Weird hesitation

Hey guys,
I'm having problems with some hesitation. I replaced the spark plugs and such and I thought for a minute that fixed it, but no. It's hesitating when I press the accelerator then at times it will kick in and go. Then it will start to hesitate again. No SES light coming on. Any thoughts? TPS? I've got to fix this, it's driving me crazy

2000 Blazer LT 4.3 Vortec

What other things have you replaced other than just the plugs?

That's it. for now. I was gong to change out wires and cap and rotor this weekend.

What spark plugs did you use?
Did you gap them properly?
You need to replace the cap and rotor only. Your wires will be still good.

#1 thing I would do is change your fuel filter which is more than likely the culprit.

But still replace the cap and rotor and air filter.

I have 72000 on the car and it had the fuel filter replaced at 60,000. Should I still change it? Why do you not think I should not change the plug wires?

Plug wires don't have to be replaced after 3 years.

Hell I have factory ones on a 1995 and they work great.

Can you answer the questions I asked?

What spark plugs did you use?
Did you gap them properly?
Are you planning on changing the cap and rotor?
Air Filter?

I used Bosch plat +4 plugs, changed wired, cap, button, fuel filter still hesitation bogs down over 1800rpm than kinda sputters and spits, than comes out of it. tryed spraying throttle body cleaner in throttle body, and got backfire and popping

first thing, get rid of the Bosch +4's and take them back.

They DO NOT work in 4.3Ls and can cause damage. The electrodes tend to fall off in the cylinder causing major cylinder scoring and engine damage.

I AM NOT KIDDING ON THIS, REMOVE THEM ASAP!!!!

Get standard ACDelco plugs or the ACDelco Platinum and gap them to 0.060.

BTW, does your exhaust smell like rotton eggs?

Not any rotten egg smell, just shitty running, it was doing this with ACDelco plat plugs and thats why I switched to these.. at $9 a pop, I doubt they are gonna return them after I have put about 4000 mile on them

I have been covering them for over a year now and everyone is havng nothing but problems with them.

Honestly, remove them before you are sorry.

I would take your truck to a local mechanic and have them hook a scanner to the computer and monitor your engine.

It's the only way to do it unless you have any computer codes coming which I know you are not having.

To tell you the truth I am a local mechanic along with my brother and two employees, I have hooked the blazer to our scanner and there is really nothing that seems to catch my eye or anyone elses who has shared in diagnosing this piece of crap blazer with me.. give me some ideas of what I should be looking for on the scanner.

Here is some input in regards to a scanner. I will assume that you have a SnapOn MT2500 that will allow you to view data or a similar one (OTC, etc). At idle condition, look at the TPS voltage, should be less than a volt. Next look at the coolant Temp sensors, should be two of them, one for the guage and one for the computer, the one in the vicinity of the Thermostat is the guage and the one on the right side below the exhaust manifold is for the computer. They should be close. If the computer sensor is defective it can either cause a rich condition or a lean which could give you the hesitation when the engine is warm and most notably when it is cold (you didn't specify engine temp). Next, look to see if it is in Open Loop (OL) or Closed Loop (CL). Open Loop is when you first start the engine (cold) and the computer is not monitoring and adjusting until the engine warms up at which time it will go to CL. If it is closed loop, look at the performance of your O2 sensors or HO2 sensors. Look for the cross counts. Look at the IAC status. If this does not close properly you will have a hesitation. Lastly, if you scanner will permit, go out on a road test in the movie mode and get it to have the hesitation and then review the above mentioned sensors. There is a lot more that would be too lengthy to write but this is a start.

Yea, I would definitely take a ride with a scanner attached.

I am currently going to buy one from ebay with the cable and laptop software kit.

Blazer,
I used regular bosch platinum's gapped .060 just changed cap and rotor. The car seems to be running a lot better, but still a little hesitation. Certainly not as bad as before. So I guess that puts us back to the fuel filter. Do you think I should change that out as well?

oh yeah, Air filter is K&N

Yea, might as well seeing it is so cheap and make sure you put it on right.

Everyone is having problems with the Bosch Plats in our Blazers.

I highly recommend you go to the best plug for our engines which are the stock AC Delcos.

How long has the current fuel filter been in there? You should replace it once a year minimum. It probably only costs about $10, and considering what you've been through I wouldn't hesiatate to replace it.

Whats your status 1869??? I'm having the same problem.

Changed out the wires now as well. I noticed the wires had wear on them so I went ahead and did that. I still seem to have some hesitation, so I guess I'm going to do the fuel filter next. I'll do that soon, so I'll let you know

I had the same problem and my mechanic said it was the mass air flow sensor or something like that. All he did was clean it and it works fine said it is a common problem with these vehicles.

i have the same problem i've replaceed cap roter wires plugs o2 map injecters still the same has not made a differance please help [email protected]

Check you fuel pressure.

