Please Fix My Tahoe!!!

[dilli]

Help guys!!!! I am a female driving old 1979 and 1989 Blazers.....finally saved enough $ to buy a 1999 Tahoe Sport with a 5.7 [ I think :}] 70,000 miles, real black beauty.....thought I was in heaven!! Guess again! Here's the details........starts out when I would go up a big hill [ about a mile long] I would get 3/4 of the way up and it would start missing/shuddering. Service engine light came on and started blinking.........code stored said 02censors and this time it said random misfire on cylinder 4. Have replaced 4 02censors, plugs,wires,dist. cap. Drove it 2 weeks.......today I go to go up the same big hill and here we go again.....doesn't feel like a miss....feels like it is shuddering/shimming....service engine light flashes a couple times...pull off the road....light stays on but doesn't flash....drive 30 miles and all is fine. Head back home and it does the same thing on a hill. Take off again tonight and it runs fine about 25 miles......light goes off.......3 miles later on a small incline it starts shuddering again..light flashin the whole works! I have close to a grand in the repairs already and it's still not fixed....every mechanic has their own opinion.........please tell me yours!!!! Thanks guys!!

[dstrick32]

Just becauseyou get a O2 sensor code doesn't mean the sensor is bad. Could be many things that cause the engine to run rich or lean, wiring circuit or etc. Can you be more specific and state the TDC's?

[dilli]

dstrick..nice to meet you! You mean to tell me I might not have needed the 02 censors at all?? This just keeps getting better......... I will try to get any info needed to fix this.....but I need to know what you mean by state the TDCS?? What is a TDC? I have no clue......Thanks!

[mrjohnwayne]

It should be DTC (Diagnostic Trouble Codes)

[daman]

Have your truck scanned again for codes and post them here, you said
you replaced the dist. cap,what about the rotor?,thats with the cap but
under it.

[chevyguy]

Sounds like a bad coil to me. It will drop a cylinder and usually cause a check engine light. Excessive unburnt fuel can cause the O2 sensor to read rich.

[436'd skylark]

Change the fuel filter and check the fuel pressure. my guess is its working to get up the hill, and running out of fuel pressure. The engine runs lean, and falls on it's face. hence the stumbling/sputtering. I'd start there. The filter is like 5 bucks, as long as the lines are decent, it should be an easy job.

[nnunez]

I would also look into the possibility of the fuel filter being clogged or something.

By the way, how much gas is in your tank when you are on the hill?
Do you have any gas smell after it sputters?
Have you checked for vacuum leaks?
Is it Fuel Injected or Throtle Body Injected?

I WOULD CONSIDER CHANGING THE WATER TEMPERATURE SENDING UNIT. IT IS CHEAP TO FIX AND WHEN IT IS BAD, IT CAN MAKE YOUR CAR RUN LIKE ****. MY 95 S10 DID THE SAME THING AND I NEVER IMAGINED IT WOULD BE A WATER TEMP SENDING UNIT.

[nnunez]

Originally Posted by chevyguy

Sounds like a bad coil to me. It will drop a cylinder and usually cause a check engine light. Excessive unburnt fuel can cause the O2 sensor to read rich.

How would a coil drop a cylinder if it is connected to the center of the distributor cap?

Or do these things have coli packs?

[bradrhale]

its a 99, its going to be multiport.