87 Surging idle when cold
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Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
87 Surging idle when cold
My 87 has an idle surge problem when cold. After start-up and the idle drops from about 1200 down to around 700, it will begin to surge between 700 and 1000RPM. The numbers on the digital tach read-out are constantly changing between this range.
When water temps get to around 120 or so the RPM surge range drops between 650-800RPM. After it reaches operating temp (has a 180 thermostat) the idle settles down to between 700 and 800RPM.
The car has a ZZ3 cam (about 4 years old) and some port-matching has been done. The shop that did the engine rebuild said they set the tps voltage a bit higher than spec but I don't know what the voltage value is that they used. They said they also installed a new IAC at the same time. They mentioned to me that they knew it idled this way, but the previous owner didn't do anything about it or didn't know if it was a problem or not. There are no codes and overall throttle response is great and runs very smooth. The chip is factory and a new fuel pressure regulator was installed when the motor was put together.
Ideas??
[Modified by c4cruiser, 11:12 AM 3/28/2003]
When water temps get to around 120 or so the RPM surge range drops between 650-800RPM. After it reaches operating temp (has a 180 thermostat) the idle settles down to between 700 and 800RPM.
The car has a ZZ3 cam (about 4 years old) and some port-matching has been done. The shop that did the engine rebuild said they set the tps voltage a bit higher than spec but I don't know what the voltage value is that they used. They said they also installed a new IAC at the same time. They mentioned to me that they knew it idled this way, but the previous owner didn't do anything about it or didn't know if it was a problem or not. There are no codes and overall throttle response is great and runs very smooth. The chip is factory and a new fuel pressure regulator was installed when the motor was put together.
Ideas??
[Modified by c4cruiser, 11:12 AM 3/28/2003]
