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I bought a 2000 Ford Focus with a blown SPI engine. I swapped a 2001 Zetec engine and trans w/ 30k miles into the car. I used the harness from a 2001 as well. The PCM is from an early build 2002. The car starts and runs but idles very high (2k plus RPM). The idle will start to come down to a normal base idle for a few seconds but it stumbles and jumps right back up to the high RPM repeatedly like a cycle every few seconds (slight backfires occur when this occurs at low RPM before it jumps back up). The header is glowing bright red within minutes. If I disconnect the TP sensor the idle issue is still present but the headers are no longer glowing. The vehicle will not run or start when the MAF sensor is disconnected (MAF is from the SPI engine). Has anyone ever run into this with a zetec engine swap? I'm hoping to have my IDS from work this weekend to scan the car and run pid data just looking for some quick ideas. Thanks.
 

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[:)][:)][:)][:)][:)][:)]Update: I disconnected the IAC to eliminate that as a cause due to PCM command. When I did this I noticed the vehicle idled normally at a base idle 525-550 RPM and the headers were a normal color. However, at random with no throttleplate changes the RPM would spike to 2k plus similar to what it was doing when the IAC was connected. Since the IAC/PCM idle control has been taken out of the picture I started focusing on unmetered air/vacuum leaks. I've blocked off the VMV valve, EGR valve, and PCV with no change. The car will idle normally for awhile (at times of 5 minutes or more) with no concerns and at random the RPM will spike up and hang for no explainable reason. My thoughts are a vacuum leak but I've never had a random leak that occurred and then stops and then reoccurs with no reasonable pattern. The only large vacuum source I have not disabled yet is the brake booster. I'll know more when I get the scan tool hooked up and monitor the fuel trims but this one is just odd.[:)][:)][:)][:)][:)][:)]
 

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[:)][:)][:)][:)][:)][:)]Fixed[:)][:)][:)][:)][:)][:)]
After monitoring pids with the IDS I didn't notice anything really out of line that would cause this symptom. The RPM's were actually ranging between 4900 RPM and 2500 RPM. However, the majority of the time it was at above 4k. With the large vacuum sources blocked off I proceeded with blocking off the IAC passage for the throttlebody. The car idled normally. I removed the IAC to find it had minimal spring tension on the plunger and it would move with hardly any pressure. Replaced the IAC and it idles perfect. This is a first, I've never seen a faulty IAC cause a vehicle to idle at almost 5,000 RPM.
 

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Thanks for your post. After my SPI to Zetec swap, I'm getting a similar high idle (~4k RPM). I'm going to remove and check the IAC tonight.
 

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Actually, my issue was a simple fix... the 2003 SE SPI car's speed control unit's cable is shorter than the 2002 ZTS DOHC car's speed control cable and it was keeping the butterfly open slightly at rest which caused the high idle.
 
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