Engine vibration and metal noises

[Ryan S.]

I have been driving my D for nearly every day for the last 8 months without any issues. I just came back from a week long trip. I drove my D for a few miles without any issues on Friday. Yesterday evening, I started D and noticed an engine vibration. I figured it would go away once the engine gets warm. It really didn't go away even after engine warmed up. Engine continued to vibrate (cyclical type of vibration). When I accelerate from stop, vibration gets worse. It shudders at it goes from 0 to 15 miles. I also could hear a faint metal rattling noise from engine area. Once I reach the cruising speed, everything seems normal. I am not 100% sure but feels like I have less power now. I get a slightly more vibration when I put the transmission from P to D.

Other facts:
Idle is at normal, 700RPM and it doesn't fluctuate.
Air temperature here is at around 60-65F
Engine temp is within range
All fluid, including oil, transmission, and coolant are normal
Oil pressure is normal
Checked air filter and looks clean
No hissing sound from engine area.
Fuel injectors are secured and in place.
Oil filer cap is secured and in place

This car has
Automatic transmission
Dave's RPM relay
DMC integrated fuel pump with external check valve
Cold air intake

I would appreciate any advices or recommendations.
Thank you


http://www.youtube.com/embed/YhRjpBs2TM8


http://youtu.be/YhRjpBs2TM8

[vwdmc16]

Yeesh, that is a new sound. Maybe the flex plate of loose? Id like to come hear It in person. Don't recommend driving It until we fix It.

[Ryan S.]

Also, if I accelerate hard from the cruising speed, I could hear the metal rattling noise from engine.

[Jonathan]

From the video, I don't quite get the "feeling" of the vibration or to what extent it is doing so. Likely different in person I'd imagine.

One thought on a bit of shuddering/vibrating my car did in the past was related to a spark plug cap or two getting wet after a car wash. Not sure this is the same vibrating you're describing, but it is the first thing that came to mind. If that happened, get it dried out, confirm the connection is tight and sealed and reevaluate.

When the "metallic" sounding noise comes and goes in the video, it seems to me like it could be a fastener or bracket a bit loose. Check in the immediate vicinity to the engine and exhaust to see if all your nuts and bolts are tight. It seemed like it was centred around the muffler, but that could have just been because of where the camera was being held. There are 12 nuts to check on the rear fascia support strip (5 upper and 7 lower) that could be it. Or the cover near the latch mechanism or the lower engine cover latch itself. Perhaps also the brackets on the passenger side holding the cold/warm air intake duct as well as the coolant reservoir. Someone posted on here recently about taking their three way valve out and putting the cold air only duct in, but I don't remember if that was you. To me it sounds like something simple is loose outside or around the engine rather than something goofy going on inside it.

EDIT: sorry, just looked again at your list of car mods and see the cold air intake listed. Have a look there and see if something isn't snug.

[DMC5180]

Well, a several thoughts come to mind. This kinda sounds like something is contacting a Trailing arm shield or is not properly installed (clipped to the frame). Another possibility is a broken right side muffler heat shield bracket. I had that happen to me, the spot welds failed and the two parts would bounce against one another. If you still have the stock exhaust, there is a heat shield on the crossover pipe that could be rattling. Lastly you could have something failing with the flywheel Flex Plate.

[SS Spoiler]

Had strange rattle, traced to heat shield. Big ss hose clamp silenced it.

[WelmoedJ]

Racerx also mentions "loss of power".
So the rattling and this loss of power make on think more engine related than merely bracket problems.

Since it's an automatic the pressure regulator could have a damaged vacuum line.
You will not be able to hear that one hissing when over the engine, only when under the car.

Nevertheless that would not cause rattling.
Perhaps a defective (broken) transmission support bracket could cause that.
And has rupted the vac line to the pressure regulator?

[Ryan S.]

I checked all fasteners and they are all good and nothing is lose. I didn't hear any whistling sounds when I was under the car. Car is pretty dry. It has been in a garage for over a week and haven't washed it for over two weeks.
I will try to check spark plugs.
I always had some transmission fluid leaks and I did see leaked fluid around transmission area but the level was normal. Other than that, I didn't see anything unusual.
It is hard to see engine vibration from the video due to image stabilization system. Definitely it is vibrating.

[Ryan S.]

