Surging idle when cold then stalls
Thread Starter
Advanced
Joined: Oct 2021
Posts: 61
Likes: 14
From: Long Beach CA
Surging idle when cold then stalls
So this problem started to happen last week, I cold start my 84 and it idles fine at 1100 for about 2 minutes. After, the idle drops to 800 then starts going all over the place while it’s warming up. It’ll drop to about 450 then stall when the temp is around 150°. I’ll try to start it again and it’ll start then immediately stall again. I have to floor the pedal to put into flooded start mode then it’ll run again. Once it’s at operating temp, it runs so good it’s hard to tell the motor is even running. I’m at a loss for what else to look for. The car does have bad valve seals that I plan on replacing soon and because of it, it only moves for street sweeping or to take for a short drive. All the gaskets are new, entire ignition system is new, new IACs, new TPS set at .54v, replaced the fuel pump and no codes set. Only thing I haven’t checked is the O2 sensor since I plan on replacing it anyways when I do the valve seals since it’s original.
Thread Starter
Advanced
Joined: Oct 2021
Posts: 61
Likes: 14
From: Long Beach CA
Update
I found a few problems to try fix this weird issue with the car. One is that the original harmonic balancer was separating and threw the timing way off. Replaced it and set the timing. It didn’t like the factory 6° BTDC so I played with it till I settled on 11° which it does like. It’ll still stalls as it goes into closed loop from open loop but once it’s around 175 degrees, the idle will
settle and it’ll run great. Could one of the new IAC valves be faulty?
settle and it’ll run great. Could one of the new IAC valves be faulty?
Thread Starter
Advanced
Joined: Oct 2021
Posts: 61
Likes: 14
From: Long Beach CA
Yes, I disconnected the EST while setting the timing. I disconnected the battery to reset the check engine light and the car ran nearly perfect the rest of the day. After a cold starting this morning, the car idles so smooth the idle only fluctuates a little bit while warming up to operating temp. I think the problem was caused by the old harmonic balancer starting to separate and throwing the whole engine out of time. It used to make really prominent “rocks in a can” noise that I assumed was the catalytic converter guts rattling around, but now I think it was really bad pinging. The car will chirp the tires under heavy throttle from a stop now
