1998 Trans Am knock sensor problem

**90ARAPAJ** · 06-09-2011, 08:26 AM

Hey guys, i have a 98 t/a and i have the usual bolt ons and my knock sensors are bad according to my brother because i hav a roll cage and subframe connectors and it stiffens the ride hence the knock sensors going off.....what can i do to get my full engine power and replace them?

**pajeff02** · 06-09-2011, 06:04 PM

I highly doubt that is the problem with your car. The knock sensors could be an issue... but not for the reasons you stated. If you suspect a knock sensor issue you need to connect a scanner to your car and see if the PCM is pulling timing due to knock.

What specifically are the problems that you are experiencing?

**90ARAPAJ** · 06-10-2011, 05:50 AM

Originally Posted by pajeff02

I highly doubt that is the problem with your car. The knock sensors could be an issue... but not for the reasons you stated. If you suspect a knock sensor issue you need to connect a scanner to your car and see if the PCM is pulling timing due to knock.

What specifically are the problems that you are experiencing?

Well to egin with im getting robbed of power...when i rev it steady to about 1600 rpm and keep it there you can notice the car kinda vibrating choppy ya know? also i dont redline at 6000RPM like i tuned it to with the hypertech...it only goes to about 5800 and when i make it 6100 it goes there but im scared to blow my motor.....sooooo??

**pajeff02** · 06-10-2011, 09:57 AM

Originally Posted by 90ARAPAJ

Well to egin with im getting robbed of power...when i rev it steady to about 1600 rpm and keep it there you can notice the car kinda vibrating choppy ya know? also i dont redline at 6000RPM like i tuned it to with the hypertech...it only goes to about 5800 and when i make it 6100 it goes there but im scared to blow my motor.....sooooo??

Clean the MAF and go back to the stock tune.

**JayTA98** · 06-10-2011, 10:56 AM

agree with Jeff. The SFC or roll cage won't have nothing to do with this issue. Clean the MAF, go back to stock tune and if you have a SES light get it scanned.

***SMWS6TA*** · 06-10-2011, 07:15 PM

Not picking on you OP, bbbbbuuuuttttttt.......

Give your brother this "Your Stupid!!" on a piece of paper and say "here's your sign!!"

As stated roll cage and SFC's have nothing to do with KS.

Again as stated your KS may need to be replaced, but are you throwing any codes?

If so, which ones?

Is the MAF OEM or aftermarket? If aftermarket which brand? (They tend to have a lot of issues and require serious tuning.)

Cleaning the MAF with this:

If you don't know how, please say so, so that we can give you detail instructions.

Do not use carb or brake cleaner on your MAF.

Now if you do in fact need new KS you will need to order for the 99-02 yr and get a 99-02 wire harness. They no longer make KS for 98 and older. Some parts stores do carry them but do yourself a favor and "upgrade" to the newer KS (99-02) If you need an idea on what to order ask and I or someone else here can give you a detail list.

**JayTA98** · 06-10-2011, 07:52 PM

Originally Posted by SMWS6TA

Not picking on you OP, bbbbbuuuuttttttt.......

Give your brother this "Your Stupid!!" on a piece of paper and say "here's your sign!!"

As stated roll cage and SFC's have nothing to do with KS.

Again as stated your KS may need to be replaced, but are you throwing any codes?

If so, which ones?

Is the MAF OEM or aftermarket? If aftermarket which brand? (They tend to have a lot of issues and require serious tuning.)

Cleaning the MAF with this:

If you don't know how, please say so, so that we can give you detail instructions.

Do not use carb or break cleaner on your MAF.

Now if you do in fact need new KS you will need to order for the 99-02 yr and get a 99-02 wire harness. They no longer make KS for 98 and older. Some parts stores do carry them but do yourself a favor and "upgrade" to the newer KS (99-02) If you need an idea on what to order ask and I or someone else here can give you a detail list.

or BRAKE cleaner either. They will damage your MAF

**90ARAPAJ** · 06-13-2011, 08:27 AM

My mass airflow sensor is not stock it is aftermarket....hoestly i forgot what kind but it has no screen for better flow...and my car was tuned awhile ago and we used the hypertech crap for gears and all that but that RFG and NON RFG idk what either of them mean...

