ryanmax

i bought my 91 max se from a mechanic and he said he checked over every thing on the car except he didn't replace the cap and rotor so he said I should do that soon. I've only had the car a few days and I noticed a considerable lack of low end power, the engine feels like it's not getting enough air or it's getting too much fuel. the air filter is practically new and there's no stumbling or missing during acceleration, it just feels like it's being smothered a little until it gets higher in the rpms. my question is can a worn dist. cap and rotor really cause a considerable loss in low end torque like the manual says in the troubleshooting section? and is the excessive fuel consumption (I'm almost down to half a tank and only have 100 miles clocked on the trip odometer - that definitely isn't right, is it?) thanks in advance.

Matt93SE

iTrader: (44)

those can be some of the symptoms, yes. also check ignition timing. If it's too late, it will cause a huge amount of power loss. shoudl be around 15 BTDC from the factory, but you can advance to about 17-18 and get soem power gains if you use premium fuel. right now, I'd concentrate on just getting it running right first.

also check your O2 sensor for proper operation... turn your ignition on, turn the ECU screw colockwise and back, watch for your check engine light to blink... if it does 5 short and 5 long, you're okay.. that's "ECU normal".. if it does anything else, then you have a stored ECU code somewhere. let us know what it is.
if you get a code 55, then leave the ECU in diagnostic mode and start the car. let it warm up a couple minutes, then rev the engine a fwe times.. watch and see if the check engine light flashes or stays on/off solid. this is "Diagnostic mode II" according to the service manual, and the check engine light comes on/goes off based on the oxygen sensor reading rich/lean. If the sensor is operating correctly, then the light will flash somewhat randomly as you play with the throttle. usually it will run rich as you're on the gas and run lean when you're off the gas. normal stuff.. but while you're idling, it'll flash on/off about half a second at a time or so..

95turbo gxe

iTrader: (25)

Torque ... What is that?

ryanmax

what about the excessive fuel consumption? could a worn dist. cap and rotor cause me to only get 100 miles out of a half tank of gas? And I drive like a grandma, i drive like 45 mph everywhere

95turbo gxe

iTrader: (25)

Yeah if it is worn fuel milage will suck. Hey if it is worn replace them. You can get both for like $30

ryanmax

alright i will replace them tomorrow night and then test drive it and see

Matt93SE

iTrader: (44)

if it's running poorly, then yes.. you'll have poor fuel mileage. fuel economy only gets better as the engine runs better. see where I'm going with that?

Wiking

If u tst and wanna save that $, clean & spray a layer of lacquer (not on contacts). The cap crakcs and should be replaced 'every 5yrs.'

The so called 'wires': http://www.cardomain.com/memberpage/748507/12

Zillion other reasons: http://www.cardomain.com/memberpage/748507/14

ryanmax

i replaced the cap and rotor which helped, but i think it's still using too much fuel. i will check some of the other things like the 0 2 sensor and maybe the ignition coil, thanks for the great advice, lots of stuff for me to check now.

Eric95se

Matt93- You spoke of advancing timing or spark for premium fuel. I am very interested in this. Any advice. Also I would like to buy your grounding kit if possible! Thanks.

Wiking

15 degrees seems to be the global nissan setting for any kind of fuel, starting from ? 89 octane. The ign advance is normally adjusted for different octane fuel: the higher octane, the further advance. 20 degrees might be ok using 95 or over. In most cases adv means more pwr.

Nissan VGE FSM says 15 degrees +or-2, without any octane note.

Danger: too much advance breaks engines. Thats why theres the Knock Sensor, used to retard ign (by ECU) in case of pre-ignition (or too advanced ing) ping.

Working Knock Sensor + too advanced timing + low octane --->ping. This results in ECU retarded ignition, loss of fuel&pwr... so not really wise.

I had a bad KS which meant that ECU retarded ignition. This cannot be seen at idle, with adj. lamp, it affects only higher rpm's.
Now bypassed the bad KS with .5MOhm resistor and got real boost in mileage; 95 is the lowest octane level here. Ign stands now at 17degr.
see: http://www.cardomain.com/memberpage/748507/9

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