Timing/idle rpm interdependent?

DanTheMan · Feb 6th, 2005, 03:29 AM

I recently advanced timing from about 11'BTDC to 15'BTDC on my 97 ga16de
and can hear/feel the difference, especially with my HS header and CAI. I also have the UR crank pulley and JWT flywheel installed as well as a hyper-ground system and ported TB (the part before the butterfly is funnel shaped).
I have a timing light (duh) and it's exactly on the 15' mark on the UR pulley.
Something weird though (even after warm-up) I will accelerate moderately and if I let off of the gas the engine will drop to idle and surge back up to like 2500-2700rpm. It's not a prob really when I drive "nice" but if I'm like 90-100% throttle when I go to shift it's a beeeeeetch cause the engine is surging right when I need to shift!
I had this prob before when I adjusted idle speed (down) it seemed to go away but I would be concerned if it has to idle so low (stock idle) it wants to bog off the line (maybe just the flywheel being light?) so I like a slightly higher idle speed 700-780rpm, but the fsm and Kojima's garage says it should be like 625 for the manual which is what I have. I will drop it down to 625 today when I get off work and see if the surge goes away.
What causes the surge in the first place?
Is advancing the timing making it too rich at that idle speed? Or is it air-pressure/intake related (maybe the long tube of the HS cai is causing this?)
I have no engine codes and no other driveability problems.
If there is anyway to get a high idle on this car without surging (I don't care about gas consumption)?
Why are these engines so boggy? they really could use some lower-end.
(yes I know it's at the top end from like 4k to 7k it pulls hard but from 1-4k rpm these cars have like virtually no butt-dyno torque!)
After I smooth this idle out (Tomorrow am) I would like to get a nitrous kit (wet) and use a 50 shot (max) but I need some info on how to make that "safe as long as it's set up right" so i'm thinkin' one big bottle with warmer, remote open ,blow-down tube, purge-kit, but how/what do I need to engage it incrementally and only between certain rpm's?
What is the lowest rpm (in ea. gear) i should nail it with the 50 shot?
I saw venom had something close to this with computers and you program it yourself but I still need the rpm/gear info to program it for our car.
Thanks for your patience and YE$ I did search and read alot of really great posts, just need some advanced advice/info.

Nostrodomas · Feb 6th, 2005, 01:14 PM

When was the lat time you cleaned your IAC/AAC valve, or throttlebody? If you have never done it, you might as well do it. That might fix your problem.
Also, have you djusted your throttle cable recently? It could be to tight and binding, hence causeing the surging.
As for the nitrous questions, you might want to ask them in the nitrous section of the forum.

DanTheMan · Feb 7th, 2005, 01:34 AM

OK, this morning I adjusted it to make sure it's at 15 exactly, and I adjusted the idle to between 680-710 (won't give exact on my timing light) the under-hood data says idle for this manual is to be set at 680. The drive to work went well with the surge limited to about 1500rpm, which is about normal from what I remember when this car was stock.
The shifting was much improved and I can hardly detect any surge between gears or when I pull it out of gear it now drops rpm instead of surging then dropping so I must have gotten down this whole timing/idle setting thing finally. Even with help and instructions it just takes alot of time and test-drives to get it "just-so".
The TB was ported and is cleaned whenever I clean the air-filter (once a month) and I take apart the whole intake and clean it as well as the crank-case vent tubes (these can really get gunky sometimes so check once in a while guys!).
I think what I need for nitrous is a wet (non-zex system) whith all the safety stuff like blow-down tubes and heater. I figured out the little computer I need to set it is called a Progressive Controller, these things sound like the shiznit to me, so IF I do nitrous I will use one. (I'm still not 100% sure It can ever really be "safe" and it's another tank).
Thank you for the suggestions, I truly respect any opinion(s) rendered as I am still a newbie to car mod's (even though my GA16de has all the bolt-ons) I don't know jack about "nos" or even what rpm to hit it so I'll pass on it for now)