Bravada acts like it is going to die and bogs down

jeanniereeves · #1 05-13-2005, 03:17 PM

I have a 98 Olds Bravada. It has 154,000 miles on it. It started to act funny a couple months ago, where it acts like it is either not getting gas and bogs down, this happens in town and on the interstate. At first I thought it was the transmission because it seemed like it was not shifting correctly, but now I think it is more bogging down from something else. Someone told us that it could be the EGR valve. We took this off and cleaned it out the best we could. It seems somewhat better afterwards, but the problem was still there and then got worse again after only a few days. We purchased an EGR valve off ebay that is used and a GM tech guy refurbished it. He had wonderful feedback and sells tons of these refirbished EGR valves. Anyway after putting it in, I could not tell that it was boggin down while driving in town, however when I got on the interstate it really acted like it wanted to die going 70 with the cruise was set. It has never died on me yet and I am still not sure what this could be. I guess we could check the fuel filter or something...
Please help.

Chris Stewart · #2 05-14-2005, 10:10 PM

Sounds like low fuel pressure, I'll check my book.

jeanniereeves · #3 05-14-2005, 11:04 PM

we are going to replace the fuel filter tomorrow. We will let you know how it works out.

Chris Stewart · #4 05-18-2005, 01:02 AM

Sorry for the delay, you should be getting 60 to 66 psi at the Schrader Valve pressure test port near your fuel injection on top of the motor when you turn the key on but not start the motor and 56 to 60 psi while the motor is idleing.
Is the Check Engine light on?
How long since the last sparkplug/plug wire replacement?

A remote possibility is one of the O2 sensors not "seeing enough oxygen"...low voltage but not enough to set a trouble code(DTC) and causes the computer to keep cutting fuel back because it thinks the motor is running too rich due to the low temp/voltage from the O2 sensor. This is makes a scanner necessary to diagnose.

jeanniereeves · #5 05-18-2005, 01:39 PM

Okay, we replaced the fuel filter and it still runs like crap. We replaced the coil pack and put in higher octane gas with a bottle of cfoam. We took to AutoZone and a code of PO300 came back. The plugs and wires were replaced about 3 months ago and the fuel pump was replaced 6 months ago. The only other thing that I see on the net about the misfire code is the fuel pressure regulator or something like that. The bad fuel was one of them too and maybe it will take a while for the cfoam to work, but I really want my Bravada to run better. Thanks for your help.

clariveros · #6 05-19-2005, 10:45 AM

check your fuel pump like chris said first, then also pull the negative batery cable, wait for computer to reset, and then get the codes, ur problems does not sound like a misfire, bad o2 sensor maybe, good luck

jeanniereeves · #7 05-19-2005, 11:29 AM

The fuel pump is brand new and we did reset the codes before getting the Po300 code. We had the battery disconneted while putting in the new fuel filter.

Schrade · #8 05-23-2005, 06:37 PM

I thought I had a tranny problem, but this past weekend, I read 650 blazer/bravada/jimmy 'posts', and I got my 'tranny' problem solved 100%. It's the ign. switch, and it's intermittent, and can be proven by unplugging the battery for a few minutes. It clears the codes, and faulty positives are reset. Doesn't sound like the switch, but try again...

Schrade · #9 05-23-2005, 06:42 PM

Hey Chris, I think you're a little off, on the O2 sensor function...
WAY BAD CALL 94JIMMY!!!
A finely tuned motor does NOT even use the O2 sensor. A finely tuned motor uses ALL of the O2 which gets burned in the combustion process, and the O2 sensor does no work. A poorly tuned motor lets O2 get through the combustion process (by not burning it all), and into the exhaust, and the O2 sensor tells the ECM that compensation is necessary to fix another problem. If you'd like to see that in print, I'll be happy to get it to you. A bad O2 sensor is an extremely common myth!!!

Chris Stewart · #10 05-24-2005, 05:48 PM

Quote:

Originally Posted by cbec1999

Hey Chris, I think you're a little off, on the O2 sensor function...
WAY BAD CALL 94JIMMY!!!
A finely tuned motor does NOT even use the O2 sensor. A finely tuned motor uses ALL of the O2 which gets burned in the combustion process, and the O2 sensor does no work. A poorly tuned motor lets O2 get through the combustion process (by not burning it all), and into the exhaust, and the O2 sensor tells the ECM that compensation is necessary to fix another problem. If you'd like to see that in print, I'll be happy to get it to you. A bad O2 sensor is an extremely common myth!!!

Allright! Yeah, send it to me, I accept all the help I can get.

MHBolton · #11 08-20-2005, 12:07 PM

jeanniereeves,

If you are still having the problem, try cleaning the carbon out of the plenum. I had all kinds of trouble at lower speed (stalling out) on and off, and replaced the EGR etc. Sometimes it seamed like replacing the front left spark helped as well (it burns hotter than the rest on my '94). Finally I had a BETTER mechanic figure out about the plenum. He said it was fairly common, design related. One note however, make sure all the lines to the plenum are cleared out or the problem could pop up again. Good luck

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