Bogging, no power when warm.
Bogging, no power when warm.
Ok now i've just been looking around posting in mayn different places but no one seems to be able to help me out with this problem although it seems pretty commong. Hope a mechanic could help me out, or anyone. When the car is cold it runs a lot stronger and well once it warms up it just dies, it has barely any powr, and it bogs, and sometimes at the tap of the acceleration it sputters, now i just changed the 02 sensor the air filter the fuel filter the spark plugs and the wires i dont' know what else to do, i also switched the CTS from another friends car and nothing. Please help or refer me to someone that can. Thank you
When the car is cold it runs rich, which will cause it to run lean and have power, even with a bad MAFS. Once it warms up the MAFS cant control the air/fuel ratio and makes it run like crud. Take it to a mechanic and have them test the MAFS. I have a extra MAFS for a 89-90 ka24e I could get rid of for 40 shipped if that is the problem.
yeah, i meant that wheni start it up in the morning is and the temp is cold, once it runs for like 10 mins and warms up is terrible, a huge loss of power, i already took it to a mechanic so hopefully they could solve the prob. They told me it could be that the catalityc is clogged, bad, etc.. Lets see I'll keep you guys informed
I have a similar problem on a 93 240sx, auto trans with OD, and 103k miles. The area I live in is very humid.
When I start it in the morning, the car tends to want to kill. Driving it after start up, it feels as though it's going to die. Kind of like a bad fuel filter. When it warms up, this goes away. BUT the car is extremely sluggish. If I floor it from a red light, the car picks up speed very slow (this happens when the car is cold and when the car has warmed up). Sometimes it doesn't shift into 2nd until about 3k rpms (sometimes higher). If I change to overdrive off, I can get a little extra power. I find that if I get a rolling start at a red light, the car will take off with a little more power. As I get going, it takes a little while to shift. When it does, I can feel it pulling into the next gear.
This is what we changed/cleaned:resistor copper plugignition rotorignition wire setvalve cover gasketfuel filtercleaned injectorsfan belt, power sterring belt, and AC beltoil changevalve cover bracket
Car still shifted the same, but idled better. Sent the car to a transmission shop. They ran a diag, but did not find anything on the transmission.
Sent the car to an exhaust shop. They did a back pressure test, and all was ok (they said the catalytic converter was fine).
Anyone have any ideas what to check next? Other have changed an 02 sensor (not sure what it is). Others have suggested the MAFS. Is the engine slowly dying?
When I start it in the morning, the car tends to want to kill. Driving it after start up, it feels as though it's going to die. Kind of like a bad fuel filter. When it warms up, this goes away. BUT the car is extremely sluggish. If I floor it from a red light, the car picks up speed very slow (this happens when the car is cold and when the car has warmed up). Sometimes it doesn't shift into 2nd until about 3k rpms (sometimes higher). If I change to overdrive off, I can get a little extra power. I find that if I get a rolling start at a red light, the car will take off with a little more power. As I get going, it takes a little while to shift. When it does, I can feel it pulling into the next gear.
This is what we changed/cleaned:resistor copper plugignition rotorignition wire setvalve cover gasketfuel filtercleaned injectorsfan belt, power sterring belt, and AC beltoil changevalve cover bracket
Car still shifted the same, but idled better. Sent the car to a transmission shop. They ran a diag, but did not find anything on the transmission.
Sent the car to an exhaust shop. They did a back pressure test, and all was ok (they said the catalytic converter was fine).
Anyone have any ideas what to check next? Other have changed an 02 sensor (not sure what it is). Others have suggested the MAFS. Is the engine slowly dying?
I recently cured my '91 240SX's irregular idle / running rich problem. Mine would start and run okay when cold, then also get worse with warm-up. The idle would sag(about every 20 seconds) from around 900 down to 100, sometimes even die!
I tried many things, but the last straw(and final cure) was replacing my MAF with a used MAF from the boneyard for $60.
Here's a simple test you can try if your problem is the same as mine was. Leaving the MAF connected, pull back the rubber on the wiring harness side. Measure the DC voltages on those 3 wires. One is ground 0v. One is close to Battery Volts. One is the MAF output and should be somewhere between .3 to .5 volts with Key On, not running; and 1V to 1.4 volts with engine idling(the faster your idle, the higher the voltage.) My "bad" MAF measured 0.5 volts; and 1.5 volts. My "good" MAF now measures 0.3 volts and 1.26 volts. My 240 once again idles and runs like the day I bought it. I'm guessing that since my MAF was outputting slightly high on the voltages, it was telling the ECM that the airflow was up, and the ECM would respond with more fuel(running rich). Good Luck !
