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 |
lsintampa |
Jan 27 2015, 05:07 PM
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#2
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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 |
Don't know if anyone is still following this or not....
Anyway, thanks to Carr914 I was able to borrow a MPS and ECU that he has as a spare to go with one of his cars that he's selling. ECU looked old - mine has a nice shiny sticker on it (it may have been rebuilt). I did notice however when I sucked on the loaner MPS, there was a distinct thunk and you could feel stuff moving about inside. When I suck on mine, nothing feels like it is moving inside - so I was somewhat optimistic.... with caution. So with just those two parts, I fired up my car - with my stuff to let it warm up and start acting funky. Didn't take too long. After swapping out every combination of parts, the bottom line is that the MPS from the loaner is much more at home with my ECU. I can get it to run at idle - with no surging. If I shut the car off and put my MPS back in, it starts - but dies - won't stay running. Shut it off, put the loaner in and it starts and keeps running. Shut if off, hook up my MPS, surge - sputter - die. Will do more testing tomorrow morning when it's cold. Maybe on the road to recovery..... we can hope. |
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