1986 328 loud engine clicking sound and stalling. Diagnosis? | Page 2 | FerrariChat

1986 328 loud engine clicking sound and stalling. Diagnosis?

Discussion in '308/328' started by sahn44, Oct 21, 2020.

Tags:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. sahn44

    sahn44 Rookie

    Aug 29, 2019
    40
    New York City
    Full Name:
    M. Sahn
    Ok, so made some progress today and narrowing things down some. Oil was actually low, below the min line so added a quart of 5W40 synthetic to get it back above the min line, and probably need to get one more added. Saw that the AC was actually engaged the whole time of the last run with the noises, and was on when I had gotten it home from the long drive where it stalled at the very end. I often run the AC at the end of a drive to let it run and check if it's still cold, but never turned if off when parking, probably because I was pre-occupied with the idling issue.

    So, this time there was some new oil and AC turned off before starting her up. The startup was good and no loud clicking noise this time! Even after engaging the AC after a bit, still no noise. So, best guess is that it was perhaps "cold" AC belt before that was making the noise? Whatever it was, it's not happening now, so focus is back on the low idling. Didn't need to use my new stethoscope. Oh well, $8 on Amazon and sure it will come in handy soon enough.

    On startup, it did the same behavior as last time, starting at 1,000 and then, after 45 seconds, dropping dramatically down to maybe 300-400 RPM (normal would be to start at ~1,300 and drop to ~800 after 2-3 minutes). It stayed there fine on its own (AC off). Later on, I tried engaging the AC and that was enough to drop the idle some more and cause it to stall. This would explain why it had stalled on me the first time after the drive when I parked it, because the AC was still on at that point, which is enough for it to stall at idle, while out on the drive I didn't have AC on so the idle still hung in there.

    video of today's startup: https://photos.app.goo.gl/cFoZC2hrHLRzyw9H6 (idle drop happens at 0:45)

    So, at this point, I think I can maybe rule out spark/ignition and it's more likely fuel/air issue? @moysiuan's theory of air injection seems pretty plausible to me now. If one of those valves has failed, that could happen suddenly and then there would be exhaust going into the intake which seems like it could definitely cause the reduced idle right away. I took some pics of those parts. The t-connector looks a bit rough, but intact. The front and rear valves are definitely different so one must have been replaced and not the other, which makes it more plausible that whichever is older might have failed.

    Image Unavailable, Please Login

    front valve:
    Image Unavailable, Please Login
    rear:
    Image Unavailable, Please Login

    So, if it is a bad valve in the air injection, what's the best way to confirm that? Looking at the diagram, there's a vacuum valve (circled red) that would be open or closed to allow air from air box to get to the exhaust. What conditions make that to be open? Could I open the airbox and feel the inlet there in blue to see if exhaust is coming in? Seems like that would be easier than disconnecting hoses.
    Image Unavailable, Please Login
     
  2. conan

    conan Formula Junior

    Nov 13, 2011
    389
    Is the fuel pump or filter old ? Maybe the system pressure is too low. Any air leak ? There are plenty of hoses ...
     
  3. Brian Harper

    Brian Harper F1 Rookie
    Owner Silver Subscribed

    Feb 17, 2006
    4,078
    San Jose area
    Full Name:
    Brian Harper
    Those air injection check valves can be removed and just blow through them. More than likely they are bad, they fail quickly. It crosses to a cheap Chevy part, $15 by memory.
    You can simply remove the vacuum hose from the top of the air valve you circled in red and check for symptoms. Ideally you would plug or fold over the hose to seal it, but it won't make much difference.
    Also I'd bet none of this is your problem.
     
  4. sahn44

    sahn44 Rookie

    Aug 29, 2019
    40
    New York City
    Full Name:
    M. Sahn
    fuel filter replaced a year ago. I don't see any evidence of fuel pump being replaced in the documentation I have going back ~20 years.
     
