TUNING ISSUES

[ViperPete]

Not sure if this goes here, but wanted to see is anyone had any advice.

1998 Dodge Avenger
Megasquirt II ECU
Mitsubishi 6G75
Shelby Daytona a543 5-speed

So I made some pretty good progress tuning the Avenger today. Much crisper throttle response and more pleasing AFR's.

Ive got an issue though. When WOT or anywhere near WOT, between 3,000 and 5,000 RPM the Avenger bucks, and spits, and "whoohaas" like crazy. Just a little while ago it was doing it's thing and was spinning the tires around 30 mph at the top of one of its "fits".

You can hear in the video, see on the tach, and see how I could barely keep the camera steady while it does it. It is most noticeable when I first take off at the beginning of the video and then again just after I stop at a stop light.

So, what causes this typically?

Thanks,

Peter


[ame=http://www.youtube.com/watch?v=Zz1HId2sNbc]3.8L Avenger Tuning - YouTube[/ame]

 

[VENOMOUS1 RACING]

What are your A/F at those RPMs? Map sensor? Vacuum to map? Above map capability? Correct plugs? Blowing spark out?

 

[ICPREY]

I would data log and study the logs. I assume it still has a knock sensor installed? Can you log AFR? Timing? I doubt you'll get a good answer from the video you posted.

 

[moparviper]

Idk if this will help but I had a 1990 jeep with a grand national swap and it did the same thing. Turned out the fuel filter was clogged

 

[ARRESTmeRed04]

Idk if this will help but I had a 1990 jeep with a grand national swap and it did the same thing. Turned out the fuel filter was clogged

Even if his filter isn't clogged the factory pump might not flow enough fuel for the engine...

 

[moparviper]

Even if his filter isn't clogged the factory pump might not flow enough fuel for the engine...

Id at least pull the filter and see before spending money to upgrade the fuel system

 

[ARRESTmeRed04]

Id at least pull the filter and see before spending money to upgrade the fuel system

Yup, throw a fuel pressure gauge on it and see what's going on

 

[viperhauler]

sounds like fuel to me, too... first place i'd start...

my VR4 did this at 26lbs... funny... it didn't at 22:burnout:

 

[ARRESTmeRed04]

sounds like fuel to me, too... first place i'd start...

my VR4 did this at 26lbs... funny... it didn't at 22:burnout:

Mmm...twin turbo AWD v6, I shoulda bought a gtr

 

[viperhauler]

if you've ever been rear ended by a cement truck... that's what that car felt like outta the hole...

i sold it to get married, no shit... i'd say i shoulda kept the car, but ask a few... apparently i married up

 

[viperhauler]

however i'm already planning my next build after this datsun sells...

hint: it's a convertible... that will soon have v8 power

 

[ARRESTmeRed04]

if you've ever been rear ended by a cement truck... that's what that car felt like outta the hole...

i sold it to get married, no shit... i'd say i shoulda kept the car, but ask a few... apparently i married up

Haha, yeah the viper has tons of power but can't use any of it in 1st gear...I'll buy some drag slicks to fix that

 

[ICPREY]

Yea my Vr4 launches pretty good and it's not too bad in the snow either.

 

[ARRESTmeRed04]

however i'm already planning my next build after this datsun sells...

hint: it's a convertible... that will soon have v8 power

Prowler with a 6.1 swap?

 

[viperhauler]

Yea my Vr4 launches pretty good and it's not too bad in the snow either.

donuts in the snow, say what????

 

[viperhauler]

Prowler with a 6.1 swap?

HELL no! though i've seen a few... this one will handle like it's on japanese rails (hint)

 

[ARRESTmeRed04]

HELL no! though i've seen a few... this one will handle like it's on japanese rails (hint)

240 vert with an LS swap?

 

[viperhauler]

240 vert with an LS swap?

getting warmer... but no...

it'll be 2700lbs. and over 400hp (another hint)

 

[ARRESTmeRed04]

getting warmer... but no...

it'll be 2700lbs. and over 400hp (another hint)

Rx7, LS swap

 

[viperhauler]

still warm... but no... (though it's on my radar... an FD with an LS)...

hmmm...

ummm..... running out of hints here...

used to rev to 9k... now 6k will be the max...