Clint came over and helped me check out my car. Clint thought that not all cylinders were working. Spark plugs were all firing up and looked ok. We test drove the car together and heard the rattling noise at full acceleration. Clint suspects fuel related issue. Per Clint's recommendation, I plan to take in my injectors for cleaning. Also replace spark plug wires and distributor.

[vwdmc16]

Right, all plugs looked clean and tan. All wires looked fair but with unknown age with cap, rotor and wires. When driving I heard a definite Knocking/pinging/detonating sound from a cylinder. Im leaning towards a dirty injector which also don't know the history of. New plug wires/cap/rotor and injector cleaning could go a long way to making it purr nicely.

The flex plate rattle noise was no evident anymore at idle.

[David T]

Right, all plugs looked clean and tan. All wires looked fair but with unknown age with cap, rotor and wires. When driving I heard a definite Knocking/pinging/detonating sound from a cylinder. Im leaning towards a dirty injector which also don't know the history of. New plug wires/cap/rotor and injector cleaning could go a long way to making it purr nicely.

The flex plate rattle noise was no evident anymore at idle.

Pull the valve covers and check the valve adjustments. From the video (and it is really hard to make assessments from them) It sounds like a valve on the left side. That would account for the metallic noise, engine vibration, and loss of power. In person I would use a long screwdriver, held against the ear and the other end touching the motor (or a mechanical stethoscope). Where the noise is the loudest is where you are closest to the source. You can at least narrow the noise down to which side and maybe which cylinder. Dirty injectors don't make noises (you may also have dirty injectors too).

[djdogbone]

That alternator belt looks loose....take a look at that and the alternator bracket as well

[vwdmc16]

Valves are not loose. The noise while driving is detonation.

[Ryan S.]

Thanks. I'll check belts. I definitely get vibration at low rpm. But at high rpm, vibration is gone. I plan to clean injectors but not sure if that is going to help or not since my idle is so stable and car starts with no issues. :confused:
Still...Vibration at low rpm, power loss, and metal rattling noise at full throttle. Uggggg....

[rdarlington]

Thanks. I'll check belts. I definitely get vibration at low rpm. But at high rpm, vibration is gone. I plan to clean injectors but not sure if that is going to help or not since my idle is so stable and car starts with no issues. :confused:
Still...Vibration at low rpm, power loss, and metal rattling noise at full throttle. Uggggg....

Bearings in the water pump? Alternator? AC pump or idler pulleys?

I'd do a simple test of just taking the belts out completely and listening for a short while. I stress SHORT if the vehicle is already warm as you won't be pumping any coolant around. Go with the AC/Accessory belt first. You can run that way for years if you don't want AC. The other belt will cause your battery to drain a little while running, and again, no coolant circulation, but it's an easy test to narrow down where the problem is or is not.

-Bob

[jawn101]

Just noticed this thread. I hope you figure it out, Ryan! You're lucky to have Clint in such a short driving range :)

[DMC_PRIME]

I had what I could of swore was a rattle years ago. It was a injector not working correctly. It is a amazing how your ears can play tricks on you....

[DavidProehl]

Interesting sound, doesn't sound like anything is about to fly apart though, seems pretty subtle to me. You have the right man looking at it though with Clint!

[Ryan S.]

I am happy to report that my engine vibration issue has been resolved, thanks to Clint. :partyhat:

Per Clint's recommendation, I sent in my injectors for cleaning at a local shop. (Doctor Injector) Shop owner told me that my injectors weren't too bad but was able to increase the flow by 5-10%. He didn't think my injectors were the problems. Darn... wasted $81.
I just reinstalled injectors and started the car. Much to my amazement, no more vibration. It ran smooth and no more noises. I guess it was injectors after all.

Thanks everyone for recommendations and feedbacks. Again, Big thanks to Clint. You da man

http://2.bp.blogspot.com/-d6nZSCGuXuQ/USeK3ISpBXI/AAAAAAAAOBc/aLwrz23AQj8/s1600/you+da+man.jpg

[Jonathan]

Thanks everyone for recommendations and feedbacks. Again, Big thanks to Clint. You da man

http://2.bp.blogspot.com/-d6nZSCGuXuQ/USeK3ISpBXI/AAAAAAAAOBc/aLwrz23AQj8/s1600/you+da+man.jpg

Glad to hear. Nice job Clint! Whodaman? That name's already taken, lol (...it came pretty naturally years ago when I already had the last name to go with it :) )

23646

[DavidProehl]

So glad this is resolved! Great work!

