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1989nissanB12 »
https://forums.nicoclub.com/1989nissanb12-u280920.html
Sun Mar 04, 2018 9:43 am
Updated Description of Issue: 1989 Sentra idles rough, idles and then dies, loses power (that is, goes into limp mode) at stoplights, loses power driving at low speeds, loses power driving at higher speeds (40mph). The farthest I've been able to drive before losing ability to accelerate is approx. 4 miles. Although the car frequently dies during idle, I don't ever recall it dying while driving. Instead, the engine is still running but without ability to accelerate. There is no check engine light. The one constant: the car always starts. That is, it always turns over.
Mechanic Recap and Inability to Scan: 1st master mechanic gave up after replacing spark plugs, distributor cap and rotor, fuel pump and fuel injector. 2nd master mechanic gave up after testing alternator, getting 47 psi on fuel pressure gauge, and replacing fuel filter. His last guess was engine cylinder head failure due to white exhaust smoke. Yesterday, 3rd mechanic came out to give it a try. 3rd mechanic arrived convinced it was a clogged catalytic converter. I informed him new flex pipe, cat, and tailpipe already installed at a professional exhaust shop due to rusty pipe separation and rust hole leaks. His highest priority was to hook up his OBD1 scanner to my car. He has a connector which he labeled "1990 Sentra". It did not fit my 1989 Sentra. Without the use of his scanner, we spent the next 6 hours testing the car. Assuming he labeled the connector correctly, does anyone know if the 1990 Sentra has the same scanner plug in/receptacle under the dash as the 1989 Sentra?
Testing: Mitchell resource gave 140-180 compression range as acceptable. With the car running, but cold, we got 160-185 compression range on the cylinders so my mechanic concluded the engine is good. He tested the battery and his multimeter went right to green=good. He ohmed the 20 yr old spark plug wires: 9k, 8k, 9k, and 6k. He said don't sweat the 6k b.c. that is the shortest wire. He pulled the new spark plugs, tested them and measured the gaps. We did not test the (brand new) distributor cap and rotor. He tested the coil wire and got 6000 which he said was "good enough". He tested the grounds. During EGR testing, the car "stumbled" which according to Mitchell indicates proper EGR functioning. We ran the ECM again in self diagnosis mode=mode 3. Still spits out code 55=no faults detected. Oil he said was okay, just overdue to be changed (4,400 miles on it, not 5k as I had thought). I spent most of my time feathering the gas pedal trying to keep the car running so actually more testing was done that I did not see. Also replaced 10 feet of small diameter hoses-my receipt reads 9/32" but quickly ran out of hose before complete. Does anyone know the proper diameters and approximate lengths of the different hoses to purchase?
My current (3rd mechanic) is very experienced but not with the Nissan brand. One of the biggest challenges was identification/location and proper testing procedure for the different components. Can anyone link me to such a resource?