. The two TID 07's relate to EGR tests. One seems to indicate the EGR is not opening off idle and the other something related to EGR decel test which again sounds like it is not seeing EGR flow. Could have a stuck EGR valve which could make it idle rough. Pull it off and check to see if the pintle inside of it moves freely with a small pocket screwdriver.
The TIC 0C relates to catalytic converter efficiency for bank 1 side of the engine. Could be setting that do to misfire concerns.
Coolant leak is probably intake gaskets or water pump. I would try to pressure test it and see if you can find the drip like you were saying. Sometimes the coolant can leak into the engine and you might see it in the oil.
That was going to be my second guess . I got the part right about asking Chris
Lost in the 60s said
Mar 10, 2014
Might be a leaking head gasket allowing the coolant to enter a cylinder, cause the misfire and get burned up, leaving no trace on the external surfaces.
bowtie said
Mar 11, 2014
67ss wrote:
You are looking at what is called Mode 6 data. It is like reading greekbut I can tell you a few things about the perameters with X on them. The two TID 07's relate to EGR tests. One seems to indicate the EGR is not opening off idle and the other something related to EGR decel test which again sounds like it is not seeing EGR flow. Could have a stuck EGR valve which could make it idle rough. Pull it off and check to see if the pintle inside of it moves freely with a small pocket screwdriver.
The TIC 0C relates to catalytic converter efficiency for bank 1 side of the engine. Could be setting that do to misfire concerns.
Coolant leak is probably intake gaskets or water pump. I would try to pressure test it and see if you can find the drip like you were saying. Sometimes the coolant can leak into the engine and you might see it in the oil.
Might be a leaking head gasket allowing the coolant to enter a cylinder, cause the misfire and get burned up, leaving no trace on the external surfaces.
Mitch I really hope its not a head gasket! Already took that into consideration , but I really don't feel like spending that kind of money on a truck with cancer spreading rapidly! Whenever I change the oil, it doesn't seem milky or discolored from coolant being in it. Could the coolant be just leaking into cylinder and essentially getting "burned?"
67ss wrote:
You are looking at what is called Mode 6 data. It is like reading greek but I can tell you a few things about the perameters with X on them. The two TID 07's relate to EGR tests. One seems to indicate the EGR is not opening off idle and the other something related to EGR decel test which again sounds like it is not seeing EGR flow. Could have a stuck EGR valve which could make it idle rough. Pull it off and check to see if the pintle inside of it moves freely with a small pocket screwdriver.
The TIC 0C relates to catalytic converter efficiency for bank 1 side of the engine. Could be setting that do to misfire concerns.
Coolant leak is probably intake gaskets or water pump. I would try to pressure test it and see if you can find the drip like you were saying. Sometimes the coolant can leak into the engine and you might see it in the oil.
That egr valve would make sen 0C code relating to the cat, is there anything I can do about that? I had that cat replaced probably about 5 years ago now.
Should I still look at doing that timing chain, or is that going to be to much of a pain in the ass, and see little results.
67ss said
Mar 11, 2014
I would not do the timing chain, it is not going to cause the misfire. I would go buy some Tekron fuel injector cleaner and dump it in the tank. These trucks are prone for injectors sticking and getting dirty causing misfires.
I kinda doubt a headgasket as if you have been driving it this long without it overheating until you let it get low on fluid. Once cylinder combustions starts getting into the cooling system it should be overheating all the time and gotten worse in a short time.
If it is not setting a P0420 or P0430 code don't worry about the cat related stuff until you get the misfire fixed.
69SSConv said
Mar 11, 2014
I have a 2000 GMC Sonama 4.3, that I had to do the intake gaskets on a while back. It was leaking out the front of the intake by the water pump. I would only notice it if I started it up to move it, without letting it warm up. Short start and shutoff and it would drip down off the front of the engine. If it was run for a while, it would not leave any spots?