**pajeff02** · 06-13-2011, 08:32 AM

Originally Posted by 90ARAPAJ

My mass airflow sensor is not stock it is aftermarket....hoestly i forgot what kind but it has no screen for better flow...and my car was tuned awhile ago and we used the hypertech crap for gears and all that but that RFG and NON RFG idk what either of them mean...

RFG? Non RFG?

As long as the tuner included an update of the MAF tables to compesate for the aftermarket unit, that is probably ok. Cleaning the MAF should be considered routine maintenance. If you run an oiled cotton gauze air filter element then the MAF should be cleaned more frequently as accumulations of oil and debris on the MAF filaments will act to insulate it and result in reported airflow being off.

**90ARAPAJ** · 06-13-2011, 08:37 AM

Originally Posted by pajeff02

RFG? Non RFG?

As long as the tuner included an update of the MAF tables to compesate for the aftermarket unit, that is probably ok. Cleaning the MAF should be considered routine maintenance. If you run an oiled cotton gauze air filter element then the MAF should be cleaned more frequently as accumulations of oil and debris on the MAF filaments will act to insulate it and result in reported airflow being off.

no it doesnt come with that update,,,but im very sure its the knock sensors just because it robs me of power i mean back then when my bro bought the car he had this problem fast because he modded the car a month after he bought it and thats what he was told my many mechanics

**pajeff02** · 06-13-2011, 10:17 AM

Originally Posted by 90ARAPAJ

no it doesnt come with that update,,,but im very sure its the knock sensors just because it robs me of power i mean back then when my bro bought the car he had this problem fast because he modded the car a month after he bought it and thats what he was told my many mechanics

Get a scanner on the car and watch to see if it pulls timing due to knock. That is the only way to know for sure if it is indeed a problem. What grade fuel do you run? Have you ever run a fuel system cleaner through the car?

If the car is lean, you have excessive carbon buildup in the combustion chamber, or your cooling system is not up to par, these conditions may also result in knock under load. Can you hear it knocking?

**RichWS6** · 06-14-2011, 08:23 PM

Here is what I would do, buy a new knock sensor harness and 2 new sensors they got upgraded for 2001 and 2002 but it's all compatible.

If I had to guess when engine upgrades were going on he prob busted one of the tiny wires on the knock harness, well that's my idea!

***SMWS6TA*** · 06-15-2011, 09:03 AM

Originally Posted by RichWS6

Here is what I would do, buy a new knock sensor harness and 2 new sensors they got upgraded for 2001 and 2002 but it's all compatible.

If I had to guess when engine upgrades were going on he prob busted one of the tiny wires on the knock harness, well that's my idea!

Good point. If the wire harness was pinched or like the pic below, it will go bad quick. When I installed my LS6 Intake the 1st time my harness slide in between the intake and the cylinder heads, got pinched and also burnt.

**WS6S** · 06-15-2011, 02:29 PM

you can have them tuned out of the computer and never worry about them again...

**az gt eater** · 06-15-2011, 03:30 PM

Originally Posted by WS6S

you can have them tuned out of the computer and never worry about them again...

Why would you do that? Then you won't have any protection from bad gas.

**WS6S** · 06-15-2011, 06:36 PM

Originally Posted by az gt eater

Why would you do that? Then you won't have any protection from bad gas.

just bought my sons 01 ws6 up to vengeance racing here in ga to get some tuning and i was telling them about the nightmare i had trying to change the sensors and harness on his last ws6 that had extra long studs installed in the intake,they said i shoulda just brought it up to them to tune them out,and we do not need them on our cars...

**WS6S** · 06-15-2011, 06:38 PM

but before going up there and talking to them i to woulda replaced both sensors and the harness with gm stuff.at least thats what ive done 3 times before on these ls1 cars.

**90ARAPAJ** · 06-20-2011, 10:12 AM

Originally Posted by WS6S

you can have them tuned out of the computer and never worry about them again...

how can i do that? and if i do the cost will be what? and will i gain all my power that i lost from it?

***SMWS6TA*** · 06-20-2011, 10:58 AM

tuning out the KS will not give you any performance gains, but WILL open you up for damage to the engine if it knocks and you have no way of knowing.

Knocking in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise time in the piston's stroke cycle. The peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive.

Basically it means that if your PCM is not able to register knocking in the engine it can not adjust the timing to compensate.

Serious drag racers will run without KS because they run for very short durations and will rebuild engines or swap out between/after events if an issue comes up.