Hesitation at acceleration

I have a 2000 S-10 and with 64000 miles and it just started to hesitate bad at accelerating from a stop only it accelerates fine when passing. I changed plugs, wires and fuel filter at 50000 miles so can anyone help me where should I start looking.

Thanks

First, what brand of ignition system components did you use? Next, have you ever cleaned the throttle body out with throttle body cleaner. My father-in-law has a 2000 Blazer that had the same problem. There was so much gunk in the throttle body that it took and hour, a whole bottle of cleaner, and three rags to clean it out. He had never cleaned it and the crapy shop he takes it to never took the time.

First, what brand of ignition system components did you use? Next, have you ever cleaned the throttle body out with throttle body cleaner. My father-in-law has a 2000 Blazer that had the same problem. There was so much gunk in the throttle body that it took and hour, a whole bottle of cleaner, and three rags to clean it out. He had never cleaned it and the crapy shop he takes it to never took the time.

No I have not cleaned the Throttle body but I will try that. Ive aways used the mix with gas cleaner. Thanks I will clean it good and see what happens.

Make sure you wait a while before starting the engine when using the throttle body cleaner. On older engines, like my '95, you could start the engine and rev it up a bit while spraying into the throttle body but yours requires everything to be connected for it to work (Mass-Air flow sensor). If you wait a while before starting the engine it will allow time for the cleaner to evaporate. Also, don't be surprised if it is hard to start at first. What brand of ignition parts did you put on the truck at the last tune-up.

Cleaned Throttle Body was not that dirty and still same Hesitation at fast acceleration anyone with any other ideas.

Thanks vtmecheng

The reason I keep asking about the brand of parts you used in your tune up is because our trucks really don't like anything but AC Delco. For some reason most shops use Bosch or other brands, that make our trucks run like poop.

Clean your MAF sensor by removing it from the vehicle and spraying brake cleaner through it to remove the deposits from the MAF wires.

To get the rest of it off if it is really grungy, take a q-tip and very VERY gently remove the reset of the dirt from the sensor wires.

I had Bosch platium +4s in my truck and it ran like poop.I put AC Delco platiums in cleaned the MAF like BlazerLT said and I noticed a difference.Try it out.

Hey BlazerLT, where is the MAF sensor? I have never touched mine after 138000 and wonder if it wouldn't help to give it a bath.

it should be right after your air cleaner assembly and it will be connect to the air flow duct that runs into the throttle body. Its worth cleaning as well, I just cleaned my a few days ago and I can notice the difference :D

Thanks to all
I believe I did use Bosch plugs I will change them even thought changing that one plug can be a pain in the ohhhh.
I will also try cleaning the MAF sensor and see what that does I will let U know how I make out.
Thanks again

Tried cleaning the MAF sensor and installed new AC plugs gaped at .60 and still no luck.
Also took the time to try and clean the EGR valve and none of these were that gummed up.
Appreciate any other ideas you might have.

Thanks

I hate for you to just throw parts at it but...How old is your O2 sensor? It can screw up your mixture if not working properly. A new AC delco from the dealer is only $45. But like I said, this throwing parts at it sucks. Have you looked at a Haynes book for it?

Have you checked your IAC? Simple job to remove and clean. You mention that the hesitation is from a dead stop but when you pass a car it accelerates fine. The difference here is the IAC. It would be something to check since it only operates when idling.

When is the last time you did a tuneup?

wut does iac stand for? do they have it on older s10s to?

IAC = Idle Air Control Valve

s10 go back to 1983-84

s10 go back to 83-84? what was that suposed to mean?

Cleaned the IAC valve and still same problem this one has me baffled.
Tune up was done 15000 miles ago the only thing I did not change was the distributor cap maybe that’s it.
Hate to just start changing part by part any other idea will be appreciated.

P.S wouldnt the O2 sensor give me a check engine light, the O2 sensor was changed under warranty at about 20000 miles it now has 64000 miles.

Thanks

The O2 will only trip a code if it gives an off the wall signal. Sometimes it can trip the code if no signal is given but not always. It should be changed every 60000 miles and is really easy to replace. I would change out the distributor cap and rotor, no question. I do mine every 30,000 and it always shows a lot of wear. There is a lot of voltage going through it and that rotor is spinning as fast as the engine is, all this equals wear. Even if it isn't the problem I would change it anyway so you have a better combustion.

hotwheelsgt,
The IAC is just what BlazerLT said...It is a little motorized valve mounted on the throttle body. The computer uses this to adjust the intake airflow at idle. From what I can remember, this unit is on all S10's with fuel injection, but don't quote me on that.

oh alright. well blazer has pretty much the same problem so im just try to what everybody elses is doin and try the sugestion.

have you checked your fuel pressure and the timing?