  5. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,257
    UK
    Do you recall a significant drop in power? If so I'd suggest you might be losing a whole bank.


    In which case check the coil leads, rotor arms, caps & the ignition amp modules ( and connections to them) located on top of the coils. The ignition amp module is a favourite if this I'd what is happening. I had one go south once. I also had a connector just come loose on one as well once.

    Ignition problems are much more common than fuelling with these things.

    It wont be crank sensors, there only 2 on a 328 and if one of them goes the whole thing dies. Likewise there Is only 1 ignition box so it's not that either. Theres no half measures with those like a 308.
     
  6. sahn44

    sahn44 Rookie

    Aug 29, 2019
    40
    New York City
    Full Name:
    M. Sahn
    Seems easy enough to check so i'll do this next. I see in the service records that one of the check valves was rusting and replaced 17 years ago. So, will check the other one (pretty sure it's the rear black one).
     
  7. sahn44

    sahn44 Rookie

    Aug 29, 2019
    40
    New York City
    Full Name:
    M. Sahn
    No, I never noticed any significant loss of power. I was driving pretty hard intermittently and the first indication of an issue was when I was slowing down to brake or at stop sign and had foot off the accelerator with the clutch pressed. But, getting back on the accelerator, everything felt fine.
     
  8. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,626
    Canada
    #33 moysiuan, Oct 24, 2020
    Last edited: Oct 24, 2020
    Well you are making progress, looks like the snapping noise was the belt so good to have that out of the way. Although the thread went into details on the extenders, it appears you have not seen anything obvious there, so that somewhat common issue appears to not be the problem. As I noted originally, and with your further description, it appears fueling is the issue, not spark.

    I see non-OEM clamps on the t fitting, and one of the air check valves (the clamp with the blue on it is not OEM), so these have been worked on before. The one with the original clamp has almost certainly failed inside, even the 17 year old "new" one may have failed, so I am going to continue on this theme as the issue. If the exhaust gas has leaked backwards it can sometimes damage the vacuum valve you circled which is itself another check valve whose operation is controlled by and electrovalve and the computer which gives vacuum to the unit and allows air from the air box to be sucked into the engine exhaust. The air injection takes place when the engine coolant is between 15 C and 50C. It is all designed to reduce emissions after a typical startup.

    While I think your check valves have failed, they may not be the direct cause of the problem you are trying to solve, if the vacuum valve itself has not failed and exhaust is being sucked into the air box (although you can imagine hot exhaust gases backflowing would not help the hoses or plastic vacuum valve, your gnarly t connector suggest some exhaust gas corrosion is going on in there). But let's assume for now the vacuum valve is ok. What else would cause the idle to start lower than it should, and then fall too low after brief warm up? That would be the AAV, the auxilliary air valve. Another common problem area, and can also be damaged by the exhaust gas backflow in the event of a failed check valve. The AAV works as follows: It is a disc that is partially open at rest, and closes further based on the car warming up using a simple bimetallic strip to push the little disc closed. What this means is that when cold the car gets extra air to make the idle higher at start up and get the cats warmed up more quickly. After a short time, a built in heater causes the valve to close, and that is why your idle drops. What can happen is this disc can get stuck, and not be doing its full range of movement, especially if you had an exhaust gas blowing back and carbonizing things. See if you can remove one hose going to the unit (in my Mondial it is very accessible, not sure in your 328), and liberally spray some WD40 in there. There is not much in there, and it will free up any sticking and clean out some carbonization.

    As a bodge, you can unscrew (counterclock) the big air bypass bolt half a turn, it is the one with the spring behind it, it is on your fuel injection plennum at the bottom the the big air intake hose. This is the bolt that is used to adjust idle speed. This won"t directly solve your problem, but it will raise the idle, and might keep the car from stalling while you start the car for continued diagnosis. Might even cause you to be able to drive the car to a mechanic. If for example the AAV was not working properly, and is not getting your car the correct airflow, this screw will add more air and compensate. If turning this screw solves the problem, it will further point the AAV as not being up to the task. If the car still idles and dies, albeit at a higher starting rpm, then put the screw back to its original position, such that if you end up at a mechanic you have not altered the base settings from where the car last previously ran well.

