Hey guys,

I have a problem with my 1993 N14 Pulsar SSS SR20.
It has a flat spot between 1000-3000..well you could say the engine is really dull through that range...however after 3000 it spurts back into life and revs well to redline.

The following has been done to fix it:-
Injectors have been taken off and cleaned
new fuel filter
new plugs
new oil
K&N air filter has been cleaned and reoiled
running good quality 98 octane unleaded

the car has been plugged into a diagnostic computer whilst driving and ecu and all sensors passed as satisfactory...however....
between 1000-3000 the timing retards itself back to 6 degrees (which is under factory spec for even idling which is severely retarded) and then after 3000 the timing then jumps to 18 degrees and then advances close to 30 degrees under full acceleration to redline (which is normal operation after 3000).
BTW the knock sensor has been verified to be OK...same with the TPS (throttle posn sensor).

Also the flat spot is accentuated when you put the air filter back on the throttle body. remember it is a hi-flow K&N reusable one ans has been cleaned so that shouldnt represent a problem.

I am at a loss....help me Obi-Wan youre my only hope.

I've heard that oiled filters aren't recommended for cars with air flow meters.

Get some metho and clean the AFM hot wire with a cotton bud.

Try temporarily disconnecting the 02 sensor to see if that makes any difference. If it's an old one it might be worth replacing.

I've also heard that there are differences in the maps on the ECU between different models and manual/auto. I can't confirm this though.

Try cleaning the the AFM first. You've done all the other things I'd think of.
Chris

Thanks Chris i'll give it go tomorrow

looks like the boys from the Pulsar club reckon its a blocked EGR pipe, I'll try that too.

I have a mate with the same car, had the same problem, tried everything. Ended up being the O2 sensor even though it kept passing tests

Also SR20's LOVE to go through coolant temp sensors...mine has been acting up lately a little bit. The car will think it's hotter/colder than it really is and retard the timing to compensate. Also the electric connections get corroded resulting in poor performance/bad signal to the ECU. Check it all and do one thing at a time based on people's recommendations and what you feel makes sense or might work to solve the problem. Eventually you'll find it, but 9/10 times on SR's it's a sensor or electrical signal problem rather than a mechanical problem.

Craig,
I'm no expert by any stretch, but from what I have read while researching my Z18T, I agree with Chris. Oiled filters pass a film of oil over your AFM during use and gradually coat it, rendering most readings useless. AFR also has good advice, most problems seem to be mis - information to the computer hence be totally sure of all input devices no matter how insignifigant.
Good luck !!
Cheers

I also agree with AFRacer.

Joel aka "Mr Drift" in his fishtail happy 1200/ca18det sedan racer at Datnats 2005 had all sorts of timing issues +-15degrees.. It was the temp sensor in the end. These things suffer from corrosion in the connector and it's pins, especially after the 'import-related' cleaning they get in Japan.

I replaced mine with a freshly replaced one from an RB30E from the wreckers. I'm not running factory ECU..so I can't comment on the RB30E one working on your SR.

I'm sure that you'll let us know when you find it.

After visiting the boys on the pulsar they reckon its really coomon for the EGR valve and pipe to be blocked and cause this problem.....exactly the same symptoms...anyway i'll look at all the above suggestions this week.

What about some milder cams??? Should give you the bottom end back. . .

How often does it fall below 3K on the track anyway?

Just stirring. . .