My timing issues - 45BTDC + 15PSI = no no

[huguetpj]

Some of you may remember I posted a while back about ignition problems I was having. Well, I've changed my stock wires to some nology wires (great spark by the way) but I still detonate after 11.5PSI and only gets worse when you push the boost up.

I connected a Scan tool to my car and it seems that what I was afraid was going to happen is happening. The AFC is telling the ECU that less air is entering than it really is so the ECU thinks my car needs more power and pushes the timing up to 45°. I have my stock timing at 15°BTDC. This means that at full boost my car is seeing 40°BTDC. WAY too much for over 11PSI. I know this is the problem cause I bumped the base timing to 0°BTDC and the car does not detonate anymore up to 14.5PSI, where I did not push further. Of course it is more powerful @ 9PSI and 15BTDC than @ 14.5PSI and 0BTDC. And it's really difficult to even start the car with my 550cc inyectors and that timing.

So I'm gonna try it out with some VP110 fuel at the track this weekend to see how much I need to retard the ignition to prevent detonation at 15PSI. My mechanic suggested 2 gals of VP110 per 3 gals of 93 octane pump gas. Anybody recommend anything else? I'm also gonna use some Chemical X in the mixture (octane booster).

Of course my next steps is to either get an emanage, a reprogrammed ECU (still trying to have the time to do it myself) or a BTM.

Just wanted to beware those running an AFC with big inyectors. By the way, my AFRs @ the dyno show 12.0-12.5 across the board.

[Structure240sx]

45 degrees is where you should be at for cruising, are you sure this is at WOT? does the car sputter at all or fall on its face when tryin to make power?

[virus77]

is it 45 degrees when you get on full boost and around 5k rpm. becuase if it is part throttle you will see timing numbers like that on normal crusing. Its only when you get on it that the numbers will fall to the 10's and 20's.

EDIT: damn you structure, a hair before me.

[NateDogg]

Hugue...I am thinking TPS. Maybe it''s reading part-throttle when you're pedal to the metal. 45 degrees doesn't sound right, especially on a full throttle load.

[huguetpj]

45 degrees is where you should be at for cruising, are you sure this is at WOT? does the car sputter at all or fall on its face when tryin to make power?

Actually I have not made any WOT runs with the scanner yet. I'll get back to you on that. The car sometimes just sputters all the way up to redline (I only tried this on the dyno), but sometimes it just falls on it's face (this happened to me last Saturday at the track) and won't rev anymore until I stop accelerating.

Even with the VP fuel mixture the car still detonates. What was very weird was that when I set the timing to around 0BTDC the car still detonated when that did not happen when I tested it on the street, even with the VP fuel mixture. Although bare in mind it was quite hot at the track.

Once the car comes out of the paint shop I'll do some more testing with the scanner to see what it may be. I'll check the TPS to see, but I'm sure we set it up fine last time the motor was put together.

If the ECU is not advancing timing as was my first thought, what else could it be? I'm currently running Nology coil + Nology wires and when testing the spark by jumping it to ground I can tell you it's a BIG spark Although I might try gapping the spark plugs closer, I have them currently at around .035". On the dyno the AFRs were rock solid at 12.0-12.5 so I don't think I'm running lean. Neither does the EGT get past 1200F on extended runs, maybe 1300 tops. So I'm positive I'm not running lean.

Right know I have no idea what could be happening...

[Structure240sx]

whats the fuel setup? i doubt your are detonating and probably jsut blwoing out spark.

saw your plug gap, how much boost are you running?

[huguetpj]

Fuel system: Stock FPR + Walbro 255HP fuel pump + 550cc injectors dyno tuned to 12.0-12.5 AFRs.

Ignition system: Stock everything except for Nology coil and Nology wires. I believe I set up my gap to .035 (although my gap tool is average at best). Anything above 10.5-11PSI will detonate or blow out the spark whichever the case may be. How do I know if I'm detonating or blowing out the spark?

I definetely still need to do more controlled conditions tests, but just wanted to see if anybody has any better ideas. Currently my only ideas would be to use the OBD1 scanner to measure ignition timing and set base timing to either 15 or 10 degrees BTDC, gap my plugs with a good tool at 0.025-0.030" to try it out and maybe do a trip or two to the dyno again although I don't think it would be necessary.

[virus77]

At .035 gap my KA wouldn't go past 11-12 psi. took it down to .026-.028 and it was fine up untill 16 psi. Im sure it would go higher but my motor blew Drop the gap

[fiznat]

You guys can use this for comparison if youd like for timing vs. throttle and load. It's a few parameters from a log I did last week:



Click here for a very large version: http://www.afreeimagehost.com/...g.jpg

This is a log of a pull through 3rd, 4th, and 5th gear. The red line is ignition timing in degrees, the green line is throttle, and the blue line is engine load (boost). You can see that I hardly got on the throttle at all in 3rd gear, then got more into it in 4th and 5th. The graphs are in sync so each "time" mark at the bottom corresponds to each parameter at that moment.

