Hi Scotty, Wish you a Merry Christmas and a Happy New Year.
My car is Mazda Protege 2001 zm 1.6 L Automatic 180,000 miles. The car works fine until the coolant temperature reaches the operating temperature. Then the problem starts when taking off after stopping at traffic lights. The car moves very slowly, however much I press the gas pedal. I have to pull over the car and drive slowly at 2000 RPM until it picks up the speed. Sometimes I do get backfire via exhaust.
The knock sensor was bad ( trouble code 0328) and it was replaced. After clearing the trouble code, no more codes are coming up but still, the problem continues.
The 1st cylinder compression is 140 psi whereas 150 psi for the other three cylinders. After checking I found the timing is correct. All 4 spark plugs are firing. No carbon deposits on the spark plugs.
The fuel pressure readings are 35 psi with the vacuum hose attached to the regulator and 45 psi with it detached. The pressure holding is okay after the engine is off. I also took the readings when the engine reached the operating temperature. It's the same as before.
Pressing the gas pedal didn't raise the RPM even in the neutral position during the hesitation time.
I suspect a lean mixture after the coolant reaches the operating temp. I would like to know which sensors could malfunction without throwing trouble codes and their output signal is based on the coolant temperature.
Please help me to find out where the problem is.
Ford Laser/Mazda Protage.
Have you analyzed live data?
I do not have the correct scanner for this car because the port is 25-pin under the bonnet. I used an LED light to scan and was unable to analyse the live data.
might want to check for a plugged up cat
The fuel pressure readings are 35 psi with the vacuum hose attached to the regulator and 45 psi with it detached.
sounds low. Do you know what the specification is for your engine?
The workshop manual says as following.
Fuel line pressure
210—250 kPa {2.1—2.6 kgf/cm2, 30—36 psi}
After disconnecting the vacuum hose
Fuel line pressure
270—310 kPa {2.7—3.2 kgf/cm2, 39—45 psi}
If the problem is with the cat, I wonder why the car didn't throw a trouble code.
You are correct. The cat is clogged. I removed the O2 sensor and did the test drive. The car was running well. Before removing the o2 sensor, I replaced the TPS and MAF sensors with no success.
I cannot afford to replace the cat with a new one. I want to clean the existing one. Please give some advice on this issue. Many thanks for your suggestion.
you cannot clean a plugged cat. It's plugged because the insides have disintegrated, not because it's dirty. The cat must be replaced, but before that you need to find out what caused it to fail, or you'll just ruin another one.
I doubt whether the broken pieces are thrown into the pre silencer blocking the way
pieces can go all over. Because exhaust is subjected to oscillating pressure waves, pieces are even known to work their way BACK to the engine where they get stuck in valves and stuff.
Scotty thinks you have clogged cat. converter or fuel filter at 3:37
https://youtu.be/EYu9pvpc2VY?si=N5kOg-hK3cz73b8N
The workshop manual says as following.
Fuel line pressure
210—250 kPa {2.1—2.6 kgf/cm2, 30—36 psi}
After disconnecting the vacuum hose
Fuel line pressure
270—310 kPa {2.7—3.2 kgf/cm2, 39—45 psi}
I do not have the correct scanner for this car because the port is 25-pin under the bonnet. I used an LED light to scan and was unable to analyse the live data.
If the problem is with the cat, I wonder why the car didn't throw a trouble code.
Sorry, the car has done 125,000 miles, not 180,000 miles as mentioned before.
I cannot afford to replace the cat with a new one. I want to clean the existing one. Please give some advice on this issue.
You can try something like Cataclean but if the converter is plugged up so badly that it's choking down the engine I'd be surprised if that helps much. You could also try removing the catalytic converter to clean it more thoroughly. How much success you have depends on how badly the contamination is baked in. Also you would need to find and fix the source of the problem which typically would be engine misfires or oil burning or it's just going to clog up again.
https://www.wikihow.com/Unclog-a-Catalytic-Converter
Thanks, Chuck
I have ordered the catalytic cleaner. It will take 2 weeks to arrive. Can I try with lacquer thinner which is available locally? Is it not safe if I spray a degreaser on the cat through the o2 sensor hole and then flush it with water?
I have ordered the catalytic cleaner. It will take 2 weeks to arrive. Can I try with lacquer thinner which is available locally? Is it not safe if I spray a degreaser on the cat through the o2 sensor hole and then flush it with water?
I'll preface these comments saying that I have not used any of the catalytic converter cleaning techniques myself. After 27 years and over 370,000 miles the original converter on my daily driver still flows well and works fine. Catalytic converters will generally last the life of the car if not abused. Your converter plugged up due to engine problems which, if not resolved, will just clog up your converter again.
The major ingredient in Cataclean is lacquer thinner but it does have other ingredients as well. I don't know what straight lacquer thinner would do to your fuel system.
I'd think to get enough pressure through the O2 sensor hole to do any good you'd need to use a pressure washer. You wouldn't want water backing up through the exhaust pipe to the engine, if that happens you're in for another whole world of hurt. So I'd say that's a pretty risky approach.
Bear in mind you are dealing with a vehicle that is well past its expected service life. You need to use reasonable caution and not subject the car to undue stresses or you'll wind up with more problems.
I removed the cat and found the inside material was broken. I could see many cracks in the material, still sticking to the wall with a big hole in the middle, when viewed through the pipe hole. So, there was no blockage. My son has a car which is a Ford Laser 2000 1.6 L Automatic, the same as the Mazda Protege model. The Laser is running well. I just wanted to confirm whether the problem is with the catalytic converter, so I replaced it with the good one from the laser. Unfortunately, the problem persists. The same symptoms are still there.
The other day I was doing a test run with the o2 sensor removed from the exhaust and noticed some improvement in the pickup. It was a very cold day and the coolant temp might have been below the operating temp. So, I was wrong to guess that a faulty cat was causing the problem.
I doubt whether the broken pieces are thrown into the pre silencer blocking the way. These models have only one o2 sensor before the cat and do not have one after the cat.
The car has done 200,000km. I made a mistake when calculating the miles and gave the wrong figure.