Mid rpm question
Thread Starter
Drifting
Joined: Oct 1999
Posts: 1,722
Likes: 0
From: Gloucester Va
Mid rpm question
I've gotten my car running really well at this point. The only problem I eem to be having at this point is a dead spot at 3500RPM-3800RPM. The car pulls very strong, but will fall on it's face between these rpms, then once it hit about 4000 RPM it picks up again. I also noticed that it seems to do it under say 50-75% throttle, if I floor it it doesn't seem to happen which has me puzzled because my WOT is set to about 50%. I've played around with fuel and timing, can't really seem to get it worked out. HELP :banghead:
Burning Brakes
Joined: May 1999
Posts: 760
Likes: 1
From: Greenwich, CT
Re: Mid rpm question (88_vette)
Which ECM/mask are you running? What does the scan data show when you observe the problem?
Generally speaking: In that RPM range, the SR/cam are near their torque peak, so you should be getting max cylinder filling & cyl pressure. A 'flat spot' could easily be a manifestation of too much spark, too little fuel, or a combination of both. Fuel situation should be visible on the O2 sensor log; spark is more subjective.
You could try reducing spark a little at that rpm/kpa in the PE or main table (if it's SD); and/or adding some fuel in AE or PE for that rpm range. Log the resulting run and see how it feels. Then try another chip with just the opposite changes - see if it feels better or worse.
That should tell you in which direction to go. Then it's just a matter of continuing to make small changes, logging the results, and keeping good notes until it behaves the way you want it to.
HTH
Thread Starter
Drifting
Joined: Oct 1999
Posts: 1,722
Likes: 0
From: Gloucester Va
Re: Mid rpm question (DOCTOR J)
Thanks guys. Did what you said DR. J and it seems you are right about the power band. I added 2* spark advance for the kpa, and rpm range, and increased PE by .4 in that area. I can feel a little still but no where near as much. I plan to fine tune it today after work. Hope to get it ironed out 100%
