Check Out My Datalog, Please!

[Mickroy]

I have a 95 r33 gtst...

Its had a shitty idle for quite a while. Ive attached a link to an excel sheet with a datalog from the nissan datascan software.

It shows a warm start, idling for a moment, then easy acceleration to 100km/h.

I would really appreciate it if I could get some opinions on it. The only thing I notice is the very very unstable timing at idle.... but what on earth could be causing this??

Thanks in advance.

Datalog

[rob82]

Is the value of AF Base the learned AF correction? In which case it is quite lean. Check the O2 sensor grounds and its bias with chassis and ECU ground. Also maybe a noisy crank signal. Try running another ground to the CAS. If this dosn't work try one from another car.

[Sydneykid]

Changed the plugs lately?

chers

[Mickroy]

Ive tried 3 O2 sensors, spark plugs are fine too... replaced recently.

I'm glad you've mentioned the CAS rob, coz that is the next part im planning to look at.

Anyone got anymore ideas?

[Mickroy]

Ok, swap tested the CAS.... same deal. WHY!?

Not the AFM, O2 sensor, plugs, coils, battery, CAS, AAC valve. I tested the A/F ratios with a wideband O2 sensor & they were spot on too.

I got a shit idle, no power, and my ignition timing is all over the shop.

I'm gonna drive the f**ker off a cliff!!!!

[Cubes]

The pfc uses ign in an attempt to lower idle in conjunction with the AAC.

This is what it looks like it is trying to do.

Whats your base idle set to in the pfc?

I would disconnect the aac and reset your idle when warm to as close but ensure its not over the pfc's set idle a/c off. Reconnect the aac.

Init the pfc, load in your maps, start the car and send it through the 30min idle learn. For the next few days it will still occasionally play up, let it do its thing then all of a sudden you will think.. oh shiet its idling perfectly smooth.

DO NOT attempt to change the idle rpm as it will bugger it up and you will constantly have a crap idle from then on. For some silly reason I've always had to init the pfc for it to relearn the idle properly.

If this doesn't work ensure your aac is clean from gum (remove and pull apart, soak and clean) Also ensure the solanoid is working. Hitting the A/C button is an easy way to test, idle should raise, same with turning your power steer.

I would then attempt swapping of the cas and all the other harder and more expensive solutions.

Edited January 4, 2006 by Cubes

[Mickroy]

cubes, the datalog is from nissan datascan.... plugging into the STOCK ecu.

AAC valve has been cleaned, cas has been swap tested.

cheers

[Cubes]

Shows I skim read.

My stock ecu always had a funny idle, the pfc idle is now rock solid providing I set it up properly.

Edited January 4, 2006 by Cubes

[rob82]

Whats your plug gap? Is your base timing correct? There should be some variation in ignition timing depending upon desired idle variences. Positive numbers for below desired idle and the oppisite for above desired idle.

[Mickroy]

mate, i cant set a base idle.... doesnt matter how i adjust the cas, the timing will jump everywhere at idle. I have tested my datascan cable & software on another r33 & got a rock solid 15 degrees...

plug gap is .8

cubes, i actually have a pfc by the way... havnt had it tuned yet coz i wanna sort this shit out first... but i CANT!

Edited January 4, 2006 by Mickroy

[Cubes]

As I said, the pfc sorted out my slight idle hunt.

I believe the stock ecu has a small idle adjust screw? Mine didnt appear to do anything though.

[Mickroy]

I went to my car to drive to work this morning.... oh look, a flat tyre! yippee!!

Why do the skyline gods hate me so much?? I swear to god im not meant to have this car.