Ok so I installed a CC503 cam in my 1994 LT1 last week along with all the goodies (Comp 1.6RR, Hardend Pr's, LS7 lifters, Comp 918 springs, etc). Upon first start it fired right up, however I did notice raw fuel coming from the exhaust and it didnt run well. Once I asked on here I was told I was an idiot for running it etc etc because it was untuned. I just installed my tune that I had emailed to me from Ion (MadZ28) and it fired right up again. I let it idle for a while and noticed a definite difference from before.

I went to drive it and all seemed ok, albeit I had a little bit more valvetrain noise than desired so a valve adjustment is definitely in my future. However once the car seemed to be at operating temperature it changes completely. It pops, and backfires, and doesnt want to move. It runs like its on 4 cylinders. The Opti Spark is new as of last year and maybe has 3000 miles on if that and my plug wires are OTVC style and only a year old. Im not sure which way to go from here, so any help would be appreciated.

 

First off, as far as I remember, noone called you an idiot - it was highly suggested to you by multiple members, including one I would label an 'expert', to not drive the car untuned but you chose to anyway

For your current issues, how old is the coil and icm and are they spaced off the head? Shbox will show you how if not.
Also, may as well replace the coolant temp sensor in the water pump while you're at it
Both will cause issues once the car is warm

 

Haha my bad I meant to say I FELT like an idiot, I knew better. Anyway the coil and ICM are both pretty new (2 years max) but no they are not spaced from the head. Coolant temp sensor is a good point as well.

I was also considering o2 sensors... I want to try to unplug them while its running to see if it changes.

 

How are your O2 sensors? When the car warms up it is going into closed loop and depending on the feedback from the O2 sensors to adjust the AF.

 

Optis, coils, ICMs can take a dump at any time....brand new or 100,000+ miles on them it does not matter I've learned from experience. I would look at the ICM first since it seems to be heat related; then coil and last but not least OPTI replacement!

 

I did replace the o2 sensors maybe 3 or so years ago but since then Ive done ceramic coated longtubes, and whatever the raw fuel did to them when I started it untuned, who knows. So I am just trying to find the best approach

 

I replace 02 sensors after every retune I have had.

 

I dont know about '94s but my '93's O2 sensors were less than $20/ea...

 

O2s, ICM, coil, temp sensor in the pump, and fuel pump.

Those are the things that would make it run like **** once it is warmed up. Get a scan tool on it to watch your O2s and temp sensor. Hook up a pressure tester on the fuel rail to make sure pressure is constant and within specs.

 

the obvious question that hasnt been asked yet. is there a check engine light on..?

 

No there is no SES light on as of now. I haven't had much time to diag because I had to go into work. I'm thinking o2 sensors myself but all other possibilities are just as likely

 

Well....does it seems to run better at wot?

 

def a tune issue........sounds like the closed loop fueling as all jacked up......no reason it would run perfectly fine then soon as it transiitions into closed loop puke itself......

 

Readjust the valves first then hook a scanner to it and look at the datastream so u know what is going on, no sense in throwing parts at it. Parts Till It Starts is not a good idea. Could be a tune issue as well call the tuner.

 

This is a closed loop issue, unplug the MAF and go drive it and see what it does.

DO you have a way to datalog?

Report back.

 

It won't reach WOT it runs that badly. But it will when cold

 

I don't have a program to datalog but I do have an obd1 cable

 

why would you try and rev the **** out of it if its not running correctly? that's a great way to blow **** up quick. Mail order tunes are only good enough in most cases to get your car to a tuner so the proper tune for your car can be met. every car is different and act differently same parts or not. If you know the valves are not adjusted properly and can hear that. warm car up pull covers and adjust running. Fix every issue you can before even trying to tune it at this point. Have a FP gauge on it the entire time, even when tuning i run one.
Now running the car too rich might have ruined the o2 sensors but the best way to find out would be to Data log your car, this will point you in the direction for tuning and possible causes of your issues as well. keep the rpm below5k till you figure out your issue

 

Ya, def not telling him to go out there and rev it. But he may have already experienced it. Logging is always the best but not always an option. Do as FASTFATBOY says and let us know.

 

mass air flow alright?

my car would idle fine but wouldnt rev up.
is it getting enough air?