Surge / Idle |
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Surge / Idle |
lsintampa |
Dec 22 2014, 08:53 AM
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#1
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Senior Member Group: Members Posts: 520 Joined: 28-January 13 From: Tampa, FL Member No.: 15,441 Region Association: South East States |
75 2.0 FI
I'm in Florida - so the weather outside is somewhat warm (50's maybe right now). I'll try to be as detailed as I can. I've had this issue since I started driving the car - about 8 months ago. It underwent a motor rebuild - along with some other mechanical repairs. All hoses are new (air supply, and fuel). ECU and other FI components are original - best I can tell. When I start the car - it starts right up. At idle RPMs go to about 1500 with a very slight surge (maybe 1450 - 1550). If I pull the air supply that goes to the AAR from the air filter and plug it, the idle goes down to what I'd expect - about 900 RPM still with a little surge. This is while the motor is "cold" - so to speak. Within like a minute of starting. As the car warms - just at idle, the RMPs start to come down and the vacuum from the AAR isn't as strong - but still present. However now the surge is crazy - like from almost a stall up to maybe 1200, back down, back up, etc. Pulling the hose from the AAR - does nothing - I can plug it or leave it and the air filter wide open and there is no change. I put the hose back on - again no change. I did not let it get to a full warm state - IE the temp gauge just started to move up. I've heard there are three states (cold, pre-warm, and fully warm) that come into play. Various tinkering, like turning the air mixture valve to a total closed state, and mucking with the ECU dial has had some success, but at BEST, I get like a 1200 RPM idle still with some surging. To the best of my knowledge there are no air leaks - at least not from any hoses. I've some concerns that the air plenum may have some stress cracks around the support studs. But I don't know that would cause the surging? I'd think the idle would just be high - period. YES / NO? I don't know where to begin to figure out why it behaves this way. Thanks, Len |
ThePaintedMan |
Dec 30 2014, 03:37 PM
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#2
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Advanced Member Group: Members Posts: 3,886 Joined: 6-September 11 From: St. Petersburg, FL Member No.: 13,527 Region Association: South East States |
You're still just walking around in the dark until you can isolate entire component systems. You haven't told us whether you've tested for leaks yet or not...
The computer is working against you at this point because somethin ain't right and it's trying to make it right. Once we know for certain there are no leaks, then you can begin to narrow things down. The next step at that point is probably the CHT sender, as others have mentioned. Think about the symptoms - it runs fine till it warms up, right? You need to follow that logic through. You're a smart dude Len, don't get frustrated. Isolate systems first, and then rule them out. Changing parts and turning dials is not a great way to troubleshoot IMHO. |
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