R34 Gtt Hates Timing?

[Kinks]

RB25DET Neo

Standard side-mount intercooler, turbo, injectors

3" JJR dump, metal cat, poxy custom catback with triflow muffler

Adaptronic

Yellow jackets

10psi

What sort of timing would this usually take in the midrange (4500RPM)? I would have expected early 20's, but it won't take more than 10-14 degrees.

Also, VCT helps lower in the rev range but makes no difference from 4500 to 6000RPM. I would have expected it to help until ~5800. Power nosed over at about 6500, making 178rwkw. Is this a reasonable figure or a bit low? Also a torque hole in the lower midrange ~3500-4500.

Checked cam timing (it's fine). Issues with coil packs on the day but I wouldn't think they would count for a big difference? Seemed like an intermittent bad connection (would miss at idle then do a full power run no problem), maybe it was dropping out power to the coil primary halfway through dwell and causing some of the detonation issues? I think I solved the issue this morning by bending the pins #1 ignition coil slightly, then plugging back in. the coil pack harness is new (18months) from nissan.

[Kinks]

pictures tell 1000 words.. dyno sheets attached. first one has torque, second one has AFR.

can't speak highly enough of Mark from MRC. He showed me everything he was doing and the intermittent miss was a real time soak. He did well to improve what I had (blue line morning, red line afternoon) despite the temperamental behaviour.

R34 GTT Adaptronic baseline pwr,torque,boost.pdf

R34 GTT Adaptronic baseline pwr,afr,boost.pdf

[KiwiRS4T]

I presume the adaptronic can control the VCT so you would normally do a run with VCT on and one with it off to determine the changeover points. Figures look ok for a stock engine. Have you gapped the plugs down to 0.8mm? Looks to be running quite lean. Is that by choice or is your pump not up to it?

[zoomzoom]

Do you mean its pinging at 14 degrees? Ive got 20 degrees of timing at 4500rpm and 173kpa. While 12:1 is on the upper end on boost, it doesnt seem dangerous, and shouldn't cause pinging at such low timing. That's like stock in how conservative the timing is.

Tuning idle on the adaptronic is a little strange. My engine seems to naturally go richer at idle with the same VE value compared to the nearby cells. In order to get a smooth idle Ive added about 3-4 to the VE values at idle, bringing the idle AFR to around 12.8-13:1. Quite rich, but that's what the engine wants.

As you progress to 14.7:1, the idle becomes increasingly rough, and misfires are more frequent, giving the impression of bad coils. (whilst running fine under boost)

[Kinks]

Yes Adaptronic can control the VCT. We actually did a run with it inverted - ie the opposite state to which you would normally use. The upper midrange showed no difference for about 1500RPM which was weird. below 4000RPM it was horrible without VCT.

Plugs were replaced with new iridiums gapped to 0.8mm. AFRs are by choice, running richer makes you lose power.

[Kinks]

Do you mean its pinging at 14 degrees? Ive got 20 degrees of timing at 4500rpm and 173kpa.

Yeah. Depending on the exact cell, it was 11-14 degrees at about 4500rpm. Have you checked your timing by locking it (Adaptronic) and verifying with the crank marks + timing light? We had to fiddle with the trigger offsets to get it to line up properly with the CAS set in its normal spot. Otherwise we would have been about 7-8 degrees out.

What wideband are you using (and where is it installed)? Your symptoms sound similar to mine - I'm using the Innovate LC2 with the sensor about 10" in front of the cat and the calibration seems to be off compared with the dyno wideband. The LC2 appears to be reading a richer number than it actually is, so we retargeted my light load AFRs to be 13.8:1 to compensate. The engine was a lot happier with that.

[zoomzoom]

Im using the innovate MTX-L, and the bosch sensor is installed just before the cat (only place that fits, other than the standard narrowband bung).

When is the last time you did a free-air calibration? Innovate recommends doing it after install, then a few months later.

I have noticed that the wideband reads a little richer than the narrowband, however since the adaptronic is sharing the standard ECUs wiring, there should be a voltage drop on the sensors, which would explain the leaner reading on the narrowband.

Haven't checked the base timing since I had it on the dyno....

[Kinks]

Yeah I saw last night that they recommend doing another calibration 3 months after install. I have not done that, only the cal at install time.

[Dose Pipe Sutututu]

Install an intake air temp sensor (if you don't already have one), Andy has them for pretty cheap and the adaptronic is already prescaled for the GM sensors.

Could be high intake temps that are causing the car not to take timing.

Another thought is a dud CAS.

Run your car on the street and log a 3rd gear pull and post it here.. would help to see what's going on provided there's a wideband and an IAT connected.

