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New head in place and all put back together. I bypassed the air and fuel coolers this time. Following the new engine break in procedures, she cranks up but there's an intermittent miss in it somewhere. When idling at about 700 rpms it just stalls out like it's not getting enough fuel. Cranks back up no problem. When I increase the rpms a little, it doesn't stall and purrs nicely. Going to check / clean IAC valve. Swap fuel lines with the other engine which has a separate fuel cell. I haven't run it in the water yet, just on a hose in the driveway. Probably ran it a total of 30 minutes yesterday, off and on. Want to get this idle issue fixed before I dunk it in the water and continue the break-in further.
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SELOC manual has good info on testing sensors etc. Much more so than the factory service manual. IAC valve should read between 8-12 on the resistance setting with multimeter. Mine tested at 8.9-9 so I have to assume it's functioning correctly. Swapped fuel lines and engine idled better but after 10-15 minutes on the hose in gear, it started trying to stall out. It never did but acted like it wanted to a couple of times. This behavior is between 650-800rpms. Any suggestions on what else to try? Plugs are new. -
That is only telling you the resistance of the coil wiring in the valve, you need to do a base idle adjustment and set the duty cycle up, it will tell you how to do it in your manual.Comment
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I saw something about that. Raising the rpms to 1k by backing out the air bypass screw. Should start beeping. I'll read through it again and try it. Thanks.Comment
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I am just curious, did you do a compression test (and possibly a leak down test) to make sure everything is working properly with the new head?
On the IAC valve, did you try cleaning it? (You got to make sure the plunger is clean and moves freely so it can actually control the idle air flow).
On my 140, I finally decided to quit chasing gremlins and set the RPMs at 800. That seemed to fix everything. (Spec is 650-700)
Good luck!
-ShawnComment
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Since reassembled, I have not done a compression or leak down test. Head, valves, etc are all brand new. Bought it fully assembled that way. Been sitting on a shelf for years but never been used. Had the block surfaced, cylinders honed, lash checked on new valves and installed new rings. New head gasket and engine holder gasket of course. Followed the factory service manual step by step for the reassembly process. I can do a compression test if needed. It idles pretty good mostly, this is an intermittent issue. When it's not acting up, it sounds smoother than it ever has. I'm confident I've solved the water in the oil problem with the new head and confident I've got it reassembled correctly. Since I've put it back together, all I've done is run it on the hose a few times at or near idle speed. Hoping to hit the water this weekend and get on with the next steps of new engine break-in.Originally posted by WEDOCQ View Post
I didn't disassemble / remove the IAC for cleaning, just put the ohm meter to the terminals. I will do that before I do the base idle adjustment so that's eliminated from the equation.
I would have sprung for a new engine instead of dealing with all this, but I have twins on a SeaCat, port side runs great. Quote on 2 new engines was almost $20K so I bought a factory service manual and got my metric tools out!
Shawn, you say chasing gremlins... What was yours doing that increasing the idle resolved?
Thanks for any help and input guys!Comment
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I personally don't like trying to fix faults with things "bypassed" put it all back together as it should be first. You have gone this far, just replace the IAC and be done with it, when you say "it cranks up" do you mean starts, or "cranks" meaning the starter spins the motor over?Comment
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Cleaned and reinstalled the IAC. Set duty cycle. Didn't help a bit. Stalled out while idling at about 700 rpms after 15 minutes or so. Not getting any alarms or flashing lights. Starts right back up. Is the IAC a normally open valve? And it actuates based on voltage signals from the ECM when the engine hits a certain rpm level? I was able to manually move the plunger up to a closed position. Don't know how well it sealed. Maybe a clogged injector or Ignition coil not firing consistently? Both high and low pressure fuel filters are new. I see how to check the timing but how would one go about adjusting it? Isn't the ECM supposed to control all that? No alarms leads me away from any sensors and towards fuel or fire. Thanks for any input.Comment
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How was it running befor you replaced the head, if the answer is yes then you need to be looking in that erea, It sound like a fuel related problem to me.Did you check and inspect the VST, Mabey while moving things around you may dislodged some crap and its restricting fuel, check if there is good fuel pressure. Are you positive you have allined the timing marks as ilistratedComment
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Ran like crap before replacing the head, but #4 was full of water. Timing chain has 2 blue links and 1 **** one that align with marks on the cams and drive sprocket. I'm all over it.Originally posted by catacom225 View Post
I think... I hope I found the problem. Ohmed through the coils. Suppose to get a resistance value of 1.9 to 2.5. First I checked the top coil and it read 0.8. Checked the bottom coil on this engine and it read 2.3. Checked top coil on port engine and it read 2.4. Going to swap that one with the one reading 0.8 and see if it clears up.Comment
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Mine was a rough idle, and would die occasionally. My motor was a little special though. It originally was a DF115, and when the engine holder corrosion took out the powerhead, I bought a low hour DF140 powerhead and attempted to convert everything over. I eventually got it all together and ran it for 6 seasons. It ran good, but never wanted to idle very well at 650 rpm. I tried everything! Including several IAC valves. So, I bumped the idle up to 850 and called it good. HahahaOriginally posted by Lunchmoney View Post
-ShawnComment
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''''''So you got the engine warm, checked and made sure the closed throttle switch was working, removed the plug from the throttle body and screwed the iac screw out till the engine rpm went over 1000 and the buzzer sounded, what was the duty cycle on the meter at that stage. Connect up a vacuum gauge to the engine while it is running and see what the vacuum is and come back on the forum with the results.Originally posted by Lunchmoney View PostComment
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Checked compression, all 4 came out between 185-190. Ohmed through the coil terminals and found the top coil was out of spec. Read .08 and should be between 1.9 and 2.5. Swapp ed it with a good one off the port engine and it Idled better. That miss is gone. Noticed it having a little more vibration to it than the other engine comparing them at 650rpms or so. Increasing the rpms to 1000 with the warm up lever and the vibration is much less noticeable. Had some prop rattle when idling in gear on the hose. Seems to be normal at idle with a heavy ss prop from what I have read. Thanks for the help and pointers along the way gentlemen.Comment
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Mate these engines run sweet as, if you have to bring it up to 1000rpm to get it to idle properly, something is not right, that's why I want you to hook up a vacuum gauge and tell me what the reading is.Comment
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OK. Can you please enlighten me on where the gauge is to go and what the process is once installed? On the intake manifold somewhere?Originally posted by redlowrey View PostComment
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