quadgoat

iTrader: (1)

Hey guys!
A little while ago I got my Stealth Ram up and running with the Commander 950 engine management system. I was home on break from school for a week so I had some time to pull the intake and reseal it to stop a couple oil leaks. For once I think my leak stopping endeavor was a success, so then I started working more on tuning the car. My first question relates to timing. As I mentioned in my earlier post when I first got the EFI up and running all the Holley base maps had way too much timing to allow my engine to run very well at all. It would barely idle and wouldn't rev past 2500 RPM without popping like crazy. One thought that occured to me was that maybe my timing tape that I installed when I built the motor was off, so when I had the intake off for resealing it I double checked the timing tape and it appears to be right on. I put everything back together and re-set the timing and adjusted it so it was in sync with the ECU. Everything works just as it did before and I still can't run as much timing as all the base maps have. Is it possible that maybe my configuration just won't allow for that much timing, even though the base map I'm working with is set up from Holley for my heads and cam (SysteMax II kit)? I'm running around 10 degrees of timing at idle versus the Holley maps at around 20ish. Basically I have the spark map set up with values similar to what a mechanical/vacuum advance distributor would yield on a carb'd engine. Do any of you guys have experience with setting up timing with this system or have you had a similar experience? Also, on tuning, do any of you have any tips or advice to add to what the Holley manual provides? Right now my fuel map is pretty much rich all across the board except for a few random spots where it's really lean, which is driving me crazy because the fuel graph is really pretty smooth overall. I've been trying to tune it with a friend of mine driving, but I feel like I'm going around in circles with it at some points. Anyway, sorry for the long post, but I really appreciate any input/help with any of my questions as well as any tuning advice you DFI gurus have to offer! Thanks so much!!

-Paul

64duece

Have you checked the modifiers section to be sure timing vs coolant temp is not -32? These should be zero'd or add just a few degrees for cold start.

Have you confirmed the timing is accurate balancer vs computer? Wanted to be sure balancer hasn't spun etc and you have them sync'd up.

Finally, check your cranking compression. Something could be mechanically wrong (ie cam timing etc) that is causing high cylinder pressure and it may not like the timing.

As for the fuel map tuning. A smooth map doesn't always work the best. Some engines have efficiency areas that really make the map look weird. I suggest you look into the timing before continuing on. Good Luck!

quadgoat

iTrader: (1)

Yep, checked that and all is well there

That was my initial thought, but as I mentioned in the post, just now when I had the intake off I checked the balancer/timing tape vs the cam. (checked to make sure #1 and #6 TDC were correct via comparison between the timing tape and which valves were open or closed) After I reinstalled the intake I resync'd the dizzy and the computer so that I was getting the same reading from the ECU as from my timing light so they should be in sync fine.

This is certainly a possibility, however the engine only has 4,000 miles or so on it and was running just fine (although a bit rich) with my Holley vacuum secondary carb and mechanical/vacuum dizzy, so I don't know why there should be a mechanical problem now?

Agreed, I imagine the fuel map may not look gorgeous when all is tuned properly, but what's throwing me for a loop is that the Holley base maps for my heads and cam show a pretty smooth fuel map, but they run very rich on my engine and it does not perform well

Thanks for your help, I appreciate any and all additional input!!

-Paul

fast_broker

iTrader: (1)

Might be a timing problem but could also be a lean condition. Especially if you took out 10 degrees across the board and still have it.

Diagnose your fuel delivery/return and also get an accurate reading of AFR while the driving and when the "popping" is going on.

quadgoat

iTrader: (1)

When I pulled the timing out of the spark map I got rid of the popping all together. I'm running about 45 psi of fuel pressure with 24 lb/hr Accel injectors and after some tuning the 02 readings are still on the rich side, except in a few spots where they're really lean which kind of confuses me. The engine runs pretty decent at this point, besides needing the fuel map tuned. I'm just fishing for ideas about why I needed to pull timing like that, and advice for tuning overall. I'm hoping that once I get the fuel map tuned I'll be able to bump the timing back up, but I really don't know.

gavmeister

sorry to revive a dead thread but I am running into the same problem as you and have a pretty similar set up as you. What did you do just to get the car up and idling and if it is even possible would it be possible for you to send me you fuel and spark map?

quadgoat

iTrader: (1)

Hey gavmeister! Sorry, I didn’t get a notification when you replied to this.

In all honesty, all these issues with the initial setup on my C950 were sooo long ago, I really don’t remember exactly what all the fixes were, unfortunately.

I’m now on a 3rd different engine setup since that one, and it’s all in a different car, running Holley HP EFI now. I’m turbocharged now too haha!

I do know that when I first got the setup together I had a faulty distributor that caused me all kinds of headache, but I don’t recall if that was already sorted out by the time I originally posted this or not.

Feel free to post here or PM me with questions and I’ll try to help you out if I can. I do still have my old laptop with the C950 software and maps on it kicking around, so I may be able to get some of that stuff off there if it’ll help you.


-Paul