Installed new cap and rotor still same kicking and bucking at acceleration
someone said change the O2 sensor which one upstream or downstream and they say ther good for about 100000 miles and my new sensor only has 45000 miles on it.

Thanks for the ideas keep them coming still need help!!!!!

P.S. Dont have a fuel pressure gauge to check the presure

Did you check for any check engine lights or stored codes? You said there was a check engine light. If there is , go to your local Autozone and get your codes scanned.

It will tell you what the problem is.

Also, check your transmission fluid in hot idle in park.

Have you replaced the fuel filter ever?

Did you check for any check engine lights or stored codes? You said there was a check engine light. If there is , go to your local Autozone and get your codes scanned.

It will tell you what the problem is.

Also, check your transmission fluid in hot idle in park.

Have you replaced the fuel filter ever?



No check engine light and changed fuel filter 15000 miles ago.
Would low Trans fluid cause kicking and bucking at acceleration from a stop?

Tell me I was wondering if the TPS could be bad and causing the hesitation only at acceleration when trying to take off fast at idle?

Let me know what U think.

Usually they will kick out a code.

Maybe you should go to Autozone and have them check the computer for stored codes.

Not all codes illuminate the check engine light.

the autozone were i live chages like $40 to check those codes :/

Nope, someone will come out with a code scanner for free and hook it up where you park.

All autozones are free for this.

If not, talk to the manager.

Just for the heck of it last night I changed the fuel filter and still has that kicking and bucking at take off. :mad:
I guess its about that time to take it to a repair shop and have them test fuel pressures and any thing else they can come up with at a cost. :2cents:

Thanks and keep the ideas coming maybe we can get it before next week.

Get the friggin codes read bro.

Stop throwing random parts at it and find out what the real problem is.

That is what the codes are for.

I will get the codes read next week if there is any. Im stuck up here in upstate NY and the nearest Autozone or any free check is 45 miles away but I plan a trip to Autozone next week and I will let U know if we get any code.
Again thanks!!!
P.S. I still would like to get the fuel pressure checked how much can that cost.

Shouldn't cost much.

Took the trip to Autozone and no codes found and no ideas.
Still trying to come up with a fix but no luck.

Again please help

P.S. Fuel pressure was fine.

A few questions:

If your sitting in park, engine running, does the engine respond smoothly?

What was the fuel pressure measured when it was checked?

Did you try running injector cleaner in a tank of fuel?

You said you changed the Cap, rotor, wires and plugs, Take a spray bottle of windex and spray the coil and see if it is arcing.

When was the last time the air filter was changed?

You mentioned earlier that you tried to clean the EGR, what do you mean by try?

You also mentioned you removed the IAC and cleaned it. Did you inspect the pintle and the seat for wear? Did you clean the seat for the pintle?

Hesitation is normally associated with carburaetion or fuel/air delivery, however, a weak spark can also be the culprit when first applying a load to an engine which is what you are doing when you first pull out. When you are already driving and accelerate, the load is not as great as accelerating from a dead stop for there is no inertia.

Waiting to hear from you.

I checked coil as U said but I didnt see no sparks jumping as for what I meant try to clean EGR is that it was not carboned up still cleaned what was there. Im not sure what the fuel pressure reading was he just said it was ok.

Can U think of any other way to check the coil it sounds like U know what your saying and I think you might have hit on somthing if I dont get it fixed this weekend next week it goes to the shop. I guess I will have to pay big time.

Thanks and keep the ideas coming!!!

I checked coil as U said but I didnt see no sparks jumping as for what I meant try to clean EGR is that it was not carboned up still cleaned what was there. Im not sure what the fuel pressure reading was he just said it was ok.

Can U think of any other way to check the coil it sounds like U know what your saying and I think you might have hit on somthing if I dont get it fixed this weekend next week it goes to the shop. I guess I will have to pay big time.

Thanks and keep the ideas coming!!!

Ok, you checked the coil by spraying and saw no arcing. We can assume for the time being that it is ok.

You said when you removed the EGR (actually, you should have an LEGR with only wires going to it and no vacuum lines) and it was closed, correct?

You said the tech told you the fuel pressure was Ok. I question that but we can assume that you accelerate fine that it must be close or it really is ok for now.

When was the last time you changed the air filter?

I am now back to my original assertion. I would check the IAC again. You said you pulled it and cleaned it, ok. You don't have a scanner capable of a data stream, correct? You also asked if a TPS could cause this problem, yes, I have seen it. The wear on a TPS is always on the low end since that is where the most movement is. When you first start to move the pedal, the resistance doesn't changed like it should and the ECM will not dump enough fuel creating the bogging condition. If you have a Haynes or Chilton's, they may give you the resistance reading in ohm's if you have a digital VOM. Pull the plug and perform the test and look at the response from idle up. If the reading is erratic, change it.

