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Discussion Starter · #1 ·
as the tittle says i experimented this problem, when the car are cold it´s worst, but only when load, no on idle, the idle is fine, very fine.

but i´ve notice that it´s worst when i desacelerate after a mid range of rpm, tomorrow i´m going to check all the sensor and codes at my friend´s workshop.

last month i went to autozone and found a bad o2 (before cat) so i replaced it, then the car runs good the next 2 or 3 days, but it start when the car are cold and stop when warm (normal temp).

but since last saturday it start to shutter anytime, it´s intermitent.

last sunday i drive on a highway, and notice that when the car are cold because of the speed the horse came back, like missfire, then when o stop the car it warm up and start again the car sputter again and you can smell the gasoline, to much rich the a/f mix.

what could it be?

fuel pump OEM, after 265000 km
new upstream O2
NGK sparkplug wires have 2 years
Autolite platinum spark plug have 6 month, i check it today and they are black (rich that why i replace the O2)

best regards
best regards
 

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Discussion Starter · #2 ·
Update

today i checked the ecu and no codes available, no codes.

but i´ve notice that the problems is if you try to keep a constant velocity of the car, also when you take out the gas pedal but after a constant velocity.

can abybody help me with this problem?

can a exhaust leak causes that the car can´t control a constant velocity?

best regards
 

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It would have to be a bad exhaust leak. I have had exhaust leaks in the past, but nothing that caused the car to loose the ability to maintain a certain speed.

If the plugs and plug wires are good, I would look other directions. How old is the fuel filter? How long has it been since you ran some fuel injector cleaner through the system?
 

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Re: missfire under load not at idle, rich a/f new O2

Panameno said:
as the tittle says i experimented this problem, when the car are cold it´s worst, but only when load, no on idle, the idle is fine, very fine.

but i´ve notice that it´s worst when i desacelerate after a mid range of rpm, tomorrow i´m going to check all the sensor and codes at my friend´s workshop.

last month i went to autozone and found a bad o2 (before cat) so i replaced it, then the car runs good the next 2 or 3 days, but it start when the car are cold and stop when warm (normal temp).

but since last saturday it start to shutter anytime, it´s intermitent.

last sunday i drive on a highway, and notice that when the car are cold because of the speed the horse came back, like missfire, then when o stop the car it warm up and start again the car sputter again and you can smell the gasoline, to much rich the a/f mix.

what could it be?

fuel pump OEM, after 265000 km
new upstream O2
NGK sparkplug wires have 2 years
Autolite platinum spark plug have 6 month, i check it today and they are black (rich that why i replace the O2)

best regards
best regards
i'm assuming bad ECT sensor
 

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Check your plug wires. I had a similar problem and it turned out I had accidentally put a small hole in one of the spark plug boots and it would only arc under load or high RPM's.
 

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Discussion Starter · #7 ·
Update

good morning and thanx to everyone

yesterday i check my spark plug (autolite platinum) and they are ok (0.054")
also check the wires with a autozone wire check, like a lamp one to ground another to the wire, and all the wires don´t have leaks in the whole lenght, also check the resistance and the biggest was 6,4 kohms (NGK power cables, silicone) the same resistance when i bought it.

but i found, well i can´t see but i know i have a leak in my exhaust system, because when you drive the car on traffic the car are hot, but when i take the highway i notice that the temp on the engine bay low like 20° (i put a extech termometer) and i can hear the sound of a exhaust leak, also i can smell the exhaust, outside and inside the car if i have a open windows. I think that the leak it´s between the flange and the cat (welding zone) but if i have a leak that causes issues in my a/f so i think my leak it´s in between manifold and block or what you think?

today i´m going to buy all the gasket, manifol vs block, manifold vs cat flange, flex tube vs the rest of the pipe.

i´ll keep you post it guys

can anybody explain to me why a exhaust leak can cause this kind of symptoms on my 97, because last year i found a leak after the CAT and the car don´t make that kind of problems, only sound.
 

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Discussion Starter · #8 ·
good morning everyone: today i changed the exhaust manifold gasket and run the car cold and the problem has gone, when i take out the manifold i found a couple of screw a little bit loose so i think that was the problem.

let me test the car and i´ll write you back ASAP

best regards
 

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Discussion Starter · #9 ·
well today at night i drive the car and it runs good but i still smell the exhaut inside the cabin if open the window.

dave94lx
my fuel filter have 6 month, and last year i take off the injector and send to calibration, also change the hole filters.

madmatt
as you know i checked the resistance and made a arc test to the whole system, but not in the boots, but if i have a problem with the spark, why th system don´t tell me that the ECU found a missfire, i have no codes, i remember that the ecu found missfire when i had problems with my TAYLOR´s spark plug wires, the reason that i change it to NGK.

juggalo
my ECT have one month, it´s from autozone, i change it because the HS Fan start at too much temp, also i replace my thermostat in that time.

fordman
i clean my MAF and test it with a scaner and the readings are ok vs the reference manual. no vacuum leaks, the idle of the car it´s fine.

my problem is not solve, because now i can keep a constant velocity but when if i keep the speed on 3 gear i can feel a little bit the problem, less than after change my manifold gasket, but i think i have another exhaust leak. also the reaction of the car when i take out the gas pedal after acceleration reduce but still bother, the car feels like when step the brakes.

also i put a pressure gauge in the common fuel rail, and when i put the key ON (not motor) the pressure rise at 40 PSI, then it shut off and the pressure start to decrease. remember the fuel pump are the OEM (264000 km)

best regards
 

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Discussion Starter · #10 ·
Update

good night everyone: today i make a test, i use a dielectric tape (8000 volts) and cover all the 4 spark plug wires, i run the car and runs better, a little bit of hesitation at middle RPM on 3rd gear and 4 gear, so tomorrow i´m going to buy a new spark plug wires for test.

if my spark plug wires have the normal ohms can produce this kind of problems?

best regards
 

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Discussion Starter · #11 ·
well, yesterday i put a brand new spark plug wires and NGK TR55-1IX iridium spark plug.

the car runs good, today in the morning at the high way i pass near a wall and step the gas pedal and i can hear a leak in the exhaust system, and the car start to sputter, so i think i have a exhaust leak after manifold, because my manifold gasket are new and the screws are very tight.

i thin next week i´m going to send the car to fix this leaks that only occurs at high rpm when i force the car.

can any body tell or explain to me what happend with gases in the exhaust system when i step off the gas pedal.

best regards
 

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Discussion Starter · #12 ·
well i check my OEM Motorcraft coil pack and i have problems in the sec resistance

primary have: 5 ohms on both circuit
secundary have: 14,8k ohms and 14.9k ohms when it´was cold, it´s rise when temp rise

the manual say that if you have more than 5 ohms in the primary change the coil pack, or if you have more than 14,5k ohms in the secundary change the coilpack, so i change it and run the car, right know i don´t have a sputter engine, so i think the problem have solve.

my last accel coil pack have 22k in one secundary circuit so that give me a reason to chen my 264000 km oem coil pack

best regards to every one
 

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Discussion Starter · #15 ·
well today i went to the muffler workshop and the guy check the whole system, no leaks found when he close the exhaust, but we drive and when i step the gas to rise the rpm then the noise start and yu can smell the exhaust inside the cabin.

we take out the cat, from manifold flange to union before the flexpipe. He welded all the union of this part and put again all and drive the car and no noise and no sputter when you take out the gas or at constant speed.

right know the car runs good so i will keep you post it about it

best regards
 
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