Weird...

[TSiTalonawd96]

So as some of you might have read my last thread, I had a crazy high knock count and a intermitten running rich problem. Well, I have fixed those problems (ended up being a bad knock sensor and the TPS was out of adjustment) but have one last issue. Around 4500rpm I'm getting about 10 counts of knock, but only because my AFR's are going back to 14.7 to 1 for a second, then going back to 9.5 to 1. I have replaced my MAF (it was also out of wack), and knock sensor, and have tested and readjusted the TPS. The only things I can think of that would make it do this would be a fauly 02 sensor(which seems unlikely) or something wrong with my ECM... Here are some logs.. (note: they are all the same log, the values are changed from minimum, average, and maximum). Any suggestions?

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[gofer]

THATS CRAZY! My car does the same thing right at 4.5k too, it spikes lean for a second and then back down to a safe AFR. On my car it would happen so fast dsmlink wouldn't pick it up (we only saw it on the dyno) and luckily my car doesn't knock because of it either. Because my car didn't knock when it would spike lean I never looked for the fix to the problem so I'm sorry I can't help you there. I can tell you it wouldn't be your o2 sensor, the ECU only uses the front o2 during closed loop operation and your in open loop at WOT.

 

[1995gsx20g]

question can you log tps on the same graph as this?

gofer- i think he meant that there might be something wrong with his ecu

 

[TSiTalonawd96]

^^Im glad to see im not the only one with this problem!

Yea, I can log TP but it just says 99.5% through the whole thing.

So I bought a SAFC II last night in hopes to just correct the airflow at that rpm so it doesn't happen anymore. I've been doing a lot of reading on here today and it seems you really can't do much changing with stock injectors(most said + or - 7.5%) Maybe that will do the trick. Im new to this tunning thing and im a bit confused...

Air/fuel correction is pretty straight forward but the low and high throttle settings is where it gets me, I hear to start at 30%low and 80%high. Does this mean the SAFC wont kick in until it hits these percentages with the TPS? If this is true wouldn't you want the high to be at 100% so it will correct under WOT?

It would be nice if I knew somebody that could show me in person, I know I could pick it up pretty quick.

 

[1995gsx20g]

THATS CRAZY! My car does the same thing right at 4.5k too, it spikes lean for a second and then back down to a safe AFR. On my car it would happen so fast dsmlink wouldn't pick it up (we only saw it on the dyno) and luckily my car doesn't knock because of it either. Because my car didn't knock when it would spike lean I never looked for the fix to the problem so I'm sorry I can't help you there. I can tell you it wouldn't be your o2 sensor, the ECU only uses the front o2 during closed loop operation and your in open loop at WOT.

when this happened what did RRE say?

im very curious about this problem but can't come up with solutions or even leads to go on. gonna keep thinking..

 

[gofer]

when this happened what did RRE say?

im very curious about this problem but can't come up with solutions or even leads to go on. gonna keep thinking..

Honestly, the look on Sams face when he saw it spiking lean on the dyno it didn't look good. But he looked at his log in link (which didn't show it) and it didn't knock so he pretty much said, #### it. I did ask him what could be causing it though and he didn't have anything to say... he might not have been listening because he was tuning my car and playing with my DA maps in link.

If it was causing problems on my car the first thing I'd replace would be the MAF, which the OP has already done. Then I'd start checking the wiring going to the connector that plugs into the MAF... I'm deadset on thinking its MAF related since its at that same RPM everytime. My guess is that whatever Hz reading is at 4.5k at WOT the MAF isn't inputing to the ECU so it goes lean until it starts seeing your at WOT again.

I can't see your logs, they look like

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to me.

 

[TSiTalonawd96]

If it was causing problems on my car the first thing I'd replace would be the MAF, which the OP has already done. Then I'd start checking the wiring going to the connector that plugs into the MAF... I'm deadset on thinking its MAF related since its at that same RPM everytime. My guess is that whatever Hz reading is at 4.5k at WOT the MAF isn't inputing to the ECU so it goes lean until it starts seeing your at WOT again.


^^I agree... It must be something with the wiring because I have already replaced the MAF and still the same thing.

I have a question about this SAFC... Im just trying to change my AFR's (mostly at 5K rpm), do I need to do anything with the throttle settings other than set them to 30 and 80? Also, under WOT(100%) with the SAFC still do its job since my high setting is only 80%?

 

[1995gsx20g]

hmm...

what gets me is that its at exactly 4500rpm and if both of you aren't running the same exact boost levels with VERY similar mods then hertz could be very different. the maf just sees airflow not rpm and the ecu is what puts it all together.

im thinking it has something to do with the ecu or some other vital sensor.

im going on a wing on this one..
both of you have logged it but could it be that with the super fast data transfer rate your logging at that it's slowing down how fast the ecu can look up maps and change accordingly?

it also might not help that a 16g makes close to peak torque and peak hp at that rpm iirc

 

[TSiTalonawd96]

I think you may be on to something^^

I just installed my SAFC and did some logging. Since the computer was reset the first logs were more accurate. I have an atmospheric BOV right now and I did some pulls and logged more. I noticed everything started going crazy, AFR's, knock ect. So first off I need to recirculate it. The more and more me and my buddy talk about what you said, it makes more and more sense. The car runs fine with everything 0'd and if I add some fuel at 4500rpm then I can feel it on the but dyno. It almost hesitates for a milisecond at that rpm. I have been beating the snot out of this car since I got it and no problems so far... I have also had someone else tell me they were getting high counts of knock when logging but then when they weren't logging it was fine. (I don't remember what he used instead of the logger now)

 

[1995gsx20g]

if your exhaust isn't crazy loud you should be able to hear severe knock.

 

[Calan]

if your exhaust isn't crazy loud you should be able to hear severe knock.

You're way past the danger point if you can actually hear the knock.

 

[1995gsx20g]

You're way past the danger point if you can actually hear the knock.

ok let me rephrase this. i don't have anything over 250whp but i can hear timing being pulled when i get knock.