At the end of my rope!

A few months ago, I was running my supercharged Z28 all out. I hit the laughing gas, but the gas was empty. The empty bottle caused a backfire when I activated the system. At the same time, actually before I did this, I had a rocker nut that was backing out and I had to re lash the rocker. I got the rocker lashed correct and then I make this run. I jump on it and then my engine made a huge detonation, so I back off and limp it homes. I pull my valve cover off and the intake push rod on the intake side ( #6) was bent. I bought a new pushrod & I put my Z back together. It started and was idling like crap and then got worse to the point it will hardly run! I’m thinking…wtf? I do a compression check and I have an even 190psi in all cylinders except for two on the other side that read 175. I pull my fuel rail and I see a few leaking injectors. I pull my heads and have a leak down test preformed, then had my heads looked at by a reputable machine shop. I had a 20% leakage on two valves; not the affected side so they lapped the two valves. Heads are fine now. Then, I replace my injectors with new injectors. I put my care back together and now, my car will still hardly hold an idle, no change at all! I’m getting 5 inches of vacume and I have to advance my timing to get it to hold an idle. I lashed my valves ½ turn past zero lash. I’ve not a clue of why I can’t get my car to idle? Current compression check is 190 in each cylinder, brand new fuel injectors and plugs. Plugs are BLACK, 5 inches of vaucme leads me to believe a huge vacume leak or something messed up in my valve train. I’m throwing no codes at all. So what will cause my vaucme to run at 5inches? And why will my car hardly hold an idle? My thoughts are leaning toward a huge vacume leak, but I’ve taken down my intake twice and have had no change in my idle and vacume issues? I put a vacume gauge to the egr and it holds 25 inches. The diaphragm does stick if I put 30 inches of vacume to the egr and that was making me think to block of the egr to see if that resolves the low vacume and no idle issue.

I don’t think one bad cam lobe or bad lifter on one half of a cylinder would cause such a drastic change in my idle and create such low vacume??? When I try to open the throttle, the car stumbles and hardly gets past 3500rpm's.

If it was a bad cam lobe or lifter, how would I check for any variances? I have a dial indicator.

I’ve a 91 Z28, roller cam and lifters, standard rocker arms, 9.5/1 compression with a paxton sn 2000 blower ( I run 9 psi boost)and a 75 shot of N20 via NX express, 30lb injectors, crane hi 6 s ignition, new cap and rotor, AFR 190 heads, slp runners.

Help…please

Thank you

 

i dont get it the bottle was empty? you are running N02 with this supercharger?

what about the side that bent a pushrod? did you check that for bent valves or bent valvestems? what kind of cam? solid, roller?

any smoke from the engine

 

Yea, I'm running a supercharger and N20. for some reason, the empty bottle with the added fuel was causing me to backfire @ wot when the sytem activated.

Hydraulilc roller cam
Heads completely went through @ a reputable machine shop
No smoke, just fuel comming out the exhaust

 

that is interesting i would post this in the power adder section

 

Definitely ask the power-adder guys.

I hope you were on a track when this happened and not the highway

 

You check your timing chain or gears. I have had backfires that completely destroy a timing chain, If it has an inch or more play I would start there.

 

I was on a back road (very desolate road!)near my house when this happened. I checked my timing chain and the two dots line up. I have one of thoes quick release timing chain covers so you don't have to drop the oil pan to revome the cover.

 

Almost sounds like it could be something electrical too, like in the ignition system, but it's weird you have no codes. Sounds like you checked everything internally, and if it's not broken or bent, it's pretty straight forward inside. I would just give a quick check to the ignition system, and make sure theres no problems there. Is it like a misfire kind of "running shitty?" Not too sure what could cause the lousy vacuum either, but I dont think that would cause such a drastic difference in the way it idles and drives.