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Post by boostcreep222 on Jan 6, 2019 23:19:19 GMT -5
so this is an interesting issue,have had the issue since swapping it into the ranger , its a 1988 turbo coupe motor was running on a la3 now on mega squirt, while driving in boost out of boost when i hit 5k rpm i loose 2 cylinders, and they are gone for about 3 min , idling driveing whatever and then they come back, during this time the injectors fire twice as fast, this has been an issue with the la3, figured mega squirt would fix it or help me find the problem, not so much. so far ive got a new coil, intake air sensor, coolant temp sensor, wires plugs, distributor pickup and tfi, wire harness is a new ron francis, new computer (megasquirt) same issue , still scratching my head any input is appreciated, if i drive it under 5k its mint drives perfect, wheni bring it over it dose what i said and it fouls plugs, just dont know lol
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Post by Stinger on Jan 7, 2019 2:52:20 GMT -5
How do you know the injectors fire twice as fast when it happens?
Sounds like weak valve springs allowing the HLA's to pump up and hold the valves open, takes a couple minutes for the HLA's to drain the excess oil and get back to normal.
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Post by boostcreep222 on Jan 7, 2019 10:24:20 GMT -5
I think you might be right , I found out the injectors pulse twice as fast because, when I was using the la3 I figured out I could do a brake stand in 1st over 5 k rpm to make the event happen and then instantly start Trying to diag it, put a steathascope on the injectors and could hear an incredibly fast pulse , then and the two cylinders came back the injectors pulse went back to normal, thank you for the input , I was basically down to the injectors , maybe one hanging open but buzz tested them last night and they seemed fine , distributor signal, but like I said I rebuilt it , or a hyd lifter collapsing never thought they would hold the valve open but that’s a good thought , have you ever seen this before ? Is there any way to test that , or just change the springs and hyd lifters and try it ?its a 180k mike motor btw , under the valve cover looks brand new surprisingly , but I know that doesn’t mean anything as far as the valve springs being weak . Side note the mega squirt made it run so much better lol below 5k but good job on the instructions and packaging of that unit I love it ! It hauls ass How do you know the injectors fire twice as fast when it happens? Sounds like weak valve springs allowing the HLA's to pump up and hold the valves open, takes a couple minutes for the HLA's to drain the excess oil and get back to normal. |
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Post by Stinger on Jan 7, 2019 14:10:01 GMT -5
The lifter isn't collapsing, it's overfilling with oil because the spring pressure isn't sufficient. Too long of a lifter holds the valve open. If it collapse the valve would be closed all the time and the follower would be loose and would fall off and destroy the cam in the process.
Yes, this is a common problem with old springs. Spring pressure has to be higher for turbo engines so if people don't account for that, they end up with weak springs. If they are new then it certainly requires a little more research/testing to try to figure out what they are and how much pressure they have.
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