Weird hesitation

[ringersoll1869]

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

[ringersoll1869]

2000 Blazer LT 4.3 Vortec

[BlazerLT]

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

[ringersoll1869]

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

[BlazerLT]

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.

[ringersoll1869]

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?

[BlazerLT]

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?

[rblenkhorn]

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

[BlazerLT]

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?

[rblenkhorn]

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

[BlazerLT]

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.

[rblenkhorn]

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.

[Mikado14]

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.

[BlazerLT]

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.

[ringersoll1869]

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?