200sx Stuttering problem

[240sxjeff]

Hey whats up guys, My little brother just bought a 1996 Ser about 3 months ago and it has this stuttering problem around 3k. The check engine light was on and it was the EGR sytem, knock sensor, and a 3rd cylinder misfire. So I replaced all those parts about a week ago and cleared the check engine light, it hasnt come back on yet. I also bought all new NGK wires and plugs, fuel filter, dis. cap and rotor. But after all this it still stutters @3k and gets poor gas mileage(210-220 miles per tank). Does anyone know what could possibly be wrong?

[RED_DET]

Try regrounding the MAF, its simple and its free. If that doesn't work, O2 sensor. When they go out, they cause bad gas mileage and piss poor performance. But a bad maf ground will cause the same symptons. Might want to check the TPS voltages while you are checking the MAF.

[240sxjeff]

How exactly should I reground the MAF?I'm going over to my paretns house tomorrow so I should be able to check out the MAF.Also I had turned the car on last night and was letting it idle, then unplugged the IAC/AAC valve and the car stalled, is it supposed to do that?

[RED_DET]

First, you need a volt meter to check the current maf voltages. Then you can continue.

http://www.se-r.net/engine/maf_ground.html

Yes if you unplug your IAC valve, the car should stumble and possible die out. If it doesn't thing something would be wrong.

[240sxjeff]

Ok I just bought a multimeter about three days ago, so I will be able to check that. I'm waiting for him to get out of school right now so I can check but I'll post here again once I finish.

BTW, I LOVE your B13 classic. I've been looking for one as a daily driver for about 4 months (on and off). My best friend used to have a red one that looked just like yours except it had different wheels until he crashed it and the INS. company wrote it off

[240sxjeff]

I just finished checking the MAF and TPS they both seem to be working fine.Wouldnt the o2 sensor throw a code if it is malfunctioning?

[RED_DET]

Maybe, maybe not. Poor gas mileage is also a result of a bad o2. Change it out and see what happens. One last free option would be to check the timing. Should be at 15*BTDC.

[240sxjeff]

Iv'e been wanting to check the timing since he got the car but I don't know how to use the timing gun. A shop shouldn't charge too much to adjust timing right?

[240sxjeff]

would you think that one of the injectors could be faulty?

[RED_DET]

Timing light is very simple to use. Hook up red to positive terminal on battery, black to negative. The other piece is hooked onto the number 1 spark plug wire.# Warm up engine to regular operating temp, and ensure idle speed stays below 1000 rpm.# Race engine 2 or 3 times under no-load to 3k rpms, then run engine at idle speed. [this heats up the oxygen sensor so it is working]# Turn off engine and disconnect throttle position sensor (TPS) harness connector. [It's on the side of the throttle body facing the firewall - driver side of the engine, down low and past the brake master-cylinder]# Start engine. Race engine (3x to 3000 rpm) under no-load, then run at idle speed. [You may have trouble keeping it running with the throttle sensor disconnected. Depending on where your timing is set, it may stall. If so have someone sit in the car and press the gas *very slightly* to keep it running. Don't rev it up or you will not get an accurate timing reading/adjustment. Keep it at idle speed, about 800 rpm]# Check ignition timing with a timing light. It should be 15 degrees plus or minus 2 degrees Before Top Dead Center. [The timing mark at the extreme left (counter-clockwise) is zero degrees there are lines at 5, 10, 15 and 20 degrees to the right of it. There is a wide paint mark from 13 to 15 degrees, which the factory probably set yours to. Eyeball 17 degrees between the marks and that's what you want.]

OLD marks at 0,5,10,15,20 B.T.D.CNEW marks at -5,0,5,10,13,white paint,15,20 B.T.D.C (USE THESE MARKS FOR 91 or newer)

-5 0 5 10 1315 20

# If not, slightly loosen two bolts holding the distributor, and twist it [toward the the cabin to advance, toward front of engine to retard] to obtain the desired timing. [Recheck the setting after tightening the bolts!].# Shut off engine and reconnect throttle sensor.

you need to rev the motor past 3000 rpm 3 times for the motor to lock the timing (after disconnecting the TPS)

Got any problems just let me know.

[240sxjeff]

OK I'll see if I can pick up a timing gun this week so when I go down there on the weekend I'll try it out. Is there any specific timing gun I should buy?And what do I point the gun, at the big pulley on the left side?

[RED_DET]

I think I bought my timing light for 40 dollars @ autozone. If you look at the crank pulley, right at the top of it dead center you will see a niddle sticking out. When you point the timing gun at the top of the pulley, you will see the timing marks on the pulley and the needle will identify the timing mark to which the timing is actually set at.

[240sxjeff]

Oh, OK. I've seen the little needle you are referring to

[240sxjeff]

Well my dad took it to the mechanic for a diagnostics or something like that and he said everything was fine except that one of the plugs were messed up and the spark plug o-rings that go on the valve cover needed to be replaced. So he changed it and it still has a slight stuttering problem.

But I did have one more question: he has a k&n filter with the little adapter thing. The sensor that plugged into the airbox is just hanging there. Is it supposed to go somewhere specific?Because I was thinking of drilling a small hole in the intake tube and siliconing the sensor in there

[RED_DET]

That sensor is the air intake sensor. You should be able to just support it somewhere out of the way. But I also had the same problems you are speaking of when I tried to put a pop filter on my g20. Car ran worse. But stock airbox back on and car ran fine. So who knows.

[240sxjeff]

hmmm sounds interesting. So I guess I should pull the pop charger off and run it for a few days without it. Its odd because the car does not do it all the time, it just does it sometimes.

[Cheezit]

EGR valve, tube and passage may be clogged. I have a SR20DE. Cleaning the carbon out of the egr valve and the passage from the egr tube has seemed to help. Use carb cleaner to remove the carbon deposits, just don't let it touch the rubber diaphragm in the EGR valve when you do. I used a little screw driver and carb cleaner for the valve and a piece of bicycle brake cable for the EGR tube gasket area.