E85 - runs aweful during warmup - more enrichment?

[awdonly]

Running chrome and E-85. Air temps are in the 50's. GM MAF has no IAT sensor so ECU is seeing constant IAT of 79.

Starts fine, idles fine during warm-up, runs great when up to temp, but if you try to drive it during warm-up its a nightmare. She bucks and hesitates at pretty much any real world load and any RPM below about 3k.

Wideband shows she is running pig rich during warm-up, but reducing coolant temp vs enrichment table didn't improve situation. I'm now back to stock table settings and plan next to increase table values.

Does making it even richer make sense? Has anyone else encountered / solved this? If so, was solution simply adjusting the coolant temp v enrichment table values or something else? Can you report the enrichment table values that worked for you?

[Chris@Rvengeperformance]

Usually the car will have to be extremely rich to break up from that. Like 10.0:1. Most times I find its a lean condition causing this.

I have not tried this and don't run chrome anymore, but you may want to look into the accel enrichment vs engine temp comp table. When you try to move the car and its cold you may be hitting a very momentary lean spike and might not even see it if your wideband isn't really fast.

The other issue is the closed loop part throttle respond can hide a lot of sins, so it may just be once it is warmed up that's covering it up. Might want to disable o2 feedback and see where the tune is.

[awdonly]

Thanks.

[awdonly]

Tried going richer on "Coolant Temp Fuel Enrichment" table but it didn't help. Did get a descent log though and it showed exactly the type of lean spiking with throttle that Forest predicted.

Adjusted the "Accel Enrichment Base -vs- Engine Temp" table by increasing the trim %s for temps below 122F by 20%. I believe this table is the "tip in" table, but could be wrong. The other similar table "Accel Enrichment -vs- Engine Temp Comp" is a similar table with temp vs correction factor rather than trim %. I didn't touch this one - but might have them backwards.

My next test drive was vastly smoother (90% better) - coolant temp was still low but not as cold as start of first test. This issue requires long test cycles to get the engine truly cold again. Will retest again tomorrow and validate the solution.

[awdonly]

Today's cold test was a failure. Back to rough. Going to increase the Accel Enrichment -vs- Engine Temp Comp table now and retry again either tonight or tomorrow after its lost all heat.

[awdonly]

Found that increasing both accel enrichment vs Temp tables substantially (like by 40% for temps below 122F) was what worked for me.