Sputter, Miss, on Acceleration. 95 TBI

jham0077 · July 16, 2014

I'm having an issue I can't resolve with my Tahoe. It's a 95, 4x4, 2dr, 5.7, with a 5 speed manual in it. It wants to miss on acceleration and pop a lttle through the exhaust. It doesn't matter if its cold or up to temp. When it first started, about 3 weeks ago, it was only in 3rd gear under medium acceleration. Then it started in 5th gear under a load, like pulling a hill. Now it's in every gear but 1st.

I have replaced, since the issue plagued me,

TPS & connector

MAP

EGR

CTS

Distributor

I have replaced the fuel pump since I've owned it (little over 3 years). The tune up is less than a year old. Knock sensor is less than 2 years old. IAC is maybe 3 years old. All with Delco/Delphi parts with the exception of the distributor. It's NAPA, Cardone I think.

I replaced the distributor because the trigger wheel(reluctor?) had a pretty good crack in it. So last night after replacing, setting time, and clearing the code, I drove it about 20 miles with no problem. Get in it this morning and pull out on the road, get to 2nd and feel a tremble, go to 3rd and it bucks and misses. I feather it out, hit 4th, bucks and misses.

Disconnecting the battery is the only thing that makes it go away, temporarily. On the next startup, it's back to bucking. Any fresh ideas would be appreciated.

jham0077 · July 17, 2014

No takers?

I drove it yesterday afternoon, a good 40 miles of stop and go on backroads. Eventually the problem went away. By the time I got close to home I couldn't make it miss. Get in it this morning and it misses like hell. I put about 30 mile on it this morning and the problem fades away. O2 sensor not heating up maybe?

Squirrely · July 17, 2014

That sucks.

What was your code that you cleared?

lee123 · July 19, 2014

^{Did you physically check ignitiom timing}

jham0077 · July 21, 2014

The code was form disconnecting the timing wire. Which also answers lee123's question, I set the timing with a light.

I pulled the plugs Thursday afternoon to find they were all frosty white(bad lean). I brushed them off, checked gaps, put them back in, and disconnected the battery to clear the CTS code. It set the CTS code because I wanted to see if being unplugged made a difference in anything. It idled a little higher, which I expected, but didn't resolve the main problem. I only drove it a couple of miles with the CTS unplugged, I squirted a little WD-40 on the grounds by the water neck and took of on a test drive. It never acted up for the 40 or so miles of starting and stopping I did on the backroads, and I didn't expect it to.

I jumped in it Friday morning and expected the miss and nothing happened. Drove out like a champ. And it's been good since. So either the plugs were that big of a problem, which I doubt, the issue finally reset with a battery disconnect, or the grounds needed WD-40. I found someone with a live-data scanner that won't rape me like the dealer would if I went to them. When the issue hits again I'll be ready.

jham0077 · August 5, 2014

The miss came back about 10 days later. It started small, occasionally in third, then worse and worse by the day. Always bad on first start of the day and getting better the longer it ran. It acted up until the scanner was hooked on it. Then it didn't miss a beat. It was a nice SnapOn scanner, but it couldn't tell us anything usefull. Only whether or not it was in open or closed loop, the temp, rpm's, and lean/rich from the 02 sensor. No live data, like TPS % or IAC and O2 counts.

So I think I'm gonna throw another 20 bucks at it and put an oxygen sensor on it. If that doesn't do it, I'll start replacing connectors.

txab · August 5, 2014

Have you checked for intake or unmetered air leaks?

jham0077 · August 6, 2014

Yep. I've waved an unlit torch around about everywhere I can think of.

This things got me. I went home for lunch, spit and sputtered. Came back to work, it didn't miss a beat at first. I slowed to make a turn, had to downshift to 2nd, accelarated with no miss, shifted to 3rd, hit the gas and wham, big miss. Then nothing the rest of the way. And it doesn't seem like it's wanting to settle into it's idle. Like it's a fuzz higher than usual. Got a different tone to it or something. Just doesn't seem right.

Chidy1776 · August 8, 2014

My truck had somewhat similar issues when my dad had it. I am not very knowledgable but after a new ground wire was installed it fixed the issues.

jham0077 · August 22, 2014

I had the distributor cap off of it Tuesday afternoon and noticed the center terminal, coil terminal, was loose. I put a cap on it yesterday and fixed the problem. That was the third time I've had the cap off since this issue started. I touched the terminal just right to feel it wiggle.

Thought I would post back because I've seen so many topics on forums all over yet nobody ever posted the fix. But my fix may not be someone else's.

johnc486 · December 2, 2015

I know this is an old thread but thanks for posting the fix, I'll definitely remember it if and when needed.

Newton98 · October 30, 2019

My 1990 chevy 4x4 heavy half ton with the 350 tbi only does it when i try to accelerate fast

Fred DeDear · September 19, 2020

On 7/17/2014 at 9:05 AM, jham0077 said:

I am having almost identical problem in my 1997 GMC Sierra C1500 4X4.

No takers?

I drove it yesterday afternoon, a good 40 miles of stop and go on backroads. Eventually the problem went away. By the time I got close to home I couldn't make it miss. Get in it this morning and it misses like hell. I put about 30 mile on it this morning and the problem fades away. O2 sensor not heating up maybe?

On 7/17/2014 at 9:05 AM, jham0077 said:

No takers?

I drove it yesterday afternoon, a good 40 miles of stop and go on backroads. Eventually the problem went away. By the time I got close to home I couldn't make it miss. Get in it this morning and it misses like hell. I put about 30 mile on it this morning and the problem fades away. O2 sensor not heating up maybe?