My car is possessed timing keeps changing

[datsunan]

OK so I finished the build I set the timing and locked it down checked it again 20deg. A month goes by and now I'm working up the boost, but the car runs like crap above 3500. So I read post after post and try everything no good. So I check my timing and its at 10deg I adjust it to 20 blast around a bit I'm stoaked So I call up my good friend and take him for a ride miniutes later and its running like crap again Check the timing and now its at 30deg, adjust it back to 20 and go for another ride, come home, check it its 24, take it for ride, blow off IC pipe and call it a night. Next day go for ride, runs crapy, check 24, adjust, so on and so on. Now i'm What the hell? I always tighten and check timing after tightening and the car is always at temp CHTS has no effect nor does the TPS Any ideas.

[datsunan]

You guys are stumped too huh.

[Guest Aaron]

Is there play in the distributor shaft? I would mark the distributor housing/engine to see if it is moving or if somthing else if affecting the timing.

[Bernardd]

Make sure the car is fully warmed up. Make sure that the tps is closed when checking base timing by inserting a jumper across the tps terminals. With the jumper installed reving the car should cause it to rev to about 2k then die out and rev up to 2k , die out etc etc. Then check your timing. BTW what does JWT recommend you to set the timing at? What do mean that the CHTS and TPS has no effect?

Bernard

[Dan Baldwin]

Check the springs for the mechanical advance weights. I bet you're missing one or both of them.

[Guest bastaad525]

Make sure the car is fully warmed up. Make sure that the tps is closed when checking base timing by inserting a jumper across the tps terminals. With the jumper installed reving the car should cause it to rev to about 2k then die out and rev up to 2k ' date=' die out etc etc. Then check your timing. BTW what does JWT recommend you to set the timing at? What do mean that the CHTS and TPS has no effect?

Bernard[/quote']

 

 

that's really funny my car does NOT do that. With a jumper installed the car runs REALLY well... a little TOO well... problem is the timing will either advance too much or it will not supply enough fuel, because at WOT at about 4000rpm under load it will start to ping if I leave the jumper in there. I'm assuming it's advancing timing too much because oddly the car feels like it's running MUCH stronger if I leave the jumper in there. I can rev the motor all day long in neutral though with the jumper installed.

 

 

TPS definately has an effect on timing.

[datsunan]

Thanks guys I'll check that out. Bernard you might be onto something with the tps because at a slow cruz at about 2000 +- 100 the revs drop out then come back on and off. It's really annouying. Does that mean I don' t have the tps set right? I tried to set the timing with it disconnected but I guess from what your suggesting it should be jumped not disconnected. I'll do that tonight. Jwt tells me to set it at stock timing which is 20deg, right? If I plug and unplug my tps at idle should my timing change? Same with CHTS or is that just for fuel enrichment? Glad to see Bernard and bastaad525 responding to this I've read alot of your posts and have leard a thing or two along the way. Thanks. No offence to the rest of you responding I appreciate all the help I can get. Paul

[datsunan]

Any other Ideas? Seems no matter what I do I can't get my timing to stay at 20deg. Two nights ago it was running great, the next day like crap again and of corse the timing was off. If the car is warmed up and idling if I pull the plug from the cylinder head temp sensor should my timing and rpm change? cause it does'nt, only when the car is not up to temp then it will make a diff.

[Bernardd]

When you check the timing next time short out the connection for the tps at the ecu instead of at the tps plug. Check to make sure you don't have a faulty CHTS. Can you put the ecu into diagnostic mode and read the codes? I thought I had the a similiar problem and it ended up being the connector to the tps.

[datsunan]

I don't have a FSM so I so I don't know how to check the codes. I adjusted the tps and the dropping out at 2000 stopped so thats cool. It ran well at the dino the other day so I will see if the timing stays now. I will be posting dino and 1/8 mile ets later. Thanks Paul

[datsunan]

Well I'm still having problems with the timing and now I can't adjust my dizzy any further to compensate so I'm stuck with my new 20,000 dollar z that runs like a yugo. Why would my ecu keep changing my timing and how can I get some adjustment back? If I unplug my ecu should I be able to reset it? Is there a proceedure for setting the timing on the 83 electronic dizzy? Someone please help, I'd pull my hair out if I had any!! Thanks Paul

ps I now have a new chts and my tps is adjusted correctly and the dropping out at 2000 rpm is gone, some good news!

[Guest Paranoid_Insider]

I had the same problem with my 78 280. However mine was all stock with 220K miles. At some point the reluctor had hit the pick-up coil and bent the dist shaft. After replacing the shaft it would never hold time. I'd set it, the next day it would run like crap. I ended up replacing the dist and it runs fine now.

[clarkspeed]

I'm not sure about your electronics, but it could be mechanical. I had the same problem. Turned out my distributer/oil drive shaft ate itself alive. The crank gear is steel and so is the shaft gear, if you push high RPM's niether one will give. Nissan comp made a brass gear for the crank to solve this problem on the race engines.

 

If there are metal shavings in your oil, better pull it.

[Pop N Wood]

I was going to say. Any kind of mechanical slop could cause what you are seeing. Worn distributor gear, bad bushings, slop in your timing chain, stuck vacuum advance. Might have a broken or missing screw on the dist hold down plate.