I have a 95 Formula with the LT1, I had it bored 30 over and stroked to a 383 and a little bigger cam. I changed injectors from 24lbs to 36lbs. Every thing on engine is new, sensors and all. Problem is I have bad viberation that seems to being caused by possible misfire. No check engine light. Machine shop has checked everything to make sure its not a balance issue. Found plugs were very black so changed back to 24lb injectors and put in new plugs and runs worse now then before. Not sure where to go from here.

 

Was the engine tuned for the cam and injectors? Have you hooked it up and scanned it? What year/make/model of car?

 

95, Pontiac Firebird Formula LT1, OB1,, no programming changed, bought the Cat Turner but unable to figure it out. Just got it back from shop yesterday and going to start my own diagnostic today.

 

The motor needs to be tuned for the injector size and cam you now have. It will run pig rich with the larger injectors and no tune. You could wash down the cyl walls with to much gas

Self tuning...doable if you know what you are doing....as you can really FU stuff if you don't

on the engine vibration...is the motor now "internally" balanced and you are still using a stock flex plate or flywheel?

 

Motor is internally balenced, I have. New ATI balencer on it and the flywheel is o balenced, No one in my area offers tuning, How can I do this myself. The CAT Tuner is garbage. Machine shop worked on it last week and they think its a misfire problem.

 

tuning is above my pay grade. I have always gotten mail order tune by Ed Wright. He is retired now IIRC but still may do mail order.

There are people who still tune mail order. moehorsepower, Solomon are 2 names that come to mind

I am sure others can give suggestions on who still does it

If you want to self learn that is fine but you will wind up being a lot of trial & error IMHO. Doesn't work like Spinal Tap where you turn everything up to 11....

 

Ok, thank you, I well see if I can find a mail order tune and try that.

 

Plugs were black because you upped the injector size, cubic inches, and ignition and cam timing and didn't adjust the tune, and given the cam change - your entire A/F/ignition process is all sorts of fucked up. Sounds like you may need to learn a bit more about how PCM controlled engines work, and so does your "shop". Go over to http://www.gearhead-efi.com and do some reading.

Step 1 is get it tuned. Nothing you do before that happens will be of any relevance and will be simply time and money wasted. Google LT1 tuning and avoid PCM4Less as they will rob you. Solomon, PCMPerformance, Moe Bailey are some of the tuners that do mail-order tunes. They'll also burn the tune into your PCM and send it back to you. Then get a good OBD1 cable (NOT red devil river) and a laptop. Download eehack to the laptop, run it, and hook up to the car. At this point, look for someone that knows what to watch for in the logs and try to learn from them. Once the car has been datalogged, you will have a much easier time knowing what to start testing.

... and all this is to say that the car actually does have a miss and its not just the cam - because some cams can really make the engine chop.

 

Yea we already know all of that, and we did try to tune first with a Tuner program by CAT which is junk, go to send out.

 

I'd caution you against thinking you "already know all that" because just from what you're posting here - you, and your mechanic - appear to still have some learning to do. I'd strongly suggest heading over to that link I posted and rooting around. Its a goldmine of info for OBD1 tuning and the users are really helpful. TunerCat is pretty far from "junk" - but it does have a pretty steep learning curve. Unless you understand all the adjustments necessary to make a cammed, increased displacement LT1 car run by adjusting AFR, ignition curves, etc via your choice of tuning software, you're just wasting your time. Tunepro and Tunepro RT are both great software packages you can use to monitor, log and tune an OBD1 car, and eehack is also a great tool to have in your toolbox and works great for uploading BINs to the PCM. All of those programs are free.

You must have a good cable to do anything, and its something that anyone with an LT1 should have. If you have a cable and eehack you can just tell the tuner what you have, and what your build specs are, and they can email you the tune. You then upload it yourself to the pcm. More often than not - its cheaper to do it this way.

 

OP

Atlanta has given you solid advice...your choice on whether to follow it.

Contact one of the tuners suggested. They generally charge around $200 ish to tune it. You fill out a form noting whatever mods the motor/car has and ship them your PCM.

The tune you get will then allow the motor to run as it should with the cam/injectors. etc you have. You may have a "mechanical" issue that is causing problems but you can't begin to address whatever that might be until the motor has a tune to run it properly

Having the ability to then log data or at least view live stream data while you drive is very helpful in confirming tune is good for your car. If you feel there is some drivability or performance issue because of the tune, the Tuner will ask you to log x.y.z something so he knows wtf "your" motor is doing. Sometimes these issues are tune related...or more often something mechanically wrong be it part...or the way it was installed (valve lash for example). The tuner can then make revisions if it is tune related based on the data log parameter (s) he asks for.

Along the way you will learn more about what the hundreds of parameters/cells mean and if you then want to make "tuning" adjustments you can if you have the software to do so

383 H/C build is well known stuff for a qualified mail order tuner.

 

Yes thank everyone for there help and as I keep saying I am sending it out to get programmed.

 

Having it programmed is great. You still should get a cable and software to look at what the engine is doing in real-time. Rarely - if ever - is a mail order tune good the first time out of the gate. You plug in the PCM, get it to operating temp, and then datalog the car for a while. Then send the log to the tuner. Most tuners will give you one or two re-tunes after the initial tune in order to adapt to what the log is telling them.

This cable is the one I suggest. I bought the Red Devil cable first, and it cooked three PCMs due to running counterfeit FTDI chips. Bought the other cable and have flashed dozens of times without a hitch

 

Yes already have all of that, I have a snap-on solace and snap-on prodemand program. Or are you talking about something differant?

 

Neither the SnapOn or Prodemand will flash tunes to the PCM. And most tuners don't have access to SnapOn's proprietary 'ShopStream Connect' service to read or interpret the datalog from that device. Spend the $50, get the cable, then download and set-up eehack and Tunerpro/TunerproRT so you can datalog and flash.

Or you can waste time and money sending PCM's back and forth and having your chosen tuner make random shots in the dark.

 

Ok, i have had no luck in finding that for a OBD1

 

Finding what?

 

A easy to use flash program for OBD1,

 

I'm not sure what you are missing. I've mentioned an easy to use flash program - twice - in above posts.

 

Ok, all of this is beyond my capabilities so I found a Dynotune shop 90 miles from me so I am going to take it to the professionals, I have to much money invested to take chances with it.