Waiting to hear from you.

After reading your last reply I called the guy who was suppose to have checked the fuel pressure and he just said it was not the problem and didnt really check it he didnt charge me hes one of my sons freinds.

So I just got done droping my truck off at the local Chevy dealer and he said he will check it out and get back to me will let U know what he tells me.

After reading your last reply I called the guy who was suppose to have checked the fuel pressure and he just said it was not the problem and didnt really check it he didnt charge me hes one of my sons freinds.

So I just got done droping my truck off at the local Chevy dealer and he said he will check it out and get back to me will let U know what he tells me.

So what was the pressure he read?

So what was the pressure he read?

Come on LT, read the post, the guy he took it to never checked it because he didn't think it was the problem. He must one of those individuals who can pop the schrader and measure pressure with his eyes.

Come on LT, read the post, the guy he took it to never checked it because he didn't think it was the problem. He must one of those individuals who can pop the schrader and measure pressure with his eyes.



He said that because it did not hesitate when you were moving and got on it that he did not beleive that was the problem.
Thanks

P.S. What would be a fair price for a dealer to replace pump?

Come on LT, read the post, the guy he took it to never checked it because he didn't think it was the problem. He must one of those individuals who can pop the schrader and measure pressure with his eyes.

Can you fuck off with the arrogant replies. kthx

He said that because it did not hesitate when you were moving and got on it that he did not beleive that was the problem.
Thanks

P.S. What would be a fair price for a dealer to replace pump?

The pressure needs to be check before you replace the pump, and that is the point I am trying to get across.

Just heard back from dealer and he said the fuel pressure is in spec and they found somthing wrong in the wiring harness but not sure what.
They said that when they moved the harness around and tryed it it went away the bucking and hesitation.

Im going to pick it up soon becuase they are closing at noon today and I guess bring it back to him during the week.

Just heard back from dealer and he said the fuel pressure is in spec and they found somthing wrong in the wiring harness but not sure what.
They said that when they moved the harness around and tryed it it went away the bucking and hesitation.

Im going to pick it up soon becuase they are closing at noon today and I guess bring it back to him during the week.

Don't allow them to replace the pump if the pressure is "Within spec."

Just picked up my truck and the tech said he had a code P0339 and removed and checked the cam shaft senor and it checked out ok.
reinstalled and said problem is in the wiring harness and needs to be checked further.

But for now the truck is running just fine and we will see if it happens again, maybe a loss connection or he fixed it by removing and reistalling the cam shaft sensor.

Well I thank you all and I will let U know if it starts doing it again.

That would do it.

the code is for an intermittent signal from that sensor.

Caused by a bad connection or maybe a broken wire.

Maybe reseating it will fix it as he has done.

Can you fuck off with the arrogant replies. kthx

Is that your best? Must you always resort to vulgarities? You little insecure pup. There was no arrogance, you don't read the post before you answer.

so what, so do a lot of people on the forums.

And when I have an inbox full of 30-40 replies and PMs, I am sorry if I don't reread every fucking full thread and miss a couple from time to time.

Doesn't give you the right to post arrogant shit back at me.

If you can't post anything other than insulting garbage, then don't post at all.

I'll just wait until you slip up then I will be all over you like white on rice and see how you like it.

Until then, fuck off.

And yes, with assholes like you, I do get vulgar because I am not about to talk nicely to an arrogant fucking asshole.

kthxdie

so what, so do a lot of people on the forums.

And when I have an inbox full of 30-40 replies and PMs, I am sorry if I don't reread every fucking full thread and miss a couple from time to time.

Doesn't give you the right to post arrogant shit back at me.

If you can't post anything other than insulting garbage, then don't post at all.

I'll just wait until you slip up then I will be all over you like white on rice and see how you like it.

Until then, fuck off.

And yes, with assholes like you, I do get vulgar because I am not about to talk nicely to an arrogant fucking asshole.

kthxdie

You wouldn't now arrogance unless you looked into a mirror. Besides insecure perhaps we are looking at self rightousness, super ego, impudence and a few other descriptive adjectives. I am sure all of this provides you with great opportunities in life and business, I'm sure your parents are proud of their little pup. Other people use vulgarities in speaking about something, you use it when speaking to people that have upset you, there's a difference, but then, not to you I'm sure. You claim you have so many degrees but your communication skills say something else.

By the way, I slip up everyday with something or another, it's called being human. And I learn from it and not make excuses for it. You might want to learn what that means.