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M20 engine vibration and rough running at 1800 rpms and above: Video added

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  • citizen_insane
    replied
    Originally posted by Von Soman View Post
    Where should i look or look out for developing down the road ?
    Have you done a compression check on it? Pulled the plugs to look for signs of detonation or incomplete combustion? That's where I'd start.

    Leave a comment:


  • Von Soman
    replied
    Its not going to be the mounts, 6clr engine running properly is perfectly smooth and would free rev smooth on bricks. If you are getting as bad of roughness as you describe when you are free revving then its something fundamentally wrong. If nothing jumps out i would have the shop do a compression test, then you can at least get some confidence that the mechanical job was done well. Then start looking at the injectors or the ignition system and try and pinpoint which cylinder is not firing properly. If the injectors haven't been cleaned and flow tested as part of the overhaul they really should have been.

    Did they adjust the valves properly?


    New 19lb injectors were used with a new Ssquid chip, new 274 bimmerhead cam. I am not sure if the injection system was addressed. it was functioning properly when the car was sent in.

    in the next week i will shoot a video with my phone of it idling and revving with the rubber mounts installed.

    Leave a comment:


  • Von Soman
    replied
    For what it's worth, I have poly 95A engine mounts and stiffer E28 rubber trans mounts w/ stiffening cups and I have no vibrations at all. I was the one who swapped them out so I can compare before and after, there was almost no difference, just a tiny bit more vibration at idle. Like e30davie said, it's a 6 cylinder engine w/ perfectly balanced pulses, it should not vibrate. If you pop the hood of my car while it's running you can't see the valve cover move at all. I still wouldn't be 100% convinced the issue was just the mounts, they may be masking a larger issue.

    Where should i look or look out for developing down the road ?
    Last edited by Von Soman; 03-26-2020, 03:02 PM.

    Leave a comment:


  • citizen_insane
    replied
    Originally posted by Von Soman View Post
    update: solved issue. its been about a month since i sent the 325i back to the shop. I got a call last week saying it was ready and the vibration was gone. I have been in PT Reyes California remodeling a home so the shop knew they had time to get to it with out a rush. They changed the Poly engine and transmission mounts out for german rubber mounts. I am happy to say it's true No more vibration. the rear differential mount is rubber. I certainly learned something here. The amount of vibration is astonishing with poly. My car has the door panels off so the noise was accentuated i am sure.
    For what it's worth, I have poly 95A engine mounts and stiffer E28 rubber trans mounts w/ stiffening cups and I have no vibrations at all. I was the one who swapped them out so I can compare before and after, there was almost no difference, just a tiny bit more vibration at idle. Like e30davie said, it's a 6 cylinder engine w/ perfectly balanced pulses, it should not vibrate. If you pop the hood of my car while it's running you can't see the valve cover move at all. I still wouldn't be 100% convinced the issue was just the mounts, they may be masking a larger issue.

    Leave a comment:


  • Von Soman
    replied
    update: solved issue. its been about a month since i sent the 325i back to the shop. I got a call last week saying it was ready and the vibration was gone. I have been in PT Reyes California remodeling a home so the shop knew they had time to get to it with out a rush. They changed the Poly engine and transmission mounts out for german rubber mounts. I am happy to say it's true No more vibration. the rear differential mount is rubber. I certainly learned something here. The amount of vibration is astonishing with poly. My car has the door panels off so the noise was accentuated i am sure.

    Leave a comment:


  • e30davie
    replied
    Its not going to be the mounts, 6clr engine running properly is perfectly smooth and would free rev smooth on bricks. If you are getting as bad of roughness as you describe when you are free revving then its something fundamentally wrong. If nothing jumps out i would have the shop do a compression test, then you can at least get some confidence that the mechanical job was done well. Then start looking at the injectors or the ignition system and try and pinpoint which cylinder is not firing properly. If the injectors haven't been cleaned and flow tested as part of the overhaul they really should have been.

