Scanning for KR

im unsure as to how i scan for KR. do i need to be viewing a datastream as i drive or is there a specific trouble code or what

What year is your Riv?

AA wrote:

What year is your Riv?

97

from: https://rivperformance.editboard.com/series-ii-engine-transmission-f4/smaller-sc-pulley-t3656.htm

1998 Riv wrote:

Josh, you do NOT want to run a 3.4 without several supporting mods in place first, plus have the ability to scan for Knock Retard (KR) before dropping pulley sizes. Look at all the mods in my sig. I've got a problem somewhere, as I had to go back to a stock 3.8 pulley and still am seeing up to 6+ degrees of KR.

Take the time to put your car info in your default signature, and spend some time reading the FAQ sections. All the info you need can be found here, but you need to put in the effort to read existing threads.

Is your knock a constant thing or just when its under load?

Only under load. Eventually I'll find time to play with my PT, definitely need to do some tuning work, and I do have some local help available when I'm in a position to spend time on this. Oh to be 25 and single...

Dave bought up a good point....

How many times do you guys scan for knock?

How many of you scan for knock while your riv is under load? Like climbing a hill, even a small grade? Is the car cold or hot when you scan?

What are the numbers you're seeing and at what temperatures?

(AA...if there's a lot of posts for this, can you please start a new thread?)

These are good questions. Here are my answers:

How many times do you guys scan for knock?

I scan for KR every time I make a change to car's modification level, when experimenting with fuel octane, after engine maintenance (filters, etc.), when the temperature is very hot/cold, or whenever I "feel" something isn't right. This ends up being about once per week for me.

How many of you scan for knock while your riv is under load?

ALWAYS under load. Otherwise there's no point, as normally the engine is running 8.5:1 compression, when conditions for knock don't exist. A good test is from 0-100 mph with your foot to the floor.

Like climbing a hill, even a small grade?

Yes! Not many think to do this, imo. But engine load can be high under these conditions. A stock vehicle might not have issues in this area, but with a smaller SC pulley, or using less than premium octane fuel, this is most definately a concern.

Is the car cold or hot when you scan?

Both. By "cold" I mean "warm" - right after the t-stat has opened (never race the engine cold). By "hot" I mean after the transmission has warmed up to above 200ºF (usually takes an hour or more of normal driving). I have noticed less KR when the car is warm compared to hot. So for average street or race track driving, it's good to know the hot value. For the drag strip, the engine actually stays pretty cool in the lanes, so the "warm" value should be fine.

What are the numbers you're seeing and at what temperatures?

Not sure if you mean ambient temps, but it is a very good idea to scan when the weather is extremely hot or cold, as IAT makes a big difference. I have noticed that when sitting idle in very hot weather, my IAT will rise above 100ºF, even above 120ºF, although I try to shut the car off by this time. If I launch the car from a stop with IAT this high, I will see some KR that will disappear after I get moving and IAT comes down to near ambient.

I am seeing 0 knock when the car is started and driven, and it seems to stay this way even under load. However, If I park the car after being driven, say for an hour or two, then restart (temperatures of IAT, Tranny, Coolant are rather high by now) I see 2 - 3+ degrees on knock when I'm climbing a hill, even a small, but long gradient with outside temp of around 86*

So, is it safe to say that your always, under the right conditions going to have at least some degree of knock?

Yes, it's safe to say that with your 3.5" SC pulley at 85ºF, you will see some KR after the engine is hot.

Heat is the culprit. When the weather changes to cold, you may not see any KR. The engine take a lot longer to warm up to "hot". Parking the car will help things instead of hurting you.

Tuning with DHP or HP can keep you out of TCC lock-up when climbing a hill. This is a great help, and one of the early steps I took with my tuner.

Using an intercooler can keep you at zero KR all the time. I would assume a tranny cooler could also help delay the warm-up time of the trans.

But 2-3º KR isn't the end of the world. either. In small amounts, I don't think it hurts the cylinders. Our iron 3800s are pretty tough.

Thanks...I feel alot better now.

...and I think I'm going to drop my pulley size from 3.5" to the size of a nickel...

j/k

A dumb question I'm sure, but I have no idea how one would monitor this. I know you all say a lot "Do this mod and check for KR" - what tool or instrument do you need to do this?

Tape Measure/Ruler

Measure the height of the boost bypass valve. Stock is about 1 3/4 inch's every 1/8 inch up the boost bypass valve goes is considered 1* of knock

https://rivperformance.editboard.com/series-ii-scans-tuning-pcm-f5/what-is-engine-knock-what-is-kr-t28.htm?highlight=knock

or you can just use the search button

any correlation?

lol, we never checked knock on it but for the record it was not and never was my car. His first mod was the 3.4" pulley (Yeah, that was smart...).

cont'd: https://rivperformance.editboard.com/series-ii-scans-tuning-pcm-f5/good-scanner-tuner-software-to-use-t2100-15.htm