I am just about finishing up on installing new injectors on my 85 Coupe. This swap out although appearing simple to me ended up frought with peril. I had a good selection of tools but ended up buying more. The biggest headache was the re-installing of the runners and plenum. I didn't realize that i needed to leave the runners loose before installing plenum.
Also didn't know that that fuel rail pressure and return fittings wouldn't line up. Biggest headache I only could spend two hours here and there while it sat in the driveway. A good mechanic told me $300-400 plus parts I should've let him do it because in the end the time, aggravation and extra tools bought easily would've justified having him do it.





















Yes there is some satisfaction to doing it yourself and your buddies say OMG you did that!

 

I love working on my cars but sometimes you have to ask yourself what your time is worth. Of course, I have to consider doing an unfamiliar job twice...once to figure out what I have to do, and then spend time taking it back apart to put it back together the right way LOL!

 

amen to that brother

 

I used to love working on my Corvettes. Now at 65, I realize time is very important. And I now can afford to have my mechanic fix issues. My mechanic knows these cars very well and saves me time and aggravation. Small price to pay for me personally.

Best of luck.

 

I too prefer trying to do all my own work. Being retired i wasn't worried about having the time to do it. And because I'm fortunate to have a couple of other vehicles having one
down for repairs isn't a problem. But recently because of health issues I've had to have the work done. I'm hoping that will change soon.

 

I did it on my 85 this past fall, after dealing with 4 nicely secure torx bolts , i think i will be driving the bus to hell after the finely tuned words that spewed out of my mouth, my mormon neighbor said i heard you working on the car, i said no that was that new found music...lmoa

 

pushing 72 - still enjoy the wrenchin' end of the hobby, and i'll continue to do so as long as I can. nowadays, there's no rush to get anything done - it's called retirement. my dad was still working on his "toys" well into his 80's - :

 

It's on my list of things to do... which injectors did you go with and where did you get them from?

 

not to jump in, but in my 85, i installed 24 pound, bosch3's from Jon @ FIC. absolutely no issues. installed several sets in L98's and a LT1 over the years - FIC multi-X customer -

 

Thanks for jumping in! Looks like that's the way I'll go then!

 

I did the same on my 85. No issues either.

 

geez, trying to remember when I did mine 4 years....jon told me then there was some issues with the 85 , I got 22# and raised the fuel pressure.....sure has worked ok.....I've seen too many posts over the years regarding FIC and Jon.....he's the man for fuel injectors.....

 

car is running better but i still have some sort of miss. Can't seem to locate it. Had several good mechanics all who are puzzled. New fuel pump, new fuel filter
just cant seem to locate the area ? Totally baffled anyone help?

 

If you pull all the spark plugs do they provide any clue as to which cylinder has the issue?

 

no flames, but your posts are somewhat vague - need specific details. you say a "miss" - ??? - slight, noticeable, at idle, cold/hot, through the whole RPM range, or what? same miss, "before/after" the new injectors? first, have you or anyone run an actual fuel pressure test? L98's are a bit temperamental when it comes to fuel pressure (and air leaks). also, doesn't hurt to throw a noid light at the thing. prior to installing the new (?) injectors, did you double check the injector's coil resistance? have you modified anything - e.g., eliminated smog, egr valve, anything emissions related? did you check for codes?

it very well may not be fuel related, but maybe ignition - maybe air or vacuum. once you've sorted through everything fuel, move on - check everything related to spark - cap and rotor, plug wires (BTW, how is all that stuff?). plugs? what's your timing set at? one other thing I might add - if original, all your vacuum lines or tubing are 35 years old. they may look perfectly good, but it doesn't take much for a leak - thus, choppy idle. a few years ago, I replaced all my vacuum and emission systems rubber hoses on my 85 with new - made a noticeable difference in idle quality. speaking of vacuum, has any of those "good mechanics" thrown a vacuum gauge on the thing? vacuum readings can tell you much about the engine's health and the engine's internals. gauges and readings are "old school" basic. it very well could be you have a weak cylinder - a bad valve seat, valve guide, etc.. a couple other areas to look at - a slightly clogged cat, and the O2 sensor. I consider the O2 sensor as a maintenance item - if it's over 5 years old, i'd replace it.

personally, if fuel pressure readings are spot-on, start looking at outside the fuel system. trying to diagnose this on-line is somewhat difficult - much is second guessing. so, go in baby steps, and be **** with everything you do. no short cuts - no helter-skelter maintenance where you're all over the place. be systematic and don't throw parts at the thing without preforming basic diagnostics. do you have a FSM? if not, get one! good luck....

 

compression readings 125 lbs across all cylinders
FI coils were within spec before removing at 16.7 ohms
two spark plugs were almost totally clean cylinders 2 & 4 since the injector swap these plugs now have same coloration has rest
yes noid light showed injectors were pulsing

I have not put a Vaccuum gauge on it

I'm going to pull all plugs now and see if anything not correct

car runs a lot better but still has a noticeable miss cold or hot, idle or full throttle

plugs, cap, rotor and coil changed
AC Delco 8mm wire changed
new fuel filter

the PO had some ungodly large after market Throttle Body on it. I got used one from 85 Corvette and new air snorkel. It came with TPS installed. I will also test the voltage with key on at TPS tonight.

From my motorcycle racing days I have a digital thermometer I'll start car let her warm up and then take exhaust temp readings on each cylinder and see if
I see any difference on any cylinder.

Would an OBD II scan tool with OBD I connector help ?

Do you know if an oscilloscope can be used to pinpoint the trouble?

Thanks for taking the time to help.

I have FSM, Chiltons and Haynes manuals

 

How did you raise the fuel pressure

 

Oh yeah, if you're stock, you can't....had to put an adjustible fuel pressure regulator on there....not that big of deal, as at the time I wanted a new one anyway....for the chrome....