Massive misfire when put in gear

Hi Guys

Got a bit of an odd one here.

I have a dropbear v2 speeduino ECU using tunerstudio on my car which is a frank-motor (1995 GM 3100 bottom end with GM 3400 top end). I've got a pretty good basetune going but have been chasing the following issue.

When idle and in park or neutral around 800rpm, the engine idles beautifully and slightly rich around 14.2-14.7 and is very smooth.

The second I put it in gear (reverse, drive, low), the car shakes quite bad but AFR's look to be pretty much the same as in park...RPM's do drop a bit down to 680 to 750rpm.

I tried increasing target RPM but didn't seem to have any affect.

I tried enabling Idle advance, which actually makes it worse.

MAP looks solid, I know vacuum is slighly lower then what it should be after doing a vacuum test. I smoke tested it and found no obvious vacuum leaks so suspect a valve isn't sealing 100%.

Using a 24x crank sensor and getting good solid signal, voltages look good as well.

i'm running out of idea's on what could be causing this. anyone have anything else I can check or try?

obviously it's load related, just not sure how to account for it or what to adjust next.

after typing this out. I have two theories.

1. Dwell time is a bit on the lower side. I upped it a wee bit and will need to retest.

2. TCC is acting up and causing extra load on the motor (yes I know it's an Auto lol).

thankfully TCC is pretty easy to test and confirm, so will probably try this next.

update....dwell time helped a bit on response but not for the weird roughness when in gear and stopped.

I did notice one thing, that when it's cold it's a lot smoother, super rough in gear idle when it's warmed up.

still haven't tried disconnecting the TCC yet though due to prepping for winter.

I think that will tell alot. if that doesn't make any change then I suspect it's vacuum related.

running out of nice days to test this.

but man, am I learning the hard way the relations of things like map and ignitionload and where it should be with the spark table.

a little disheartened that there's been 104 views on this and no other comments....oh well, I shall speak with myself and hopefully someone else can see this in the future and find it helpful once I figure this out.

Hi Steven, sorry for the slow reply. The very first thing I'd suggest is to ensure the TCC is not locking at or close to idle. This is going to put excessive load on your engine and naturally make life difficult. If you have the ability to enable an idle up based off the gear position then I'd use that o raise idle speed when you're not in N/P. In addition you can add some resolution around the idle area of the map in terms of rpm and increase the ignition timing in the region the rpm drops to when it is pulled into gear. If the TCC is genuinely locked up all the time however you're going to be fighting an uphill battle.

Hi Andre

no worries, I figured you guys were busy...just figured I was talking to myself and documenting my journey lol.

TCC is all that makes sense at the moment.

the motor isn't that far off from what others have done on the stock ECU for Beretta's (some have put in 3400's without issue) and I recall this happening before I put in the dropbear ECU and but it was also stalling out on low rpm/high load, like when I would put it into reverse and go slow or get into my garage pad.

so i'm leaning towards it being the TCC that is causing the extra load and causing the roughness.

ignition timing i've tried bumping it up while it's happening with no effect.

Does it seem odd that it's worse as it warms up vs when it's cold?