Vacuum, Timing, Injectors...

[Grenyaer]

s13 redtop, stock SMIC w/ ducting.

Idles fine, CAS setup the correct way, new plugs, firing on all 4 cyl.

When given a small amount of throttle there's a bog then it will not rev correctly. If I try to rev to 2k rpm, it will go up and down from 2k to 1k.ish and back and forth. If I try to drive it with small throttle (2k.ish) it will buck and not go. Once im over 2k, it accelerates fine, but when I release throttle there is a small buck, same when I give throttle again over 2k, buck then go. It's tough to drive because I can't maintain speed I either have to accelerate fast or decelerate both with constant bucking.

I have reset the CAS twice to make sure it's correct, but i have no timing light and have only turned the CAS by hand to set timing to what works right. It makes the car run good, just 2k rpm is like a dead spot.

I've been through all the air ducting and hoses a couple times and can't find any vacuum leaks, but I don't know for sure.

No codes thrown at all.

When I first started my engine the injectors were stuck so I thought it may be they were all gummed up still, but that wouldn't explain the 'low rpm only' bucking would it?

In conclusion I can't figure out what it is. I have been trying to get over to my buddies shop to use his console to check if it's the timing but he's gone for thanksgiving for a week so I'm trying to figure it out myself while he's away. Anyone have a practical way to check for vacuum leaks? How do professionals do it? Thanks.

[mynismo]

you notice how no one here has an sr, lol

did you lift the valve cover while setting the timing? check out http://www.store.yahoo.com/phase2mot...tosetcaso.html

sounds like your timing is still off. your car will run like sh*t if it is. sounds like the same prob i had after i got mine swapped.

you need to pull the cover off and line up the timing marks. there are two of them, one you line up while sliding it in and the other moves as you put the cas in.

either that or it could be a bad maf. if setting the timing in the above method does not work, its definitely your maf.


if you want good sr advice go to www.freshalloy.com, forums, then s13 advanced. some of the most knowledgable sr guys are over there.

[Grenyaer]

Well I couldn't figure it out so I waited for my buddy to get back and took it to him today. Turns out, my TPS was at 0 volts at idle, and about 25-30 when revving. So we adjusted it to 36volts at idle and the surges went away. Also my timing was advanced about 8 degrees so we set back a little. Got it fixed and it runs like a gem now.

[D-Bo]

whats tps

[logik23]

Throttle positioning sensor or something like that.

[ExTrEmEDrIfT]

yah its throttle position sensor