Everything was perfect this morning, car started and ran without any problems. Park at work come back out 9 hours later. Start the car, it idles really bad. Like 5 cylinders.
I give it gas, no reaction for 3-4 seconds then sort of catches and surges and inmediately lets go (some sort of popping sounds coming from engine compartment). It did it several times before it idled normally. Drove home 15 miles without problems (65 mph steady). I get to the first light, no problem. When starting to give gas same thing again, no response when given gas, then all of a sudden (popping sounds) surges and runs without problems. I get home and park it idles like crap again, in neutral, park, reverse, drive.
I give it gas it does not responds, it hesitates, shakes, pops and it revs up again normally and idles ok.
I go for a drive, in the beginning it hesitates,pops, almost dies, revs up tires screech and runs and idles like a champ.
Come back home idles OK, shut-off, start again and no problems.
Go out 2 hours later no problem.
What will tomorrow bring?
Done Very recently:
Oil-filter change every 2500 miles
Done recently (within 6 months or 10K miles):
New OVP, New coil, sparks, distributor, rotor, air filter. Recently went from NY to Fl back to NY and now NC, ran fuel injector cleaner-techron.
Done not too recent:
Wires, fuel filter
This car is a 1986, codes are not retrievable. I believe On/Off testing on terminal 3 of X11 connector is only possible. If I am wrong please correct me and give me the info on how to retrieve the codes.
It worked very well today, with one exception. When back from work (engine at normal operating temperature 87C), the car did not go back to normal idle (approx. 650-700 RPM in park or neutral). It sort of oscillated between 500-900 RPM for about 15 seconds before settling at normal. It did it several times, in intervals of about 3 minutes.
What should I look for?
On a car this old you may have a vacuum leak. Either a hose has died, the connectors for the hoses, or a breather tube. Soapy water, in a spray bottle, look for bubbles. Start at the cold start valve check for leaks before you start pulling things its easier. Tell us how this ends up.
I bought a DMM with duty cycle reading. It reads a duty cycle that oscillates between 29-35%. I have read that it means I am running rich, in another website states that I am running lean. What gives?
By the way, when engine off and ignition on I read a duty cycle of 30%, what does that mean? (I know 50% is no faults)
1986 300E
Chris, how can leaky vacuum lines give bubbles when soapy water is thrown on it? The bubbles would be on the inside.
A good way to check for vacuum leaks is to spray carb cleaner or starting fluid at suspect areas with the engine idling. When you spray in a certain spot and the idle goes up, you've found your vacuum leak.
Another way is with a propane tester - make one out of an old propane torch - take the head off the tube and use a long piece of vacuum hose that fits tight. Propane is safer to use than spray flammables, but can still "flash", so be careful, especially since you mention popping sounds.
I'm curious about "popping" under the hood. Is this backfire or something less conspicuous?
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No, it is not backfiring, it is hard to explain.
Like something opening and closing. Thum...
No, it is not backfiring, it is hard to explain.
Like something opening and closing. Thumping, bopping.
I have noticed it does it if I park on an incline, with the engine at the lower level. I depress the accelerator down and it does not respond. It keeps rolling, then it sort of surges, hesitates, shakes, thumps-pops-bops and surges normally.
That link appears to be the same problem.
Did you solve it?
If you did, how?
Some p...
That link appears to be the same problem.
Did you solve it?
If you did, how?
Some people call the Mass Air Sensor, the whole unit under the air filter.
Others say the potentiometer is attached to it somewhere. Does you know?
Linear Mode
