surging

V8BUG · Post by **V8BUG** » Sat May 06, 2006 5:28 pm

283 sbc, tpi intake, 214/224 degrees, .442/.465 lift cam,9.4:1 cr MSII, fuel and spark. 8 pin hei, desktop dyno says 300hp@5500rpm, 330lb-ft @4000

I'll try to keep this short. I can get my engine to idle around 1000rpm and for no reason it will drop in rpm and quickly recovers and then idles along for 10-15 sec or so and then drops in rpm again recovers.......
ignition timing is about 35 degrees, pulling high 30's low 40's kPa at "idle"

I have tried many different ve tables by generating new tables, I have tried making a flat spot around the "idle" on the ve table, I have tried changing the req fuel. The most I have been able to do is changing the rpm but it still surges.

Any ideas or pointers would be great!!!!

Bernard Fife · Post by **Bernard Fife** » Sat May 06, 2006 6:30 pm

V8BUG,

This likely isn't a issue with the VE table, it's much more likely to be something like accel enrichment coming on inadvertently (which does exactly what you describe).

A giveaway is that the LED furthest from the DB9 on MegaSquirt flashes quickly when the engine speed drops (if it hasn't been reassigned for some other use).

If you could post a datalog, that would be very helpful for confirming or denying this, as well as for looking for other causes.

Lance.

V8BUG · Post by **V8BUG** » Sun May 07, 2006 4:35 am

yeah thats exactly what happens, on megatune or the MSII computer itself the accel light comes on real quick then turns off.

I'll go make a datalog and post it asap!!!

thanks

V8BUG · Post by **V8BUG** » Sun May 07, 2006 5:00 am

heres a data log of it idling and I watched megatune and the tps accel was always coming on. I went to the accel wizard and set it too 0% so there was no tps accel and the tps accel light still came on? the data log was with 25% I think

V8BUG · Post by **V8BUG** » Sun May 07, 2006 7:35 am

I don't know why my attached datalog did not show up.

heres the data log and my msq, lets try again

V8BUG · Post by **V8BUG** » Sun May 07, 2006 7:39 am

oh I get it, they attachments only show up when I am loged in!!

HaHa, now I feel really stupid

Jedrik · Post by **Jedrik** » Sun May 07, 2006 9:08 am

I went to the accel wizard and set it too 0% so there was no tps accel and the tps accel light still came on?

What did you set to zero?

Usualy I stop the AE by setting the threshold very high. Like 24

V8BUG · Post by **V8BUG** » Sun May 07, 2006 3:55 pm

I tried setting the acceleration wizard bending bar to 0% which means all map accel I guess