LS1Silverado05

iTrader: (41)

Ok guys. After my recent cam swap the car was running pretty great since a friend helped me get it running with HP tuners. I was happy with the power, but wanted to iron out some idle issues and shift-points. I went to a local Mustang dyno last weekend and we ran the car. I ended up having some trouble that day because I ended up needing an 02 Bung welded in and I had a coolant Temp sensor on the fritz. We had made a couple pulls to 6000 but I simply needed to fix the car before we went any further. We took it off the rollers and on the way home the car just seemed to lack power, and had an odd vibration to it. Almost like a misfire. Fast forward now to this weekend. We put it back on the dyno and we got the A/F flatlined to 12.5 and my timing is around 28*, I should have made some good numbers. But I made 270HP, and it feels like it. I can get walked by a stock LS1. We datalogged the car...NO codes. I went home. I have since changed the plugs, my wires are good, checked all the coil connections etc. I did a WOT pull on the street with a fuel psi gauge and my fuel doesnt drop below 55 psi. I moved on to a compression check, and so far have seen 175-185 on the four cylinders I checked. (They only bled down to about 160 in two hours). I am 100% lost at this point. The tune looks good, my fuel looks good, my spark looks good, my compression looks good, O2s are in range, I used a stock timing set so there cant be any deviation from cam timing, I am running 7.425 pushrods, new 918 springs, new lifters, etc etc. Above all, the car runs fairly quiet and drives ok and has no codes. But has NO power, odd vibration, exhaust just sounds different. Something has broken or changed. So now it is the garage to stay until I figure this out. Please help....no matter how crazy the idea may seem. I am out of ideas.

JMBLOWNWS6

iTrader: (17)

First of all your car is a A4 and has a stall. So in my .02 I dont care for dyno numbers. Now the first thing I would check if my MAF was clean. After that I would have your buddy come and datalog the car with a wideband. Then go from there. Sounds to me like your tune is off. But this is the internet.

RIDINFILTHY

iTrader: (10)

damn that sucks, so it feels much slower than it did when u first put it in, thats wierd sounds like it is in the tune... but that is very low hp hope u figure this out.. good luck

BigBirdTA

Broken pushrod. Broke on the dyno maybe. Pull valvecovers, check rockers. If they're OK, pull them off and check the pushrods. Roll them on a mirror of glass table to check they're straight.

DaveX

Perhaps your cam timing is off

zeekracing

iTrader: (5)

does sound like it could be a push rod and your knock sensors should be picking it up and retaring your timing very badly. Your buddy should be able so see that when he is data logging your car.

LS1Silverado05

iTrader: (41)

Guys...I watched the datalog playback. There is no KR and the tune is solid. We checked and double checked. The tune is the same overall as it was before it started running like ****. So the tune didnt change itself. Yea, BlownWS6 I have already checked my MAF, and I dont care about the damn dyno numbers, but I want to be faster than a stock M6! I guess I need to pull the covers and look....though it is not making any noise. Think it could be a tranny issue? Though it is up on good fluid and seems to shift fine and the converter pulls hard.. Thanks for the help...keep the ideas coming.

LS1Silverado05

iTrader: (41)

Ok..I just pulled the covers, rockers, and pushrods. All look ok. None of them bent or cracked etc. All the valvesprings look good. Should I put it back together and compression test every last cylinder? I have done a couple on each side including #7. Any chance a vacume leak of some kind is doing this yet not throwing a light? There is alot of power missing here...Also, keep in the forefront the slight engine vibration and the different exhaust note (More of an underwater gurgle to it...sounds weak, not a smooth note like it was)...anymore ideas?...hit me..

LS1Silverado05

iTrader: (41)

Bump for the night...

radkon

iTrader: (2)

+1, was the cam installed straight up? What cam? Was it degreed to check for accuracy? With those kind of numbers I suspect either the cam was ground incorrectly or installed incorrectly.

LS1Silverado05

iTrader: (41)

Yep, I thought of that too. But if that was the case it would never have ran good in the first place. See, I was able to blow tires off at 30mph and now I can hardly break them loose from a stop!

wootang99gt

if i were you, i would finish the compression check. Then i would sell it for a mustang GT.

p.s. just tear it down and build a 6.0..............don't be a *****.

LS1Silverado05

iTrader: (41)

Why buy a Mustang? I could probably STILL show you taillights! Will someone please this guy for lack of constructive posts?!

jrfango8

usually a huge power loss like that will throw a code and the check engine light would be on. how big is the cam?

how many miles have you put on it since the mods. might need high flow pumps. most people i know that cammed their ls1, also upgraded the heads, valves, springs, rockers, manifold, throttle body, and full exhaust. might not be getting enough air flow, or maybe not enough fuel. still dosnt explain the gurgling sound. if somthin broke on the dyno and you cant figure it out spend a little money and get it fixed.

i do know that before i tuned mine it had alot of vibration, no funky noises, but i raised up the idle and it smothed right out

however in my experience the a4's are pretty slow unless heavily modified. my buddys wife has a 99 a4 z28, with just a knn intake. ive drivven it, and i serriously think my sisters 2000 v6 camaro will run with it, next time he comes back to GA im gonna borrow my sisters ride.

and oll buddy with the mustang, get over it, go break your t45 or somethin

LS1Silverado05

iTrader: (41)

Im not sure you read my original post. The car has full exhaust, came with an LS6 intake, I did eveything but heads. The thing should still scream. I have 55+psi of fuel....28* of timing, and a 12.5 A/F. No codes, no noises, good compression. etc etc...

BES Stroked Nova

iTrader: (24)

sounds just like how my cam install went in my A4 car.... i had everything your car has, plus a MS3 4200 stall and true duals... thing still only ran 12.50's...

go get a M6 car.. no really i have no clue, i tried EVERYTHING with mine, even sold it.

Z28Camaro30Ann

iTrader: (15)

Jeez..I sure hope MY cam install doesnt go haywire like this! *crosses fingers* I wish I could help. Sorry this isnt a constructive post, but I hope you get it fixed up...

BigBirdTA

You running cats? If you are, they could be plugged up and car can't breathe.

LS1Silverado05

iTrader: (41)

Nope.. No Cats.

radkon

iTrader: (2)

If the cam was installed incorrectly (off a degree or a few) your powerband may be peaky rather than flat which would give you the illusion that you had power in some instances but not in others. Can you post a dyno graph?