hello all,

i have a 97 blazer with 185k. I just started to have a new problem. i notice if i am sitting at around 2k rpms and very light on the throttle, i get a hesitation or hiccup/bucking feeling. it does not have a consistency to it. if i give it gas its goes away. if i'm not at 2k its not there.its most noticable when i'm on the highway at 70mph cause i'm light on the throttle to maintain speed which puts me at right around 2k rpm. it does it in all gears though i found.

things i've changed in the last 3k miles:

spark plugs
wires
rotor cap
ball joints
wheel hubs
oil cooler lines
lower trans cooler line
battery

last 10k :

fuel filter

everything has been running well until this minor issue. tranny fluid level is great, oil level is great. no smoking or loss of power either.

any ideas?

 

Check your cap and rotor. I had the same problem shortly after changing them and found corrosion. Since then I only got with AC Delco.

 

cap and rotor are ac delco. maybe 2k miles since changed. this problem just started in the last 300 miles or so.

 

Test your TPS (throttle position sensor). Since this is the RPM which is most common when cruising down the road, that throttle position wears more on the TPS. I am betting that you have an intermittent loss of TPS signal right around that same throttle position.

 

how would i test this? thanks!

 

some more info:

there are no codes thrown. It seems to drive fine with no power loss on acceleration. that hiccup feeling is between 2-2.3k rpm.

would replacing the TPS fix this or is something not giving it the right signal?

 

You can test it with a DMM (digital multimeter) by back probing the wires. There is a ground wire, a +5V reference from the PCM and then the sensor signal to the PCM which should be 0.5V at idle (closed throttle) and then around 4.5V at full throttle.

 

if i just replace the TPS would that fix the problem? they are only like $45 or is the actually tps not the issue

 

after some more research, other that had what sounded like the same issues resolved it with a new ignition coil.... is that a possibility? i found a new ignition coil and module for a good price. is that a good possibility?

 

I'm having the same problem with my 1992 4.3 and usually fix my problems without having to sign in and ask questions because searching helps alot. But i can't pin point this problem. i changed the fuel filter andplugs the other dayand the cap and rotorin the summer.