TrevorH454

Hey guys, I am pulling my hair out on a little problem, thought somebody might have an idea for me. 1990 454SS, Edel cam, heads, single plane intake, various other goodies, and a swap to a 7060 ecm $85. Using an Autoprom, Tunercat RT, and Zeitronix wideband. Okay, I can play with the fuel/timing tables a little and get the truck to just destroy the tires while loading against the brake. I leave the tables alone and try again - good, and again - good - and again - not good. It goes back to bogging then going lean. And it won't run just right again until I play with the tables a little bit. Anyone have any idea what could cause the truck to do great one second, and then another under the same load, rpm, etc. it do terrible? BTW, running open loop. Thanks.

RednGold86Z

iTrader: (1)

Acceleration Enrichment vs Temp table

Getting engine warmed up might be getting you into a place where the AE vs Ctemp multiplier is just not friendly to your setup. See which temperatures are OK, then which are not OK, and as a starting point copy A to B (as long as both temps are in the "somewhat warm engine" or higher region, i.e. don't triple the AE multiplier at warm engine just yet).

Not sure if that's the cause.
Could be a hardware issue as well, but let's assume it's a prom problem for now.

TrevorH454

Hmmm... I don't see that table in mine at all. I wouldn't think that it would be the problem anyway. We played with this for a couple of hours last night and I'm sure we would have hit in the same temp range several times. Thanks for the thought, though.

va454ss

iTrader: (1)

Full fuel tank?

TrevorH454

Better than half, and I'm not hitting it hard enough to slosh. I'm just loading against the brake, like you would heat the tires or something.

JP86SS

iTrader: (1)

Maybe try clearing the ECM after each "reload".
Might be holding some BLMs that will take time to correct during a subsequent change to the fueling.

TrevorH454

BLM min/max both set at 128

TrevorH454

Another thing to note... AFR's in the upper RPM ranges (2500-5500) on full out runs are very consistent, and there are no problems there.

7Point4

Do you have to change something in fueling, or will any change straighten it up?

Its not getting knock detected is it? You logging during these 'Trials'?

Wierd one Trevor.

TrevorH454

I only was logging through the wideband - didn't have Datamaster up and going. I changed to where I wouldn't allow the computer to pull timing, and it made no difference.

JP84Z430HP

Really need some more info to help on this one!

I think redngold is hitting on something there. Have you paid attention to the coolant temperature when it runs good as opposed to running bad? A datalog should show you SOMETHING that you can go on, without us guessing!

luke4907

iTrader: (5)

I can't help as far as the prom is concerned, but I have a crazy thought. Maybe the warmer tire/brake rotor temperatures (after doing a few burnouts) have a measurable effect in this case? I don't think the coolant would have enough time to cool down while quickly modifying the tables, while tires and brakes (sitting in the open air) would. It sounds stupid considering those tires/brakes are sitting behind a 454, but it's the only thing not mentioned that I can come up with.

TrevorH454

The thing is, I'll stop and do this after driving and the engine is very close to t-stat temp. After I do the burnout, I will drive around more, and then stop again to ensure temps are close. I'm going to have to try some Datamaster logs when I get time. Working 6 days a week is no good!