    Did they adjust the valves properly?




    Leave a comment:


  • E30-325iS
    replied
    I don't think that people aren't interested, it just seems one of those things that's hard to diagnose without seeing it.
    You could try posting a video or taking the car to another shop for a second opinion.
    There's a trouble shooting thread by jlevie that you could follow posting results as you work through it.
    Motor mounts are easy to replace so you could try replacing them to see if it helps.
    Same with the chip.
    Did the shop measure the P to V clearance when installing the new cam?

    Leave a comment:


  • Von Soman
    replied
    Update: The Shop thinks its the poly engine mounts. I do not have any experience with this car. Bought it with bad rings, took it to them and my first real drive was the other day when they said its ready. I do how ever have experience with solid engine mounts as my 914-6 race car had solid aluminum trans mounts and poly engine mounts those mounts connected to the metal bulkhead mount that I welded to the chassis. That car with a 220 HP, 2.5 ltr, big cam, 10.5 - 1 compression did not vibrate as the RPM's increased. Sure the I could feel the car twist under load but the harmonics did not change. I see this is not an interesting thread for many, especially the experienced crowd but any experienced advice would be welcome.

    Leave a comment:


  • Von Soman
    replied
    Before It was loaded on the tow truck I had a bit more time to run it without any distractions. I warmed it up then in neutral, I slowly revved it and at 2,200 RPM's the sound and vibration are noticeable. The sound is a slight miss in the rhythm an engine makes. No popping, no backfiring, just vibration and the sound increasing as the RPM's increase. I fear that its internal since the block, crank, rods, pistons, rings were not changed as their inspection deemed that not necessary. The head was rebuilt, 274 bimmerheads cam, squid chip, main and rod bearings were the only internal parts changed. I am hopeful my next conversation with them is on the details of what's wrong before any attempt to fix is made. I have stated that I want to know what is going on. I do not want a come get your car we fixed it already. That would make me suspicious as to what I am getting from them.

    Leave a comment:


  • M_3_X
    replied
    Interested in the outcome. Following.

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  • Lugnuts
    replied
    Crank position sensor?

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  • Von Soman
    replied
    tomorrow I am having the e30 towed back to the shop. all hoses, belts and gaskets are new and on. the shop thinks it could be the chip from Squid but They handed me the keys at closing time and it did not run smoothly at all. So it was not running properly for them is my conclusion. its either vacuum, fuel and spark or compression. I suspect compression. I will be sure to keep this going as they say they will fix it.

    Leave a comment:


  • e30davie
    replied
    someone leave a spark plug lead off?

    Leave a comment:


  • M20 engine vibration and rough running at 1800 rpms and above: Video added

    I just picked up my e30 from a reputable shop at closing time. I drove off and right away i notice the engine doesn't nt sound right starting at 1800 rpms with vibration that increases with the rpms.and doesn't go away. A few blocks later i am able to put it neutral and rev it up slowly and it does the same thing while in neutral and no load. The Shop is closed, they are gone and I will return tomorow but I would like to gain some knowledge here from the experts on this forum. The sound and vibration are similar to an engine not firing on all cylinders. the shop has had this car for several months. I like the shop and the people at the shop but somethings not right.

    The details

    I dropped off my 90 325i with bad rings according to the PO. along with a supposed to be good 88k mile M20b25 motor pulled by a different shop for an m50 upgrade. I wanted the good motor freshened up with new hoses, drive belts, compete gasket replacement, water pump, belts, crankshaft seal, motor mounts, oil level sender, thermostat, ignition wires. it was decided to rebuild the head with HD rockers, 274 cam, new head bolts, rocker shaft plug, camshaft seals and gasket. Additionally they thought I should replace the rod and main bearings so we did.

    Any common traits with this since it sounds and feels rough in gear under load and with no load.
    Last edited by Von Soman; 04-10-2020, 06:11 PM.
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