Hopefully this helps people see how timing should work along with throttle and load...

[huguetpj]

At .035 gap my KA wouldn't go past 11-12 psi. took it down to .026-.028 and it was fine up untill 16 psi. Im sure it would go higher but my motor blew Drop the gap

I'll do that first once I get my car back.

And thanks fiz for the graph. I hope it's gonna be very helpful.

[240SicknessX]

umm, someone said tps and you have a safc? i installed a safc II in my friends NA s13. His we found out after the fact that his tps was bad and thats why we had 44% throttle imput at idel.... that was in the monitoring mode, i installed a safc II in my car with no problems so ive done it before correctly. and i followed and rechecked every procedure. Well the tps is not sending the correct voltage to the ecu which corrosponds to throttle imput. ( yes i have the arrow pointing up in that menu w\ 4cyl)

btw you can go into i think its sensor check in the safc. and then it will read the voltage that is coming from the tps to the ecu. 0% throttle should be <1 volt, wot is suppost to be 3-5volts.

[Jookmasta]

[huguetpj]

umm, someone said tps and you have a safc? i installed a safc II in my friends NA s13. His we found out after the fact that his tps was bad and thats why we had 44% throttle imput at idel.... that was in the monitoring mode, i installed a safc II in my car with no problems so ive done it before correctly. and i followed and rechecked every procedure. Well the tps is not sending the correct voltage to the ecu which corrosponds to throttle imput. ( yes i have the arrow pointing up in that menu w\ 4cyl)

btw you can go into i think its sensor check in the safc. and then it will read the voltage that is coming from the tps to the ecu. 0% throttle should be <1 volt, wot is suppost to be 3-5volts.

I did check the TPS voltage with the sensor check and it seems ok. I didn't actually see the exact value but it seemed ok.

[240SicknessX]

I did check the TPS voltage with the sensor check and it seems ok. I didn't actually see the exact value but it seemed ok.

im assuming your using the safc II, i dont know if its the same for the safc I. ( im using safc II, thats what im talking about). If you go into sensor check you should get <1 volt at 0% throttle then 3-5 volts at WOT. providing you have everything hooked up correctly and your voltages are there, then your tps is fine. if you arent gettin the correct <1 volt at 0% or more or less then 3-5 volts at wot, your throttle %age would be off when driving the car. which will screw up how the safc alters the mafs signal. If your reading the throttle imput 0-100% then everything should be good.

with out the correct translation of the mafs signal from the safc, it will throw off the timing map when compared to tps voltage and you could get your weird total timing numbers.

[huguetpj]

Yes it's the same for the SAFC 1 & 2. Yes my SAFC 2 is reading the correct values and working with the 0-100% range. What I meant is that I did not check if the TPS voltage @ idle is ~0.4V as the FSM says it should be or 4.5V (??) at WOT.

Couple of more days to go before I get my car back and start testing again. I'll let you guys know how it goes.

[huguetpj]

At .035 gap my KA wouldn't go past 11-12 psi. took it down to .026-.028 and it was fine up untill 16 psi. Im sure it would go higher but my motor blew Drop the gap

hey virus.... it just took me 2 and half month to try out your suggestion and you were right on the money. I gapped my plugs down to 0.026 and I can boost up to 15PSI no prob. I can't go higher because it seems the WG is opening up on me probably because the boost drop between the compressor and the TB is more than the WG spring's rated pressure (3.75PSI). But hey... that kinda problem I don't mind.

So I'm up to 15PSI know... hopefully I'll reach my goal of 18-20PSI before I leave for China in late August.

Thanks again everybody for your inputs.

[virus77]

No problem man, you learn from other peoples mistakes and experiances.

[WDRacing]

Congrats on the boost Pedro. I know you've been working on that thing as long as I have...which is to say you've had a ton of down time. Glad your up and running.

WD

[huguetpj]

Thanks. Man do I know about down time.

Anyway... I've been playing around with the gap. At 0.030 it works great @ night or when it's cold outside. Once the temp starts to rise it starts to blow out the spark again. So I'm going to take it down to 0.028 and try it again. I'm also working on moving the boost signal (for the WG not the digital readout) for my SBC closer to the compressor outlet in order to make it possible to boost more. 18PSI was my goal and I'm almost there. Just need to go the closest hydraulics store a buy a damn $5 T to replace the 90deg elbow I have on the outlet port of the compressor.

[virus77]

actually if you put the wastegate signal by the turbo you will boost less, if you put it off your FPR or some vacuum line by the TB it will see less boost and increase you boost.

[huguetpj]

Nah... I meant the line that goes to the top port on the WG which keeps it closed... the signal line controlled by the SBC. The side port on the WG is connected by a stainless steel hose to the compressor outlet... for safety.

What I want to do is move the top signal line closer to the compressor so it does not read the boost drop through the pipes and intercooler... which I believe to be more than 3.75PSI... so the WG will not open because of this difference in pressures.