ive got about 300 miles in now and i noticed a slight knock around 2400 rpm. not on every acceleration but on most. anyone have the same? :steering:

 

Yes, on warm days (above 80F) I've noticed the same thing. Usually audible for me in 3rd and 4th gears only under hard accel once past 4800 RPM or so. This was with quality gas (Mobil/Chevron 93 octane) During the summer, I just shifted early to avoid it. Didn't occur all the time - just on hot days. I wasn't overly worried as it was minor - and avoidable.

Note: With a supercharger, you MUST use the highest octane fuel you can get. Brand name 93-94 octane is best. Going with 92 or less and you WILL most likely get some pinging.

Over this past summer, I called LPE about it a number of times. Mine was the first 2002 Z06 they did. (June last year) When I first reported it to them, they weren't aware of any other cars doing this. I called back a few weeks later and they told me that they had experienced another install pinging slightly under the same conditions. A few weeks after that, LPE told me that since my install, they had now run across a few other cars doing the same thing and had dailed in their tuning a bit more and had eliminated the problem. I'm hoping they did! (It really didn't bother me a lot - but it would be nice to use that last 1000+ rpm left in the powerband in 3rd and 4th. :yesnod: ) I waited till the end of the season to pull the PCM. Mine's at LPE now getting re-flashed - I just sent it to them last week. I'll have to wait for a warm spring day to see how it does.

Don't get me wrong - this was a minor problem. I avoided it by shifting early.
Enjoyed the car all summer. I have faith in LPE's re-done tuning. Hopefully the ping bugs have been elimintated!

 

This is in no way intended to be a comment on LPE but I've had first hand experience tuning one of their Magnuson cars (I'll leave the car/owner nameless). The owner brought the car in purely to get rid of the pinging experienced relatively frequently. I'm posting this purely in the hopes it might help someone out...

One issue that I personally did not agree with was the placement of the IAT sensor. On this particular car the IAT was placed in its stock location. The ambient temp was ~64F. The car was very inconsistent between dyno runs. The tuning was such that there was a significant amount of timing advance but this led a significant amount of KR throught each run. We made several attempts to correct the timing tables but we could not get consistent power output. One run would have 0 KR and the next would have 2-3 degrees. 1 degree of timing was equating to about 12-15 RWHP (pretty significant). It was very frustrating. According to the owner the tuning had been done up at LPE with ambient temps in the 20s.

After a number of inconsistent runs I moved the IAT to the manifold to obtain accurate IAT #s. We were seeing 180-190 F at the end of a dyno run... we also found the runs to be extremely consistent in terms of power output. It took some time but we were able to get the timing to a point where we saw 0 KR across the board. On the highway the car had 0 KR. A few days later the owner asked us to look at an idle issue (no negative reports since). While we had the opportunity we took to the highway and tweaked the timing some more. With consistent airflow the IAT never got above 175. I added 1 deg. of timing across the board and had 0 KR. The owner felt that was adequate and requested we not pursue any more.

In the end the car now exhibits 0 KR under full load on the highway. The PCM has a Timing vs. IAT for a reason... keeping the IAT at the stock location is not the correct approach in my opinion.

Again... in no way am I trying to put a negative light on LPE... just stating what I've seen/experienced.

Tim

 

im running mobil 93 . mine seems to happen more from the inital acceleration than at higher rpms. do you think i might need to get that extra degree to prevent kr? i think i can get race gas pretty easily, but its a hassle and a little expensive. what about a colder stat, i have a 180 hypertech in there now would a 160 be better? its really cold here today about 20f. what about colder plugs, they are stock now?

 

TimZ28,

Where on the manifold did you relocate the IAT to?

 

There is a sensor port on the left side of the manifold, about 6" from the boost/vacuum port. It is plugged with a dummy IAT sensor and held down with a metal clip.

F

 

jfk c5,

As for the thermostat that's a tough call considering the temps you are seeing right now. The issue is getting the car up to temp in the climate you are in. I'd leave the 180 in there for right now.

If you are getting KR upon initial acceleration I would guess there is too much timing advance. If you have access to EFILive V5 (preferred) or A-tap it would be worth the time to capture some WOT runs and see what is happening

RPM
TPS
Timing Adv.
KR
IAT
ECT

Stock plugs? I'd purchase a set of TR6s and gap them around 0.035". Stock plugs are too hot of a plug for that setup.

Flintstone is correct... you will find the IAT port on the driver side of the manifold.

Tim

 

Are you running the stock fuel pump? If so, fuel delivery could be the issue especially at high RPMs. Check out racetronix for an aftermarket pump.

 

I guess I must be lucky, or should I wait until August to say that because I haven't had any knocking problems although when I was in Daytona I talked to someone who was working out this very problem. I've got a 160 degree thermostat and stock plugs, when summer comes if I have problems I'll take it to Ed Wright and have him fine tune it. :yesnod: :cheers:

 

Tim -- thanks for sharing your expertise, and importantly, your experience. Quick question if you don't mind -- is this same tuning issue any easier with either the ATI or the Vortech? I'm particularly curious because here in central Texas we sometimes see temps & humidity that match that in Florida. Thanks. :cheers:


[Modified by SteveL2, 5:15 PM 1/22/2003]

 

tim
i installed the ngks today like we discussed, but with the snow today -3"- it might be a while before i can try them out. overnight low around here near 0 F tonight!

 

Would someone be able to post a picture of this location. :confused:

 

I added an older style (89 vette) IAT to the charge cooler outlet due to the 01 MAF containing the IAT. I was seeing 30 - 40 degrees over outside temperature on my EFI Live. :cheers:

 

If that car is pinging, you better get a professional to tune/diagnose it for you. You may blow up the engine if you leave it like it is.... :cry

vetterdstr :cheers:

 

ok , so i change to ngk's gapped at .035, still have the same pinging around 2000-2500. then i get a code from the maf. so i change back to stock maf, still have a slight pinging at those rpm's. then going up a steep grade at about 4500 rpm's i get a knock that sounds like its going to blow!, back it down and still have the same pinging at 2000. im running 93 from a different brand, how do i get rid of this knock?

 

You better take it in and get it tuned as you'll end up ruining the engine running it like that! :eek:

 

Update: I sent my PCM to LPE last week. They re-reflashed it and got it back to me in 4 days. LPE rocks! :cheers:

I installed the PCM module this past weekend. the car cranks/runs/idles great... in the garage. :cry I'll have to wait for all the snow to melt and the weather to warm up before I can test if the slight pinging in the upper RPM range has been erradicated. (I'm thinking it is).

jfk c5 ls1, from what you are describing, I WOULD NOT drive your car. Get it to a reputable tuner ASAP! Or pull your PCM and send it to them. That sounds like an engine on the verge of self destructing do to bad programming!

 

You may find in the future that having a good dyno tune will give you the best results for your S/C application. :)

vetterdstr :cheers:

 

I used the manifold location that was indicated in the instructions. It is located on the drivers side. Haven't had any problems with pinging, but I usually throw in a quarter tank of 101 octane to my 93 just for good measure. :yesnod:
I also understand if the car senses knock it will retard the timing for several hundred miles or the equivilent of a tank of gas. It will assume you have bad gas and will not advance the timing back until it feels sufficient time has passed for you to have put in better gas.


Tod :seeya


[Modified by GraveDigger, 5:48 PM 1/29/2003]

 

so today my pcm takes a trip to oklahoma. its running lean for sure and the ltft will be adjusted. but the thing that is really off is the timing! at 1900 it was at 30 degrees so it will be nice to have it right when it comes back. hope there's no snow next week. :steering: