Weird Hessitation

What's up Everyone,
I appologize in advance if this is long and confussing. I have a 2000 S10 Chevy Blazer with a V6 Vortec in it with 34000 miles. I have so far put in a new fuel pump, fuel filter, fuel pressure regulator, cap and rotor, plugs and wires, computer, air filter, and i changed the oil just recently. My problem began with a Missfire Piston #5, any ways that problem is now solved. The problem im having now is if I disconnect the MAF sensor the truck runs good but shifts hard and I cant accelerate fast or it just revs until I let go. If I connect the sensor it shifts good but "boggs", it runs but hessitates. Any ideas??? Some one suggested the TPS and/or the PCV valve. Could this finally solve my problem? Oh I forgot to mention I already cleaned the MAF sensor.
:confused:

You need to get a scanner on the truck and see if it has any codes come up. Could be a few things for sure.

I've had this problem before with my 4.3. All it was was the oil breather hose was disonected confusing the MAF. It's on the backside of the air cleaner right above the Throttle Body. If it comes undone it will let unfiltered air in, for one, and it bypasses the MAF so the MAF isn't sensing the air moving through. It tries to compensate for the air not moving through and bogs it out. When you disconnect the MAF it goes off the last good reading it had. Also make sure the air cleaner is tight against the TB. That's what I did and I was suprised it worked.

Thanks for the info. I just changed the PCV valve lastnight I also bought the TPS, I'll change it today and I'll take a look at what you mentioned. BTW the TPS has 2 screws with a star shape, what are these called and what size are they? Thanks again.

Just an UPDATE I changed the TPS and NO CIGGAR!!!! It still BOGGS!!! Now I think I should finally give up and take it to a mechanic. BTW mudslinger88 I checked the oil breather and it was ok, thanks though. Any other suggestions would be greatly appreciated.

What's up Everyone,
I appologize in advance if this is long and confussing. I have a 2000 S10 Chevy Blazer with a V6 Vortec in it with 34000 miles. I have so far put in a new fuel pump, fuel filter, fuel pressure regulator, cap and rotor, plugs and wires, computer, air filter, and i changed the oil just recently. My problem began with a Missfire Piston #5, any ways that problem is now solved. The problem im having now is if I disconnect the MAF sensor the truck runs good but shifts hard and I cant accelerate fast or it just revs until I let go. If I connect the sensor it shifts good but "boggs", it runs but hessitates. Any ideas??? Some one suggested the TPS and/or the PCV valve. Could this finally solve my problem? Oh I forgot to mention I already cleaned the MAF sensor.
:confused:

OHMIGOSH!!!

Was all those parts bad? And the TPS too? Bad voltage reading at TPS?

I say the air freshener is stale - maybe swappin' it out with a new or rebuilt? Different flavor maybe?

Just kiddin'... Have you tested anything yet? Besides swappin' different parts? Do you have a multimeter?

Save yourself money and a headache, get a scanner on it, see what your getting from these sensors. That way you can narrow it down and go from there.

LOL..... Funny you mention the air freshener cbec1999, cause I just changed that too. I'm gonna follow blazes9395 advice and get a scanner on it. Only thing is, I hope I even make it home today. On my way to work the truck took a turn for the worst.....Now it boggs even with the MAF disconnected!!!!! I barely made it to work, but as soon as i step on the accelerator it boggs big time even if I floor it.

The symptoms you're describing all sound like a fuel pressure problem. Check fuel pressure and leakdown. Key on engine off, fuel pump running, must be 60 to 66psi. After the pump shuts down, pressure must remain above 55psi for 3 to 5 minutes.

Thanks for the advice Old Master..... I made it home.....called a mechanic and took it to them. They will be checking it this morning and I will let you guys know what happens. The mechanic did mention he was going to check the fuel pressure and put it on the scanner. Im crossing my fingers, it's not going to cost me an arm and a leg. Thanks again guys.

Thanks for the advice Old Master..... I made it home.....called a mechanic and took it to them. They will be checking it this morning and I will let you guys know what happens. The mechanic did mention he was going to check the fuel pressure and put it on the scanner. Im crossing my fingers, it's not going to cost me an arm and a leg. Thanks again guys.

If you don't want to spend an arm and leg or other bodily parts, tell him to show you what is wrong, before he 'repairs' anything.

WHEN HE SAYS, "I CAN DO THIS, AND THIS, AND THIS, AND THAT WILL PROBABLY FIX THIS, AND IT PROBABLY NEEDS TO BE DONE ANYWAY...", THEN YOU KNOW WHAT TO SAY - RIGHT???

If you don't want to spend an arm and leg or other bodily parts, tell him to show you what is wrong, before he 'repairs' anything.



Autozone and many other parts stores will read your codes for free. There is no reason to guess, buy unnecessary parts, or spend your hard earned cash needlessly. Write down the codes that they tell you on a piece of paper. Then you can tell your mechanic what you already know.

For all the money you can save, E-bay sells Code Readers and Scanners as cheap as $25. Autozone is prohibited by Corporate Policy from erasing your codes anymore, but you can certainly get them read for free and post the results on this forum for help.

Do you have a Check Engine or Service Engine Soon light? You could try simply cleaning your MAF Sensor, just be extremely careful not to break any of the small wires or you will be replacing that too.

***UPDATE***

So I finally got the call from the mechanic...... My CAT is PLUGGED!!! The only thing that worries me now is whats gonna happen once I change the cat? will what ever caused it to mess up to beggin with do it again? what can I do to avoid it? I was thinking change the O2 sensors.

