nitrous_50

Hey bigtom, if you weren't too busy, I wanted to know if you could help me out?

I recently built a 11:1 motor. It's pretty stock except for the 300zx domed pistons. I'm currently using a JWT ecu with the 11:1 program on it. My timing is set at 14 degrees. I've put 450+ miles breaking in the new motor with the computer. I know the computer has to "learn", but it still slightly surges every now and then. Kind of like it retards timing, and then re-advances it again.

Do you think the computer has compensated all it can, or do you think it still needs more time/miles to learn more? I know I should usually be running 15 degrees timing, I'm currently at 14 degrees, should I try retarding it alittle more? Maybe close the gaps on the plugs alittle closer? Switch from NGK coppers to NGK platinums?

Sorry this isn't a sr20ve question. I notice you post here frequently, and you seem to know NA motors in and out pretty well

Thank you for your time,
-Bryan
96 SE-R

 

bigtom

switch to platinum temp 6. if yuo turn you timing back to 12 and the problem is still there its not your timing thats causing the surging. does it happen at part throttle, full throttle, or decel.

nitrous_50

Thanks for responding so quickly!!

Generally the surging happens at 1/2 to 2/3's throttle. I haven't finished breaking in the motor so I haven't taken the motor up over 4000 rpms, or full throttle yet.

Sometimes I can shift at 3500-4000 rpms in 1st, 2nd, 3rd, and 4th gear, in succession, with no surging at 1/2 throttle. Other times I get a little surging in 3rd and 4th gear at 1/2 throttle.

I will try switching to platinums tomorrow and dropping timing to 12 degrees and see what that does.

Thanks again for your input, I'll let you know the outcome.

-Bryan
96 SE-R

bigtom

do you have a nitrous program?? that will run rich and like butt if it is on while driving with the bottle off. really sound strange maybe you can take it to a shop near you and have them give it a good once over. set the tps to the propper setting. the idle switch should be on when you have 0 tps and turn off when you touch the gas slightly. full throttle should be near 4V.

nitrous_50

--Well, I used to have nitrous. I had JWT unplug the nitrous program when they re-programmed it for 11:1. Just haven't changed my user name yet

--I changed timing to 12 degrees, and closed the gap on my copper NGK's from .044 to .030. Closing the gap seemed to make a bigger difference then dropping timing. It still surges though .

--Is switching to platinums that critical to high compression? I am currently running BKR6E-11's copper NGK's. I couldn't find any platinums locally, that's why I tried dropping my gap down on the coppers. I thought the main difference with copper versus platinums were the length of time they lasted. If it is important, I will order some though. I was trying to get PFR6B-11's, is this correct? (This was off the NGK website)

--Just for trial and error, I bought some octane boost. Here in Portland, Oregon, all I can find is 91 octane super unleaded. With the octane boost, I should be able to hit 93 or 94 octane. I want to see if this takes care of the surging, or doesn't do a thing.

--As far as a good once over, I had a mechanic shop professionally install the motor. So far everything checks out there. I haven't specifically had them read the volts on the tps though. Maybe next week sometime I can get that checked out for sure.

Hey bigtom, I really appreciate your help and insight. Hopefully I can get this thing solved without major surgery!!

-Bryan