1.7L running rough in the mid RPMs, Potential Causes of rough running (MIDS) |
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1.7L running rough in the mid RPMs, Potential Causes of rough running (MIDS) |
scwade |
Oct 12 2003, 08:43 PM
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#1
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Newbie Group: Members Posts: 10 Joined: 31-August 03 From: santa clara, ca Member No.: 1,091 |
I have a 1971 1.7L (with big bore kit) running FI. I'm having some odd behavior between 4,000-4,300 RPM. It runs rough at that RPM regardless of gears/speed.
I've checked timing at 3,500 (fine). I've swapped spark plugs (bosh) // got rid of some pre-detination ping, but still have the roughness (cutting out) I've put in 91 octane (best I can get here in CA) Still happens. PS - it idles rough as well. When I remove the "retardation" line it idles fine. I've not tried to run it full boar with no retardation though. Any ideas? Scott |
2teeners |
Nov 7 2003, 08:28 AM
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#2
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Member Group: Members Posts: 79 Joined: 2-January 03 From: Arlington DFW, TX Member No.: 78 |
I found this pic, courtesy of Dave D. at the Pelican site. It came in handy last week when I had to time mine. Thanks Dave D. I check it against a 1.7 fan I had too (his pic was of a 2.0). So you can time it relative to the big square rib of the fan
pelican pic The first thing I would look at is my tach. if it gets jumpy when you have the engine miss then it would indicate troubles in the distributor primary circuit (points/condensor or electronic mechanism). If it's stable, than it's something else. 4000 rpm is above the point where the dizzy should be fully advanced, so it seems unlikely it's the advance mechanism. can you induce the behavior other ways, at different rpm's? is it in all gears ? Does it feel like 1 or 2 cyls dropping out, or a complete failure? I will say this, I once tried aftermarket points condensor in my teener and they didn't last but 10miles or so. I would only use bosch parts there. But electronic is the way to go. |
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