[Ryan S.]

One thing that I noticed is... now I have a slightly high idle, 900rpm when in neutral. Goes back down to 700 when car is in D or R.
Is this because of more efficient injectors? I also need to get smoged. Would this mess up my smog test?

[DavidProehl]

I was successfully smoged when idling at 1,000, but my guy went easy on me. I would expect you'll be fine at 900, that doesn't seem terribly high. You might also be able to adjust your throttle linkage to compensate, I found that playing with it fixed my high idle.

[Rich]

One thing that I noticed is... now I have a slightly high idle, 900rpm when in neutral. Goes back down to 700 when car is in D or R.
Is this because of more efficient injectors?

You want 775+/-50 RPM. 700 is too low. 900 is too high.

The idle speed control system is designed to maintain idle speed regardless of the engine load (Drive vs. Neutral, A/C on vs. off, etc.) so there is likely something wrong with it. And the root cause isn't "cleaned injectors" since the system runs a closed loop.

You can try troubleshooting any of these components or their connections:


LINK: Idle Control Circuit Parts List (http://store.delorean.com/c-338-2-5-0-motorecumicroswitch.aspx)

The idle microswitch is an easy one to check by observation and connection/bypass tests. And there is the issue of the throttle linkage being OK, as mentioned by David.

And a high idle like 900RPM isn't doing your driveline any good when shifting out of Neutral. Clunk.

[vwdmc16]

Awesome new Ryan, Im glad my idea worked out and you can drive easy with better running car.

[Ryan S.]

Thanks guys. Per your suggestions, I played with linkage and microswitch. :wrenchin:
Now everything is back to normal. I just have to pass smog.

[Ryan S.]

Well... It's back. It was running so well for over a month. It's sputtering again. My car has been sitting in the garage over the weekend. This morning, car wouldn't start. Sounded like battery was low. I couldn't even crank the engine. So I hooked it up a battery tender charger and went to work. When I got home, I restarted the car, took some effort but eventually it started. But I car started to sputter and vibrate. I definitely felt loss of power. It actually seemed worse than before.

I guess, I will inspect and test fuel system this weekend. I will check the usual suspect, injector and spray patterns. I am glad that I still have those mason jars. Based on Jon's experience, I will also check accumulator hoses.

[Jonathan]

Ryan,

If the battery was weak and the car wouldn't start, and putting a charger on it helped enough to get the car to start, wouldn't this imply the problem is the battery (or at least electrical) and not the fuel system (injectors or hoses)?

I'm not sure what else is going on with your car, but if charging a weak battery got your car to start, then I would consider a new battery and rule that problem out at least before diving into the fuel system.

How old is your battery? The rule of thumb is they last 5 years, and I tend to agree with that from experience. A $100 battery every 5 years is a pretty reasonable maintenance expense compared to the other money we all put in these cars.

[David T]

Ryan,

If the battery was weak and the car wouldn't start, and putting a charger on it helped enough to get the car to start, wouldn't this imply the problem is the battery (or at least electrical) and not the fuel system (injectors or hoses)?

I'm not sure what else is going on with your car, but if charging a weak battery got your car to start, then I would consider a new battery and rule that problem out at least before diving into the fuel system.

How old is your battery? The rule of thumb is they last 5 years, and I tend to agree with that from experience. A $100 battery every 5 years is a pretty reasonable maintenance expense compared to the other money we all put in these cars.

When the system voltage gets very low the motor will run but not well. A battery tender is not meant to charge a dead battery, only to "top off". You should figure out why the battery is low. It may be old, you may have things draining it, and you may have a problem with the charging system.

[Ryan S.]

Current battery is about 1.5 years old. Date sticker says 7/12. Never the less, I install a new battery but no luck. Still the same.
I don't think it's an electrical issue.

[Jonathan]

Ok. New battery didn't work. When you mentioned charging the battery with your tender/charger and it helped you get the car started, it made it sound to me like it was either an electrical issue or a coincidence of something else not related to electrical (like fuel as you mentioned).

As David pointed out, I would check the other charging system components. Alternator belt, battery warning light in instrument cluster, fuse or ground connections checked for corrosion. How does your inertia switch look under the steering wheel? Connections on it are okay?

[Ryan S.]

