SR rough idle and bogs lower RPMs

[kota2240]

I have bought a brand new MAF, 255lph, and 300zx fuel fiilter,brand new NGK spark plugs gappedd at .028 I set the timing at 15deg the second mark from last notch, the motor seems to be idleing funny which causes the marks to jump making it difficult to set. When the car is warm the idle changes from 1000- 500 changing everytime i rev it. I had the idle at 850 but the motor kept bogging. My vaccum reads 20 so i dont think i have any leaks. When i drive the car between 1500-3000rpms the motor sputters and bogs then when i hit past 3000rpms the revs are smooth and the car flys. so what should i do??????

[180fan]

clean your iacv, check your injectors to see if they're working, change your water temp sensor, do a compression test, check your ignitor/distributor, coilpacks/ignition wires, the wiring for the mafs (corrosion), fuel pressure regulator, for vac leaks, and some other stuff. you can read about my trouble on the online nissan mechanic section under "sr strange idle" or something like that.

[Hijacker]

also, check for boost leaks. I've seen some weird stuff happen cause of boost leaks.

[kota2240]

its happening when im not boosting

[180fan]

http://www.nissaninfiniticlub....69364

there's the link to the thread i've had up for about a month now while I wrestled with my own idling issue. It should be of good use for you since it'll address basically everything that could jack up your idle on the SR.

[rudee023]

1. Check all vacuum lines and silicone couplings for leaks.2. If you are running electric fans wire them through a relay. 3. Change coolant temp sensor with new KA24DE sensor.4. Set idle and timing via FSM procedure exactly. Marks should stay on 15 BTDC and not jump. If they jump around while you are setting them the car is not in timing mode.5. Set TPS voltage to .5 at closed throttle on the harness side of the connector (middle wire) usig a voltmeter. Key should be in 2nd psotion with engine off.

This all took me about 6 weeks to trouble shoot but I finally got it!!! Don't give up.

[NoStickers]

I used to bog down all the time but once I turned up the boost it stopped. Not sure if it helped any but it doesnt bog anymore.

[kota2240]

2 of my coil packs i found out were pretty much shot. one was not firing and the other one was barely sparking. , i really do need to set my timimng though...... i have people telling me second mark from the left second from the right.. use a sprk plug wire use the black wire on the coil pack.. what the hell

[rudee023]

People say to use the (-) wire on the number 1 coilpack or the loop at the rear of the coilpack harness near the firewall. I got the same reading from both but some people have mixed results. 15BTDC is the second mark from the right. Second mark from the left is TDC. It depends on if you are initially stabbing the CAS or simply adjusting the timing. Someone correct me if I am wrong.

[180fan]

yeah sounds bout right for the loop and timing marks. I personally don't use the coilpack wires since it's too much hassle with the 6 allen screws. I just clip to the loop and match the timing.

[pampadori]

also, you must have the idle set right before checking the timing.

then you turn the key to off, unplug tps, rewarm engine, check again and set to 15 to 17 btdc.

i use a techtom mdm100 or a apexi multichecker when i set the timing. i read what the display says and make the timing light agree with it. this way you know when you set it to 15, the ecu also "wants" it at 15. the trouble with using the techtom or a consult is that you have to wire up the diagnostic wires that lead to the dash harness. its a total of 4 or 5 extra wires. and only 1991 and up have the wires for you to tap into with. if you are 1989 or 90 you must cut the diag plug from a junk car and wire in the above 4 or 5 wires, plus a power and ground.

i had to wire in the diagnostic plug into the 1980 datsun 210 we put a sr20det into so that i could trouble shoot a lean condition it had. the techtom becomes a neccessity when you are dealing with a car that has no harness, but you need to use a oem ecu and engine loom.Shaun

[kota2240]

when the car warms up with the tps unpluged the idle still jumps making it hard to set the timimng

[180fan]

you're supposed to wait till it's warm with the tps unplugged and the idle adjusted once it's warm then check the timing. Also the acceptable range is + or - 2 degrees from 15 so you're good from 13 to 17 BTDC.

[rudee023]

Here is the run down of the FSM if you ain't got one. Warm the car to operating temp. Rev at 2k for two minutes. Rev past 3k three times. Let idle for one minute. Turn off engine. Disconnect TPS. Start engine. Rev past 3k three times. Adjust idle to 850. You are now in timing mode. Adjust timing using the CAS to 15 BTDC. Turn off engine. Reconnect TPS. Start engine. If it will not stay at 15BTDC for more than a couple of seconds while you are adjusting,(jumps around) you are not in timing mode. Repeat enitre procedure.

[kota2240]

adjust idle using the throttle body or iacv

[rudee023]

Iacv ccw=higher idle, cw=lower

[kota2240]

the ****ing idle is hard to set. the damn motor has a life of its own. no matter where the idle is set at the motor jumps. i have the tps set at .050.. I tried using the fsm procedure to set timing, I bought a brand new coolant temp sensor, maf, fuel filter, 255lph walbro pump, spark plugs gapped at .028.. motor runs like crap during timing setting. when i get the idle is around 850 the timing starts jumping all over the place. ahhhhhhh

[kota2240]

the closer it gets to 15 the worse it runs and i set it at tdc also.Is it my CAS or timing chain????????

[rudee023]

knock sensor?