Dan Williams said
Mar 11, 2014
I drive a 99 S/10 4.3 and the intake gasket had to be replaced several years ago. The water pump was also leaking and changed it at the same time. Both real common on them I've been told. Try the stuff Chris P mentioned, I also had the MAP sensor acting up (don't remember the code) Went to NAPA and they actually have a spray cleaner just for the MAP sensor that you pull the air intake off and spray clean the sensor and seemed to have fixed it. Haven't seen the check engine light since. Funny thing about that truck is that it absolutely eats batteries, bought it new and have had to put at least one a year in it. Been checked by two different Chevy dealers and a couple of independent shops and a few guys that are just car guys. never figured it out. Just went to leave and it is dead now. Will slap a new one in (Warranty as it is only 8 months old and will test as "replace"). Don't think it is anything I am doing as I have 4-5 other vehicles that don't seem to have that problem. Otherwise the truck works pretty decent and isn't worth much so I just keep it and drive it.
Lost in the 60s said
Mar 11, 2014
If the coolant is going into the chambers, the exhaust will smell sweet when it burns. Have you ever noticed that when you start it ?
Since the oil is clean, that probably isn't what's causing the loss or mis-fire, but it can happen.
Chris R said
Mar 11, 2014
I had a 95 GMC Jimmy, GMC's version of the S10 Blazer. I ended up needing to do the head gaskets on mine before I sold it. Ive done many intake gaskets on these as well when I was working in the field. The first thing I would do as also recommended by Chris P is to pressure test the system. Rent a pressure tester from the parts store if you have to. Next thing to do is pull the plugs and take a look at them and see if there is evidence of coolant being burned on the electrodes of the plugs.
Ill warn you though. The #1 spark plug thats further most forward on the right side (left side when standing in front of the vehicle looking down) is a real PITA. GM was nice enough to put the steering shaft from the column down to the steering box right there and getting the plug out is not fun on the S10 models with the 4.3.
Dan Williams said
Mar 11, 2014
Chris R wrote:
I had a 95 GMC Jimmy, GMC's version of the S10 Blazer. I ended up needing to do the head gaskets on mine before I sold it. Ive done many intake gaskets on these as well when I was working in the field. The first thing I would do as also recommended by Chris P is to pressure test the system. Rent a pressure tester from the parts store if you have to. Next thing to do is pull the plugs and take a look at them and see if there is evidence of coolant being burned on the electrodes of the plugs.
Ill warn you though. The #1 spark plug thats further most forward on the right side (left side when standing in front of the vehicle looking down) is a real PITA. GM was nice enough to put the steering shaft from the column down to the steering box right there and getting the plug out is not fun on the S10 models with the 4.3.
Ah, the dreaded S/10 steering shaft plug. Seems to me, we had to loosen the steering shaft collar and pry the shaft over. These guys are actually very good. http://www.s10forum.com/
Chris R said
Mar 12, 2014
The shorty spark plug sockets work. Some spark plug sockets have a hex on the outside of the socket that allow you to put a wrench on it, that has worked for me in the past but still a pain. Easiest thing I have always done is if the customer was already getting spark plugs replaced anyways. I break off the entire porcelain of the plug flush with the hex using the tip of a prybar and a light tap of a hammer on the tip of the plug, and then a socket goes right on and you have it out within minutes instead of struggling the other ways, too tedius. Even the spark plug sockets I have with the built in universal joint are too big.
cooz65 said
Mar 12, 2014
Thanks guys for all the help! Chris R, I know exactly what you are talking about with that spark plug. The last time that I changed the plugs and wires, I think we ended up unbolting part of the steering shaft to get it out of the way enough. I'll try removing some of the plugs and see if I can't notice anything on any of them. I've never smelt any coolant coming out of the exhaust, but then again, I've never specifically gone to the tailpipe to take a sniff.
Alright so timing chain is out, I will do a pressure test, and see if I can tell if I'm loosing coolant at the intake gasket, or water pump and that should solve the coolant issue. I will then buy some injector cleaner here,and run through and then take a look at the egr valve to see if that is sticking. I will also looking into buying some map sensor cleaner and running that through. Hopefully this will address some of my issues.
