rush7

iTrader: (2)

I've heard all this talk of the sensors on the 98's being bad, but I guess I have yet to experience it. I do show some KR (it can get up to 3 but usually stays around 2) but only when pulling in a higher gear (5th or 6th) at really low RPM's (~1500), while commanding some throttle. I'm not sure if that is actual KR (the car does shake a little bit) or whether something else was causing the shaking and the sensors are picking up on that. Of course I want to get rid of knock across the board for performance purposes, but when I'm trying to get from point A to point B fast, I'm generally not going to try to punch the petal out of low RPM's anyway (I'd downshift before doing anything). Anybody have this problem or know whether it's false knock or something that I need to turn out?

(also sorry for the mini-hijack...just people inside here that seem to know about this subject)

Another_User

It's false knock in my car for sure. No matter how much timing I pulled or how much fuel I threw at it, the car would still get 3-4 degrees of KR. I have never heard any detonation in my car other than an occassional ping if I hit the gas too hard at a really really low RPM.

dvanorder

4 degrees is really the max KR for a 98 PCM? Is this just F Body? I've had more in my 98 C5---but it was also built late June 98.

V-10 Killer

iTrader: (22)

I had a problem with the knock sensors in my '98 TA last year. Every time I'd log a run I'd see knock, so I'd pull timing and run again. Just to see the same thing again. By the time the season ended, I was still getting knock and my timing was all the way down to 19.5 degrees at WOT. I put two of the OLD 10456222 knock sensors back in because I found out about different part numbers and wire harnesses too late. I haven't picked up ANY knock on any logged runs this year and am currently running 28-29 degrees of timing now. I'd still recommend the new versions, but I think the new "old" ones run pretty good for me anyway.

speedo

iTrader: (15)

Dang graphed mine today and I get 3.5-4 degrees at WOT.. So is this bad or what? What does this actually effect? I don't see the knock with normal driving, only when I floor it.

Is it good to just get them tuned out?

Predator

Hey speedo, it's better to fix the problem rather than desensitizing the knock sensors. With 4-5* of knock retard, it puts you in the low octane table costing at least 20 ponies.

Predator

Just wanted to add that you need to determine if it's false knock or real.

speedo

iTrader: (15)

Well with my set up, I THINK it is all false. My car is very loud when I step on it due to cats delete and the flowbastered in the rear that is if I don't have the cutout open. My cam is on a 112 LSA also so I am sure all that shaking isn't good for knock either. Am I totally off here? Plus all this reading about the 98 sensors being junk don't help either. But I am not 100% sure..

How can I tell. Only have the Autotap version 1 so it really don't tell me a whole lot. I want to upgrade, but just don't know if I have the knowledge or the time to learn the software.

If I go in for a dyno tune would they be able to fix this situation, or should I just start saving up for better sensors?


Thanks for the info.

SmokingWS6

iTrader: (1)

As I stated before late model 98's already have the revised 99 sensors so no suprise there. I assume the easiest test is to scan for KR, if your getting a ton of kr on a stock tune chances may be you have bad sensors.

Also, it doesn't hurt to go to the dealer for parts. I called them and got my harness(even though it turns out I didn't need it) and sensors the next day

Predator

Yup, if you don't have the newer sensors I would swap those out. Chances are you will have to anyway, and it just might solve your problem. Also, you need to perform the GM TSB which involves making a silicone dam (RTV red) around the sensors and removing the foam square under the intake.

speedo

iTrader: (15)

Talked to my tuner today and he is going to try to get them down first, before I swap them out. I figure this is free, so I will try it. Well see. I am sure I will probalby end up doing the swap down the road here. Plus my mechanic said they had some of the upgraded ones at the dealership down the road and they only carry stuff on hand that there is allot of known problems with. So that tells me something right there.

Ah well we will see. 20hp is allot to be losing for something so dumb....!

obZidian

iTrader: (2)

im getting tons of knock retard from 1200-2k....all at part throttle AND when the tc is locked...the car seems to "Run'out" of fuel or hitting a wall... i mean the highest i have recorded is 15 k.r.!! im not kinding...and when the ac is on, fo get it, kr all the time is pegged at 16k.r. (this is all on hptuners...)

Im getting her tuned on friday so well see wat we can do, hopefully jeremy (rev extreme) can help, thouh i have no other expectations..

SmokingWS6

iTrader: (1)

Insane

Mat

I just finished my VE tuning, and my MAF calibration. The car is still going through knock learn to get itself back into the high octane tables and I'm already seeing 2* of retard at WOT with only 22.5 degrees of total timing. Gimmie a break. Knock my ***!

Our 98's do have issues. I wonder if it's because of what the TSB fixes. As mentioned if some of us have replaced our "old" sensors with new "old" sensors and had it disappear.....

I'm gonna use Another_User's very helpful advice on how to tune it out for a temporary fix this year or maybe just into the fall. Depends when I get the moolah sitting around for an SLP LS6 EGR intake.

ND4SPD _SS

iTrader: (52)

does anyone know where i can get a wtire up or some kind of install help? i am going to change mine and can't seem to find any write ups. i would appreciate any help.
thanks in advance.

obZidian

iTrader: (2)

okay, so which one should we change to?

Im confused because i have read two different stories here...any help?

either:
1. a set of 99'z with the harness
2. revised 98'z # 10456603
3. 10456222 (i think these are another set of 98'z but new/old ones? )

also, swapping them out, should i do this? and why?

from Predator.
Yup, if you don't have the newer sensors I would swap those out. Chances are you will have to anyway, and it just might solve your problem. Also, you need to perform the GM TSB which involves making a silicone dam (RTV red) around the sensors and removing the foam square under the intake.

any help would be great, just want to clear all of this stufdf up in my head...thanks!

Predator

obZ, I think 1&2 are the same. As long as you get the sensors that are used on '99s and up you'll be okay. You'll need a new wire too because the connection is different on the '98s. Just stay away from '98 sensors altogether.

Predator

As to why, if you have a '98 you probably have 4* degrees of knock retard. If you have a '99 and up, there is a GM TSB out on the knock sensors because moisture, from weather or washing your engine, cause the sensors to corrode and short out.

Viper

iTrader: (6)

People have also used teflon tape when putting them in to help eliminate false knock, fwiw. On my 99 I desensitized the knock sesnors in HPTuners.

obZidian

iTrader: (2)

thanks, and yes....4 degrees all over the place...especially at idle and low throttle acceleration.

as for the tsb, is there a pic or a write i can take a look so i can make sure i will be doing this right?