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Knock retard issues

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Dukesie79

Member
Joined
Jul 25, 2010
Messages
63
Hey guys, I'm new to the GN world and need some help. This is a long post, but please bear with me.

At WOT I'm getting some knock retard (up to 10) and my O2mV are going low (680.) I also have an LC-1 WB that reads a little lean (~13.0) at WOT also. The guy I bought the car from pretty much bought the car as I have it as far as turbo (TB03 60mm), 3"DP, Delphi 50# injectors, SMC round tank 2-nozzle alky injection, MAF Translator and 3.5" LS1 MAF, Kenny Belle front mount IC, Scanmaster 2.1, and installed is a chip of UNKNOWN origin. The only marking on it is a sticker that says "To the MAX" on it.

He did, however, completely rebuild the engine, including forged crank and pistons. He swapped the cam out for a hydraulic roller Comp cam. He says he can't remember the specs on it, but it came from Jegs a couple years ago and was the milder of the two hyd roller cams available at the time. He also said it was milder than what was in the car, but for whatever reason wanted the hyd roller.

I am about to start checking fuel pressures, Scanmaster values at idle/WOT (although it scares me since I'm reading lean and knock.) The car is running a manual "bleeder" style boost controller and I'm getting around 18# of boost.

My first question is...Does changing the cam make a huge difference in the tune? From what I've read about ordering chips, you MUST specify the cam (206/206, 212/212, etc) in order to get the tune right. Could this be a cause for the conditions I'm seeing? I feel like with alky and 50# injectors, I should have enough fuel to run 18# of boost. Like I said, I'm going to check fuel pressure, etc but want to make sure I'm not going to be chasing my tail if the chip's tune is WAY off.

Also, if anyone can help with the cam identification, that would be great. He says he knows int/exh were equal and was pretty sure it was 206/206, but I want to make sure before I go and order another chip. Plan on upgrading to turbotweak soon anyway.

Thanks for reading through and for any help you can provide.
 
OK I checked idle fuel pressure, 43psi line off, 36psi line on. Revving raises to 40psi or so.

Scanmaster values at idle:
AF 02
L8 25
bat 13.5
Int 133-137
bL 160
mph 00
clt 162
Ats 99
r 825
tps .46
IAC 00
cc 53
PL 2.4
SP 25.0

So just by reviewing others values, I think have some issues. AF seems low for sure. Anything else or advice on where to start??
 
If your chip were an Extender chip I would understand the AF reading. But since it isn't then the AF reading indicates a bad MAF, and as a result of the extremely low AF value your BLM's are also pegged at their max.

You're running EXTREMELY lean because of the low AF reading and this is likely what's causing your knock.
 
OK that makes sense. So is there any way to verify a bad MAF? Is it possible I have an intake leak somewhere or something causing the low readings?
 
OK did more checking. Pulled the chip out of the ECM and on the underside, it says Extender 24/23/21. Any clue there?

Also, the MAF was installed backwards, ie arrow pointing toward filter. Putting it in correctly did NOT help, still AF 02 at idle. It does increase to about 10 when you rev in park. After pulling the chip out, INt and BLM started at 128 like I thought they would, WB was reading almost 20. After about 30 seconds, Int and BLM climbed to 150 and 160 respectively and WB came down to around 15.5.
Checked the MAF translator settings, seem to be default for the GN, MAF 0, WOT 0, switches 1110. Also, there were no screens in the MAF and it looked like someone had tried to grind inside it or something from in to out along the 12oclock and 6oclock positions.
 
like he said, it looks like a bad maf. put AF on the scanmaster and go for a drive. look to see if the numbers rise progressively with throttle input. youre probably going to see they dont. thus your lean condition. like he said
 
Since we now know that is is an Extender, An Alky Extender at that, this would explain the low AF numbers. The numbers on Extneders read 1/2 or 1/3 of normal. This is the way they extend the MAF's range and is normal.

I suspect the reason you're seeing knock is because it is an ALKY chip with high timing, and if you're not running the alky that's on board that would account for the knock.

Everything in alky chips relys on a good working alky injection system.
 
AND if you continue to run the car with 10* of knock @ WOT it won't last long! so I would not do that until you figure that out 100%.. Listen to what Dave has to say he's the (Cal Hartline of Translators/extenders)!!! ;)


SW.
 
