Driveabilty problem! Help
02-03-16, 02:48 PM
#1
Driveabilty problem! Help
Ok fellas,
This is first time I've have a problem with performance characteristics with my ride. Over the last week or so, there's been a weird drop in how my car is acting. There's been a lost of power, strange engine/exhaust like noise during moderate acceleration when I get up in speed and RPMs. The shift from 3rd to 4th gear seems to take forever while noticing some sputtering giving it gas. I'm wondering if something went bad after my car shut off while idling and having the exhaust pipes blocked while I dug the car out of snow a lil over a week ago. Could it be transmission related? Car does shift into all gears normally and when starting out there is no shifting problems. I do noticed my symptoms get worse the longer it runs. My car has 186k. Plugs been changed at 120k, air filter isn't due until another 7k. Just had an oil change and cleaned my MAF and throttle body. Never had the transmission serviced so that's making me worried.
Any ideas before she goes to the dealer for a check up?
This is first time I've have a problem with performance characteristics with my ride. Over the last week or so, there's been a weird drop in how my car is acting. There's been a lost of power, strange engine/exhaust like noise during moderate acceleration when I get up in speed and RPMs. The shift from 3rd to 4th gear seems to take forever while noticing some sputtering giving it gas. I'm wondering if something went bad after my car shut off while idling and having the exhaust pipes blocked while I dug the car out of snow a lil over a week ago. Could it be transmission related? Car does shift into all gears normally and when starting out there is no shifting problems. I do noticed my symptoms get worse the longer it runs. My car has 186k. Plugs been changed at 120k, air filter isn't due until another 7k. Just had an oil change and cleaned my MAF and throttle body. Never had the transmission serviced so that's making me worried.
Any ideas before she goes to the dealer for a check up?
Last edited by Slvr surfr; 02-03-16 at 02:52 PM.
02-03-16, 08:11 PM
#6
Instructor
Did the problem only occur after the MAF and throttle body cleaning? I've seen a few cases here and on other forums of people cleaning the MAF and throttle body and the results were that the car operates much worse after. The problems usually trace back a damaged MAF even if they did not touch the wires, and/or from manually pushing an electronically-actuated throttle body flap and throwing off the calibration, requiring a recalibration of the TPS or replacing the actuator.
From those situations I've read anecdotally (nothing solidly proven), I would just put a brick on the pedal to open the throttle body flap, and consider the MAF something to replace once every several years (like an engine coolant temperature sensor), especially if it runs worse after cleaning.
You can also chart the MAF voltages and TPS sensor readings (and every other sensor) in Techstream to see if something is sensing+reporting abnormal values.
From those situations I've read anecdotally (nothing solidly proven), I would just put a brick on the pedal to open the throttle body flap, and consider the MAF something to replace once every several years (like an engine coolant temperature sensor), especially if it runs worse after cleaning.
You can also chart the MAF voltages and TPS sensor readings (and every other sensor) in Techstream to see if something is sensing+reporting abnormal values.
02-03-16, 09:17 PM
#7
It's been about a month since I cleaned the sensor. I started noticing this problem about a week and a half ago. I cleaned it the same way I normally do. Disconnect and use a Qtip with alcohol making sure no residue left behind. I may take it to get a diagnosis done from Lexus. If it's a sensor then I can replace the part myself. If i cant then the next best cheaper option. How can I test the TPS?
Trending Topics
02-03-16, 10:26 PM
#8
Instructor
Sounds like the typical case of Q-Tip + alcohol permanently damaging the MAF. When MAF cleaning, never use anything to touch the wires, and never use alcohol, 99% or otherwise, and never use methanol. ALWAYS use real MAF sensor cleaner - not carb cleaner or electrical contact cleaner.
"Q-Tips", medical grade or otherwise, are not guaranteed to be free of particulates. Q-Tips likely deposit particulate matter on the MAF sensor wires. Store-grade alcohol is the lowest grade and does not dry as residue-free as you would think, which is why they make several different grades of 99% isopropyl. On top of the normal alcohol residue, you are dissolving whatever glues hold the Q-Tip cotton in place, plus whatever chemicals are in the Q-Tip cotton and stick, and distributing the dissolved glue and chemicals all over your sensor wires.
Alcohol also absorbs moisture and has a low surface tension, the combination of which causes residues to stay on whatever you are trying to clean instead of carrying the residues away in run-off. Alcohol is also much slower to dry than solvents designed for MAF sensors. With a real MAF sensor cleaner, you need to wait at least 20 minutes before reinstalling. Much longer with alcohol. If the MAF's hot wire is activated when the sensor is not completely clean and dry, you will permanently damage it.
I suspect your MAF is permanently damaged from your cleaning since the car doesn't throw codes and shows the symptoms of a damaged MAF, so that would be my first thing to check/replace.
MAF:
1) Apply battery voltage across pins 1 and 2 (pin 1 is on the left when the harness clip is on top). Using a voltmeter, connect + to pin 3, connect - to pin 2. Blow into the MAF and check that the voltage fluctuates.
2) Measure resistance across pins 4 and 5. At -20C/-4F, resistance is 13.6-18.4kOhms. At 20C/68F, resistance is 2.21-2.69kOhms. At 60C/140F, resistance is 0.493-0.667kOhms. Replace the MAF if results are not to spec.
You can also check other driveability components that don't throw codes, as follows:
Throttle body motor:
1) Turn ignition ON, while turning the accelerator pedal position sensor, check the running sound of the motor. It should be running smoothly without friction sounds.
