98 sc2 bogging/ not running right

I have replaced : EGR, ECTS, CATALYTIC CONVERTER, PLUGS, WIRES, A COIL PACK, I have also cleaned the throttle body, the o2 sensors and have bought a scan tool to check codes. No Codes but yet the car runs rough, idles at 1200 rpm's, and when i give it gas it acts like it bogs down. If i hold the throttle wide open it will get through the bog and rev up. If i put it in gear ( its a 5spd) and let out it will shake rappidly or will act like im not giving it gas until i push in the clutch then it will rev up high and back down. When this happens i have to rev it through the bog with clutch depressed and then let out on clutch to get moving. ANY ADVICE IS HELPFUL.

The first thing I'd check or replace is the thermostat. If it isn't working properly it makes these cars run like crap. If the temp needle consistently resides lower than the 3/8 mark or takes a long time to warm up the thermostat is definitely bad. Only replace it with a 192* CST/Duralast p/n 3179 (AutoZone), 195* Stant p/n 14279 (Advance Auto), or 195* NAPA p/n THM 268.

Inspect the ECTS wiring for any corrosion or contamination since these cars heavily rely on this sensor to run properly.

If the A/C works and is turned on or if you are coasting (either with clutch disengaged or in neutral) at a speed greater than 15 MPH the 1200 RPM idle is about right.

FWIW if it is fairly warm out, the air is really humid, and the A/C is on I still have to rev mine up to 2000 RPM before I start to engage the clutch for the car to start moving smoothly. It sounds like your situation is beyond the realm of this normal behavior though.

What kind of plugs do you have installed? Standard copper plugs work best gapped at .040"; preferrably NGK or AC Delco, but any popular brand is acceptable. If you have any other type of spark plug installed I'd strongly suggest replacing them.

I might also check your grounds, battery terminals, and the coil/ICM mounting bolts (two of these bolts provide the ground for the ignition system) to make sure they are clean and free of corrosion.

It might be redundant at this point, but have you checked/replaced the air filter? Make sure the clamps on the air intake are tight and make sure there are no leaking vacuum hoses.

Not knowing much else, at this point my money is on the thermostat.

I'm thinking leaky fuel injector or plugged fuel filter.

The thermostat doesn't take very long, within 2 minutes of idle it is between 1/4 and 1/2. I have not used the A/C in any of these situations. The ECTS connector was replaced the first time the sensor went out, it was done by dealership, I have since then replaced the sensor to see if that was the problem and it hasnt changed. All conections have been either cleaned or checked and no corrosion. The air filter and fuel filter are both new.

If it idles at 1200 RPM after it is warmed up, without the A/C on, and not while coasting above 15 MPH; then I think you have a vacuum leak or an IAC (Idle Air Control) valve that is not closing completely, but the following factors will only worsen the issue...

What brand/type of plugs are installed?...As I mentioned before, Standard copper plugs work best gapped at .040"; preferrably NGK or AC Delco, but any popular brand is acceptable. If you have any other type of spark plug installed I'd strongly suggest replacing them.

What brand of fuel filter?...OEM, WIX or NAPA is best since they are designed strictly for use with the S-Series. Virtually all of the others are of the one-size-fits-all variety that maintains too high fuel pressure and made for use with a variety of cars.

What brand of oxygen sensors?...Bosch = junk. OEM/Denso or NTK/NGK are the only brands worth using in these cars.

I have installed 4 NGK # 5643 spark plugs and an OEM fuel filter. I completely removed the throttle body and cleaned the internals of it, i also removed the butterfly and the the sensor from the TB and cleaned them. I cleaned the o2 sensors, they are stock. I have sputtered around enough to throw 2 codes, low voltage on o2 sensor 1 and o2 sensor 2. There are still no other codes. (by the way thanks for the advice, it has been very helpful so far.)