Also remove and clean your MAF sensor by apraying throttle body cleaner though it to dissolve the gunk off of the sensor wires.

Then reset your computer and you should be good.

blazerlt please instant message me at krseb5 on yahoo messenger or wildpeater on aim

Sorry, I only post here on the forums so everyone can gain from the advice given.

Besides, I don't use those IM clients.

the maf senser ,would this cause the truck to studder and hesitate after i resume driveing from a complete stop or even at times during normal driveing?

Very much so.

ok where is it located and how do i clean it?

i have my hanes manual in my hand and can't find it

What year is your truck?

1987 chevy c(v)/10 305 5.0 tbi auto 4x4

1987 chevy v/10 (c/10) 305 5.0 auto trans 4x4

oh ohh.....

Ok, the original guy had a 2000 and you said you had the same problem so I assumed you had the same year.

Checked the timing lately?

can the timeing be off if it idles perfectly?

can the timeing be off if it idles perfectly?

Sure it can.

Also, have you replaced the fuel filter lately?

starting my own thread

new thread 1987chevy305tbi wierd hesitation

http://www.automotiveforums.com/vbulletin/showthread.php?p=2563490#post2563490

Well hate to bring it back up, but the hesistation is still there after changing back to ACdelcos and gapping them at .60 - now it shows a code of MAF Sensor out of range.. should I just replace MAF Sensor or is there any thing else that would put it out of range.. ?

Well hate to bring it back up, but the hesistation is still there after changing back to ACdelcos and gapping them at .60 - now it shows a code of MAF Sensor out of range.. should I just replace MAF Sensor or is there any thing else that would put it out of range.. ?

Remove the MAF from the intkae assembly.

Grab a can or carb or TB cleaner and a very soft toothbrush.

Wet the two small filament wires on the engine side of the MAF with the cleaner, then wet the toothbrush and gently message the gunk on the wires.

Then rinse and repeat until they are shiny and clean.

Then reset the computer, and start it up.

Remove the MAF from the intkae assembly.

Grab a can or carb or TB cleaner and a very soft toothbrush.


Carb and TB cleaners have oils in them to lubricate parts, especially carb cleaners. They can leave a residue on the MAF sensor wires, which can make the sensor not work properly, or give incorrect values to the computer. Use something like brake cleaner of electrical cleaner solvent, as these do not leave any residue after they dry. Also I would not be touching the sensor wires. They can be easily damaged. Another thing since we are this topic is the use of K&N filters with MAF equiped trucks. To people who have K&N filter, you know that a light oil is sprayed on to these filters when you buy them, and again when you clean them, the K&N cleaner specifies to use the spray on oil to make the filter work properly. Over time, some of this oil gets sucked up through the intake and passed the MAF. This oil can cover the filtments of the sensor and over time cause the sensor to be a little or a lot off, giving hesitatition and all the symptoms a MAF sensor problem has. I myself use K&N in all of my vehicles and like them a lot. So if anyone has a problem with the MAF sensor and they are using a K&N, keep this in mind.

Carb and TB cleaners have oils in them to lubricate parts, especially carb cleaners. They can leave a residue on the MAF sensor wires, which can make the sensor not work properly, or give incorrect values to the computer. Use something like brake cleaner of electrical cleaner solvent, as these do not leave any residue after they dry. Also I would not be touching the sensor wires. They can be easily damaged. Another thing since we are this topic is the use of K&N filters with MAF equiped trucks. To people who have K&N filter, you know that a light oil is sprayed on to these filters when you buy them, and again when you clean them, the K&N cleaner specifies to use the spray on oil to make the filter work properly. Over time, some of this oil gets sucked up through the intake and passed the MAF. This oil can cover the filtments of the sensor and over time cause the sensor to be a little or a lot off, giving hesitatition and all the symptoms a MAF sensor problem has. I myself use K&N in all of my vehicles and like them a lot. So if anyone has a problem with the MAF sensor and they are using a K&N, keep this in mind.

The TB cleaner I have leaves no residue and evaporates completely.

Also, gently massaging the gunk off of the sensor filament wires will not damage them if it is don't very carefully.

If you want proof, check on google and you will se that is lots of people that have done it and it works well and will not damage the sensor.

Your right some TB cleaners don't leave residue, some do and almost all carb cleaners do. Also yes some people do use a brush or something to clean it, but if they take the screens off and touch the filaments, from personal experience I would'nt. I am not saying not too, its up to you whether or not. But if you damage it because you broke the filament wire, now you have no choice but to get another MAF. LAst time I checked they wern't to cheap either.

Your right some TB cleaners don't leave residue, some do and almost all carb cleaners do. Also yes some people do use a brush or something to clean it, but if they take the screens off and touch the filaments, from personal experience I would'nt. I am not saying not too, its up to you whether or not. But if you damage it because you broke the filament wire, now you have no choice but to get another MAF. LAst time I checked they wern't to cheap either.

