Detonation Problems, Problems Problems! What Gives???

[Dimitrios]

ok had the car tuned over the weekend. VOS did a great job on tuning it but the pinging is still there.

on the dyno there was no detonation whats so ever and the AF was at around 12 through out the whole range.

took it for several test drives and it detonates on heavy load or when mashing the gas. we pulled timing and had the water/meth come in sooner and it fixed it by alot and only was doing it at around 3-3,500k rpms.

today when i first took it out this AM there was no pinging till later on after about 30 mins of driving. im also getting a check engine light with a code of 0174 which is LEAN. Whats going on here. is the motor not getting enough fuel under boost? should i go to a smaller 8lb pulley? someone said i needed race gas for a 10lb pulley. HELP! this is driving me nuts!!!!

[Eric H]

could it be bad gas? or could you fuel pump be dieing? Very odd.

[99 R/T 10]

D,
Do you have a boost-a-pump? Also, keep in mind the A/F will change with the colder temps. When you dynoed, your A/F should be about 11.5, so in the colder weather it is still safe. You can also use a couple of gallons of race fuel to keep the octane to the safe side. I know most don't like the octane boosters, but I will use the XR1 product mainly because it "says" it boost the fuel 20 points or 2 octane numbers(in my area 93 up to 95). Good luck and let us know the outcome.

[Joseph Dell]

Dyno and the street/track are two different things. plus the car heats up on the street.

take out some more timing!

JD

[Dimitrios]

boost guage shows 11 lb instead of the 10lbs.

also could it be anything to do with the PCM. i have the 96 instead of the 2001 PCM. i also have the other PCM that originally came with the car..

[99 R/T 10]

No, I think it's either a matter of timing or fuel delivery. What Octane rating do you guys have up there? If it's 91, I would consider pulling some timing out if you don't want to keep adding race gas or octane booster.

[Dimitrios]

using 93 octane

[dansauto]

What do you have for a fuel upgrade? I would just richen the fuel mixture under boost. Do you have a wide band? Do you know how to add fuel with your vec2? I am thinking that the cold weather is giving you a denser air mixture. What did you tune it to? 11-1 is a pretty safe ratio to compensate for the cooler weather. I had to richen mine up a little over the weekend.

[Mr Hemi Head]

Dimitrios you can help fix this with a Wideband Monitor linked to your VEC2.
Data logging while driving will provide real world A/F information.

I have compared Dyno A/F with street runs. A/F was about 1.5 leaner on the street.

The VEC2 software will allow you to make corrections on the fly. Sean is most helpful in getting it right. Once you are familiar with the program you can DIY.

Rick

[Schulmann]

Dimitrious,

You performed the tuning on dyno while your car was "red" hot. The test drives were also likely performed with a very hot engin. The VEC2 program was made for that engin temperature and supercharger temperature

When you drive on the road your engin runs cooler and you need more fuel to keep the 12 AFR. One of the problems with the PCM and the VEC2 that they don't have appropriate models to modify the fuel delivery in function of the temperature (the other issue is the knock sensor). In Canada it even gets worst.

93 fuel is good but you need a better quality fuel to run under so much boost (or you have to retard the ignition). In my area I get 10psi boost with the 6.5lb pulley ! When I ran on 91 fuel I have to retard my ignition 6 degres at 2000rpm and 4500rpm. On 93 fuel I retard 3degrees at 2500rpm advance 3 degrees at 4500rpm.
Only on 94 fuel I don't touch the ignition at 2500rpm and at 4500rpm I give 6 degrees advance.


Your possible solutions:
- add more fuel
- retard ignition 1-2 degrees if you stay with 93 oct fuel and 10lb pulley
- Add even more methanol and inject it earlier
- Keep the 96 PCM
- Check crankcase ventillation
- Last solution, use the 8.5lb pulley


Dimitrious, you never told us how you vent your crankcase.
What is the type of your crankcase ventillation ?


NB: I did over 20000mi with my SC viper in a year in all type of weather and temperature. Now it is running really well but it took me a lot of time and HELP to master it.

[Simms]

I was always told you should use the dyno as a starting point when tuning with the water/meth. Then tune it on the street using a lap top and wideband.

[00prowler]

Hi D, It took me a few times to get mine right too. Dave gave me a larger W/M injector for one side. Overnite Shawn you card, with your dyno sheets..explain whats happening he will send you a few different cards with some different timing/fuel programs, change the injector, and you will be running great...keep the 96 PCM, that has nothing to do with your problem. He sent me 3 cards and the first one did the trick...Keep the card you have now for your race fuel program...NO MORE PINGING...AL...

[davem]

We've found that Vipers have so much power the intertia of most dyno's don't load the car enough to simulate road driving. What we do now is use our load cell on the chassis dyno to add increased load to tune the car for knock, especially for part throttle stuff. This provides a much more accurate road tune.

Next time you dyno tune go to a dyno that has a load cell on their dyno and try having them tune it this way. Everyone's comments have been right on, I would add fuel first and then pull timing to get rid of the knock.

good luck,
Dave.

[Bill M]

D, Left you a voice mail. Give me a ring.

Bill

[Bill M]

Davem. We have a Mustang with the load cell and we did run the car in simulation mode.