I tried many things, but the last straw(and final cure) was replacing my MAF with a used MAF from the boneyard for $60.
Here's a simple test you can try if your problem is the same as mine was. Leaving the MAF connected, pull back the rubber on the wiring harness side. Measure the DC voltages on those 3 wires. One is ground 0v. One is close to Battery Volts. One is the MAF output and should be somewhere between .3 to .5 volts with Key On, not running; and 1V to 1.4 volts with engine idling(the faster your idle, the higher the voltage.) My "bad" MAF measured 0.5 volts; and 1.5 volts. My "good" MAF now measures 0.3 volts and 1.26 volts. My 240 once again idles and runs like the day I bought it. I'm guessing that since my MAF was outputting slightly high on the voltages, it was telling the ECM that the airflow was up, and the ECM would respond with more fuel(running rich). Good Luck !
No.
The spec's I mentioned are the exceptable ranges for a good MAF.Measure yours, and if out of that range, it may be bad. Maybe you can swap with your friends MAF, if you suspect yours is bad.
My Bad MAF measured: #1 ) 0.5 V - Key On, Eng. off. #2) 1.55 V - Key On, Eng. idlingMy Good MAF#1) 0.3 V - Key On, Eng. off. #2) 1.26 V - Key On, Eng. idling
Strictly by the numbers my Bad MAF didn't look that far out of spec. But once I replaced it with the Good MAF, my problem went away.
The spec's I mentioned are the exceptable ranges for a good MAF.Measure yours, and if out of that range, it may be bad. Maybe you can swap with your friends MAF, if you suspect yours is bad.
My Bad MAF measured: #1 ) 0.5 V - Key On, Eng. off. #2) 1.55 V - Key On, Eng. idlingMy Good MAF#1) 0.3 V - Key On, Eng. off. #2) 1.26 V - Key On, Eng. idling
Strictly by the numbers my Bad MAF didn't look that far out of spec. But once I replaced it with the Good MAF, my problem went away.
Use a voltmeter with a digital readout(preferred) with some small tipped test probes. "Leaving the MAF connected, pull back the rubber on the wiring harness side. " You should be able to poke your positive(usually red) test probe into the back of the wiring harness connector to touch the metal contact of each of the 3 wires. (You don't have to pierce the wire but that is another option). At the same time your negative test probe should he held onto(or clipped to) a good chassis or engine ground. Measure each of the 3 wires and record values with key on, engine off. One wire should measure 0 Volts. One should measure Battery Volts. One is the MAF output and should be somewhere between .3 to .5 volts with Key On, not running; and then 1V to 1.4 volts with key on and the engine idling.Make sure your voltmeter is set properly to measure DC Volts. If your MAF voltage tests check out okay, then it's probably not your problem. Tell us what you find out.
have you tried unplugging the O2 sensor? mine had the bogging problem till i unplugged it. Its the plug on the driverside behond the motor... the one that has wires that go all the way down to the exhaust by where the steering rack is. Just unplug it and drive it to see if it fixes your problem. If not than thats not it...
The MAF is the metal tunnel like thing where the air filter goes connected to. It has a connecter running into the side of it. I think you should definitely check the MAF voltage and then go with the 02. I didn't have time to do it myself today but tomorrow morning it will be done, and i will post results.
Ok i just checked my MAF and here's what i got, Key on, engine off .2VEngine On 1V-1.1VIt seems a little low when the engine is off, don't you agree, as well as when it is on?I also noticed that when the car is cold, now it tends to smoke a bit, and really rich. Even when im driving sometimes, when is cold is rich. Do you think the actual Temp of the car could have an effect on the volts the maf sensor is reading? Thanks
I believe that you are supposed to check the MAF voltages with the car warmed up, I will check and reply tomorrow. The engine is designed to run richer when warming up. Also, I don't think that the temp of the car will directly affect the MAF volt output, but instead the onboard computer takes the MAF voltage, the temp sensor info, and other info and then decides how much fuel to send to the engine based on those conditions. What year is your car and is it a DOHC?
