1990 Iroc sputters when accelerating
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1990 Iroc sputters when accelerating
Hey guys and gals iv got a 90 iroc 5.7 350, and lately iv been racking my brain over this issue recently the car has been sputtering and lagging when accelerating at any speed at all anything from a complete stop and easing out of it or doing 60 down the road and matting it and everything in between it gives the car a very brief feeling similar to running out of gas that's the best I can describe it but only for a second or 2 and then the car levels out just fine. We have replaced the fuel filter thinking that was the issue to no avail unfortunately I don't have the cash to blindly throw at it I'd rather take educated guesses now IDK if this information will help but the fuel pump MAY be bad in the car it has a tendency when the car is hot to sputter and die and by hot I mean running temp that's been going on for a while not a big problem cause putting fresh gas in the car will stop this long enough to make it home iv been putting off a fuel pump replacement so if you think that these 2 different issues have the same cause then just call me a idiot lol. Other than that I can tell you that the car does seem to idle high much higher than it ever did before if I let off the brake on a flat road the car is idled so high it almost shifts into 2ND gear without even thinking about touching the gas. Other than those 2 thing yall will totally know better than me if u need any questions answered please just ask and I'll answer to the best of my ability thanks guys so much
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Joined: Oct 2006
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From: erlangen, Germany
Car: 1991 Z28 1LE
Engine: LS1
Transmission: T56
Axle/Gears: 3.42
Re: 1990 Iroc sputters when accelerating
Sounds like a fuel/tune-up issue. When was the last time basic tune up stuff was done? (Spark plugs, wires, cap, rotor?)
I don't like the idea that the fuel pump shuts itself down when it gets hot. I would certainly put replacing fuel pump on my short list of things to do.
Put a pressure gauge on the fuel rail and get some cold start pressures and once it gets hot pressures. Also get some cold and hot resistance readings for your fuel injectors. Looking for 12-16 ohms on them, anything out of that range in either hot or cold readings needs to be replaced.
To fix the high idle I would adjust the throttle body back to OEM specs, there is a tech article on this site about how to set the TPS, minimum air, and idle air control valve.
You could also make sure the ignition timing is correct. I've bought a number of TPI and TBI cars where previous owners tried adjusting timing without unplugging the EST wire and create a great deal of drivability issues for themselves.
I don't like the idea that the fuel pump shuts itself down when it gets hot. I would certainly put replacing fuel pump on my short list of things to do.
Put a pressure gauge on the fuel rail and get some cold start pressures and once it gets hot pressures. Also get some cold and hot resistance readings for your fuel injectors. Looking for 12-16 ohms on them, anything out of that range in either hot or cold readings needs to be replaced.
To fix the high idle I would adjust the throttle body back to OEM specs, there is a tech article on this site about how to set the TPS, minimum air, and idle air control valve.
You could also make sure the ignition timing is correct. I've bought a number of TPI and TBI cars where previous owners tried adjusting timing without unplugging the EST wire and create a great deal of drivability issues for themselves.
Thread Starter
Junior Member
Joined: Jan 2015
Posts: 62
Likes: 0
Re: 1990 Iroc sputters when accelerating
Sounds like a fuel/tune-up issue. When was the last time basic tune up stuff was done? (Spark plugs, wires, cap, rotor?)
I don't like the idea that the fuel pump shuts itself down when it gets hot. I would certainly put replacing fuel pump on my short list of things to do.
Put a pressure gauge on the fuel rail and get some cold start pressures and once it gets hot pressures. Also get some cold and hot resistance readings for your fuel injectors. Looking for 12-16 ohms on them, anything out of that range in either hot or cold readings needs to be replaced.
To fix the high idle I would adjust the throttle body back to OEM specs, there is a tech article on this site about how to set the TPS, minimum air, and idle air control valve.
You could also make sure the ignition timing is correct. I've bought a number of TPI and TBI cars where previous owners tried adjusting timing without unplugging the EST wire and create a great deal of drivability issues for themselves.
I don't like the idea that the fuel pump shuts itself down when it gets hot. I would certainly put replacing fuel pump on my short list of things to do.
Put a pressure gauge on the fuel rail and get some cold start pressures and once it gets hot pressures. Also get some cold and hot resistance readings for your fuel injectors. Looking for 12-16 ohms on them, anything out of that range in either hot or cold readings needs to be replaced.
To fix the high idle I would adjust the throttle body back to OEM specs, there is a tech article on this site about how to set the TPS, minimum air, and idle air control valve.
You could also make sure the ignition timing is correct. I've bought a number of TPI and TBI cars where previous owners tried adjusting timing without unplugging the EST wire and create a great deal of drivability issues for themselves.