95_muscle

So i finally got my engine built and it's acting up on me , imagine that! Here's a list of what I did to it and the symptoms. I really appreciate any help!

Le2 combo
Comp RRs1.6
.30 over
32# injectors
New plugs and wires (msd)
Mail order tune
And full bolt ons

ive Also got a 255lph fuel pump I haven't put in yet. I built it about 6 months ago but just now got it back on the road. I had it sitting unde the barn as I didn't have time to finish it.

These are the symptoms, some of which might be normal, idk cause this is my first build!
Surging. Especially at idle. If you let it keep going the whole car will buck.
Backfiring if you rev it in neutral
Runs different when cold from when it warms up
When put in overdrive it will run smooth sometimes and at others it will Humm really loudly

Thanks in advance!

TravisMcGill2000

iTrader: (2)

What size cam, gear and stall if auto. Also you need get a dyno tune. Does it run better when its warm? Also are they any ses lights.l?

95_muscle

.575 228 110lsa cam and 3.42 gears (lower gears coming soon) I do have a ses light but it kicks on and off sproadically and it always has done that so Idk I've never been able to get a read off of it. And it seems like its runs it's best after you've been driving it maybe five minutes and its halfway warned up. After that it runs decent. Thanks for the quick reply by the way!

96z28_lt1

iTrader: (3)

id get it dyno tuned, or maybe go over your tune. backfiring out the exhaust is usually a rich condition, excess fuel hitting the hot exhaust. with a cam youll experience a little bit of surge aslso, on mine i only experience it before like 2k though with very little throttle.

95_muscle

Yes it's defintly running rich as well. You don't think my plugs not being gapped right could hurt it do you?

96z28_lt1

iTrader: (3)

it would definetley hurt, gap to big or two small would lead to a weak spark not igniting the fuel correctly. Also check for exhaust/intake leaks. make sure all plug wires are on nice and snug. my cam surge use to buck real bad if i kept it on a slight throttle, does it run better cold or warm, cold engine isn't warmed up so your 02 sensor aren't operating. I'd just go over everything again real good. Also a little mor on the cam could help you gave us the lift of either exhaust or intake and lsa not to much to go off of haha.

96z28_lt1

iTrader: (3)

also you said 3.42 so you have the m6 right, i wouldn't get lower id go higher 3.73 4.10s

95_muscle

Alright heck I really appreciate it man. Y'all are lifesavers. Btw do you know what theyre to be gapped at? And tht cam is a .575 lift 228 duration at a 110 lsa

bufmatmuslepants

iTrader: (3)

Do you have any tune yet? Get a mail order for now, then dyno tune.

95_muscle

I've got the mail order. Idk I can't really afford a dyno tune right now seeing as how our local shop wants 150/hr

MEAN LT1

iTrader: (2)

Where are you located?

quik95lt1

iTrader: (7)

^what he said...........you dont need a dyno tune to drive it, somebody just has to work on the idle/part throttle stuff and it will be fine.........backfiring out the exhaust is usually too rich or too little timing, or a combo of both.........surging at idle is usually a lean condition.......sounds to me like the tune is FUBAR

96z28_lt1

iTrader: (3)

whoever your tuner is that mail ordered it i'd contact them they should have no problem going over your tune again especially when you tell them how its acting, it isn't going to be perfect but it sure as hell shouldn't run that horrible

95_muscle

im in middle tn though i frequent the huntsville al area. I think it was PCM for less? are yall confident it's in the tune? wouldnt maybe be valves need adjusting or some kind of sensor out? by the way i'm not sure what i'd do without yall haha!

96z28_lt1

iTrader: (3)

we can never really be positive unless we were there in person, you could try adjusting your valves again i know i had mine to tight at first, loosened them up and my car fired right up(there wasn't enough oil in my lifters yet) some sort of scanner would tell you things so much better, could be o2s could not be o2s, could be exhaust leaks or intake leaks causing a lean condition whihch it then requires more fuel that it doesn't need which would be your backfires.... the surging though i'm almost positive is from the cam, do you still have the stock throttle body on it?

quik95lt1

iTrader: (7)

what procedure u use to adjust the valves?

95_muscle

Yes stock throttle body. And to be honest I had my uncle adjust the valves not sure how he did it but I know there were no feeler gauges or anything like that involved on it

Chevyguy358

iTrader: (4)

I'm sure you have already checked but a double check over all intake vacuum connections, sometimes vacuum leaks can manifest into several symptoms like that you have described; surging, bucking, and differential driving manners cold vs. warmed up. Even if all lines are connected you need to make sure none of the hard lines are cracked etc. If you find nothing there I would go through your valve adjustments once more.

tonskiguy

iTrader: (3)

I'd look at the valve adjustment, temp sensor, engine and computer grounds.

quik95lt1

iTrader: (7)

you can try and readjust valves but i think its tune..........
use this procedure to do the valves


when exhaust valve is starting to open adjust your intake valve
when intake valve is starting to return from full lift do your exhaust valve