 2.0l fuel injected engine surge starve cycle? |
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| jdlmodelt |
 Jan 2 2013, 08:20 PM
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#1
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James D. Lane  Group: Members Posts: 345 Joined: 30-November 12 From: Colorado Member No.: 15,210 Region Association: Southwest Region  |
I finally got the ignition and fuel pump hooked up on my 76 2.0 L and the engine cycles between reving and stalling when I hold the pedal down to get a fast idle. What do I need to be checking now?
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| Spoke |
Jan 3 2013, 09:25 AM
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#2
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Jerry Group: Members Posts: 7,116 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None 
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Can you take some pics of this potentiometer you're talking about? There was a trim adjustment on the ECU but not one in the wiring harness. May have been some bandaid by the PO.
BTW, how is the normal idle? Is it smooth? How does the engine run if you try to go to a high RPM like 2k, 3k? Does it run good enough to drive it? |
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| jdlmodelt |
Jan 3 2013, 10:14 AM
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#3
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James D. Lane Group: Members Posts: 345 Joined: 30-November 12 From: Colorado Member No.: 15,210 Region Association: Southwest Region |
QUOTE(Spoke @ Jan 3 2013, 08:25 AM)  Can you take some pics of this potentiometer you're talking about? There was a trim adjustment on the ECU but not one in the wiring harness. May have been some bandaid by the PO. BTW, how is the normal idle? Is it smooth? How does the engine run if you try to go to a high RPM like 2k, 3k? Does it run good enough to drive it? the idle is smooth but so low that it stalls out after 3-5 seconds. If I start it with not pedal and get it idling then try to give it some gentle pedal it immediately stalls out. So, I can't even get it out of the garage yet to try it out. I had it running enough last night with short idles to get the engine warm enough that coldness should not have been the issue. (IMG:style_emoticons/default/sad.gif) |
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| DRPHIL914 |
Jan 3 2013, 11:17 AM
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#4
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Dr. Phil Group: Members Posts: 5,811 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States
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QUOTE(jdlmodelt @ Jan 3 2013, 11:14 AM) QUOTE(Spoke @ Jan 3 2013, 08:25 AM) Can you take some pics of this potentiometer you're talking about? There was a trim adjustment on the ECU but not one in the wiring harness. May have been some bandaid by the PO. BTW, how is the normal idle? Is it smooth? How does the engine run if you try to go to a high RPM like 2k, 3k? Does it run good enough to drive it? the idle is smooth but so low that it stalls out after 3-5 seconds. If I start it with not pedal and get it idling then try to give it some gentle pedal it immediately stalls out. So, I can't even get it out of the garage yet to try it out. I had it running enough last night with short idles to get the engine warm enough that coldness should not have been the issue. (IMG:style_emoticons/default/sad.gif) i have a 75 2.0 and had a similar problem. if you are running really lean, you may have a surge cycle like you described. The POT you are talking about is most likely someone put there because the CHT was out of spec and they were increasing the resistance to fool the ECU so that you can adjust the richness. have you tested your MPS yet? a bad MPS will cause lots of these problems. running rich will cause a slower idle but make sure timing i s spot on first. check the ohm reading of your CHT, make sure it is the right one and that is specs out for your car. my car would start and stall when i first go it because it would flood out, it was a bad MPS, but a rebuilt MPS sent to me that was set too lean was causing the idle surge you have, and i had to increase the richness setting and was good to go. - look at your spark plugs- are the sooty , or lite from running hot/ it really sounds like you are flooding out. DO a vac check on the MPS first. phil |
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| jdlmodelt |
Jan 3 2013, 12:39 PM
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#5
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James D. Lane Group: Members Posts: 345 Joined: 30-November 12 From: Colorado Member No.: 15,210 Region Association: Southwest Region |
QUOTE(Philip W. @ Jan 3 2013, 10:17 AM) QUOTE(jdlmodelt @ Jan 3 2013, 11:14 AM) QUOTE(Spoke @ Jan 3 2013, 08:25 AM) Can you take some pics of this potentiometer you're talking about? There was a trim adjustment on the ECU but not one in the wiring harness. May have been some bandaid by the PO. BTW, how is the normal idle? Is it smooth? How does the engine run if you try to go to a high RPM like 2k, 3k? Does it run good enough to drive it? the idle is smooth but so low that it stalls out after 3-5 seconds. If I start it with not pedal and get it idling then try to give it some gentle pedal it immediately stalls out. So, I can't even get it out of the garage yet to try it out. I had it running enough last night with short idles to get the engine warm enough that coldness should not have been the issue. (IMG:style_emoticons/default/sad.gif) i have a 75 2.0 and had a similar problem. if you are running really lean, you may have a surge cycle like you described. The POT you are talking about is most likely someone put there because the CHT was out of spec and they were increasing the resistance to fool the ECU so that you can adjust the richness. have you tested your MPS yet? a bad MPS will cause lots of these problems. running rich will cause a slower idle but make sure timing i s spot on first. check the ohm reading of your CHT, make sure it is the right one and that is specs out for your car. my car would start and stall when i first go it because it would flood out, it was a bad MPS, but a rebuilt MPS sent to me that was set too lean was causing the idle surge you have, and i had to increase the richness setting and was good to go. - look at your spark plugs- are the sooty , or lite from running hot/ it really sounds like you are flooding out. DO a vac check on the MPS first. phil what and where is the MPS on these engines? j |
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jdlmodelt 2.0l fuel injected engine surge starve cycle? Jan 2 2013, 08:20 PM
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On the top left side of the ECU, is your adjustme... Jan 3 2013, 08:32 AM jdlmodelt
Can you take some pics of this potentiometer you... Jan 4 2013, 08:06 PM Spoke Can you rev it up to 2k, 3k and stay running?
How... Jan 3 2013, 10:32 AM jdlmodelt
Can you rev it up to 2k, 3k and stay running?
Ho... Jan 3 2013, 11:14 AM Philip W. on the passenger side of the engine compartment - ... Jan 3 2013, 01:25 PM jdlmodelt
on the passenger side of the engine compartment -... Jan 3 2013, 01:52 PM brant you mentioned the wire from the distributor earlie... Jan 3 2013, 01:57 PM jdlmodelt
you mentioned the wire from the distributor earli... Jan 3 2013, 02:06 PM r_towle read
http://members.rennlist.com/pbanders/DjetPar... Jan 3 2013, 02:01 PM Philip W.
read
http://members.rennlist.com/pbanders/DjetPa... Jan 3 2013, 02:07 PM jdlmodelt
[quote name='r_towle' post='1795525' date='Jan 3 ... Jan 3 2013, 02:19 PM Spoke Does LJET have an MPS? I thought it had a mass flo... Jan 3 2013, 02:29 PM Philip W.
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Two suggestions, one take photos of your engine b... Jan 4 2013, 06:58 PM jdlmodelt thanks everyone for all of the hints to figure thi... Jan 4 2013, 07:00 PM |
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