Injectors for 85 c4
Thread Starter
Heel & Toe
Joined: Aug 2017
Posts: 18
Likes: 0
From: Michigan
Injectors for 85 c4
Hey, I'm new here and I'm looking for some advice.
I just bought a 1985 c4 and for the most part it runs and drives great except when you really step on the throttle it just pops and bangs which I'm assuming is a misfire. So I did a full diagnostics on it and fuel pressure is fine until you shut the car off then it slowly goes down. furthest I saw it drop was 25 psi. So that and reading multiple boards lead me to believe I have a leaky injector. I've been looking around at all the different injectors but I'm still not sure what to get.
Any advice on what injectors to get?
I'd like them to improve performance but also be reliable and not break the bank
Thanks,
Brad Knoll
I just bought a 1985 c4 and for the most part it runs and drives great except when you really step on the throttle it just pops and bangs which I'm assuming is a misfire. So I did a full diagnostics on it and fuel pressure is fine until you shut the car off then it slowly goes down. furthest I saw it drop was 25 psi. So that and reading multiple boards lead me to believe I have a leaky injector. I've been looking around at all the different injectors but I'm still not sure what to get.
Any advice on what injectors to get?
I'd like them to improve performance but also be reliable and not break the bank
Thanks,
Brad Knoll
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
If you had a bad injector that was leaking.........it would drop to zero PSI in less than 5 minutes. Running it should be 34 to 39 PSI. If the fuel pump is good and there is no leaking injector, it will slowly drop pressure over a 12 hour period to 5 PSI or less.
Thread Starter
Heel & Toe
Joined: Aug 2017
Posts: 18
Likes: 0
From: Michigan
Huh. Any idea what else would cause it to misfire only when I press the gas more than you would just cruising? Also it doesn't misfire when you just rev it, it has to be under load to misfire.
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Team Owner
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Likes: 3,275
From: Hartford WI
Very simple fix. New wires. But before I go that route, I'd check that there are no boogers in the distributor cap. If that is good, I'd run the car cold in a dark garage and spray a fine mist of water AROUND the wires and see what happens. Let it heat up and dry and repeat. Any sign of light, that wire set goes
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 763
if you're running OE plug wires, remember, they would be 32 years old now - same with vacuum lines. personally, i'd go through the whole system - not that this has anything to do with the "pops and bangs," and if you don't know the service history, but i'd start with the fuel filter and go from there - cap and rotor, plugs, wires, service the throttle body, belt, hoses, etc, etc, etc.. i'd run a fuel system check and give a set of bosch3's some serious consideration. service all fluids - from cooling system to differential, and establish a service history/maintenance baseline. good luck and enjoy the ride -
Last edited by Joe C; Aug 2, 2017 at 06:05 AM.