Numba20

iTrader: (1)

some of you guys have have seen my thread i had when i first got the car. and helped me figure out how to rebuild it. hoping some of you can help me determine some last few smaller issues im having since i cant get my ALDL cable to hook up for the life of me. (in car wiring problems)

i drove the car 50 miles or so today. really first time driving the car farther then the end of my driveway since the rebuild.

it really impressed me in the difference i felt from driving it home. zero cam surge. but ill go thru what i noticed today and see of anyone has has a similar problem and can possibly diagose me.

first let me say i did not let the car reach over 3k rpm all day.

i left my house, drove 7 miles to the bank, and shut motor off to hear the teller. lol started it again, pulled onto the road, and a following truck caused me to push the pedal down a little further that what i had been. maybe 1/2 throttle? and in 3rd at about 2k rpm it backfired. (it felt like a down shift that pulls you foward that lasted a fraction over a second then the pipe made the pop bang noise.) btw i was running open header. i drove 1 mile to fill up at the gas station. pulled in, shut motor off, filled up. restarted car, starts very very quick with the opti. drive about 6 miles to exhaust shop. parked outside because another car was on the lift. 15 minutes they were done. and i got in my car to pull it on the lift. tried to start it and it was just cranking like the motor had little to no compression. cranked 2 times for about 3 seconds each. let it rest for 20 seconds or so, then played with the gas while cranking and it fired up. drove the car to work, and it drives fine. then leaving from work in 2nd gear i had another backfire, it like the motor stops spinning for 1 second flat and then backfires and comes back. on the way home from work i stopped by a neighbors house to show him the car as he has been helping get it back road worthy. and when i tried to start the car it fired right up RPM just to about 2k, and then fell and died. did that twice. the third time, i applied gas as the RPM came back down to idle, and it stays running. since the first time the car started irregualry, it has done the same thing on every attempt to start. only variable is the time span the starter cranks. but it will just rpm and then fall quickly and die like a vaccum leak or something? but it gas is applied and the RPM is kept at 1k or better for the first 3 or 4 seconds, then it is fine.

anybody got a clue? lol

ascastil

iTrader: (2)

Fuel pump maybe for the hard start? Check fuel pressure to rule that out.

Numba20

iTrader: (1)

update.

started the car and was tinkering with the throttle body adjustment thinking that maybe it wasnt getting enough air because i recently messed with it. when i attempted to start the car it back fired but wasnt running and smoke came out the air filter (i was applying gas) i waited and tried again and started the car and it idled good and then all the sudden just shut off. and the check engine light stays on but when it shut off the light went off and the check gauges light came on. i restarted the car and it fired up right away no problem without applying gas. car did this twice. and it was when it was just idling. i think it may be an electrical issue...

Numba20

iTrader: (1)

i will, but not sure about that mainly because the fuel pump is only 700 miles on it and has always showed great pressure. but i will double check. i was just into that a couple weeks ago.

Blackbirdws6

iTrader: (7)

Did you space the ICM from the head? I had similar issues a long way back. Simple enough to do but check fuel pressure too.

Numba20

iTrader: (1)

i did not. i used plenty of the paste behind it, but how did you space yours? simple as washers on the bolts?

ill try a cold start tomorrow morning and see how it acts. and will i get an accurate reading of the fuel pump with ign on and not running? or do i need to have the fuel passing thru? that would explain why it does good at idle as backfires on throttle, and the start up....

ascastil

iTrader: (2)

I had an opti that had loose rotor screws which was causing backfiring through the intake. Opened up the opti and loctite the rotor screws down.

Blackbirdws6

iTrader: (7)

Just some basic washers to get it off the cylinder head. You should test to see if the fuel pump primes with the key on and monitor it running.

93M6Formula

Totally off topic from this thread...but I just noticed the spoiler on the yellow car in your sig. Is that like a camaro style spoiler or am I just seeing things?

Numba20

iTrader: (1)

I spaced the ICM, but did u put the washers behind the plate it sits on? Or inbetween the plate and the ICM? I originally put it brhind the plate not thinking... And the plate wanted to touch the coil, do I moved it between the ICM and backing plate. I think this is the better configuration.

Numba20

iTrader: (1)

It is. Rksport ducktail for camaro. I have a thread on it on here if u wanna know more

Numba20

iTrader: (1)

So after work today I tinkered with the car here in the garage. I first spaced the ICM, then I hooked up my fuel pressure gauge. Car hadn't been cranked since last night. I turned te key and she fired right up. I let it idle for 3-4 minutes and got the temp up. No signs of mischief. It he fuel pump primed around 43 psi. And dropped to 40 while cranking and at idle. It drops to around 35 with revs. Then quickly returns to 40. I drove the car down my road to a close by culdasac and turned around. Cars idle seemed weak.(around 550-600 rpm. Usually idles at 900ish) after slowing or stopping having just been in gear. But when its siting in the garage idling It doesn't do that. car never shut off on me and I cut it off 3 times to restart and see if I had to apply gas or if it was going to be slow to start. It wasn't. And I got the car to 180-190 degrees. But in the culdasas as I was turning around, I put it in first from a coast and got to around 1500 rpm and it did the pull as if I let off the gas and applied the brakes for a second, then a loud single backfire. And I just installed a new cap and rotor (MSD) and the rotor screws had Locktite in them aldready. I applied a bit more blue Locktite bc I like to be thorough. So I don't think it's the rotor screws.

BoostedDSM

iTrader: (6)

If you can tape your fuel pressure gauge to your windshield and drive it around, should be in the 40's at WOT I want to say the quote I just saw was 43-47 psi I'm pretty sure. This sounds like a fuel pressure issue to a point.

Numba20

iTrader: (1)

I was able to put mine under a windshield wiper. It stayed close to 40psi but I didn't goose it because motor has barely any miles since built and I'm going to stay easy until past break in stage.

96z28_lt1

iTrader: (3)

always possible that you mis adgjusted the rockers....ever so slightly that they occassionally hang open causing an intake backfire.... REgardless backfire out the intake is some sort of timing problem or valve problem not fuel.

SS RRR

iTrader: (2)

This is exactly when you should run the motor like a scald *** ape.

3 pedal SS

iTrader: (1)

You really need to see what code(s) its throwing. as stated,your rockers may be a little tight or out of adjustment.

defaultexistence

iTrader: (11)

Fwiw I am of the understanding that you want to break the engine in by putting pressure on it... As in DON'T Baby it ! get out there and put some pressure on those rings! Research this. Now you def have an electrical issue I was having a similar issue and found the opti harness had poor pin connections causing them to short from heat , bend the small pins in the opti harness and at the opti to harness plug connections ever so slightly and plug them back up , also check your water pump temp sensor for a poor connection as it can also cause this issue . I seriously doubt a hanging open valve would cause an intermittent issue.

pkincy

iTrader: (1)

Obviously this is not a stand alone thread, so excuse me if I am asking a dumb question that was covered in another thread, but has it been tuned since the rebuild? And also since you have the cats welded back up? But it sure sounds like it could be a simple tuning problem. Run a set of logs and post them and maybe someone can help.

Numba20

iTrader: (1)

id like to readjust the lash. but can i do that with the timing cover on? because i dont feel like disassembling the front of the motor again and hoping there was a way around it. but i do think that you all are onto something with the lash.