A restricted catalytic converter is the result of another problem. They don't just plug up on their own. An overly rich fuel mixture is the most common cause. The cause of the rich condition needs to be diagnosed and repaired or as you suspected, the replacement converter will also be destroyed.

The truck has no codes on it right now, but i do remember that it had a rich code before, due to the MAF being disconnected. It said rich bank something or other. I'll have to check it again.

So I took my truck to get a quote on a cat and found out that because I'm in California I have to pay more for mine! What a rip off. 2 shops quoted me $1,0020 parts and labor. Suppossedly the regulations changed to where I now need an ODB2 Cat that can only be bought @ the dealer. Is that a load of CRAP or what? Oh that not all..... the price for my Cat @ the dealer is only $845! Im confused....... Would a universal ODB 2 Cat cause my truck to fail a smog check just because it's not from the dealer? I can purchase one for around $100 and put it on my self.

1. What causes a cat to get plugged?
2. Will gutting a cat mess anything up?
3. How many O2 sensors do I have?

I originally posted the Wierd Hessitation Thread. I have a 2000 2WD 2DR Blazer with the 4.3 Vortec V6 with 34000 Miles. I found out that my problem is a plugged cat. BTW Thanks for the feedback on the other thread.

1. What causes a cat to get plugged?
2. Will gutting a cat mess anything up?
3. How many O2 sensors do I have?

I originally posted the Wierd Hessitation Thread. I have a 2000 2WD 2DR Blazer with the 4.3 Vortec V6 with 34000 Miles. I found out that my problem is a plugged cat. BTW Thanks for the feedback on the other thread.

Gutting a cat is a illegal operation/:rofl: :naughty: or a NO NO:nono:

Engine running rich is the main cause of a cat getting clogged.
How is it clogged or what test showed clogged cat.

Cat May still be under the 8 year 80K federal emission waranty.
And calf sometime more.


You should have 4 02 sensors but why are you asking about them?
Any codes?
Post back all code no.

The mechanic I took it to said they did a backpressure test. It has no codes right now. How can I find out if it's still under warranty. The Dealer ship price is pretty hefty @ 845 USD. I don't understand what the diff between a universal ODB2 and a dealership cat is. Reason I asked about the o2 sensors is because at some point before adding all the parts that i did, i remember it had a rich code, but it could have been from the Maf being disconnected. Could that have caused the plugged cat?

You need to contact dealer on the warrany on cat.
You may be over on 8 years depending on manf date.
When was it made or manf date?

Dealer Oem cat is what came on it and what works the best.

If cat is clogged it will need replace and the other stuff retested.

If not covered under factory federal emission warranty .
Some good parts places have a diirect fit cat replacement that works good.
Cheap aftermarket cats do not do so well.
But if you have to replace the cat always find out what made it go bad.

How can I find out without codes??? What auto parts store would you recomend to find a direct application for mine. the only ones I have seen clearly say 49 state legal NOT to be used in California applications.

How can I find out without codes??? What auto parts store would you recomend to find a direct application for mine. the only ones I have seen clearly say 49 state legal NOT to be used in California applications.

Proper testing.
Fuel pressure test and a good engine capable scanner will show engine running problems in data screen read out and also test the cat system.
And also may have stored or history code.

Check you dealer and have them test ir out and see if if is covered under warranty.

On aftermarket cat's a good parts place that has walker mufflers should have a direct fit cat set up.

2. Will gutting a cat mess anything up?


It could mess up your wallet IF you get caught, that someone gutted it before you bought it from them. :wink:

You sure it's plugged? I would check. Pull it, feel around in there, carefully, with a long screwdriver, ALL AROUND in there, especially around the sides, and check real good and real thoroughly, and if there's a loose piece or thousands, get 'em out, and when you're done checkin', and re-installed, if it sounds like a hi-po exhaust, and you seem to have a little more power and free flowing exhaust, then you mighta' checked pretty good.

Will gutting a cat mess anything up?



The OBDII system will set a DTC and turn on the SES light. It will not "mess anything up", but it will not pass the Peoples Republik of Kalifornia emission test either.

Thanks Old Master thats all I needed to know....... I dont have to smog my baby till may, then I will change the cat and the O2 sensors.

Will an aftermarket ODBII cat affect my blazer in passing smog??? I know that a Cat from the dealership would be the best option but I'm on a tight budget at the moment and the "cat" that the dealership sells you is $854 because it's the whole exhaust Y pipe, pre cat and the cat itself plus 75 for the 3 gaskets you need. I just thinks its wierd that a cat can be "legal" in 48 0r 49 states and "illegal" in Ca. Is there an aftermarke cat that's only "legal" in California and "Illegal" in all other states???? well i think you get where im going.

Aftermarket cats are rated to handle engine displacements up to a certain number of liters. Most all aftermarket TWC, (Three Way Catalyst) cats are certified for all 50, (or according to Obama, 57) states. Provided you get one rated for at least a 4.3L, and certified 50 state application, you'll be fine. Before you replace it, locate and repair the rich fuel condition, or you'll be buying another cat.

Thanks for the info Old Master and others that have offered their 2 cents.

:bananasmi Oh yeah Oh yeah!!! My Baby Is Running Like A CHAMP!!! I Gutted the CAT and that did the trick. I know I know, it's a big :nono: :headshake but im on a budget and im not do for a smog till Apr. WOW what a difference in POWER, ACCELERATION and it SHIFTS GREAT.............It really feels like a new truck!!! I wanna give everyone who put in their :2cents: a big THANKS!!! This site is really helpful and people actually respond to your THREADS.