I'm back onto this subject again. Thought I had it narrowed down to the old alky system. The pump was only producing around 15psi where I think it needed to be around 75. So I ordered a TT 5.6 chip, street tune, no alky. Took it out with the new chip today. At 17psi I STILL get KR, upwards of 6* and O2 dropping to the 530s. In fact, from about 5mph, I got 13.6* and 101 O2, both at 27mph. Quick to lift at that point for sure.

When I got back (VERY frustrated I might add) I decided to double check everything and noticed the TPS settings were a little off. Key on/engine off, I was at .44V. WOT was 4.18V. I adjusted to .46 and around 4.4. Haven't had a chance to drive it, but here's my question...

At what TPS voltage does the ECM consider WOT? Is it possible I wasn't reaching that point and therefore staying in closed loop? I'm really beating my head against the wall here. The only thing I haven't been able to check is fuel pressure while driving the car. Guess I'll try to come up with something so I can watch while boosting.

Any insight would be great as I'm about to lose my mind...Thanks
 
Is your BL still high (over 140)? If it is look for a vac leak. If BL is ok i would add a couple of pounds of fuel pressure and drop the boost to around 14. 17 is to much for 93 pump gas. If it is only 91, then it really is to much boost.
 
Your maf reading may be off. I had a similar trouble where my LS1 maf was locked on a number and would not deviate from it regardless of throttle input. causing a lean condition.
 
I'm back onto this subject again. Thought I had it narrowed down to the old alky system. The pump was only producing around 15psi where I think it needed to be around 75. So I ordered a TT 5.6 chip, street tune, no alky. Took it out with the new chip today. At 17psi I STILL get KR, upwards of 6* and O2 dropping to the 530s. In fact, from about 5mph, I got 13.6* and 101 O2, both at 27mph. Quick to lift at that point for sure.

When I got back (VERY frustrated I might add) I decided to double check everything and noticed the TPS settings were a little off. Key on/engine off, I was at .44V. WOT was 4.18V. I adjusted to .46 and around 4.4. Haven't had a chance to drive it, but here's my question...

At what TPS voltage does the ECM consider WOT? Is it possible I wasn't reaching that point and therefore staying in closed loop? I'm really beating my head against the wall here. The only thing I haven't been able to check is fuel pressure while driving the car. Guess I'll try to come up with something so I can watch while boosting.

Any insight would be great as I'm about to lose my mind...Thanks

Your slightly misadjusted TPS isn't the cause of the lean condition, but you adjusted it in the wrong direction. You want the idle value to be closer to .40-.42 ideally. The best way to adjust them is to do WOT adj. first, by pulling the tps all the way forward in it's adjustment and tightening the screws just enough to hold it there. Then loosen one of them to allow slitght up/down adjustments to the nose of the tps(idle adjustment).

YOu've got to get to the source of running so lean!! Fuel pressure rising with boost???? How's the fuel filter????
 
I'm working on a solution to watch fuel pressure with boost My tester's hose isn't long enough. I'll change the fuel filter. The car sat for a year or two with the same fuel in it so maybe it's getting plugged.

Berserker6, my MAF is brand new but I'll check it while driving to make sure its value is changing.
 
I'm not sure. I know its aftermarket and it's been hotwired too. The car ran fine when I bought it and for the 4 years before that since I bought the car from a friend and know the history. The fuel pump was in it when he bought it.
 
Update:
Had some good weather in KY today, so decided to do some more tinkering.

Don't know why I never thought about this last year when I was having issues, but I started researching through some spark plug threads on the board, wondering about heat ranges, etc. Coming from the 300ZX twin turbo world, I know that colder range plugs are a must when bumping up the boost. People praise NGK UR5s for our cars so I ordered a set back around Thanksgiving and they had been sitting on my microwave ever since.
Today, I pulled the old ones out to find that they were a stock heat range Autolite Platinum AR25. Dropped in the NGKs gapped at 0.032" and needless to say, one test drive and my knock virtually disappeared. Still getting a little (2-4 deg) at 57mph. Think that's a shift point so I'm not too concerned since it goes right away. I also ran out of alky on the test drive, but got to 17psi and I'm thrilled so far. Next good day I get a chance to take it out, I might bump up the boost a lb or two to see what happens. BTW, the lowest O2mV i saw was 800 or so, so I'm pretty sure I don't have a fuel problem.
 
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