Wow, just read this whole thread.

The car will not need the O2's for the first 2-3 minutes of operation. It runs in "open loop" mode until the O2's are hot enough to provide an accurate signal. Once it is warmed it goes into "closed loop" mode and uses the info from the O2's. If it is indeed backfiring after the car is warm you should have someone scan it with a laptop while you are driving it. Look for the air fuel ratio. watch the fuel pressure, it should always be above 40lbs. On an EFI car it should never fluctuate below this. What pcm are you using? Stock injector size? Does it backfire when you are on the gas or when you let off of the gas? ---very important difference.

A very rich car will have unburned fuel vapor in the exhaust and when you let off the gas quickly it will ignite in the pipes and cause backfires and little pops when you decelerate.

I wouldn't even think of spraying the car until you get it tuned just right.


EDIT-just watched the video. That thing is pig rich! I can see the black smoke coming out the back. Go get yourself a tune ASAP! That will cure it! pcmforless, madz28 can help you out.

 

^^^^This guy obviously knows his ****, i had the same problem untill i got a madz28 tune.

 

well it doesnt just do it when it warms up it just does it randomly. like itll run like crap sometimes when i first start it up and then run fine or the opposite. or itll run good then like crap and then go back to running good again.

the PCM was tuned sort of for what i have which is pretty much just the long tubes.
the PCM/motor is a stock 94 with vats and egr removed, told him that i just had long tubes and that it had a descreened maf (if that matters)

not gonna be spraying it anytime soon until i get everything worked out.

gonna see what happens after i put the new opti in.

 

Man....everyone just swaps out the opti as soon as something happens. 99% of the time it isn't the opti. When opti's fail they usually run like *** at high rpm. They are good at low rpm, but scatter as the rpm climbs. I would bet your opti is fine.

 

mine does all sorts of things. runs good or like *** either hot or cold. took apart the old opti and it looks like some of the plugs werent even getting spark.

wanted to change the opti anyways

 

this is where im stuck at.

PCM has had the VATS and EGR tuned out of it. and has been tuned for my long tubes. besides that everything else is stock on the pcm

New parts:
GM opti
plugs
MSD wires
coil
MAP sensor
vacuum lines
MAF
o2 sensors
knock module


The car runs all wierd. when its idling at 700-800rpms and i rev it or drive it, it runs fine but when it starts to idle up around 1000-1100 and i try to rev it or drive it. it will either fall flat on its face or backfire like crazy.

how do i make this work with my scanner? i repinned the OBD1 connector to kinda match up but i have 4 wires on the connector and only three prongs on my scanner.

 

ok good news and bad news.

Good news:
got all the wiring up and the check engine light seems to be working

Bad news when i try to scan for codes the check engine light doesnt flash or anything.

now what?

 

94+ PCMs do not flash. You must use an actual scan tool.

 

so that scan tool i have wont work?

would lt1edit work?

what kind of cheap scanner can i buy that i dont need a laptop for?

 

Aight so the vette is runnin good now. hooked up a obdII scanner and scanned it up. found out the engine coolant temp sensor wasnt getting a correct signal causin the car to run like ***. guess somewhere in the harness a wire broke. so we jsut ran a new one. fired it up and the car idles fine and sounds great.

only problem now is the ALTERNATOR and my belt.

 

Finally! JK. Glad to hear you got it running well.
Bring it to the Cali Generalz meet this month!

 

when is it? i mgiht try and make it out there.

 

It's always the third Sunday of each month.

 

where do they meet at?

 

Congrats on getting it in. Have you checked for underhood clearance IE does the hood close?

 

havent got to try that out yet. gonna do it this week. im guessin im gonna have some issues because the 84 hood is different then the rest of the years but im not afraid to cut some pieces out.

 

Lemon and Orangethorpe. Near the AMC and the Jack in the Box.

 

alright sooo........

new alternator is on,new belt is on, hood is on but...................


when i have the car running and try to put it in gear it stalls. it didnt do that before we found the problem with the engine coolant temp sensor.

what do you think it is?

 

Hey man i know this is an old thread but i'm doing the same swap as you and i wanted to ask you a few questions. For one does the F-body/B-Body bracket fit under the hood with the alternator on it? Also what did you do about the power steering lines? Thanks