2) Resistance across pins 1-2 at 20C/68F should be 0.3-100Ohms, pins 5-3 1.2-3.2kOhms
TPS: Connect Techstream or CAN VIM handheld tester to the DLC3, ensure accelerator is not pressed, turn ignition ON, ensure MIL is not on, under CURRENT DATA, THROTTLE POS, it should read between 14.4 and 16%. If not, loosen but don't remove the set screws, rotate the TPS until you hit 15.2, tighten the screws to 18 INCH lbs. Then fully close throttle valve by hand and ensure valve opening percentage reads 10-14%.
Accelerator Pedal Position Sensor:
1) When turning ignition ON, check voltage is between 0.6 and 1.0V
2) Resistance across pins 2-3 and 5-1 5kOhms or less, pins 6-3 and 4-1 1.5-6.0kOhms
Pretty sure you can graph the TPS and Accelerator voltages/positions in Techstream, so if during a smooth down-up movement, the response is not a smooth down up, you know you have a problem.
Camshaft Oil Control Valve:
1) Using Techstream, start the engine, select VVT from ACTIVE TEST menu, ensure when VVT is off, engine runs normal, and when VVT is ON, idle is rough or the engine stalls.
2) Measure resistance across the 2 pins, spec is 6.9-7.9Ohms at 20C/68F.
3) When battery voltage is applied, valve moves towards the terminal head. When battery voltage is removed, valve moves away from terminal head.
Engine Coolant Temperature Sensor: At 20C/68F, 2.31-2.59kOhms, at 80C/176F 0.31-0.326kOhms.
Knock sensors: At 20C/68F, 120-280kOhms
"Q-Tips", medical grade or otherwise, are not guaranteed to be free of particulates. Q-Tips likely deposit particulate matter on the MAF sensor wires. Store-grade alcohol is the lowest grade and does not dry as residue-free as you would think, which is why they make several different grades of 99% isopropyl. On top of the normal alcohol residue, you are dissolving whatever glues hold the Q-Tip cotton in place, plus whatever chemicals are in the Q-Tip cotton and stick, and distributing the dissolved glue and chemicals all over your sensor wires.
Alcohol also absorbs moisture and has a low surface tension, the combination of which causes residues to stay on whatever you are trying to clean instead of carrying the residues away in run-off. Alcohol is also much slower to dry than solvents designed for MAF sensors. With a real MAF sensor cleaner, you need to wait at least 20 minutes before reinstalling. Much longer with alcohol. If the MAF's hot wire is activated when the sensor is not completely clean and dry, you will permanently damage it.
I suspect your MAF is permanently damaged from your cleaning since the car doesn't throw codes and shows the symptoms of a damaged MAF, so that would be my first thing to check/replace.
MAF:
1) Apply battery voltage across pins 1 and 2 (pin 1 is on the left when the harness clip is on top). Using a voltmeter, connect + to pin 3, connect - to pin 2. Blow into the MAF and check that the voltage fluctuates.
2) Measure resistance across pins 4 and 5. At -20C/-4F, resistance is 13.6-18.4kOhms. At 20C/68F, resistance is 2.21-2.69kOhms. At 60C/140F, resistance is 0.493-0.667kOhms. Replace the MAF if results are not to spec.
You can also check other driveability components that don't throw codes, as follows:
Throttle body motor:
1) Turn ignition ON, while turning the accelerator pedal position sensor, check the running sound of the motor. It should be running smoothly without friction sounds.
2) Resistance across pins 1-2 at 20C/68F should be 0.3-100Ohms, pins 5-3 1.2-3.2kOhms
TPS: Connect Techstream or CAN VIM handheld tester to the DLC3, ensure accelerator is not pressed, turn ignition ON, ensure MIL is not on, under CURRENT DATA, THROTTLE POS, it should read between 14.4 and 16%. If not, loosen but don't remove the set screws, rotate the TPS until you hit 15.2, tighten the screws to 18 INCH lbs. Then fully close throttle valve by hand and ensure valve opening percentage reads 10-14%.
Accelerator Pedal Position Sensor:
1) When turning ignition ON, check voltage is between 0.6 and 1.0V
2) Resistance across pins 2-3 and 5-1 5kOhms or less, pins 6-3 and 4-1 1.5-6.0kOhms
Pretty sure you can graph the TPS and Accelerator voltages/positions in Techstream, so if during a smooth down-up movement, the response is not a smooth down up, you know you have a problem.
Camshaft Oil Control Valve:
1) Using Techstream, start the engine, select VVT from ACTIVE TEST menu, ensure when VVT is off, engine runs normal, and when VVT is ON, idle is rough or the engine stalls.
2) Measure resistance across the 2 pins, spec is 6.9-7.9Ohms at 20C/68F.
3) When battery voltage is applied, valve moves towards the terminal head. When battery voltage is removed, valve moves away from terminal head.
Engine Coolant Temperature Sensor: At 20C/68F, 2.31-2.59kOhms, at 80C/176F 0.31-0.326kOhms.
Knock sensors: At 20C/68F, 120-280kOhms
02-06-16, 04:35 PM
#12
This made me raise my eyebrows. Could your catalytic converter possibly overheated/damaged during this time?
02-06-16, 08:55 PM
#13
Boom! Actually I was just thinking about this all day long. What made me think this was the strange exhaust type of noise and I'm getting underneath the car right below the radio it seems. Plus this dilemma didn't start until after that incident that I just had with the snow. I will start pricing some cats along with the aforementioned sensors. Although my third, middle cat is fairly new. Could be one of the upstream ones. I noticed there seems to be almost no tailpipe output. I really think a cat is damaged/ clogged.
Last edited by Slvr surfr; 02-09-16 at 02:48 PM.
