Cannons

iTrader: (2)

402ci 242/250 112 60# Motrons Drivability Issues


Having Drivability issues, car stumbles and hesitates when being driven under 2000 RPM. Engine sometimes races from 1000-1500 up and down several times then levels out at 1000. Very hard to get going from a stop, you have to slip the clutch out pretty hard.

Heres a list of what is in my 01 C5 Coupe...

-LS2 Block w/ ARP main studs.
-Lunati Non-Twist 4.000" Stroke Crankshaft
-Callies Compstar 6.125" Forged 4340 Rods.
-Diamond Forged Pistons 4.000"
-Comp Cam 242/250, 112 .600 Lift
-Morel Lifters
-Rollmaster Double Roller LS2 Chain.
-AFR 225 Heads CNC'd w/ Hollowstem valves, Upgraded Springs, 65cc chambers. Flow 316/238 at .600 lift
-ARP LS2 Head Bolts.
-Cometic Head Gaskets .051
-Hardened Race Bearings.
-Heavily Ported LS6 Oil Pump and Shimmed Up for Max Pressure.
-FAST 90mm Intake (Ported by Tony Mamo)
-LS2 TB (Also done by Tony Mamo)
-MSD Wires
-Vararam Air Intake
-Stainless Works 1-7/8 Headers w/ 3" X-Pipe
-McLeod Street Twin Clutch
-McLeod Aluminum Flywheel
-RPM T-56 Transmission
-3.90 Differential w/ all internal goodies
- 60# Motrons

Dyno was done on Drag Radials and they only did a few pulls on it. It was on a Dynojet, it started getting late and they said the car was too loud they didnt want to do any more pulls until tomorrow. Engine was built by SLED28

515 RWHP 480 RWTQ
New Numbers....
520 RWHP 484 TRWQ

SLED28

iTrader: (7)

I think the 60's are too big? Maybe some 42's would help down low?

DrkPhx

iTrader: (15)

I agree. It could the injectors improperly scaled or the lower VE is simply too rich, but without solid information from a datalogger it's hard help pinpoint the problem.

98Z28CobraKiller

iTrader: (17)

Don't feel so bad. atleast you aren't alone. I have almost the same exact setup (including the injectors) and have the same surging problem in the range that you mentioned. I have been fighting it for some time. Looking like the injectors have to go. If you have the means to try going to a smaller injector w/o having to pay to see, please post your results so that I can follow suit. Good luck.

ninobrn99

iTrader: (8)

would changing the injector pulse width help out a bit?

Haans249

iTrader: (24)

I agree with what everyone else is saying....those 60lber's are definitely too big.

Some other things you should look into is your Spark timing table in the idle rpm ranges. If your spark isn't where the engine likes for idle conditions, then you'll see the problems you're having.

You'll also want to check on your VE table at idle as well...if its not dead nuts on, you'll be having the same problems as well.

What conditions are you seeing during these bad surgings? Is it running rich/lean? Whats your IAC count at idle?

If you can get an EFILive file, i can take a good look for you!

Hope you love that engine...it looks like a brute!! SLED28 knows how to build

Best,
Adrian

98Z28CobraKiller

iTrader: (17)

I'm not sure about Cannons but my VE table is right on 0 at idle and in the surging area when looking at averages. If I log the last time I hit the cell, it is slightly lean (positive AFR error) when in the surging cells while it is surging. I am using a wideband. My IAC counts at idle are around 30 after I am at 180 temp. Using HPTuners.

NicD

iTrader: (7)

60lb injectors are definately not too big, you just need to have it tuned properly. 60lb injectors work just fine on stock displacement barely modified engines let alone a hopped up 402.

98Z28CobraKiller

iTrader: (17)

Are you using them? If so, can I get a look at your IFR and offset tables? I have the VE dialed in pretty good. I used the IFR from Redhardsupras spreadsheet. No one has the offset info that is willing to share.

NicD

iTrader: (7)

Yes, I use them in many cars that I have tuned including my own. You calculate the IFR just like any other injector, it's nothing special. However the offset table, now that is something special. I will give you a hint, it's very close to the 26.4lb/hr 99-00 f-body injector offset table which is only a couple percent off in various MAP regions.

FigsZ28

iTrader: (70)

Mine does great! Similar to your set up, no bucking or surging at any rpm unless im under 1000rpm in 6th

Cannons

iTrader: (2)

What kind of times u turning?

98Z28CobraKiller

iTrader: (17)

Nic and Fig,

Could I get a peak at your tunes? bellos98@yahoo.com
I am at my wits end with this thing and am considering putting the stock injectors and cam back in the car and it will be your fault J/K.

Regards

Tripintaz

with a cam that big I would have about 30 degrees of timing at those rpms and at idle. Without a wideband and a scan tool your going to be shooting in the dark alot. Invest in a wideband, it will make your life much easier.

NicD

iTrader: (7)

Sorry, I do this type of stuff for money so I don't just give out tunes but I will give you advice to get you pointed in the right direction. Honestly your biggest problem is probably the 90mm TB and the tune, you have NW so it's the lesser of the evils but that isn't saying much.

98Z28CobraKiller

iTrader: (17)

I'm running 31* at idle which is fine and have had to ramp it up quickly to 42* in the problem areas to make it "better". I am running a wideband and my AFR Error in those problem cells is 0 to -1 average. I have noticed that while the surging/bucking is happening it is slightly positive (lean) if I look at the last time that the cell was hit. I firmly believe that this is a fueling problem that is somehow related to the offset voltage.

98Z28CobraKiller

iTrader: (17)

So, should I just find a stock 99-00 offset voltage table and work from there? The problem is that I don't know how changes in a given cells effect the areas where I am having troubles. Is there a way to scan against this table so that I can see which cells are causing me problems? Do you think that reintroducing my stock MAF would help this as it is an upstream restriction? I think that what you are saying is that the problem is akin to having a larger carb. I am currently tuning in OLSD. Perhaps I should try OL Maf

FigsZ28

iTrader: (70)

Well right now im have the hardest time dialing in the suspension. But no excuses the best ive run right now is 11.1 @126 1.63 60ft and this was done in 88 degree weather. My car also weights in at a tad over 3800lbs with me in it (drag setup) no weight removal other than a bmr k member.

98Z28CobraKiller

iTrader: (17)

ttt.....

Frost

iTrader: (45)

I just emailed you the offset table that I used with my 60s. I don't know that it's perfect but it came from a "PRO tuner" originally and it seems to work great for me...