Help My Timing!

[nicr4wks]

Car: 97 r33 gtst, 107xxxkm. Turbo back exhaust, fmic, ebc set to 10psi.

Car has become sloppy, throttle response seems a bit slow, mid range with foot flat the car feels like it is holding back, at about 4800 rpm the car seems to wake up and you can feel much stronger acceleration. I've locked VCT both on and off via consult as the car picks up around the switch off rpm but it has made no difference to drivability so I do not believe this is the cause.

At idle consult is reporting dead on 15 timing, the crank marks jump around between 5 and 15deg. I've tested timing by putting a lead between coilpack and the spark plug as I couldn't get a sensible reading from the wire loop at the back.

If I adjust timing via consult by +5 the car drives very well, noticeable harder acceleration through the whole rev range and midrange no longer feels hesitant.

So, I have disconnected the TPS, adjusted the CAS until the crank reads spot on 15, the CAS is in the fully advanced position to get this reading. Consult is now reporting 5deg timing, 10 lower than the crank. Driving the car runs very well, however above 4800rpm it pings quiet bad so I've put the CAS back to it's original position where the ecu reads 15, the crank jumps between 5-15, the car drives sloppy but does not ping.

Can anyone chuck some ideas at me as to why the ecu and crank both read such different figures, and how I can get timing set correctly?

Cheers!

[Kinks]

Couple of separate issues at play here.

The first thing to remember is that the ECU will only display what it THINKS it's running. It assumes you have the CAS set correctly to exactly 15 degrees.

I have had the idle timing jump around a bit too, you've done the right thing it should lock itself on 15 degrees. Does Consult sit rock solid on 15 degrees even while the timing light is jumping around? (get a mate to help watch). Maybe it's not locked in on idle timing..

CAS is definitely not fully advanced to get to 15 degrees though. It should be in the middle position, if it's fully advanced then something is way wrong.

Being as little as 5 degrees out can make the car feel like a slug, I had to put mine back to 10 degrees for a while as 98RON was making it ping. It felt horrible to drive. I then found United 100RON and put the timing back to 15 degrees wow what a difference. So if you have set it back to the middle position and managed to get 10 degrees then adding timing will make a big difference. However, you really need to make sure the CAS is set correctly. Are you sure you're reading the markings correctly?

[nicr4wks]

I have the full workshop service manual translated by & purchased from jpnz that I'm going by, if the first orange marking is 0 then 3 to the right should be 15. This is how I'm reading them which is hopefully correct

I've basically tried setting it 2 different ways, with consult reading dead on 15 the crank is jumping 5-15 constantly, each time the gun flashes the timing mark will be different, this is with the TPS disconnected and idle at 650-700rpm. The car is very sluggish like this.

With the CAS fully advanced the crank reads spot on 15 and doesn't jump around, I can rev the car and it will return to dead on 15. Consult reads 5deg exactly. The car is very responsive and accelerates well, however there is very audible pinging above 4800rpm.

[nicr4wks]

Reviving an old thread here, but the problem turned out to be a faulty fuel pump causing a lean out and I'm guessing the ECU was retarding to compensate, however there was never any errors logged in the ECU or any indication that the ECU was compensating for this, but those knock sensors must do something right?

Now with a new pump fitted there is still a slight dip in the mid range timing still but bearly noticeable compared to how the car was behaving before.