I have installed 4 NGK # 5643 spark plugs and an OEM fuel filter. I completely removed the throttle body and cleaned the internals of it, i also removed the butterfly and the the sensor from the TB and cleaned them. I cleaned the o2 sensors, they are stock. I have sputtered around enough to throw 2 codes, low voltage on o2 sensor 1 and o2 sensor 2. There are still no other codes. (by the way thanks for the advice, it has been very helpful so far.)

What keeps catching my eye is that you "cleaned" the O2 sensors. There is NO WAY to safely clean O2 sensors. Any chemicals that would be worth using to clean them contaminates/ruins the element. O2 sensors are also very sensitive to sudden movements. If they are dropped and land on the thimble or even tapped wrong they be damaged to the point that they won't ever work right.

I know they can be pricey, but at this point I believe both O2 sensors need to be changed. These particular sensors have a service interval of 60K miles and I'm betting your car is well beyond that. If the SES light says they are putting out low voltage, they are definitely bad. You can save a fair amount of cash by ordering them online from www.rockauto.com. I have ordered a lot of stuff from there without any trouble. I would order the Denso p/n 2341022 for the front ($33.79) and Denso p/n 2344618 for the rear ($56.99) from there.

I can't stress enough: DO NOT use Bosch O2 sensors. I would also advise against using universal sensors because they require you to cut the existing harness off the old part and splice it onto the new part. This doesn't seem like a big deal until you consider the fact that an O2 sensor's output (that the PCM reads) is less than 1 volt and continuously fluctuates. Since the voltage is so low and changes so rapidly, any break in the wire can significantly affect the signal which in turn will affect how the car runs.

If you absolutely can't afford the OE fit sensor and have to use a universal sensor, I would only trust soldered and insulated connections. The upstream sensor is the only one the PCM uses for engine management. The downstream sensor is essentially nothing more than a smog sniffer that makes sure your catalytic converter is working and does not affect how the engine runs.

As far as the cleaning goes i used a solvent on the rag and wiped off the carbon build up. I checked the voltage from the sensor and it reads .67-.86 volts. I dont understand how that can be low voltage. I also checked the voltage on the wire going to the sensor and it read .32-.37, is that what its talking about?

As far as the cleaning goes i used a solvent on the rag and wiped off the carbon build up. I checked the voltage from the sensor and it reads .67-.86 volts. I don't understand how that can be low voltage. I also checked the voltage on the wire going to the sensor and it read .32-.37, is that what its talking about?

How did you check the voltage on the sensor? Did you simply disconnect and test with the car running or did you remove it from the manifold? Was it heated up? Where did you place your test probes? I'm not trying to nitpick, but O2 sensors need to be tested in a very specific manner and even those results are questionable.

Heat is the biggest factor here. Oxygen sensors don't function at all until they reach about 600*F, but bad O2 sensors sometimes don't fail until it is heated for a prolonged amount of time.

As far as the voltage from the wire going to the sensor, it is a bit different since the PCM only measures the O2 sensor output and doesn't supply it with a 5 volt reference like other sensors. However, the PCM does supply a bias voltage of about .425 volt.

If the sensors are in fact original and you have a fair amount of mileage on the car (>100k miles) they are likely reacting slowly at the very least and should replaced based on that reason alone.

I let the engine heat un to normal operating temperatures. I then disconnected the harness from the o2 sensor and connected the positive lead from my voltmeter to the prong on the harness, then connected the negative lead from my voltmeter to an engine ground. In my findings, it would be hard to get a voltage reading from a sensor that is not in operating mode. I do know that if you move the leads to the voltmeter in a rapid motion that they do pick up a slight reading but this is not what I did. I assure you that I do have some common since and do know some about cars. I do not claim to know everything about cars, I have a long ways to go. I do know that I have a degree in automotive technology and one in auto/diesel technology so I hope that this will give a better understanding of what I know. Don’t be hesitant to give me parameters of sensor operating ranges to test, I have a good volt/ohm meter to use. As far as replacing them, I will do that anyway but if they are not the reason for the running issue then I would prefer to have a running car than to have 2 new sensors. I know that these parts go bad but for them to both go bad at the same exact time is unlikely. Thanks for the continuous advice.