[Kinks]

Log attached. I have a temp sensor installed on the crossover pipe. What's "high" as far as intake temps goes? I saw 40C on this short run, but it was still heading north. I'm hoping to do a track day in a couple of weeks time.

Have seen a bit of RPM jitter before, definitely not more than 500RPM but I can't remember if it was 300, 400 or 500... this run was pretty clean for RPM signal.

Also, the wideband calibration is off. It's reading up to 1 AFR richer than is actually the case - ie my wideband was showing 13.8 on the dyno while the tailpipe sensor was showing 14.7. Richer mixtures seemed to be a bit closer most of the time.. I need to do another open-air calibration on it to see if that fixes it, I did one when it was new but you're supposed to do another after 3 months as John (zoomzoom) said.. I only just realised they need a recal after 3 months.

log.txt

[Dose Pipe Sutututu]

After cat is always a little leaner (pretty normal).. I prefer to do all my tuning with the wideband attached precat OR a hollowed cat.

AFRs are good, IAT is getting towards the warm side but still ok.. on the dyno after 3~5 consecutive runs it would get quite warm ~ hot.

Timing is pretty low, I'm surprised you're getting knock... unless there's an exhaust restriction and/or a faulty CAS.

Have you checked your base timing? i.e. locked the timing say at 15 and used a gun to double check the timing?

[Kinks]

Base timing was checked while locked, it needed the trigger offset adjusted in the Adaptronic to produce 15 deg with the CAS midway. Was off by about 7 degrees otherwise. Cam timing also checked against the engine cover marks as the tuner initially suspected it was a tooth off with a midrange hole like that.

[Ben C34]

Swap cas.

Same thing happened to blah blah.

Unexplained pinging, replaced cas. Fixed.

[STATUS]

yellow jackets are junk but that rant side lol, the SMIC is your issue, 3 or more pulls will usually see intake temps creeping to scary heights even as low as 10psi. Put a front mount on and it will repeatedly run the same power and take far more timing (15-20 more kw with timing and another 2 psi).

178rwkw is not far off what it should be, in fact it is almost spot on for a SMIC result with an accurate dyno.

put it this way we wont tune R34, stagea or S chassis cars with SMIC fullstop.

but that the cas can show similar symptoms.

[zoomzoom]

How are you measuring knock? The only knock your log shows is when you let off the throttle and the manifold is under vacuum.

What are your background knock values? The adaptronic knock detection seems to be quite simple and picks up a lot of other engine noise.

The other way would be to record a sound clip of the headphone output on the adaptronic. Then you can slow it down and filter it to hear every cylinder firing. If you can post a sound clip that would be a great help.

[DJBarnstar]

Yeah my Yellow Jackets failed.

[Kinks]

I've got a set of splitfires on the way. So that should fix the coilpack issue. Was hoping to put off doing the FMIC for a bit, but I knew someone would tell me I was wasting my time with the SMIC sooner or later. Thanks Trent

John, our primary reference for knock was listening for it on the dyno. I have also set background knock by doing a run a while back with retarded timing and then using those values to zero the log. I think in the midrange my background values are around 80-100 and only from 3000 to 4500RPM, otherwise background levels are zero. I have CEL/MIL set to come on when a knock of 75 is detected (above the background) and it is fairly reliable at showing when actual knock is present. Sometimes Mark's golden ears picked up low levels of knock that I couldn't hear. But yeah, it's funny how much mechanical noise (such as coming off throttle) produces false readings.

[Dan_J]

Yeah. Depending on the exact cell, it was 11-14 degrees at about 4500rpm. Have you checked your timing by locking it (Adaptronic) and verifying with the crank marks + timing light? We had to fiddle with the trigger offsets to get it to line up properly with the CAS set in its normal spot. Otherwise we would have been about 7-8 degrees out.

What wideband are you using (and where is it installed)? Your symptoms sound similar to mine - I'm using the Innovate LC2 with the sensor about 10" in front of the cat and the calibration seems to be off compared with the dyno wideband. The LC2 appears to be reading a richer number than it actually is, so we retargeted my light load AFRs to be 13.8:1 to compensate. The engine was a lot happier with that.

could it be due to the fact that the cat/ muffler and length of exhaust distorts the exhaust gases to a leaner mixture if dyno wideband is clamped onto the muffler tip and not the fact that there is much of a difference between the two widebands ?

so the problem your having is not directly related to running too lean and the current bandaid fix that made a slight difference is just that ?

Edited May 23, 2015 by Dan_J

[Kinks]

cats do change the O2 reading... yes. They probably change it more at light load too, at full noise the air won't be in the cat long enough to react. Also, my muffler is a triflow so there's a limit to how far the tailpipe probe can go in. At light throttle it's easy to get a bit of reversion from the open air which makes the reading show lean (more residual O2). Not sure though. At any rate it's driving heaps nicer now.