A Series Of Annoying Problems!

[shyr33]

Ye I wish I could have a brand new R33 straight from the factory mmm mmm haha

Um it stands for Auxiliary Air Control valve and allows/controls the amount of air for idling once the car has warmed up. There is a DIY thread on this forum which covers it. Have a look and see what you think. There is also a cold start valve which controls the idle when cold so you could also have a look at cleaning that.

http://www.skylinesaustralia.com/forums/Di...nd-t110431.html

[benro2]

Hmm... interesting, thanks for the AAC link! Very well written writeup. Although looks like it's a fair bit of work! I'll try all the other (easier) suggestions to start with and will progressively do the longer ones to narrow down the problems I don't really have the symptoms that the guy mentions - idle hunting, stalling, etc. - but definitely worth a look if I can't trace the problem down beforehand.

Just out of interest, I was driving a fair bit today in 40C heat and at idle, the car was as smooth as anything! I figure that it's to do with the increased temps thinning out the oil more than usual, which would allow oil into the hydraulic lifter(s) that were blocked before? As soon as the temps dropped to 30-35C, the rocking was back...

[shyr33]

Hrmm well it might also pay to change to oil to the lower grade then e.g. 40 next time you change your oil and then let us know how it goes Looks like you have a few things to try hopefully one of them gives you some success!

[mosquitocoils]

You should definately spend the time to clean your AAC, only took me about 3 hours + 4 beers or so on a Sunday arvo It was my first time taking that area apart so had no idea what to do without that guide! Get a can of carby cleaner next time you're near an auto shop, and maybe a wire brush too, that way you're all set up.

[benro2]

I know it's been a while, but I've bought one of these from ebay (scroll down to view). Great little unit, the guy who sells them was really helpful and shipping was extremely quick - received it the next day!

Anyway, these are the readouts I'm getting, bearing in mind I've only been driving with it for 20 mins so I may have remembered them wrong...

These are the readouts at a constant 110km/h:

- kph = 110km/h

- rpm = ~2800rpm but is jumping around by 100-200rpm

- battery voltage is ~13.5V when running

- fuel consumption is 9-10L/100km on the flat, also jumps around a bit

- INJ (injectory duty cycle) is about 6-8% on the flat (I think! I set the injector size to 370cc)

- ignition timing is ~ 30-40 deg B on the flat, probably a fairly constant 35

- AAC (is this the same as the Auxiliary Air Control valve?) reads about 50-60 on the flat

- O2 is jumping around from 0.15V - 0.85V all the time under constant load on the flat. This doesn't seem right to me. When the ECU shuts off the injectors it reads 0.00V.

- Water temp is ~80-85C

- AFM is ~2.500V on the flat (I think)

- TPS is 8-10% on the flat - I had to change this from a voltage to %age readout. I think the voltage range was ~0.3V - 4.3V - sounds about right?

A few notes/thoughts:

1. The fuel consumption seems a bit high, although the average it calculates seems to be about right compared with what I work out myself, so I think it is accurate, meaning my car's actual fuel consumption is bad. I've heard a bad O2 sensor will do this, however people with good O2 sensors report about the same fuel economy as me (400-450km out of 50-55L). However I drive the car like a granny most of the time and it just won't go any lower than this. Can I improve this with a new O2 sensor?

2. The ignition timing is 0 deg B at idle with no electrical or A/C load. The A/C puts it to about 10 deg B. Very light throttle (1-3% maybe) makes it go to 40-50 and most normal driving (5-15%) makes it go to 30-35. Is this normal? I did my load test up Lapstone Hill and when it was surging, under a constant throttle of maybe 30-40% (still in top gear) the ignition timing was moving around a bit, maybe in a range of 5 or so. At other times it seems to be relatively constant.

3. AAC goes down to ~40 when the car is at idle. Seems to increase with throttle. What is this reading anyway?

4. The O2 sensor has me worried a bit. I would have thought a fairly constant readout at constant throttle would be expected but mine is jumping wildly all the time. Never reads over 1V (0.9 was the maximum probably) but interestingly, still reads 0.00V on injector shutoff on overrun. Could this be busted?

5. Is the AFM readout about right? I didn't look at this too much other than on the highway so I can't remember what it was at other times.

6. The rpm readout jumps around a bit, maybe by 150-200rpm @ 2800rpm, less at less rpm. Would this indicate a faulty crank angle sensor?

7. Just out of interest, on injector shutoff the fuel consumption readout is still ~1.5L/100km, yet the O2 sensor reads 0.00V. What gives??

Will get around to changing the oil and cleaning the AAC soon, but as you may imagine, I'm pretty busy around this time of the year

[benro2]

This thread was getting a bit too long and doesn't really belong in Forced Induction Performance anymore anyway, so I've started a new one here.