I have been chasing a problem with my engine in my 84 for 6 yrs and and am at my wits end and ready to sell it. it misses and skips and isnt even drivable on the road. it will wet plugs, but not always the same ones. i have put thousands into it. rebuilt ECM, injectors, distributor, coil, rapid fire plugs, wires, 85 fuel pump, filter, MAP sensor, O2 sensor, all cylinders around 170 psi when testing compression. checked all the grounds. there are virtually no parts i havent changed in the computer control system except the wiring harness and the physical castings. when i jiggle the wires under the dash the courtesy lights go on and off so I know the car has wiring issues. I'm wondering if I buy a cable and download some software and log data, if theres a chance I could get any closer to a solution. I dont know if logging data onto a computer would help find a harness / wiring problem... or even if thats what i have. if anyone thinks I should try to capture some data, I would like recommendations as to which program would be best for my needs. most of the posts i found in my search have to do with tuning. i have no interest in tuning.... i just want to finally be able to get some use out of this car. im only interested in diagnostics. i dont have many options left.... there are no more parts i can change, and dont want to spend the money to send it somewhere. i dont want to sell it b/c i would lose thousands that i've put in, but i am becoming very disheartened and frustrated. any advice would be appreciated, thank you.

 

ECU hold any codes? check that for sure. winALDL will show codes as well and give you BLM data. you may be in limp mode but that show show a service engine light.

 

How many miles on the motor? Having trouble with timing? Do you have a CEL (Check Engine Light)? What are the symptoms exactly? Owned an 84 Xfire for 24 years. I probably know what's wrong with it.

 

Hello. I love my 84 vette of two weeks. I love to fix things that don't work.
Sooooo. It is an automatic. Has a fresh motor with a bigger cam. It runs great in first and second. lots of torque. bit of a lag off the line but petters out in third and forth. In forth at 65 it sort of burbles along. it has no vaccum at start up idle for the brakes but a blip on the throttle takes care of that. It burbles at idle as well....I have new plugs and K/N filter. I think its running lean at idle and WOT in third and forth.
Can i get a chip/prom flashed to fatten it up a little?
Would a smog test tell how it was running at idle and cruize to give a prom flasher enough information to burn a new set of perameters for the computor?
Can the new flash lower the temp fan turnon to 210 instead of 230+
Will changing the temp turn on affect the computors brain.
It doesn't have a lot of miles on it since the rebuild and running lean is not good. The other guy said it ran ok just to put it back together with the original settings and was good enough for him at the time. Now I want more/better efficency.
obrian

 

Obrian,

With those changes, it really won't run well on the stock calibration.
And its really not worth trying to change the stock calibration on the stock ECM. My recommendation is to swap ECMs. Suggest you go here
www.dynamicefi.com. This ECM will run the Crossfire very nicely. Software is very flexible and more user friendly than completely stock OEM. Good place to start when you begin your journey towards "tuning Nirvana". I made similar changes to my 84. There's more you can and probably should do to it in order to make it run well. Mine ran a best of 13.3 and it had a top trap speed of 104.65mph. Still got 23-24mpg.
www.crossfire.webhop.net is also another site for good Xfire info.

 

Thanks, I reposted again as I am new and getting the hang of this site. Its much more fun here in vette land than in Caprice/impala land. more to come, pictures at 11. ob

 

So, it seems that I send my ECM to Dynamic and they install a cool program that takes care of my problems.
Q. when I plug it in does it self diagnose the situation and adjust itself to a program that's in the new box
I can then take my laptop and read what is happening to my motor and change settings as I please to fine tune
Q. If I screw up can I erase my settings to default and start over from a clean slate.....how bad can I screw it up?
Does it come with a " Tuning/Understanding this for dummies" book.
I am soooo excited to see this and to think that it looks understandable and that I could do this....What say you. ob

 

Its not exactly "plug and play". You will need to "re-pin" your harness to match a 7747 ECM. However, if you look on www.crossfire.webhop.net, there is an adapter called a "HAM". Installed on your current ECM harness connectors it will have the re-pins already done. That way you can swap ECMs back and forth. Then install EBL. Spend some time on 3rd Gen.org to learn about tuning. But EBL is about as close as it gets to an "automated tune".
However, you need to learn quite a bit first. If you have tuned the "old way" you will appreciate what EBL truly is. But it does not eliminate the need to know what you're doing. In fact, the flexibility is there for those that do know what they're doing. Pretty sophisticated stuff.
Good luck on your new journey