RobTune: knock light flickering

robertpaige · Post by **robertpaige** » Tue Nov 25, 2014 5:59 pm

I figured I would make a thread because I'm unable to find any substantial information about the knock light feature of the RobTune.

While driving if I really get on it in some gears, around 3800 RPMs the knock light will flicker or flash, and sometimes it will also flash if I'm in 4/5th gear and gas it a little bit.

Is this cause for concern? Is my engine actually "knocking" and on it's last legs? Or is a bit of knocking normal? I'm just curious on this because I'm not really sure exactly what is happening or what the knock sensor is reading.

My AFRs are in the 11's at WOT

Mods:
RobTune
550's
16G TD05
Large FMIC
3" turbo back
Manual boost controller at 15ish

James614 · Post by **James614** » Tue Nov 25, 2014 6:34 pm

Mine flicked on long 3/4 pulls too. My engine seemed to be in good shape, and had a fresh tune-up when I did my swap. Even compression on thehigh end of the spec and everything.

I'm wondering if its just normal, and our concern is the reason no such light has ever been offered by an OEM.

robertpaige · Post by **robertpaige** » Tue Nov 25, 2014 10:24 pm

Yeah, I'm hoping rob can chime in or someone who knows more. I'm hoping that it's a normal thing, but I have read people saying the knock light never comes on, besides maybe lugging it up a hill in 5th

robertpaige · Post by **robertpaige** » Wed Nov 26, 2014 11:42 pm

Does the light indicate detonation or like an engine knock? Like a rod?

James614 · Post by **James614** » Thu Nov 27, 2014 2:04 am

It indicates detonation knock, its just a visual representation of the stock knock sensor working. You'd hear rod knock.

robertpaige · Post by **robertpaige** » Thu Nov 27, 2014 4:18 am

So it flickering is normal?

robertpaige · Post by **robertpaige** » Tue Dec 02, 2014 5:23 am

Now my clutch is in and I have been able to feel the car better, sometimes when I hit the gas real hard for the first time during the drive (car is hot) the car starts stuttering and popping and the cel is flickering. I just did a 3rd gear pull and the light was flickering and cut out, almost identical to fuel cut. Boost gauge shows I peaked at 18psi so idk what's going on. Am I detonating?

kimokalihi · Post by **kimokalihi** » Wed Dec 03, 2014 5:46 am

Can you get a video? Mine flickers when there's codes. I'd like to see if yours looks like this or looks like when I actually have knock or the sensor at least thinks there's knock (could be something else clunking).

robertpaige · Post by **robertpaige** » Wed Dec 03, 2014 7:39 am

Yeah I'll take one on my drive home tonight.

robertpaige · Post by **robertpaige** » Wed Dec 03, 2014 8:36 am

Here's a vid, 4th gear.

https://vimeo.com/113473391

robertpaige · Post by **robertpaige** » Wed Dec 03, 2014 8:37 am

I just watched my AFR and I was high 12 and 13's..... So I may be running lean. I'm not really sure where to check for things that make me run lean...

SILINC3R · Post by **SILINC3R** » Wed Dec 03, 2014 10:47 am

Any fuel leaks at the injectors, boost leaks

SILINC3R · Post by **SILINC3R** » Wed Dec 03, 2014 10:49 am

Injectors clogged, bad 02 sensor?

SILINC3R · Post by **SILINC3R** » Wed Dec 03, 2014 10:51 am

oh, also spark plugs good.

robertpaige · Post by **robertpaige** » Wed Dec 03, 2014 8:43 pm

No fuel leaks that I can see, o2 sensor seems fine I think, injectors haven't been flow tested, and spark plugs are brand new.

robertpaige · Post by **robertpaige** » Thu Dec 04, 2014 8:35 am

Fuel pressure regulator wasn't hooked up, the vac line on the intake manifold was disconnected. Since plugging that line back in, it has been good in the AFR's. But still the light is flickering.

Post by **Legacy777** » Sun Dec 07, 2014 9:14 pm

I would want Rob to confirm, but I suspect the light is like others have mentioned a visual representation of what the knock sensor is reading. There is "general" engine noise at different frequencies as the engine goes through the rpm range. The knock sensor may be picking up noise that is showing up with the light, but it may not be actual knock.

My Link ECU does this very same thing. It will detect engine noise, but it's really not detonation. If the ECU isn't pulling timing I wouldn't be concerned.

robertpaige · Post by **robertpaige** » Mon Dec 08, 2014 8:45 am

My AFRs are in the 10's under WOT, definitely what I like to see.

The light still flashes here and there with the regular AFR's, so I'm just going off that it's a visual representation of the knock sensor. The car pulls so good, I love it.

What had me wondering is that people said they never see the knock light with their RobTune, so I was hoping that it didn't mean my motor was making extra noise. Maybe Rob will chime in.

James614 · Post by **James614** » Mon Dec 08, 2014 9:10 am

Have you e-mailed Rob about it? I'm curious too, but don't want to go bombarding him with the same question.

CFK · Post by **CFK** » Fri Dec 12, 2014 8:02 am

Rarely on here anymore since my shit hasn't blown up lately lol.

But my setup basically sounds exactly the same except 440 injectors. Brand new Knock Sensor.

Leak down test was solid on the motor . When I'm WOT, it does flicker a bit, AFR's are are 10.9. Brand new innovative LC-1 & Bosch O2 sensor . Checked my FPR line, all good. Brand new Silicone line.

11's still pretty rich, I wouldn't think there would be a problem ! So the flickering went away with the line re-connected and it running at 10 ?

robertpaige · Post by **robertpaige** » Fri Dec 12, 2014 6:27 pm

I'm running like 10.5 ish and yeah my knock light flickers quite a bit in throttle actually. Even after I fixed the lean issue. But the motor sounds healthy!

robertpaige · Post by **robertpaige** » Mon Dec 15, 2014 12:35 am

Hope this is normal? And rob might chime in. New plugs. V power gapped to .028

Peak boost was 18 on this pull.

https://vimeo.com/114506119

kimokalihi · Post by **kimokalihi** » Mon Dec 15, 2014 5:21 am

Hmm pretty difficult to see it in that video. There's a lot of glare from the sun. Difficult to say if that looks like knock light or CEL.

robertpaige · Post by **robertpaige** » Mon Dec 15, 2014 10:38 am

I'll try to take one at night. Didn't realize the glare was right over it -_-

robertpaige · Post by **robertpaige** » Fri Dec 19, 2014 10:24 am

What would pulling timing feel like?

Randomly the car will hesitate and buck when I get on the gas.. It went away for awhile but did it a few days ago, and then today I was pinned in 4th gear and it hit a wall like fuel cut. Exactly like fuel cut, the car just cut out. I peaked at 19psi. I'm wondering if that was like a timing cut? I noticed the light flickering a little.

I'm gonna replace the knock sensor, maybe it's bad and picking up more frequency than it should? The motor seems healthy. Plus are brand new v power gapped to .028 and the car usually runs great. Just every now and then has a bucking problem. Seems like it happens when it's raining.. Might be a coincidence.

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans