Hesitation in acceleration

[gmyoyo]

What's been done? (In order of doing, all since August 2005)
New Air Filter.
New Fuel Filter.
New Fuel Pump (actually 2).
New EGR valve.
New Nut Kit/CPI unit.

New AC Delco Plugs.
New Wires.

New (Used but dyno tested) Engine.
New Cap and Rotor.
New Fuel Pump Relay

Tested Iginition Coil.

New Cat Converter.
Back Pressure Tested twice, (remains in green zone) Once before new cat and once again after.

Whats happening now? Hesitation or (perceived) loss of power when giving gas. The jerking at cruise speed (symptom before replacing cat converter) is gone for now, at least it seems to be.

Also a rotten egg smell is noticable now with new cat. Didn't notice it before...

Latest scenario was: After taking it back to the mechanic and he can't find any cause, he does feel the problem, he suggested plugged cat. I replaced the cat after finding it was just crumbs in the bottom. Still didn't drive good so I went to dealer. They said go back to exhaust and have back pressure tested again (it would be cheaper). Back pressure is within range. Dealership said if they didn't change the muffler then it could be full of all the debri from the cat. The cat guy says he remebers that the honeycomb was on broken on the engine side, meaning no debri would have gotten past the other end and on into the muffler. But, we still only checked the back pressure, we didn't pull the muffler off and shake it or anything to see if there is loose material inside. So cat guy says he thinks it's a lack of fuel getting completly burned up that causes the smelly rotten egg smell I'm now noticing.

I'm thinking it's time to go back and recheck the plugs and possibly pull the egr valve and check (or at least put a screwdriver to it and listen for clicking??). I've read and searched and I'm not really finding any solutions other than maybe possibly the TPS or IAC's heck maybe even an O2 at this point. But I'm not getting any codes thrown.

[billibong]

When you replaced the CPI Nut Kit, does that come with a new fuel regulator?
Have you checked the plugs since you replaced to see that they are not fouled in any way?

[gmyoyo]

Originally Posted by billibong

When you replaced the CPI Nut Kit, does that come with a new fuel regulator?
Have you checked the plugs since you replaced to see that they are not fouled in any way?

I understood that it was all one piece and I replaced the entire spider unit...

I have not rechecked the plugs. I will be tonight or this weekend as I go back over this thing again.

[BlazerBoyLT98]

Definitely seems like the fuel is being incompletely burned. Do what you said and recheck plugs, wires, and nut kit.

[gmyoyo]

Originally Posted by BlazerBoyLT98

Definitely seems like the fuel is being incompletely burned. Do what you said and recheck plugs, wires, and nut kit.

egr valve once again clogged with carbon pellets...Damn I'm getting tired of this. Where can I get the gasket with the screen for this thing? I'd rather clean it with each oil change than keep on having it get a carbon chunk lodged in it.

Where is the carbon pellets coming from, how do I stop them. Don't suggest any foreign liquids, I've done that and I paid out the @$$. I thoroughly cleaned the upper intake plenum and all? What is causing this???

[gmyoyo]

Originally Posted by gmyoyo

egr valve once again clogged with carbon pellets...Damn I'm getting tired of this. Where can I get the gasket with the screen for this thing? I'd rather clean it with each oil change than keep on having it get a carbon chunk lodged in it.

Never mind, I got one overnighted to Advance Auto as they sell them but didn't have one in stock. Did a google search and found the name to be Klean Screen from Tomko. There are other ways of getting one I'm sure. It was 11 dollars.

So far the engine hasn't sputtered or hesistated, but I'm still very cautious. Unless I write again here the answer is this gasket. I will be checking it periodically for carbon build up and all. I also read where this is a pretty well known problem with these vehicles so if your getting the carbon pellets in your EGR like I am you may want to try the screened gasket.

[billibong]

I hope that you have found the problem. Good Luck.

[LTBlazer97]

Originally Posted by gmyoyo

Never mind, I got one overnighted to Advance Auto as they sell them but didn't have one in stock. Did a google search and found the name to be Klean Screen from Tomko. There are other ways of getting one I'm sure. It was 11 dollars.

So far the engine hasn't sputtered or hesistated, but I'm still very cautious. Unless I write again here the answer is this gasket. I will be checking it periodically for carbon build up and all. I also read where this is a pretty well known problem with these vehicles so if your getting the carbon pellets in your EGR like I am you may want to try the screened gasket.

Also for your consideration if the problem doesnt seem to fix after you do that i think you should check your MAF sensor, i had some long painful experience with a bad one. Replaced all the above that you did. Checked fuel pressure, check fuel pump, etc you name it i either checked it or replaced. But after my friend mentioned that i may have a bad MAF, (who just happens to own a blazer as well) i plugged his into mine and low and behold, worked like a million bucks. I had given up hope that it was a bad MAF because i tested it and it was electronically sound, it was an intermitten thing im assuming. If you can get your hands on one to test it you wont be sorry, in fact i will give you a 75% chance that this is your problems. If you can get a loner to plug in as well you cant lose. Good Luck

[gmyoyo]

Originally Posted by LTBlazer97

Also for your consideration if the problem doesnt seem to fix after you do that i think you should check your MAF sensor, i had some long painful experience with a bad one. Replaced all the above that you did. Checked fuel pressure, check fuel pump, etc you name it i either checked it or replaced. But after my friend mentioned that i may have a bad MAF, (who just happens to own a blazer as well) i plugged his into mine and low and behold, worked like a million bucks. I had given up hope that it was a bad MAF because i tested it and it was electronically sound, it was an intermitten thing im assuming. If you can get your hands on one to test it you wont be sorry, in fact i will give you a 75% chance that this is your problems. If you can get a loner to plug in as well you cant lose. Good Luck

I will look into it as well thanks. So far all seems well...
What about a code though, did you not get a code indicating this was your problem area? I finally received another code 32, but not since installing this klean screen gasket...

