TPI occasional idle surge, and check engine light
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Joined: Jun 2009
Posts: 123
Likes: 7
From: southern Indiana
Car: 86' IROC-Z
Engine: 305 TPI
Transmission: 700r4
Axle/Gears: 3 sumthin
TPI occasional idle surge, and check engine light
I finally decided 7 years was long enough to let my car sit in the corner of the garage.
Let me give the run down on the car. 1986 IROC auto trans, 305 TPI, all stock, still has the catalytic convertor and stock "Walker" replacement exhaust. I got it about 12 years ago... and had to reassemble the top half of the motor (a friend that should never own a wrench was fixing the MAF code I told him was wrong with the car. LOL!). At that time I pretty much put all new AC Delco stuff back into the car, distributor, cap & rotor, new fuel pump, new injectors, new fuel pressure regulator diaphragm, used MAF sensor.
I put fresh gas in it, a new battery and it fired right up. However, there's still issues at bay that it was having before I parked it.
At first the car would run like poo until the check engine light came on. And it was like a light switch!!!! The care would then go smooth idle, and run perfect.
Since it's been sitting I went through most of the normal stuff. I put new AC delco 43 plugs in it (gapped .035), checked plug wires (replaced them because one was burnt), tested fuel pressure (20psi engine off / 43psi engine running), tested my TPS and it's smooth and in voltage, checked all the important vacuum lines and everything is hooked up (the HVAC has been hacked so I've got it all capped off), checked compression while I was at it 180psi all 8 cylinders.
Now it starts right up and runs great with no check engine light! But I put gas in it yesterday at the gas station. It started ran for about 45 seconds and then shut off. It started right back up... but the check engine light came on. It still ran fine so I took it for a trip. And it was starting hunting for the idle again at stoplights. Of course I shut it off and the computer doesn't store a code.
I put a new IAC valve in the throttle body while it was sitting parked over the years.
Would the 02 sensors cause an issue like this? It's about the only thing I haven't changed on this car over the years.
Let me give the run down on the car. 1986 IROC auto trans, 305 TPI, all stock, still has the catalytic convertor and stock "Walker" replacement exhaust. I got it about 12 years ago... and had to reassemble the top half of the motor (a friend that should never own a wrench was fixing the MAF code I told him was wrong with the car. LOL!). At that time I pretty much put all new AC Delco stuff back into the car, distributor, cap & rotor, new fuel pump, new injectors, new fuel pressure regulator diaphragm, used MAF sensor.
I put fresh gas in it, a new battery and it fired right up. However, there's still issues at bay that it was having before I parked it.
At first the car would run like poo until the check engine light came on. And it was like a light switch!!!! The care would then go smooth idle, and run perfect.
Since it's been sitting I went through most of the normal stuff. I put new AC delco 43 plugs in it (gapped .035), checked plug wires (replaced them because one was burnt), tested fuel pressure (20psi engine off / 43psi engine running), tested my TPS and it's smooth and in voltage, checked all the important vacuum lines and everything is hooked up (the HVAC has been hacked so I've got it all capped off), checked compression while I was at it 180psi all 8 cylinders.
Now it starts right up and runs great with no check engine light! But I put gas in it yesterday at the gas station. It started ran for about 45 seconds and then shut off. It started right back up... but the check engine light came on. It still ran fine so I took it for a trip. And it was starting hunting for the idle again at stoplights. Of course I shut it off and the computer doesn't store a code.
I put a new IAC valve in the throttle body while it was sitting parked over the years.
Would the 02 sensors cause an issue like this? It's about the only thing I haven't changed on this car over the years.
Last edited by closer; Aug 30, 2021 at 11:51 AM.
Supreme Member
Joined: Feb 2021
Posts: 1,215
Likes: 453
From: WA
Car: 1989 IROC-Z
Engine: L98 350 TPI
Transmission: 700R4
Axle/Gears: BW 9 Bolt / 2.77 Posi
Re: TPI occasional idle surge, and check engine light
Hook yourself up with a moates aldu1 and aldldroid / your choice of pc software to get a datalog, then reproduce the issue while logging.
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