I took injectors out and set them up for the spray pattern test. Lined up my mason jars. Hook up my switch to RPM relay and.... nothing. I could hear the buzzing noise but no spray. Wait... #4 injector kind of sprayed a little but stopped. Other injectors produced just a few drops of fuel. Hmmm..... Is it a fuel pump issue? I have the DMC integrated fuel pump you know.

I hooked up my fuel pressure gauge to my fuel pump and... it gave me a healthy 4 bars. No issue with my DMC fuel pump. I knew that.

So I narrow down to a few suspects.

1. Distributor - Original
2. Fuel filter - I replaced it about 6 months ago. It came from DMC with my fuel pump.
3. Accumulator - I replaced it about a year ago. Part came from Hervey.
4. Accumulator hoses - Original hoses.
5. Injectors - I professionally cleaned them a couple of months ago

Did I miss anyone? How should I go about testing? Any suggestions or guesses? I am kind of amazed that car actually ran... with barely any fuel coming out from injectors.

Thank you

[Bitsyncmaster]

I took injectors out and set them up for the spray pattern test. Lined up my mason jars. Hook up my switch to RPM relay and.... nothing. I could hear the buzzing noise but no spray. Wait... #4 injector kind of sprayed a little but stopped. Other injectors produced just a few drops of fuel. Hmmm..... Is it a fuel pump issue? I have the DMC integrated fuel pump you know.

You need to press down the air plate to get fuel from the injectors. I press it about half way down.

[Ryan S.]

You need to press down the air plate to get fuel from the injectors. I press it about half way down.

Darn.... Details, Details, Details.... Thanks Dave!!!
OK, #5 was stuck. No spray came out while others were spraying. After I pressed and scrapped the injector tip with my finger nail, #5 started to spray. However #4 and #5 spray patterns are not quite even. They give out fan like pattern but only half the side. No 360 degree round pattern from the tip liked the others. Plus, #4 squirts out very little when I jumped relay without pressing down the plate.

Well... I gotta go to work now. I will try swapping injectors to see if this continues.

Thanks again Dave. You saved me from doing any unnecessary work.

[David T]

Darn.... Details, Details, Details.... Thanks Dave!!!
OK, #5 was stuck. No spray came out while others were spraying. After I pressed and scrapped the injector tip with my finger nail, #5 started to spray. However #4 and #5 spray patterns are not quite even. They give out fan like pattern but only half the side. No 360 degree round pattern from the tip liked the others. Plus, #4 squirts out very little when I jumped relay without pressing down the plate.

Well... I gotta go to work now. I will try swapping injectors to see if this continues.

Thanks again Dave. You saved me from doing any unnecessary work.

Sounds like you need to have the injectors cleaned. You can't do it with your fingernail. Keep in mind it is usually not "just" one thing wrong. As you look and test you will find many things that need work. It is the accumulation of all of these little things that make the motor run badly. To get it running as it should (and can) EVERYTHING needs to be working as it should.

[Ryan S.]

Injectors were cleaned and tested professionally less than 2 months ago. Hmmm.... do I need new injectors???

[Henrik]

Crud in the fuel tank clogging up the injectors aribitrarily - maybe?

[DMC5180]

I'd be more interested to see the inside of the FUEL FILTER and why the media does not catch the so called crud. Is it a paper element or coarse screen. What is the micron filtration rating of these filters?

[Rich]

I'd be more interested to see the inside of the FUEL FILTER and why the media does not catch the so called crud. Is it a paper element or coarse screen. What is the micron filtration rating of these filters?

Very unlikely that debris is bypassing the fuel filter unless the filter has failed/torn.

Most filter media nowadays is fiber-based (but is not actually paper) and is not a coarse screen. 10 micron nominal cutoff size. Designed to work with the fuel injectors.

A clogged filter will typically begin to cause problems at high engine loads first.

[Rich]

Injectors were cleaned and tested professionally less than 2 months ago. Hmmm.... do I need new injectors???

Assuming that at least one injector isn't spraying properly there are at least these options:

1. Clean them - or at least the bad ones - again. Maybe there was something in your system after the filter change you did. And maybe it's gone now. Or maybe they were not quite cleaned up as much as expected?
2. Replace them - or at least the bad ones. There are other reasons besides dirt for an injector to stop working properly.