THANKS guys for all your help.
cooz65 said
Mar 16, 2014
Well I read through the good ol Chilton manual, it looks like these intake gaskets could be a real treat if that's what it ends up being. If its either the water pump or intake gaskets, I'll get to drain the coolant. With the coolant out, I thought it might be a good time as well to do a coolant flush. After the flush, would it be ok to switch back to the good old green stuff, or do I need to run Dexcool? I've had Dexcool in it for the life of the truck, but I've read many mixed reviews about it. Is it truly better than green, or is it a GM money maker.
cooz65 said
Mar 20, 2014
Alright! Anyone have the GM complaint hot line! I've been here in "Dad's Garage" just , and would really like to and to whomever designed this upper intake manifold! I would be more than willing to give them a beer as I watch them try and put it back together.
John D said
Mar 20, 2014
Now you know why I have a mental/internal file-folder called "If I ever meet the guy/gal who designed this thing I'll punch them in the nuts/ovaries"...
67ss said
Mar 20, 2014
Isn't it great how the wiring harness is always right in the way for everything you are trying to do. If I remember correctly you can unbolt two of the connectors off the bottom of the fuse block and swing the whole harness off to the side and out of the way.
Derek69SS said
Mar 20, 2014
John D wrote:
Now you know why I have a mental/internal file-folder called "If I ever meet the guy/gal who designed this thing I'll punch them in the nuts/ovaries"...
I put ALL German engineers at the top of the list.
cooz65 said
Mar 20, 2014
Ahh my gosh, its driving me nuts! The wiring harness is a PIA, but its the Upper plenum, just won't go back over the injector unit. When I took it off, I had to pull up on it pretty hard to get it off, well getting it on isn't much better. It's such a tight fit, that its hitting on something and is not willing to sit flush against the lower manifold. Seeing how the injector unit is a $300+ unit, I'm a little hesitant to just push down to get her to fit. If they had only given me 1/4" of clearance around the thing, life would be better. Alright I'm done.......
Lost in the 60s said
Mar 20, 2014
cooz65 wrote:
Ahh my gosh, its driving me nuts! The wiring harness is a PIA, but its the Upper plenum, just won't go back over the injector unit. When I took it off, I had to pull up on it pretty hard to get it off, well getting it on isn't much better. It's such a tight fit, that its hitting on something and is not willing to sit flush against the lower manifold. Seeing how the injector unit is a $300+ unit, I'm a little hesitant to just push down to get her to fit. If they had only given me 1/4" of clearance around the thing, life would be better. Alright I'm done.......
Glad to see you had perseverance over brute strength.
I probably woulda broke the SOB a LONG time ago...
67ss said
Mar 20, 2014
It'a the big o-ring around the injector body I think you are fighting. Lube it up real good with some grease and hopefully it will go back on. P.s. You did need to pull the upper plenum off but I am sure you know that now.
I'm going to be home for a week and am going to try to get some maintenance done on my 99 s10 4.3L. There are two problems I'm going to be addressing.
1. Coolant leak. The thing has had a coolant leak for as long as I can remember. Hadn't been a problem until I was bad and had forgotten to refill the tank and the truck started to overheat. I have never been able to smell any coolant coming out or see any dripping. It's not a real fast leak but enough to cause me problems. I've heard some people talk about the intake manifold gasket going bad. Anyone ever heard of this and if I hook a pressure gauge up to the radiator cap, do you think I'll be able to see it coming out around there?
OTHER PROBLEM
2. Misfire. For Christmas I got a OBDII scanner. It plugs in and then you use your smartphone as the computer (the app is called Torque). It runs over bluetooth and is really pretty cool. My truck didn't have a checkengine light on, but I was running some tests and it is saying my truck is misfiring. Some days I can really feel the misfire, and other days unless you are really paying attention, you wouldn't know its there. Where do I even start looking to try and correct the misfire? My dad and I were talking and we are sure neither one of us have ever replaced the timing chain, so at 220,000 miles, that should probably be done regardless, but would that be enough to cause all the misfires? What else should I be looking at. Here's a picture of the code my phone threw at me.
Thanks for any help
Chris P (67ss) is the one to ask on the codes your throwing. To me when they're talking about "minimum voltage error reading" they are talking about the O2 sensors
-- Edited by SteveS on Monday 10th of March 2014 12:50:11 PM
You are looking at what is called Mode 6 data. It is like reading greek but I can tell you a few things about the perameters with X on them. The two TID 07's relate to EGR tests. One seems to indicate the EGR is not opening off idle and the other something related to EGR decel test which again sounds like it is not seeing EGR flow. Could have a stuck EGR valve which could make it idle rough. Pull it off and check to see if the pintle inside of it moves freely with a small pocket screwdriver.
