Hesitation before 4 - 5k RPM

[feel_ixx]

Ever since I got the car back from my clutch install, I've noticed a very obvious lag of power before 3k RPM, I would seem as if the throttle isn't opening up like as if the car was in a higher gear than it should be, and then after it passes the 3k mark it would surge forward all the way till redline. I took it back to the mechanic and he suggested it could be a timing problem - he did something simple to the engine (didnt see what) and now this lag is happening before 4 -5 k RPM. It being weekend now, I haven't brought it back. This lag happens close to every single time I open up the throttle.

I only changed my spark plugs about 7500 km ago so I don't think it will be that, and I also didn't notice this before it was taken to the mechanic either, although I doubt it has anything to do with the new clutch, or fixing the rattle of the heatshield. If it were a fuel pump, I would imagine idle would be inconsistent but it's not. I completely stumped on this. Anyone able to help on this?

[Rotary]

If he thought it may be timing, then its sounds like he must have fiddled with the Crank Angle Sensor,

Have a read through the thread
Advancing ignition timing to 14deg BTDC iz goooood
viewtopic.php?f=29&t=29755

I think that goes through how to change it

[Moto]

Do you get the same result advancing the timing on a NB8A, or is the mod for older 1.8's and 1.6's?

[cshaks]

Do you get the same result advancing the timing on a NB8A, or is the mod for older 1.8's and 1.6's?

I believe that only the NA6 and NA8 are adjustable in this way.
(someone correct me if I am wrong??)
Chris

[Alex]

You can change timing on the NB's but it's alot more work and not normally recommended, I think Rotary has done it though

[Moto]

Ah that's disappointing! Yet another reason to go aftermarket computer.

[Rotary]

You have to modify the Crank sensor, drill a new hole and then reallign,
Its reliable once done. but you can't go back to the original setting.

I measured it up to give me an extra 8'(so 18'BTDC) checked with timing light it jumps between 16'-18' so seems good

14' seems to be a forum accepted limmit i think from an idea that beyond that the gains arn't huge.
Can't verify it with test results, but there are many factors involved in choosing timing (fuel used, other mods, engine age etc.)
So would differ based on setup rather than just one working figure.
(I Wouldn't recommend any setting change unless you know why its safe for your car)

[cshaks]

You have to modify the Crank sensor, drill a new hole and then reallign,
Its reliable once done. but you can't go back to the original setting.

I measured it up to give me an extra 8'(so 18'BTDC) checked with timing light it jumps between 16'-18' so seems good

14' seems to be a forum accepted limmit i think from an idea that beyond that the gains arn't huge.
Can't verify it with test results, but there are many factors involved in choosing timing (fuel used, other mods, engine age etc.)
So would differ based on setup rather than just one working figure.
(I Wouldn't recommend any setting change unless you know why its safe for your car)

I have an NA8, running 18'BTDC, it was that way when I bought it. Looks like there are no engine mods and I have stuck it on the dyno at AVO and the figures are 74.2 RW kW @ 6532 RPM and 414.7 Nm @ 2543 RPM.
I run 98 RON all the time and have had no issues whatsoever.
Not sure what would happen if I took it back to 14 deg BTDc?
Feel ixx
As far as your car is concerned I would ask the mechanic what he did. Changing the timing by playing with the CAS can change the torque curve somewhat, shifting to further BTDC means torque curve shifting to lower RPM as far as I understand it.
Also beware that if the CAS has been moved, you will probably need to change the O-ring on it, as it may start leaking oil onto the hose underneath, causing it too become brittle and fail.
There are more on this forum with tons more knowledge than I, but they are my thoughts....
Anyone care to jump in and correct me or add more??
Cheers
Chris

[feel_ixx]

Hey guys, thanks for that, I doubt the mechanic did that though because he was in there for about 2 minutes without any equipment. However, now I'm curious about changing my advanced timing, though I'm lacking the timing light thing. What a shame. My mechanic also doesn't want to touch it so I'll have to find someone who does. Anyway, weird thing, that hestitation seems to have gone away about 2 days after I noticed it. Perhaps my new clutch was slipping from glaze or something?

[Rotary]

with NA's its far simpler, and would only take a minute to play with. just get your hands on a timing light and see what you have to start with

I have an NA8, running 18'BTDC, it was that way when I bought it. Looks like there are no engine mods and I have stuck it on the dyno at AVO and the figures are 74.2 RW kW @ 6532 RPM and 414.7 Nm @ 2543 RPM.
I run 98 RON all the time and have had no issues whatsoever.
Not sure what would happen if I took it back to 14 deg BTDc?

loose power I agree with you though, most cars will respond well to a good advance, and most n/a cars won't be damaged under light pinging anyway(at least in short term) but every car is different, as is the owners level of understanding or even hearing(pinging). (one high km car i tried it with responded with immediate ping with any adv)
thats the only reason i wouldn't say go 18'(on an everyday forum). different to what i would do myself or recomend to a race car

[bensale]

I run 14-15 deg on my na6. It definently makes a noticeable difference, the torque curve kicks in a bit earlier. I also run 98 and my fuel economy has improved since advancing the timing from 10 deg (and also switching from regualar) as the car is more 'driveable' However from what I understand advancing the timing also lead the the car running hotter, so when it gets a bit warmed I'm planning on dropping it back to 12 deg while still running probebly 98 due to it being more likely for fuel to premeturely detonate in hot weather.

I bought my light for $20 or something like that off ebay, it does the job and reads the same as a much more expensive light used to initally set the timing at stock specs. I'm sure that if you go to a Sydney meet someone could bring a light along and check your setting in as little as a minute. To me it sounds as if your car could be 'retarded' too much.

[cshaks]

Ben, I have run mine hard in 40 deg heat with no heat issues... but I suppose it depends on your cooling system ( I think I need a radiator soon....)
I don't think that you will have too many problems over summer running 14 degrees.
I didn't buy a timing light..... I have a good mate who owns a whole workshop full of tools!
YAY

Chris

[bensale]

Ok then, I have a resonably new radiator and have no problems with overheating so I guess I wont worry about changing it, but I'll keep an eye on it none the less. It would be nice to have a mate like that, would make some jobs a fair bit easier.

[Jace]

i have this same hesitation.
feels like my engine struggles to open the throttle smoothly and the revs build in small chunks that kind of slur into one another.
certain that my timing is stock, and my engine is pretty high K's (225,000k's for a 1990).

[feel_ixx]

Did you just get a new clutch install?

I think the problem with mine was a glaze or something, I burned the clutch for a bit and after a few days it went away.