[gmyoyo]

Originally Posted by gmyoyo

I will look into it as well thanks. So far all seems well...
What about a code though, did you not get a code indicating this was your problem area? I finally received another code 32, but not since installing this klean screen gasket...

I show a MAF sensor as not required on Autozones shopping site. It references to a MAP sensor. Are these one in the same. A pic of a MAF sensor in someone else's thread (maybe yours) shows a different part than what is inserted in to my intake tube from between the air filter and the intake. I must be looking at the wrong part.

Where is it and if I need to where do I buy one?

[matt rock]

{What's been done? (In order of doing, all since August 2005)
New Air Filter.
New Fuel Filter.
New Fuel Pump (actually 2).
New EGR valve.
New Nut Kit/CPI unit.

New AC Delco Plugs.
New Wires.

New (Used but dyno tested) Engine.
New Cap and Rotor.
New Fuel Pump Relay

Tested Iginition Coil.

New Cat Converter.
Back Pressure Tested twice, (remains in green zone) Once before new cat and once again after.

Whats happening now? Hesitation or (perceived) loss of power when giving gas. The jerking at cruise speed (symptom before replacing cat converter) is gone for now, at least it seems to be.

Also a rotten egg smell is noticable now with new cat. Didn't notice it before...

Latest scenario was: After taking it back to the mechanic and he can't find any cause, he does feel the problem, he suggested plugged cat. I replaced the cat after finding it was just crumbs in the bottom. Still didn't drive good so I went to dealer. They said go back to exhaust and have back pressure tested again (it would be cheaper). Back pressure is within range. Dealership said if they didn't change the muffler then it could be full of all the debri from the cat. The cat guy says he remebers that the honeycomb was on broken on the engine side, meaning no debri would have gotten past the other end and on into the muffler. But, we still only checked the back pressure, we didn't pull the muffler off and shake it or anything to see if there is loose material inside. So cat guy says he thinks it's a lack of fuel getting completly burned up that causes the smelly rotten egg smell I'm now noticing.

I'm thinking it's time to go back and recheck the plugs and possibly pull the egr valve and check (or at least put a screwdriver to it and listen for clicking??). I've read and searched and I'm not really finding any solutions other than maybe possibly the TPS or IAC's heck maybe even an O2 at this point. But I'm not getting any codes thrown.}



I did most of these things too. I would be more than excited to find that it is the MAF sensor. I thought for the longest time that it was the tranny that I replaced last year. But now, after reading this post,
I have new hope that it's not. Except for the fact that is sounds like it's running heavy.

[gmyoyo]

Where is your MAF sensor located on a 95 4.3L Vortec? The one inserted into large plastic air intake hose that is attached to the manifold? Looks like a single probe looking device probably just reading the air as it goes by from the air filter and it is engine side of the vacuum hose that is attached to this same intake hose.

I don't see anything like a three filament wired sensor device that I thought I was looking for. But, once again, maybe I'm not looking at the right thing.

For the MAP sensor my haynes manual seems to be talking about the little black rectangular device sitting just on top of the intake mainfold near the front right side of the black plate with vortec written on it (looking from front of vehicle). I see no vacuum hose attached though, it said to remove it and the electrical connector when removing...is this what everyone is referring to or is there something I'm not getting???

[gmyoyo]

Originally Posted by gmyoyo

Where is your MAF sensor located on a 95 4.3L Vortec? The one inserted into large plastic air intake hose that is attached to the manifold? Looks like a single probe looking device probably just reading the air as it goes by from the air filter and it is engine side of the vacuum hose that is attached to this same intake hose.

I don't see anything like a three filament wired sensor device that I thought I was looking for. But, once again, maybe I'm not looking at the right thing.

For the MAP sensor my haynes manual seems to be talking about the little black rectangular device sitting just on top of the intake mainfold near the front right side of the black plate with vortec written on it (looking from front of vehicle). I see no vacuum hose attached though, it said to remove it and the electrical connector when removing...is this what everyone is referring to or is there something I'm not getting???

I may have answered my own question with a search on AZ for a different year. Maybe mine didn't have a MAF sensor...

[billibong]

I amy be wrong, but after looking into it I don't think that the '95 4.3's with the CMFI engines have a MAF sensor.

On the '96 and later CSEFI engines it is located in the air intake duct just after the air filter box. It is a hardened plastic box between two sections of the duct with an electrical connector coming out on the side of it. When removed you can clearly see the wires and a mesh screen in the sensor.

[gmyoyo]

Originally Posted by billibong

I amy be wrong, but after looking into it I don't think that the '95 4.3's with the CMFI engines have a MAF sensor.

On the '96 and later CSEFI engines it is located in the air intake duct just after the air filter box. It is a hardened plastic box between two sections of the duct with an electrical connector coming out on the side of it. When removed you can clearly see the wires and a mesh screen in the sensor.

Thanks for description...
Mine isn't set up like that. I have a smaller probe like device (that I've cleaned) inserted into the side of the duct just prior to entering into the manifold. It is the only thing electrically connected to the air duct or filter area...