91 sentra 1.6 liter possible cause of stumble on acceleration?

I just decided on a whim to test the ignition coil because it was something i hadn't thought of looking at before. the specs say the readings should be .9 ohms and 13k ohms. My readings which i took multiple times were 1.6 ohms and 13k ohms. so - any experts out there willing to say that this could be a potential culprit? according to the (Haynes) manual - replace the coil if it is out of spec. So with a higher resistance I am thinking weaker spark? poor performance? - especially when a lot of fuel is being added to the fire (@WOT) ? If this is the solution I will kick myself for not finding it sooner- i was wholly focused on a fuel delivery/vacuum leak theory and used my shade tree knowledge of ignition and spark that says if a coil works it works correctly all the time! Thanks to all posters who can help me out.

Reply to
robbie
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RE: Primary 0.9ohm. Are you completely sure your meter is accurate at such a low resistance? Milliohm meters cost.

make a milliohm adaptor

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Find a 1 or 2ohm, 1 or 0.1% resistor, or put 10 x 10ohms resistors in parrallel and calibrate it. Then test test lead quality by testing resistance direct to meter terminals and though leads. Then throw the leads away and get some very good ones.

Reply to
Peter Hill

Connect some long leads to a timing light. Give it to a passenger in the car and drive around at night.See if the timing light misses a flash when the engine misses a beat. Check the article at Pico about sticky injectors.

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Ihave a 1996 sunny behaving like yours but cant get to it at themoment. Could try disconnecting the o2 sensor and also reseting thecomputer by taking battery lead off for 5 minutes

Reply to
Roger Brodrick

Old 80's Nissan ECU's have a built in diagnostic mode - mode III gives

55 for clear. Mode III is very crude, it only detects 2 things. 1: Has it shorted out to ground or 12V? 2: Is the part connected? It won't detect out of spec parts / systems. Haul it out of it's hole so you can see it when driving, select mode V real time test. Mine will flash error codes for ignition, crank angle sensor and AFM. But I only have experience with direct coil on plug systems (and only have flash codes for CA18DET) and they may have reduced/changed the diagnostics for distributor models.

New ones like your Sunny from early 90's on (defo fitted to '94 S14 with SR20DET) are quite difficult without a consult interface and a laptop/PC. They give far more detailed diagnostics but there is always a procedure for testing without the Consult interface.

Either new or old the Nissan service manual has the best troubleshooting info you can get.

CA18DET - no EGR.

14 poor driveability - stumble (while accelerating) 1: ignition 2: coil 3: air leak 4: idle switch not set correctly and/or throttle unable to close fully so it doesn't close switch at idle. An open throttle due to carbon or miss setting of factory set stop screw at idle is an air leak, the throttle plate should be completely shut. Idle is set by base idle screw and ECU control of ACC. 5: faulty fuel pressure. Pump or FPR. If you have pressure, pump is OK. If you can suck a vacuum on the FPR hose that will hold the tip of your tongue it's OK. 6: Idle mixture - mode I or II ECU test if you have a lambda sensor. Make the leds flash 9 times in 10 secs at 2000rpm. No lambda then you need a CO meter or you twiddle the screw on the AFM to get max engine speed (don't, just don't, not ever, they never ever need setting it's always something else like an air leak). 7: Mode III and V tests. 8: Unplug lambda, drive. If improved change it. Else check idle mixture (but really go back and look for air leaks).

have I said AIR LEAK?

Just for good measure AIR LEAK.

Reply to
Peter Hill

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