The TIC 0C relates to catalytic converter efficiency for bank 1 side of the engine. Could be setting that do to misfire concerns.
Coolant leak is probably intake gaskets or water pump. I would try to pressure test it and see if you can find the drip like you were saying. Sometimes the coolant can leak into the engine and you might see it in the oil.
That was going to be my second guess
. I got the part right about asking Chris 
YUP.
That egr valve would make sen 0C code relating to the cat, is there anything I can do about that? I had that cat replaced probably about 5 years ago now.
Should I still look at doing that timing chain, or is that going to be to much of a pain in the ass, and see little results.
I would not do the timing chain, it is not going to cause the misfire. I would go buy some Tekron fuel injector cleaner and dump it in the tank. These trucks are prone for injectors sticking and getting dirty causing misfires.
I kinda doubt a headgasket as if you have been driving it this long without it overheating until you let it get low on fluid. Once cylinder combustions starts getting into the cooling system it should be overheating all the time and gotten worse in a short time.
If it is not setting a P0420 or P0430 code don't worry about the cat related stuff until you get the misfire fixed.
I have a 2000 GMC Sonama 4.3, that I had to do the intake gaskets on a while back. It was leaking out the front of the intake by the water pump. I would only notice it if I started it up to move it, without letting it warm up. Short start and shutoff and it would drip down off the front of the engine. If it was run for a while, it would not leave any spots?
Since the oil is clean, that probably isn't what's causing the loss or mis-fire, but it can happen.
I had a 95 GMC Jimmy, GMC's version of the S10 Blazer. I ended up needing to do the head gaskets on mine before I sold it. Ive done many intake gaskets on these as well when I was working in the field. The first thing I would do as also recommended by Chris P is to pressure test the system. Rent a pressure tester from the parts store if you have to. Next thing to do is pull the plugs and take a look at them and see if there is evidence of coolant being burned on the electrodes of the plugs.
Ill warn you though. The #1 spark plug thats further most forward on the right side (left side when standing in front of the vehicle looking down) is a real PITA. GM was nice enough to put the steering shaft from the column down to the steering box right there and getting the plug out is not fun on the S10 models with the 4.3.
Ah, the dreaded S/10 steering shaft plug. Seems to me, we had to loosen the steering shaft collar and pry the shaft over. These guys are actually very good. http://www.s10forum.com/
The shorty spark plug sockets work. Some spark plug sockets have a hex on the outside of the socket that allow you to put a wrench on it, that has worked for me in the past but still a pain. Easiest thing I have always done is if the customer was already getting spark plugs replaced anyways. I break off the entire porcelain of the plug flush with the hex using the tip of a prybar and a light tap of a hammer on the tip of the plug, and then a socket goes right on and you have it out within minutes instead of struggling the other ways, too tedius. Even the spark plug sockets I have with the built in universal joint are too big.
Alright so timing chain is out, I will do a pressure test, and see if I can tell if I'm loosing coolant at the intake gasket, or water pump and that should solve the coolant issue. I will then buy some injector cleaner here,and run through and then take a look at the egr valve to see if that is sticking. I will also looking into buying some map sensor cleaner and running that through. Hopefully this will address some of my issues.
THANKS guys for all your help.
Alright! Anyone have the GM complaint hot line! I've been here in "Dad's Garage" just
, and would really like to 
and 
to whomever designed this upper intake manifold! I would be more than willing to give them a beer as I watch them try and put it back together.
Isn't it great how the wiring harness is always right in the way for everything you are trying to do. If I remember correctly you can unbolt two of the connectors off the bottom of the fuse block and swing the whole harness off to the side and out of the way.
I put ALL German engineers at the top of the list.
Glad to see you had perseverance over brute strength.
I probably woulda broke the SOB a LONG time ago...
It'a the big o-ring around the injector body I think you are fighting. Lube it up real good with some grease and hopefully it will go back on. P.s. You did need to pull the upper plenum off but I am sure you know that now.