surreybc

re; 1993 240sx

If I set the timing at 20 btds the car would stall.

Its always been like this for past 4 years. Is my distributor just old ?

4x4le

Ive seen this more than once and it was always a different issue causing the issue. These were all diagnosed with a consult cable and nissan data scan and i would suggest you getting that setup so you can properly diagnose it.

There is something causing the ecu to retard the timing, and since it only retards it to a certain extent if your advancing it back up it will run almost like normal.

The leading cause is detenation or at least knock being sensed by the knock sensor. Acutal knock does not have to be present. The knock sensor can be faulty or the wiring or the tq specs on the sensor.

Another cause can be water temp. You may be running a little too hot. One car I seen liked to run at 210* once it warmed up and the ecu does pull timing at that temp. With the engine being that warm it can cause some light knock too thus causing the timing to be pulled as well. His thermostat was either faulty or just too old.
If your cts is bad it can also make the ecu think its too hot and pull some timing as well as run too rich.
Your tps could also be setup wrong or be faulty. One car I looked at had a properly setup tps. Every time we checked his closed throttle voltage it was correct as well as his open throttly voltage, and the voltage climbed very liniear on the way up, BUT when the car would start to hesitate was during driving and through nissan datascan we could see that the voltage was jumping around on the tps. The wring was at fault there.

I hope that could help you some.

surreybc

Thanks. I will try to get that consult working. I have to confirm that my timing light is accurate too.

jspeedm

i think you're backwards. if the computer was retarding timing, he would have to set base at 38 degrees. i think your cam timing is just off. take off your valve cover and check your timing marks on your chain and cam sprockets.

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smelly240

sounds like another slipped crank pulley.. happens very often.

the crank pulley gets old, outer part slipsand shows timing marks at incorrect spots.

seen it happen probably 5 times now in hte last 6 months. Stick a screwdriver or long ass extension in the cyl #1 spark plug hole and rotate until it pushes the screwdriver as far up as it'll go.

then look at crank pulley... i bet its not showing tdc.

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jspeedm

nice^^^^^^ i didn't even think of that.

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smelly240

i see it quite often... 2 gtir engines i tuned had the problem in november and from there it seems to show up once every few weeks. new pulleys arent cheap either... i'll probably sell my pulley (its prefect) and get a ati damper soon... its dumb to have a nice built engine and then have a stock damper.

__________________

HREs on a S13 - check, 6262 - check, Girlfriend.... - nope

jspeedm

good to know. makes me want to go check mine.

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4x4le

Your right. I was thinking of his situation wrong. I have however had sensor problems require both more and less base timing in order to get the car to run right. I am thinking that yall are on the right page with with the crank pully possibly.

smelly240

Anymore the way i set base timing is pull valve cover, set to tdc with extended dial indicator, and check "just to see if its off on the pulley" - then set timing with the dots on the cas.

ive never had a cas/timing be off lining the dots up.

__________________

HREs on a S13 - check, 6262 - check, Girlfriend.... - nope

surreybc

Interesting. I ordered at consult cable so hopefully the software will till me the correct timing. Thank you.

smelly240

a consult cable will not tell you anything about your base timing... its a mechanical setting that syncs the engine with the ecu.

if your car needs to be set at -5deg timing theres A MECHANICAL PROBLEM.

if you havent got it into timing mode - you're wasting your time.

__________________

HREs on a S13 - check, 6262 - check, Girlfriend.... - nope

4x4le

The way I always set the base timing is with the tps unplugged and nissan datascan running. I take a timing light and shine the crank pully and make that number = the timing figure datascan is putting out.

Now if you have mechanical timing off I guess your crank pully could be reading wrong, but I know all of the engines we build are setup correctly in that since.

What nissan datascan is going to help the op with mostly is he will be able to see if the timing is advancing or retarding for any other stupid reason.

surreybc

Ok, thanks. If I look at consult during idle with tps disconnected, will it assume that the timing is at base ie 20 btdc?

When I was removing my timing chain guides, I aligned the timing pin at top dead center on crankshaft pulley but the cam lobes were not looking exactly horizontal. This happened few months ago. Should have put screwdriver in piston.

smelly240

watching timing with consult is not the proper way to set timing... its not in timing mode (tps unplugged, engine at op temp, and rev 3 times - then the engine will go into a timing dance (it'll rev up a little) That is the proper way to set it with a timing light. Since this method makes the timing static - he wont have to worry about advance or retard... because it won't.

lining up the dots has never failed me - and if the crank pulley happens to be off... it'll allow him to properly set it anyway.

__________________

HREs on a S13 - check, 6262 - check, Girlfriend.... - nope

4x4le

he will be able to hit a button in consult too though to set him in timing mode, although he will still need to have the engine warmed up.

carcrossy

I never take valve cover off to check tdc. I just take sparkplug out and stick a metal rod in the hole to check if piston is at it's highest point.

steve shadows

There is a lot of crap in this thread...

Sounds like your Distributor could be screwed and the possibility of slippage mechanically it's possible but what you are picking up on your timing light is the signal going through your spark plug wire.

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4x4le

Which is exactly why I match the consult readout to the actual readout on the pully. The ecu needs to think the timing is set exactly how it is actually set. Set it right at idle and it will be set right through out the rest of the rev band (provided there is nothing actually faulty within the dist. like steve mentions)

surreybc

I wonder how the computer decides what the timing is. Does it measure it using the crank angle sensor and makes a correction if there is a difference between base timing and what computer measures ?

surreybc

I'll find the true tdc tomorrow using welding rod in sparkplug hole. a bit tricky to do in dark. seems to be 5 degrees in advance of normal dead center which would only confuse things more.

surreybc

I just realized Im reading the marks from wrong end. I dropped the timing to spec and Im right on the 20 btdc.

The welding rod in sparkplug hole was highest at top dead center.

I guess it is official that Im retarded.

4x4le

I lol'd

But youll still enjoy your consult and datascan.