z280utlaw

Yeah, it's easy to forget that 93's are a little different, plus It's not in my sig or anything. Speed Density has it's advantages and disadvantages, hopefully I can get this problem figured out... but it would be easier if my car was obd1 or 2.

"White Knight"

Correct me if i'm wrong, but your car will run without a MAF sensor (even the ones' that don't use speed density) You will just go to open loop. Who hits their MAF sensor anyway?


spark or fuel. Throw a new fuel filter on there too, unless you've changed it recently.

Injuneer

The MAF cars will run with the MAF sensor disconnected, because they default to speed-density mode. All the programming is still in the PCM, including the VE tables. It does not switch to "open loop".... it can still function in closed loop. The only difference between the MAF and speed-density PCMs is the way the PCM arrives at the mass air flow value. From there on, the operation is identical.

Inutero

My car used to do the same thing. I would start it, it would run good for about 4 minutes, then it would sputter and idle bad and backfire. If I put my foot about 90% on the throttle, the car would just magically go from running horribly to running great. I even replaced my opti thinking that was what it was, but I found out afterwards it was my o2's.


Go unplug your o2 sensors and drive around for about 10 minutes. I bet you that your car will run great then. If it does, then you know your o2's are bad.

wrastler

I just went thru the same exact thing last week. I thought it was the egr cause i just got race headers installed...it ended up being a broken spark plug wire arcing on the manifold. It does still run rich cause of the egr though.

z280utlaw

If it were my 02 Sensors wouldn't it be throwing a code or something? I also heard it's bad to drive your car with the front 02's unplugged. Would it be alright just to hack the car up, unbolt them, and let the car run for a little while as long as I don't take it into the high RPM's?

Huntr1117

I'd say it's the 02 sensors. My car ran the same way when I replaced mine with some used ones. I didn't think it was a bad idea at the time because I didn't want to spend that much money. I learned my lesson though, after new plugs and wires. My car ran pretty good for the first 5 mins. After that anytime I would try to accelerate my car would bogg down. It felt like I was trying to pull a truck behind my car. I drove my car about 20 miles before it threw a code.

z280utlaw

Yeah, so basically just buy new 02 sensors... any recommendations? Or is there any other ways to make sure it's your 02 Sensors, besides just unplugging them and seeing how the car runs?

Huntr1117

I dont know anything about unplugging the 02 sensors. I haven't tried that before, but if you do get new 02 sensors get them from a GM dealer. Don't get the Bosch ones from a parts store.

z280utlaw

Anyone else know if it's safe to do? I plan on unplugging them tomorrow morning, and changing my fuel filter. It's my senior year so I can't stand to have my car gone for much longer, I'm tempted to just take it into the shop and tell them to bill Me, but then I will never get any mods done. It;s been down almost a month

DrivinSidewayz

does it start right up every time you disconnect the battery?

z280utlaw

If it did, what would that tell Me.

lefty

had the same sounding problem.tha cat was clogged.pull out the o2 sensor and start it and rev it.if it runs fine it's probley time for a new cat.

Injuneer

That would tell you the engine is running correctly with the long term fuel corrections set to 128 (0%). That would be an indication that its the long term fuel corrections that are screwing it up. The long terms get screwed up by faulty O2 sensors (no, not all O2 sensor problems set codes, particularly in the OBD-I cars, where there is no diagnostic for rich/lean switching speeds), leaks in the exhaust system or misfires.

z280utlaw

Well I disconnected the battery and reconnected it, now the car hesitates to start, like the battery is dead or something... but it has full charge and is connected tight and all that. Does that mean the 02's are bad? Because before the car would start right away, and now it has a hesitation.