Reference image here LINK: Spray Pattern Diagram (http://www.specialtauto.com/delorean-parts/images/injector-pattern.jpg) in case you need it to be sure you are really seeing a good spray pattern in your tests.

[DMCMW Dave]

Injectors were cleaned and tested professionally less than 2 months ago. Hmmm.... do I need new injectors???

Did you personally test them after they were "cleaned"?

[Ryan S.]

Yes, I performed the spray pattern test before I installed them a couple of months ago. They were working well and had good spray patterns.

Tonight, I tested spray patterns again. I am not entirely happy about #4 and #5 injectors but I decided to put them back in. Restarted the car and it's back to normal. No more vibrations and car runs great. I will probably get a couple of new injectors if this happens again. For now, I am happy that car is working.:woot:

[David T]

Yes, I performed the spray pattern test before I installed them a couple of months ago. They were working well and had good spray patterns.

Tonight, I tested spray patterns again. I am not entirely happy about #4 and #5 injectors but I decided to put them back in. Restarted the car and it's back to normal. No more vibrations and car runs great. I will probably get a couple of new injectors if this happens again. For now, I am happy that car is working.:woot:


If you got it so it runs try a can of Techron injector cleaner. If the injectors keep getting plugged up it is most often because you have a car that sat for a long time and the fuel system is full of dirt (stale fuel). Cleaning the fuel tank and replacing the filter is necessary but that won't stop any dirt that is already past the filter from breaking loose and getting into the injectors.

[Ryan S.]

Great. I will try techron. Fuel filter is only about 6 months old and fuel tanks was cleaned twice already before the DMCH integrated fuel pump installation. I have been driving this car almost everyday to work before this happened. I have been averaging 250 miles a week. I am guessing that old dirt, already in injector, might be causing this.

[Trstno1]

Did your metal rattle go away when the injectors were cleaned? I have the same sound that is driving me crazy! It sounds like a loose bracket or something rattling when the engine rpm increases. I too checked all fittings and brackets for looseness with nothing to report. I then removed my belts one by one and noticed that the sound went away when i removed the water pump/alternator belt. So now I'm thinking it's a bearing issue in either the alternator or water pump.

At this point I wish I could individually test the alternator and water pump without throwing money at new parts for nothing..... I'm at a bit of a stand still.....

The one thing that I have not attacked is the fuel system. I really have no idea of its condition and am a bit nervous as to what I may find.....

[WelmoedJ]

Did your metal rattle go away when the injectors were cleaned? I have the same sound that is driving me crazy! It sounds like a loose bracket or something rattling when the engine rpm increases. I too checked all fittings and brackets for looseness with nothing to report. I then removed my belts one by one and noticed that the sound went away when i removed the water pump/alternator belt. So now I'm thinking it's a bearing issue in either the alternator or water pump.

At this point I wish I could individually test the alternator and water pump without throwing money at new parts for nothing..... I'm at a bit of a stand still.....
You can test those devices: turn the alternator by hand and feel if there are moments you have resistance, pointing to a bad bearing.
You can apply the same test to the waterpump.
Both test situations of course only without the V-belt in place!


The one thing that I have not attacked is the fuel system. I really have no idea of its condition and am a bit nervous as to what I may find.....
The only moving parts that could rattle in the fuel system are the pump and (a part of) the injectors.
The injectors IMO will not cause rattling.

Does the rattling occur revving at stand still, while driving or in both cases?

[David T]

You can test those devices: turn the alternator by hand and feel if there are moments you have resistance, pointing to a bad bearing.
You can apply the same test to the waterpump.
Both test situations of course only without the V-belt in place!


The only moving parts that could rattle in the fuel system are the pump and (a part of) the injectors.
The injectors IMO will not cause rattling.

Does the rattling occur revving at stand still, while driving or in both cases?

Go underneath and look up at the bottom of the "neck" of the water pump behind the pulley. There is a hole there and if you see any staining or moisture the seal is bad and the bearings are bad. More likely a bad bearing on the alternator and you can't always feel it turning by hand. One way to pinpoint a bad bearing is with a metallic stethoscope. You go till the noise gets it's loudest. You can also take the alternator to a place like Autozone. They will bench test it for free and if the bearing is bad you will know right away.

[Ryan S.]

Mine was related to bad fuel injector(s). Cleaning fixed it but came back. I ended up getting a few new ones and I think that fixed it.