schultzsj

iTrader: (1)

I just installed a TR 227/224 569/563 114 LSA cam with Ti retainers, Comp 26918 springs, and hardened 7.400" pushrods. I drove it for a week before the tune and it ran well except for cold surging and idle problems. It felt slightly stronger but not much (hard to tell without good traction).

Got the car tuned and found the A/F was already good at about 13 across the board. There was effectively no change in power due to the tune but the idle was better. Before and after curves are practically mirrors and within 1 HP (361 rwhp). This sounded low but I was not worried until I ran it at the track and gained less than .1s and 1 mph in the quarter (ran 12.8 @ 108 with a 1.95 60'). Compare this to my sig pre-cam/ported TB/tune.

Torque curve is flat around 340 between 4 & 5k RPM and then falls smoothly off from there to about 320 at 6k RPM and 285 at 6500 RPM. The curve actually looks quite similar to the 224 curve on TR's site - just alot lower.

After telling the tuner that I got no significant track improvement from the cam and tune he tells me that I am getting 13-14 degrees of KR (running 17 degrees of timing). He says it is around 30 with the PCM reset/loaded but then immediately drops to the 17 range when hammered. He says it is going into the low octane tables (-10 degrees) and then putting in an additional 3-4 degrees KR. Neither of us hear any audible knock at any time and he backed the timing down to 10 degrees and still got KR so it sounds like it is false.

He thinks it may be the headers or Y-pipe banging (we can't hear it but you can see where it has been hitting). I relieved the areas that were hitting a few months back and I am not sure if they are still hitting. However, if this was the problem it would have been present before the cam also and the cam installation still should have showed a bigger improvement.

I have searched ideas for eliminating KR including catch can (interestingly I found that my PCV line was disconnected from the head when I was doing the can install so I plugged it back in). I also considered new engine mounts to limit possible header/pipe banging. My engine has always had significant vibration (I removed a poly tranny mount within a week of installing it a few years back) so I hesitate to install poly engine mounts. I have read that it is a difficult job so I don't want to have to remove them if the vibration turns out to be excessive and I don't know that stock one's would help. The car has 112k miles on it and the engine does move alot under load.

Sorry for the long post - anyone have any suggestions? I am considering just copying the high octane table into the low octane table and possibly living with the 3-4 degrees KR for now.

Thanks,

Steve

TAQuickness

iTrader: (28)

do you have anything to log the spark pid's with?

I wouldn't copy the high to low and call it a day. seems you got a real problem and it should be fixed. The poly motor mounts are a great idea. I think you will really like the way it drives after you install them.

MNR-0

Put some race fuel in and see what happens to the knock. OR connect a knock-box.

SMOKINV8

iTrader: (6)

Use a stethescope or the old stick trick and listen to your valvecovers. I'm betting there's either something wierd going on in there (maybe rockers need clearanced with the new springs?), or your knock sensors are fubared.

schultzsj

iTrader: (1)

I don't have any tuning or evaluation software/equipment myself so I have to rely on the place that tuned my car but they are across town and charge for their work. I believe that they will foot the bill or give me a break on the next session because of the problems I had so I want to do everything I can before I take it back.

TAQuickness: What are spark pid's? I would like to install poly mounts but I am worried about getting vibration inside that I can't stand like what I got when I tried a poly tranny mount. Has anyone found vibration from the poly tranny mount objectionable but been OK with poly motor mounts?

MNR-0: I may try the race gas but, again, I would have to take it in to the tuner to see what the effect is (I already can't hear any knock). What is a knock-box?

SMOKINV8: I have a loud, higher RPM squeal that sounds like a bad idler pulley bearing so I listened all over with my contact stethoscope to try to find the squeal and I could not hear anything unusual - certainly nothing like metal hitting metal. The rockers are stock and many people use the same springs without difficulty. I am not getting any codes including any for the knock sensors. Could the squealing cause the KR? Does anyone know of a good way to locate what is squealing without replacing every rotating accessory one at a time?

Thanks,

Steve

Var

iTrader: (1)

Using race gas on an otherwise well running motor gives a slight improvement. If it helps your ECU kick into the high octane table, you'll definitely notice a pickup in speed(wihtout going on back on the dyno). If it's still giving knock retard then it's probably something besides actual knock.

If you're getting a re-tune make 1000000% sure there is no race gas left in your tank so he'll tune it according to the everyday gas you use. (i'm sure you knew this just a heads up)

joecar

You need to log Knock Retard and try to correlate if the engine is really knocking.

If the engine is not knocking, but you see non-zero KR, then you may try to adjust the knock sensor filter sensitivity/range (involves some trial and error);
your cam, valve train and LT's may be causing noise that falls into the knock sensor filter's stock range.

Otherwise, if the engine is really knocking, then it is crucial that you find out why.

(You will find it worthwhile to purchase scan/tune/flash software, because then you'll have to ability to log and tune various things to your needs, especially if you race).

ringram

Yep Joecar has got it.
Compare your Spark knock values and parameters with an 02 Camaro.
The tables in there are quite agressive. If its an older pcm with stock values this might be your issue. But as Joecar says. Make sure its not real first.

If you log KSensor voltage you will see if they are doing much. If they are hammering around the place, then maybe its real.

schultzsj

iTrader: (1)

Thanks for the replies.

Var - that is a good point about possibly being able to feel the difference running race gas (without going to the tuner for now) if it works to keep the car in the high octane timing tables. I am not sure where I can find some without going to the track across town though.

Ringram - I assume that KSensor voltage is the knock sensor output? If there is real knock it would make sense that this would be bouncing around. Is determining that the knock is false really as easy as looking for a consistant KSensor voltange? The tuner still has logs of some runs in my car - is this something that he may have logged and could look at without me going back in?

I don't know if I can swing tuning software right now but what would be the best to get if I ever can (Predator does not have a version for 98's) - I do have a laptop.

Steve

ringram

I believe its an indication. Do lots of searches on here as well as efilive.com and hptuners.com forums. Plus any of the other LS1 tuning forums. You will want either efilive or tuner IMHO, forget the handhelds.
If you compare your 98 knock tables with an 02 camaro for instance you will see the 02 camaro is running much lower sensitivity on the knock sensors.
Im no expert, but I had lots of timing being pulled especially in the midrange. I put a later model baseline knock section in and the problems went away. Other I have spoken to have done this as well. If you decide to go down this path. Make sure you arnt getting proper knock by logging carefully and making sure you are heading in the right direction.
If time and money are an issue get a second opinion from another tuner.

joecar

Handheld is too expensive for not being versatile enough (...understatement...), and is not suitable for what you're doing or want to do.

Most people who own a tune package have either EFILive (I have) or HP Tuners.