tuning prob. 9.5:1 afr but lots of knock

[crazyboost]

So i just installed my innovate LC-1 wideband yesterday, and im going out to tune it. It shows wideband readings of 9 to 10:1 afr (really rich). So I lean it out so that my safc settings are all around -12 or -13 on the hi settings. I do another 2nd and 3rd gear pull and the readings of the wideband are around 10 - 10.5:1, still fairly rich. Just to be safe i wanted to see how my timing/knock ect was on my datalogger. Im using the technomotive datalogger through my laptop. So I do a second and third gear pull and I'm seeing tons of consistent knock, from 10-20 counts, and my timing is getting pulled. So i richen it up a bit and i still get knock, richen it up so that my safc settings are all -8 on hi throttle. I still get some knock but my wideband readings are all the way back down to the mid 9's again. wtf? Is my new expensive wideband off or what is going on here? So i checked my plugs and they are white (lean). One other thing is that when im doing a pull usually around 5000 rpms or so in third the engine will cut out like fuel cut, but is this possible with the gm maft? Anyone else have any ideas on what i should do? thanks


My mods are: 550cc injectors, safc, maft and 3" gm maf, jrc 8" fmic and 2.5" piping, 3" turbo-back exhaust, custom 02 dump, mbc set at 15psi.

 

[ian7321]

Get a new knock sensor, but first check ifn yours is bad by reaching down and feelin the back on the one on the car and seeing if it had goo on the back. it is located about 6inches to the passenger side of the car from the ac bracket.

 

[crazyboost]

I'll do that first thing tomorrow. Could a leaky bov also be creating this problem. I have my gm maf in blow-thru so it vents. Could it the turbo be spooling crazy fast to try and make the 15 psi because it keeps leaking out and maybe its just pushing hot air. Then this hot air would be creating the knock while still maintaining a rich air to fuel ratio. Or does the gm maf take temperature into consideration when measuring the air, or am i just retarded and have no idea what im talking about? This is also on 91 octane gas for reference. I know that it is crap, but thats what most gas stations have around here, im gonna install my water injection kit soon so that will help, but i just want to get this figured out soon. thanks

 

[1990EclipseGSX]

Have you done a boost leak test?

 

[steve]

So i checked my plugs and they are white (lean).

White plug also mean hot, as in hot enough to burn all the deposits off.
Unless they are glassy white or have metal specs in them it's not a problem.

Steve

 

[crazyboost]

1990eclipsegsx, so if i had a boost leak would my theory be correct where my afr's would show rich but the air would be really hot and produce knock? thanks guys

 

[1SloColt]

Where is the timing mark at on the ground strap?

 

[crazyboost]

Where is the timing mark at on the ground strap?

Could you ellaborate please? I'm not sure what you are talking about. thank you

 

[BUCK]

Could you ellaborate please? I'm not sure what you are talking about. thank you

My guess is that's CODE for - What is your Base Timing?

 

[crazyboost]

thats what i thought too but i wasn't sure. I'm gonna try and get a timing light tomorrow so i can figure out if its 5 degrees btdc. Any other ideas on why i have so much knock with such a low afr?

 

[BUCK]

Not to bring you any bad luck or anything but I don't see BSE on your Mod list...

 

[crazyboost]

Not to bring you any bad luck or anything but I don't see BSE on your Mod list...

Im guessing BSE stands for balanche shaft elmination or some thing, what would that have to do with all of this?

 

[BUCK]

It's well known they can cause knock when their Bearings are getting ready to check out... I was hoping maybe you just didn't put it in your Mod list... BSE should be a high priority Mod in your near future if you like that Motor.

Rule # 1 - Balance Shafts are the Root of ALL Evil.

 

[crazyboost]

thanks buck, ill look into that. My motor has close to 130k miles on it anyway so i might just wait til it goes and then put a BSE kit on there when im rebuilding it.

Some more info is that my vacuum at idle is only around 14 in hg and around 18-20 during deceleration. Would this mean that i have a boost leak? or bad compression? or bad base ignition timing? or?

 

[1SloColt]

Could you ellaborate please? I'm not sure what you are talking about. thank you

If you take a look at your grounding strap on the plug you'll see a small white line going across the strap. This tells you the total advancement of timing you are seeing. If the mark is too high on the bend you are getting too little timing, if the timing is too low on the bend you are getting too much advance. You want the mark to be directly in the middle of the bend.

 

[steve]

If you take a look at your grounding strap on the plug you'll see a small white line going across the strap.

It looks like I'm not the only one who has no idea what your talking about.
Which gounding strap on what plug?

Steve

 

[1SloColt]

A sparkplug has a grouding strap, its the thin piece of metal with a 90 degree bend that is over top the electrode. The spark occurs between the electrode and grounding strap.

No offense to anyone on this forum but basic sparkplug reading skills are a necessity to good tuning. Your best tuners are huge advocates of pulling plugs between pulls to see how things are going inside the combustion chamber. When I get home i'll provide an awesome link for pics and full details of what to look for in reading plugs.

 

[steve]

A sparkplug has a grouding strap.

Thank you. Just saying sparkplug instead of plug would have made this clearer to start with.
Does the fact that on one plug in the pair of a wasted spark ignition, the spark jumps from the center electrode to the ground electrode and on the other the spark jumps from ground electrode to the center electrode change the way you read this?

Steve

 

[crazyboost]

so could a boost leak and/or poor base timing contribute to my wideband reading rich afr's but still giving my lots of knock and shitty idle with 14 in hg of vacuum? could the boost leak be bad enough to make my turbo have to spin a lot faster and just blow really hot air, which leaves a rich afr but since the air is hot it just detonates and gives me knock?

 

[1990EclipseGSX]

so could a boost leak and/or poor base timing contribute to my wideband reading rich afr's but still giving my lots of knock and shitty idle with 14 in hg of vacuum? could the boost leak be bad enough to make my turbo have to spin a lot faster and just blow really hot air, which leaves a rich afr but since the air is hot it just detonates and gives me knock?

Could be a definite possibility with a large boost leak on a 14b. Have you done a leak test yet?

 

[crazyboost]

No not yet, i did make my boost leak tester though. It was raining all day and im a poor college student and have my car parked in a lot. My air compressor is at home so im either gonna have to wait til this weekend so i can go home and do it or on a decent day when its not snowing/raining, go to a gas station and use their free air. so 1990 the standard 11 to 11.5:1 afr for pump gas is assuming that the air pushed by the turbo is close to ambient after intercooling? and not hot (possibly in my case)?

 

[HighPSI TSi Guy]

check base timing. might have to set it to 3 or so to get rid of the knock.

 

[1SloColt]

Take a look at this: Sparkplug reading

 

[HighPSI TSi Guy]

Take a look at this: Sparkplug reading

shush.. don't give away the secrets!

 

[1SloColt]

shush.. don't give away the secrets!

Hahaha, I'm tired of seeing so many junk DSMs so hopefully the basic plug readings should push them in the right direction. All those SRTs at the dynowars was depressing, what we needed was 4 or 5 dsms there just to let them know where they stand .