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/**** 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/****. 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.

 

[Dimitrios]

so I went to the speed shop today and bougt 5 gallons of VP MSE100 (100 octane unleaded) race fuel to see if that will help my problem. guy at the shop seemed to know what he was talking about and said i either have to pull alot of timing and loose HP or go with lower boost like 8lbs to avoid the detonation. he also said that at a 9:1 compression the cylinders should be producing around 275psi of pressure or something like that. does any of this make sense?

 

[FLX109]

Dimitrios,
Did you run the car on these nice days we have been having to see if their was a difference? I heard the cold air might effect it.

FLX109

 

[Schulmann]

Yes it is right what this guy said.
Same as I told you earlier:

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

Again, listen to the advises.
You still don't talk about your crankcase ventillation.
Poor ventillation can yield to sever octan level drop and to knocking on certain vipers ...

 

[Dimitrios]

yes u have driven it in these warm days and its not doing it as much..kinda feels slower too.

schulman i bought the roe valve cover breather with catch can in one. it screws right into where you poor the oil.

 

[00prowler]

D, your Hp # are high for your mods, especially on a Mustang dyno..If you bring the timing back you will lose the detonation...it will probably rob you of 30 HP or so, but the car will run good...Will be faster cause you can mash the throttle without detonating...Im sure you pull the gas back as soon as you hear it ping so you really cant even feel how fast the car really is...Most cars with your mods are at 700RWHP max on pump gas...If your car doesnt detonate with the race fuel, keep the card you now have and use it when you want the extra power with the race fuel. Have Shawn make up some new cards for your 93 gas with less timing...Your car will still be on the high end, very strong car indeed...AL...

 

[GTSnake]

What type of fuel system do you have? If it's stock you may need to upgrade.

 

[Dimitrios]

stock fuel system

 

[plumcrazy]

you also have a booster pump i think

 

[Shelby3]

I think you need to upgrade your fuel system beyond a boost pump at those numbers.

 

[Sean Roe]

Hi Dimitrios,
Most of the comments are spot on.
Did you get a chance to stop by Tators or send me the card you're using yet?
I have a couple questions.
1. What spark plugs are you using? I've helped people chase problems like this and found a hot set of plugs to be the culprit. Even if you have the Bosch FR8DC plugs in place, there's still a step cooler.
2. Are you running the standard two 375ml WM nozzles? If so, we've upgraded a few folks to a 375 and 625ml when the air is really hot or the engine is making a lot of power.
Beyond that, it's just a matter of timing and fuel adjustment.
The code for a lean condition occurred at part throttle, in "closed loop' mode, not under boost (open loop).
Between seeing Chuck or Bill, or sending me your card (so I can read it and modify it) I see nothing that a tune adjustment, cooler set of plugs or larger nozzle can't fix.
Your engine is making somewhere over 850 crankshaft HP. That does come at the expense of a little extra effort on the tuning and tweaking, whether it's a racecar or street car.
Just don't hammer the car until you get a chance to get this done.
Regards,
Sean

 

[dansauto]

"dont hammer the car until you get a chance to get this done" no truer words have been spoken!!

 

[IEATVETS]

With the power D's car is putting to the ground, 1/2 throttle should be sufficient. God I want a blower now!!

 

[plumcrazy]

D has NO half throttle in him....its ON or OFF

 

[CitySnake]

D has NO half throttle in him....its ON or OFF

This is true! But I just can't bare to think of the tire wear!

 

[Simms]

Did you upgrade the fuel pump? I have similar numbers and I am using a bigger Walbro pump.