<DOHC S13> How to Adjust the Ignition Timing
What is the procedure for adjusting timing on my 1991 DOHC S-13? Are there any vacuum hoses to be plugged or disconnected? Do I have to disconnect or reset the ECU? I have been reading a lot of talk about some decent gains from advancing it. On my old car I ran my timing advanced and it worked well. Also, my owners manual says to set spark plug gap to .39-.44. I am running NGK's and I believe they are set to .39. What is the best gap setting for better performance. I run 91-93 octane gas.
If you have an FSM, the procedure is spelled out fully in there. If you don't have an FSM, here's how to do it:
Fully warm up the engine. Shut engine off. Disconnect the TPS harness connector. It's located on the passenger's side of the engine just above the throttle assembly. Attach
timing light. Start engine and set timing to 20 degrees BTDC. Check the idle speed. It should read 650 RPM; If not, adjust the idle screw until you get 650 RPM. The idle screw is located on the passenger's side of the engine near the firewall below the intake manifold. Stop the engine. Reconnect the TPS harness connector. Start engine. The idle speed should now be 700 RPM.
That's all there's to it.
You can experiment with various timing settings and spark plug gap settings. It's good first to make several stop-watch 0 - 60 runs with the OEM setting first to establish a baseline performance level and go from there.
What will happen if I change my timing?
Lets say your timing is set too far in advance. Say maybe 5 degrees ahead. Will the
computer sense this advance and retard the ignition by itself or will it have to hear
knock first? Also, what setting is "too much" for the 240 even if you are
running 92-94 octane? Performance chips basically alter timing aside from remapping the
fuel flow, right? So how much do they actually alter it? 2-3 degrees?
Kris -- 1990 240SX
There are two types of knock sensors. 1st) is a calibrated knock sensor that advances the timing till it senses a knock, and then backs of the timing a little bit. This is an active sensor that is always optimizing timing. (Better fuel, better performance) 2nd) is
an emergency knock sensor (the kind we have) it when it senses a severe knock, it backs the timing way out.
I've found that I can only advance the timing 2-3 degrees before it has a detrimental effect on power. So if your car doesn't knock, higer octane will do nothing for you, actually it can hurt you if all the fuel is not igniting (higher octane=harder to ignite "detonate").
The timing we are talking about here is only static timing. The remapped computers changes total timing according to load, throttle position, engine temp, etc.. and those points make more differnce than static timing. BTW the ecu upgrade also gets rid of the tip in retard.
Just a note
I recently had the timing chain replaced on my 89. It was making the rattle sound at start up and under acceleration occasionally. Anyway, the guides were disengrated and there was a rather large gash in the cover (caused by the loose chain). This gash was millimeters from cutting all the way through into the coolant duct. I advise anyone that has the chain rattle during acceleration to have it fixed asap, unless you like mixing your oil and coolant.
Can I replace my own timing chain (or, better yet, why would I want to)?
I was sitting at a light in my 1990 SX and the unthinkable happened (well, I guess it is thinkable now). The timing chain skipped two teeth b/c the tensioner was full of crud and wasn't extending properly. I figured "Hey, I got me an engineering degree and a Chilton's. Ain't no reason I can't tackle this myself." Parts run you about $130 if you don't break anything (I did) and the job will take an experienced guy a full weekend (it took me about three months of weekends, multiple cases of beer, and a pissed off old lady b/c I drove her car to work everyday and left her home with the kids).
First, a few simple hints. 1. Pull the front tires off to improve access. It helped a bundle. 2. Be very careful pulling the drive pully off. I broke one of the flanges off of mine and had to call about fifty junkyards to find a new one (ran me $25). Finally, the oil pan does not take a seal, only RTV. The book did not make this clear and five different parts stores (including the Nissan dealership) said "We don't carry it" instead of "You don't need it".
Pull out the fan shroud to get yourself some working space and have at it. The pumps and whatnot come off the face pretty easily. Valve cover was a pain with all the connections, so I just flipped it to one side. Someone else said have an assisant put the car in gear and stand on the brake to get the dive pully off, good idea. I just jambed my 10" extension in the holes of the cam sproket and pulled against that. Here's the pain in the ass. The book says pull the oil pan all the way off. I had to jack up the engine in the mounts and hit it with a hammer to get it out. It is positioned under the front end cross bracing and the steering crap. Getting it back on was even worse since I had to attach the suction tube bline with one hand through a 1/2" gap. I even dropped my wrench in the pan once. My advice, I'm pretty sure you can just drop the pan to get the front cover free and never really take it off. Would have saved me about a month.
Changing the chain was no big deal. Put the front cover, et. al. back on. Big key here, tighten the drive pully bolt with all 140lb or so the book recommends. I didn't (just kinda guessed at it) and, what do you know, the bastard stripped out the keyway on me and broke free. Lucky I didn't hurt the crankshaft too bad (I really don't want to pull that oil pan off again).
All in all, the job isn't real complicated (looking back on it, it's easier to say
that). Just learn from my mistakes and you should be able to make it in a long weekend at
Email: [email protected]
<SOHC> Timing Chain Parts List
I picked up all the parts yesterday, for my SOHC chain replacement consisting of:
1- Crankshaft Sprocket 13021-53J00 $9.41
1- Front Cover O-Ring Seal (Front) 15066-40F01 $3.71
1- Front Cover O-Ring Seal (Rear) 15066-40F11 $2.00
1- Crankshaft Front Seal 13510-53J10 $4.82
1- Camshaft Sprocket 13024-40F00 $37.82
1- Timing Chain 13028-8B000 $36.72
1- Timing Chain Tensioner 13070-40F06 $17.26
1- Timing Chain Guide 13091-40F15 $8.72
1- Timing Chain Guide 13085-40F10 $8.55
2- Timing Chain Guide Bolt 13075-40F10 $1.46
Those are wholesale prices, I suggest for those of you with SOHC's to save this message, as many dealers will drop their prices and "deal" with you, possibly meeting this price.. or just order them from ABC or Courtesy Nissan, as they are all excellent w/ pricing and service. Anyway, the part numbers ALONE are useful.