So how do you remove the encrusted gunk on the wires then.

A simple method I was shown was to drive the truck, warm it up, shut it off and carefully take off the sensor. What this does basically heat up the elements(thats how the sensor works), plus the heat from the engine comparment keeps it warm. Take it off and clean it with a good brake cleaner, the cans that have high powered flow sprays. I think even Canadian Tire sells their brake cleaner now like that. This will clean off the screans, and do a good job of getting the element wires clean too. This is all that is really needed, take your time and get it good and clean. If the sensor is still good, it will respond to the cleaning.

Some people have tried that and found that they could get all the gunk off so they had to use the small extra soft tooth brush with the cleaner to complete the job.

I think you are over exaggerating the soft toothbrush damaging the filaments. If done softly, you will damage nothing and probably will have less force than a high pressure can of brake cleaner.

Well, I tried the TB cleaner and soft tooth brush, this morning, and it did nothing, the sensor still gave an out of range code, so I bit my tongue and called the local Napa store, and they said they had one in, drove down, with my computer, bought it for the low price of $113 and put it on right in the parking lot, hooked up computer, reset the codes, and what do ya know it was gone.. Wanna talk about a noticable gain in power! The friggen thing wont stay off 70 at 8% throttle

Sounds like you found the problem....excellent!

The cleaning will not always fix the problem if the sensor is defective but it is a good thing to try to potentially fix a dirty MAF.

Enjoy the new found , or should I say "recovered" power. ;)

It is definetly new found power :) it has been an issue id say for quite some time I was just trying to over look it, I can definetly feel the difference though, next week I am making the time to change my broken driver side motor mount. than I gotta deal with issues with driver side CV shaft making 'snapping' sounds and the god damned cat converter sounds like a baffle or something has come undone in there and clangs and rattles like its going out of style

When does the snapping noise happen?

When turning?

When going over bumps?

Snappin occurs anytime I am in four high or low going forward, backward, left, right, from driver side. Never in 2wd though. Real bad snap if you come down on it.

Checked your front diff fluid lately?

Briefly back to the MAF... I searched this forum for hesitation, found this post. I was having annoying hesitation for over a year and getting worse with my 99 Envoy 4.3 with 70k. I delicately cleaned the wires in the MAF sensor with Carb+TB cleaner and soft-bristled brush. The sensor had a thin layer of black gunk on it. Result: Success! No more hesitation! Others might want to consider this method when encountering hesitation with no SES lights/codes. It's pretty easy to inspect the MAF sensor, but as you indicate care must be taken. Thank you BlazerLT.

Sorry for taking so long getting back :sunglasse busy. busy. of course checked the diff fluid.. turns on the axle is fried.. outer end of it is just kaput and it seems here alot of play in it so thats making the snappin .. grr chevy.. gotta love it..

Briefly back to the MAF... I searched this forum for hesitation, found this post. I was having annoying hesitation for over a year and getting worse with my 99 Envoy 4.3 with 70k. I delicately cleaned the wires in the MAF sensor with Carb+TB cleaner and soft-bristled brush. The sensor had a thin layer of black gunk on it. Result: Success! No more hesitation! Others might want to consider this method when encountering hesitation with no SES lights/codes. It's pretty easy to inspect the MAF sensor, but as you indicate care must be taken. Thank you BlazerLT.

http://www.yourethemannowdog.com/

You are welcome! :D

I just started having a similar problem. Slight skipping on the highway in overdrive, got worse in the past 2 weeks. Especially when the engine is cold. Wires, cap and rotor seemed to help a little. I'll clean the MAF. My plugs have 65k on them, but I'll check gap and condition. I also changed the fuel filter.
Should I put in some injector cleaner first?

I just started having a similar problem. Slight skipping on the highway in overdrive, got worse in the past 2 weeks. Especially when the engine is cold. Wires, cap and rotor seemed to help a little. I'll clean the MAF. My plugs have 65k on them, but I'll check gap and condition. I also changed the fuel filter.
Should I put in some injector cleaner first?

65k?

Install new plugs. They are worn out.

And no, they don't last till 100k.

I Have An 85 S10 Blazer Thats Doing The Same Thing.i Have The 2.8 Engine Carb.need Help!!!

Do a tuneup.

"If done softly, you will damage nothing and probably will have less force than a high pressure can of brake cleaner."

makes sence to me.....
high psi burst of liquid on these DELICATE Fillaments
VS. a nice soft cuddley tooth brush.....
hummmmmmmm

"If done softly, you will damage nothing and probably will have less force than a high pressure can of brake cleaner."

makes sence to me.....
high psi burst of liquid on these DELICATE Fillaments
VS. a nice soft cuddley tooth brush.....
hummmmmmmm

You hold the can of cleaner back and spray it through the sensor.