your post on club 240 forums:I've been reading alot and well done a lot of search and this seems to be a pretty common topic with 240's hopefully someone could help me out. My problem is when the car is cold, hasn't been started in hours it runs really good and strong, but then when it gets warmed up it bogs and feels powerless. Also my sparkplugs look whitish, im assuming im running rich. I already replaced sparkplugs and the wires and fuel filter, also changed the CTS with a friends that was working fine and still there. ANy help will be greatly appreciated. Thanks
my reply on club 240 forums:
black carbon fouled plugs mean you are running rich, too much fuel
whitish plugs mean you are running lean, not enough fuel
this might indicate a fuel delivery problem, but note that its ok for them to be slightly grey/whitish this is ok.
possible causes are low fuel line pressure because of a malfunctioning fuel pump or malfunctioning fuel pressure regulator. you need to hook a gauge up to the line to test the pressure. (might want to let a mechanic check these two things)
another possibility is a vacuum leak through the carbon canister. to test, disconnect the purge line comming from the canister and plug both holes. if your problem dissapears the canister is faulty.
last, check your temperature gauge, is it going above the middle line? if it does you have a cooling problem. possible causes are leaves and dirt caught imbetween your radiator and condensor, incorrect antifreeze to water ratio, or a faulty water pump. This wouldnt cause you to run lean though, it would just make the performance sluggish when the ECU retards the timing due to high temperatures.
Im just repeating this stuff here because it seems you left out a few details, Whitish Plugs, etc.... The first two suggestions were straight from the FSM diagnostic of the problem.
my reply on club 240 forums:
black carbon fouled plugs mean you are running rich, too much fuel
whitish plugs mean you are running lean, not enough fuel
this might indicate a fuel delivery problem, but note that its ok for them to be slightly grey/whitish this is ok.
possible causes are low fuel line pressure because of a malfunctioning fuel pump or malfunctioning fuel pressure regulator. you need to hook a gauge up to the line to test the pressure. (might want to let a mechanic check these two things)
another possibility is a vacuum leak through the carbon canister. to test, disconnect the purge line comming from the canister and plug both holes. if your problem dissapears the canister is faulty.
last, check your temperature gauge, is it going above the middle line? if it does you have a cooling problem. possible causes are leaves and dirt caught imbetween your radiator and condensor, incorrect antifreeze to water ratio, or a faulty water pump. This wouldnt cause you to run lean though, it would just make the performance sluggish when the ECU retards the timing due to high temperatures.
Im just repeating this stuff here because it seems you left out a few details, Whitish Plugs, etc.... The first two suggestions were straight from the FSM diagnostic of the problem.
I agree with p00t that if your plugs are whitish after a drive, you definitely have a lean condition causing your bogging when warmed up. I would definitely check out fully the possible causes he mentions above before pointing the finger at your MAF, as long as its in the 1V to 1.4(or 1.5) V range when idling, it's probably not your problem.
However, to finalize your MAF testing, I measured mine under a few other conditions that you can use for comparison(with engine warmed up:
Idling at 800 rpm = 1.26Vat 2000 rpm steady = 1.59Vat 3000 rpm steady = 1.87V(the manual also says that the max. MAF output should be around 3V, but not to rev it too high with no load on the engine!)
Also it's easy to do a resistance (ohms) measurement check on your 2 pronged temperature sensor. I realize that you once swapped it, but it's a quick and easy thing to check when cold, and then when hot. Do a search and you'll find the procedure, or also you can look in the FAQs.
Good Luck!
However, to finalize your MAF testing, I measured mine under a few other conditions that you can use for comparison(with engine warmed up:
Idling at 800 rpm = 1.26Vat 2000 rpm steady = 1.59Vat 3000 rpm steady = 1.87V(the manual also says that the max. MAF output should be around 3V, but not to rev it too high with no load on the engine!)
Also it's easy to do a resistance (ohms) measurement check on your 2 pronged temperature sensor. I realize that you once swapped it, but it's a quick and easy thing to check when cold, and then when hot. Do a search and you'll find the procedure, or also you can look in the FAQs.
Good Luck!
I copied this from the 240sx.org FAQ section:Temperature Deg. F. Resistance Ohms 68 (cold) 2.1 - 2.9 K Ohms176 (hot) 300 - 330 Ohms
You need to have an ohmmeter to measure across the sensor (with the connector removed). Check the connections too.... if the connector is all gooked up and corroded, this could cause higher readings to the ECU and give more fuel dump.
Always a good idea to only unplug sensors with engine & key off.
You need to have an ohmmeter to measure across the sensor (with the connector removed). Check the connections too.... if the connector is all gooked up and corroded, this could cause higher readings to the ECU and give more fuel dump.
Always a good idea to only unplug sensors with engine & key off.