Detonation problems, but my afr readings are good...?

[MarkyGsX]

undefinedhey guys....finally installed my zt2 wideband......my car feels like it is detonating under full boost (set at 15 psi) but my afr readings are in the 11's......it doesn't make sense because that reading indicates that i am not too lean nor too rich.....so why does it feel like im detonating.....my friend is guessing that i might have a faulty injector that is causing me to detonate in one piston.....im running 550cc rx7 injectors i pulled from the junkyard.....and i'm also running a gm maft......what do you guys think...?

 

[JiggahMan]

Wideband BEFORE datalogger???

 

[Newlogics]

undefinedhey guys....finally installed my zt2 wideband......my car feels like it is detonating under full boost (set at 15 psi) but my afr readings are in the 11's......it doesn't make sense because that reading indicates that i am not too lean nor too rich.....so why does it feel like im detonating.....my friend is guessing that i might have a faulty injector that is causing me to detonate in one piston.....im running 550cc rx7 injectors i pulled from the junkyard.....and i'm also running a gm maft......what do you guys think...?

If you had faulty injector, it would most likely show on your AFR. Log your timing.

 

[DSMTalonAWD51]

yea you want to watch your timing curve as well you cant just assume 11:1 will be fine. There are a number of reasons that could be the problem from clogged injectors/fuel pump to just bad gas. But use a logger an see what ur timing looks like. It could even be rich stutter for all you know.

 

[Newlogics]

If your timing is over 21-22* at WOT on the high end, then you'll knock even with good AFR. Usually, the cause for the timing to be that high is compensating for bigger injectors (althoguh 550s don't have it as bad as 660s and above). If too high of an advance turns out to be your problem, try lowering your base fuel pressure, and adding some fuel on SAFC.

Also, check and re-check your base timing. If it's too advanced, it will create knock problems for you. I wouldn't go past 5*. May be even 3* or so will work better for you.

Last, but not least, improper timing of the timing belt will cause knock in many cases (like being a tooth, or even half a tooth off)

At what rpm range do you see knock?

 

[MarkyGsX]

the knocking comes at around 4k then stops, then around 6k again......i haven't messed around with the timing at all since i got the car.....would it be normal for the car to still do that even if the my timing is set to oem specs....?

 

[Newlogics]

My first guess is that you knock at 4K due to too advanced of a timing, and around 6K due to being slightly lean.

 

[TimG]

Guess guess guess. Stop guessing. This is simple. Are you using a logger to check timing and knock count in those rpms ranges?

 

[MarkyGsX]

I am using a zeitronix datalogger to log my afr but it does not log timing....but the thing is i have not adjust the timing at all to my car.....you guys are saying its due to advanced timing and running lean...but i haven't advanced the timing at all.....what is the use of logging timing if you can't adjust it yet....?

 

[JiggahMan]

Wideband BEFORE datalogger???

Again, I'm going to reiterate my point. The reason you want to see what your timing is, is because you need to know if your car's running sh!tty or not. If it is (obviously) you can see W T F is wrong with it instead of playing this stupid guessing game. GO SELL THE WIDEBAND AND GET A LOGGER/MSD or what ever the hell you want for timing. (DSMLink is a very good option for the price of a logger/msd also)

BTW When your only mods are "Apexi N1 3" exhaust K&N filter hks evc" you DON'T need a wideband anyways the stock ecu will handle it fine.

 

[MarkyGsX]

Again, I'm going to reiterate my point. The reason you want to see what your timing is, is because you need to know if your car's running sh!tty or not. If it is (obviously) you can see W T F is wrong with it instead of playing this stupid guessing game. GO SELL THE WIDEBAND AND GET A LOGGER/MSD or what ever the hell you want for timing. (DSMLink is a very good option for the price of a logger/msd also)

BTW When your only mods are "Apexi N1 3" exhaust K&N filter hks evc" you DON'T need a wideband anyways the stock ecu will handle it fine.

Isee...point well taken....i think i'll keep the wideband though and just buy a logger....i'll need it eventually anyways.....i actually haven't updated my mod list in a while and i have a fmic, walbro 190 lph, and 550cc injectors now....and i don't think the ecu is taking too well right now....

 

[1993TalonTsiAWD]

The ecu will take fine to the 190 and 550cc as long as you watch them. The first gage should be a boost gage, then you need a logger always..never turn your boost up without a logger. Thats like sky diving without the chute. You have the mods, but you really need more than a wide ban, sure you can tune with it, but you can't log with it. second do you have a afpr. if not you need one, you can't just turn boost up it doesn't work like that.

Also just because you haven't touched the timing doesn't mean it's right. the ecu may have been able to handle it when you were at lower boost levels, but when you upped them the base timing was higher and it can only go too high before knock comes along.

So buy a logger can get one for cheap, and afpr to use those 550

Derek

 

[gman991057]

Guys timing is definitly a big factor when it comes to things like this but lets look at this situation a little dumber. After reading this rather short thread I have seen that he has some basic supporting mods, wideband o2 (which is nice and all) and 550 injectors. But I dont see any sort of tuning for those injectors, SAFC?? Unless he is running a 2g Maf which in this case would still be walking in the dark without a logger and still a tuning device, this car should be running very rich. Rich enough to suck a** on any kind of pull.

 

[gman991057]

My personal advice if you would like to go faster for now, considering you dont have any tuning device is to put your stock injectors back in, lower you boost to at least 16psi(not sure what your at now) and let it rip. Buy a logger and SAFC and go from there. I dont really care what your wideband is saying right now without a tuning device but you can use it with your stock injectors to make sure you are not running short on fuel. But BE SAFE and get a logger

 

[Maglin]

BTW. On craptastic west coast 91 octane fuel a AFR of 11.0:1 can be to lean. You would be better off around 10.5:1. You can do some searching to find out about data loggers. you can build a simple datalogging cable and use a M100 Palm running MMCD to log your car. Total cost would be around 40-50 bucks which is very cheap for what you can learn about what your car is doing under WOT. If you don't have a AFC either get one or a MAFT and GM MAF so you have something to tune your fuel with.

Widebands are great. I love mine. I have it also simulating my Narrowband now running a 14.9:1 Clossed loop AFR for better fuel miliage. Hope you find out your problem.