91 Nissan Sentra 1.6 4speed manual question about timing-

haynes manual for GA16DE engine (includes '91) states ignition timing should be 10 degrees BTDC (US) for manual transmission with idle set at 650 rpm.

it is normal for spark tim> I purchased a Consult unit and am running ConZult free software on my

Well at least one user thinks that this is the case and there's not much play in my timing chain. It seems to have decent power when the speed and rpms are up but its the acceleration during daily stop and go driving where the stumbling occurs. it really feels fuel starved, but that end has been checked. I am wondering if the coil could be weak since i don't have an accurate multimeter to test it's ohms reading while hot versus cold... i have never really been stuck on reapiring these minor problems before but this stumbling has me STUMPED. Anyone care to chime in again? I really have tested for a lot of different issues and have ruled out things like: temp sensor/o2 sensor/EGR valve/vacuum leaks/etc but have made no progress. I have 2 different distributors that also have been checked out and unless they both have bad sensor/control units in them then that item is ruled out as well.

MAF sensor? Symptoms sound right. I'm not sure of position of and type of MAF sensor in a '91, but by mid '90s (GA15/16 "DE") they are a "hot wire" type mounted just above the throttle body, and they frequently fail. OEM replacement is not cheap, but you might find someone offering reconditioned units at about 1/2 OEM price.

is your scanning tool sophisticated enough to tell you the condition of your spark plugs and plug wires during sudden acceleration?

if not, have you tried NEW spark plugs? theory is that increased combustion chamber pressures during sudden opening of the butterfly, can cause marginal plugs to misfire.

have the plug wires ever been replaced > >

new plugs and wires have been done with no improvement. i am suspicious of the coil but there's no good way to test it. i have wondered about the maf sensor but it is supposed to set of the CEL- which never went off and used to occasionally flash when it was running poorly but the codes always checked 55 (all clear) robbie wilson

Not sure if a fouled / malfunctioning MAF sensor would always set a CEL. If there's no reading from it at all, then probably yes, but if the voltage is fluctuating and incorrect as described in the link below, perhaps not. link:

if the wires on the 91 MAF sensor are totally sealed, you may find it acceptable to insert a (straight) pin into each wire near the connector, to allow access for voltage measurement. if the wires are NOT totally sealed, you may find it acceptable to "back probe" the connector pins with (straight) pins for voltage measurement. respondent "Me" is correct about faulty MAF sensors, the MAF allows the ECM to calculate the injector pulse width. if you ever have the need to see if the ECM is sending a pulse to each injector, you can insert a "noid" light into the specific injector circuit (i once used an analog voltmeter to see the pulse, when diagnosing an engine that would not start).

does your 91 have the TPS (throttle position sensor)? if it does, you can check he TPS using the (straight) pin method, however, i would be surprised if this is your problem.

can you give more details about the "stumbling" problem? does it occur when you suddenly open the butterfly when NOT driving? or does it occur only when you are accelerating (under load) while going through the gears?

this thread assumes you have checked for constant fuel pressure to the injectors (and that the fuel pump is NOT an issue).

would be interested in more details about your Consult device.

The car finally died and the coil completely died- after replacement the car is 100% again. So if someone says "the coil either works or it doesn't" DONT BELIEVE IT

About the Consult: The Consult device for my car I got from an ebay buyer- it has the ConZult free version of software shipped with it. It is a serial device so I had to get a USB to serial adapter to use a laptop in the car. I am currently trying to get some other more extensive software to work with it, but so far haven't found a complete package that will recognize this particular consult device. Link to ebay item I purchased: