what brand of plugs? and drive it and when it does it just hit the brakes hard a bit as to kick it out of lockup but stay in 4th gear and tell us what it does. also fire it up at night when dark and look for stay spaks from the wires.
CK5
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98 Tahoe Running rough **Update - Any help tonight is greatly appreciated**
- Thread starter justinf
- Start date
justinf
1/2 ton status
The plugs are autolites.
It has recently started to kick out the lockup when it starts to shudder, I noticed that over the weekend, it would start to shudder, and I tried to just let it go for a bit to see if it would throw a code, but it actually unlocked the converter, and the shudder pretty much went away, although it still felt like it was there, just couldn't feel it since the converter was not locked up.
I have ran it at night to check for arcing from the plug wires or coil and didn't notice any.
It has recently started to kick out the lockup when it starts to shudder, I noticed that over the weekend, it would start to shudder, and I tried to just let it go for a bit to see if it would throw a code, but it actually unlocked the converter, and the shudder pretty much went away, although it still felt like it was there, just couldn't feel it since the converter was not locked up.
I have ran it at night to check for arcing from the plug wires or coil and didn't notice any.
Where is the valve located? On the "older" mushroom shaped valves, typically you can reach up underneath the valve and push on it, see if it moves smoothly, sticks, etc.
justinf
1/2 ton status
Unfortunately this is the new style. 
trust me when i say this . vortec 96-up motors need the 6 + dollor ac delco plugs. try this and see what you get. i tryed others and had skip/ vib under load at highway speeds and put in ac delco and bam gone smooth.
blownout
Registered Member
cool
ya my 350 has a lug in er but it was just built like that . some thing u have to deal with thanks bill ont.
ya my 350 has a lug in er but it was just built like that . some thing u have to deal with thanks bill ont.
GEORGIA GABE
1/2 ton status
sweetk30 said:
ditto
gabe
justinf
1/2 ton status
I will go and buy some AC Delco's tomorrow night. Thanks.
justinf
1/2 ton status
I swapped out the plugs for some AC Delco platinums, still have the same problem. It threw another code this morning while my wife was driving to work, so I will check what code it is tonight. I am guessing it's still #6 misfire, but I am not sure what else to do about it, unless I have a fuel system cleaned to get rid of carbon.
89GMCSuburban
1/2 ton status
My 89 Suburban with 700R4 has TCC lockup in 3rd and 4th.
My 99 Jimmy with 4L60E has TCC lockup in 3rd and 4th.
So I'm guessing....you have lockup in third and fourth.
You aren't locking up in third because you're probably looking for it while in OD so the TCC doesn't lock up before it shifts to OD. Drive in D at about 60 and tap the brake while keeping on the gas. If revs go up, you have TCC in third.
Every time I experience that shudder... (94 S10 Blazer 4L60E, 87 S10 Blazer 700R4, 89 Suburban 700R4) it's been the torque converter coming apart from the inside. All those cases needed a rebuild and new converter.
NEVER blindly trust the computer! Too many times I've had the computer tell me something, and that isn't even the problem.
My 99 Jimmy with 4L60E has TCC lockup in 3rd and 4th.
So I'm guessing....you have lockup in third and fourth.
You aren't locking up in third because you're probably looking for it while in OD so the TCC doesn't lock up before it shifts to OD. Drive in D at about 60 and tap the brake while keeping on the gas. If revs go up, you have TCC in third.
Every time I experience that shudder... (94 S10 Blazer 4L60E, 87 S10 Blazer 700R4, 89 Suburban 700R4) it's been the torque converter coming apart from the inside. All those cases needed a rebuild and new converter.
NEVER blindly trust the computer! Too many times I've had the computer tell me something, and that isn't even the problem.
neverendingproject
1/2 ton status
check the tranny like the others said. the computer ties the tranny and the engine together. you might be having some nonelectrical problem in the transmission that sets off a knock sensor or something in the engine. the only other option is to look at the computer itself or the lockup harness going to the tranny. maybe its shorting out somewhere. just ideas. see what you think 
justinf
1/2 ton status
Yes, i will be looking the tranny over tonight, last night I checked compression, everything seemed to be fine, and I ran some Seafoam cleaner through it to clean out any carbon buildup. Still have the shudder. I am really beginning to wonder if it is the tranny.
i don't think it is a computer problem as it will shudder, and not set any codes. Only once in a while will it throw any codes. If I get time, I could swap computers with the one in my 98 pickup.
I may try and get the tranny flushed in a day or so. Seeing as how it throws the misfire code only when it is shuddering, I am thinking it may be the trans shudder causing it. The plug in #6 looks fine, and all the ignition parts are new.
i don't think it is a computer problem as it will shudder, and not set any codes. Only once in a while will it throw any codes. If I get time, I could swap computers with the one in my 98 pickup.
I may try and get the tranny flushed in a day or so. Seeing as how it throws the misfire code only when it is shuddering, I am thinking it may be the trans shudder causing it. The plug in #6 looks fine, and all the ignition parts are new.