    As others note, there are many things that can cause the symptom you are describing, there are a few interactive components in the fuel injection and ignition system controlled by computer, everything in the both systems needs to be working or if any one part is a problem similar symptoms can present. In the 328 there is a separate ignition and fuel computer. Unlike eg. later cars like the 348, there is no self diagnosing aspect to these cars. There are some tests than can be done using ohms and volt meters by dismantling the connectors to the spark and fuel computers to get the meter probe access, which can in effect check many of the system components. Combined with fuel pressure tests, this is how a dealer would go about diagnosing the problem. But they would first inspect more obvious things before diving in.

    My advice is around doing some of the inspections a mechanic would check first to rule out simpler issues that do not require much expertise, just a good eye and getting the hands dirty a bit on readily accessible items.

    I went through all this, and in my case the fuel injection distributor needed a rebuild. It is full of rubber o rings and a rubber diaphragm which perish with age and alcohol in modern fuel. My car presented the initial tendency to stall as your did, out of the blue as in your case, it was being flooded by fuel from the internally leaking fuel distributor. The computers can adjust the whole system to try and compensate, which further disguises the actual problem.

    As for more simple issue ideas, maybe time for new O2 sensor. The car relies on this for a proper idle, but the car can run well at speed with it not working, so that"s another simple item to replace. Much of the cars systems are actually designed to have low emissions as idle as their main purpose, and these systems have little affect once you are on the throttle.

    To provide encouragement, these are cleverly designed systems, and quite reliable, and some interactive complexity that make sense for the issues they were designed to address. Its is all the German designed systems used on all the Mercedes of the period, so it is not really that exotic.

    Just takes a bit of methodical sleuthing to sort things out.


    (By the way, save your old OEM clamps, they are becoming rare and valuable bits, even though the newer clamps have better function).
     
  9. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,626
    Canada
    Image Unavailable, Please Login The AAV is item 44, you can take off the hose 41 and spray the wd 40 in there. If you use a dental mirror, you can take a look inside with a flashlight and see the amount of disc opening when cold. It should be about 1/3 closed when the car is cold.
     
  10. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,626
    Canada
    The idle air bolt is item number 34 in the exploded drawing.
     
  11. mike996

    mike996 F1 Veteran

    Jun 14, 2008
    6,685
    Full Name:
    Mike 996
    Was that startup from cold?

    If so, your startup / reduction to idle drop process sounds normal to me EXCEPT the RPM all around is too low.

    My '89 328 startup from cold to idle time frame mimics exactly what your car did. The difference is in the RPM at startup idle/low idle. The initial fast idle is typically somewhere north of 2000 RPM, dropping to 1000 for "normal" idle.

    IOW, your engine is doing exactly what my 328 has always done but at a much lower RPM. As suggested, I would try adjusting the idle RPM to 1000 RPM with the engine warmed up and AC on (compressor energized). Then, the next morning, see what it does when you start the engine.
     
  12. conan

    conan Formula Junior

    Nov 13, 2011
    389
    It sounds like air is leaking in from the outside bypassing the air plate. When the control pressure is low at cold the car runs ok with normal idle, but when warm, the wur tries to reduce the fuel flow by applying a higher pressure on the plunger which also makes it harder for the air plate to open. Less fuel, less air and also lost air slipping by causes even less fuel.

    Of course, the idle screw could have changed position or the air channel in the throttle body might be clogged.

    I would have checked all vacuum hoses for cracks, unconnected or faults in the attached valves. Using a vacuum pump instrument, the different valves can be easily checked. Also the brake booster can be verified.
     
  13. Skippr1999

    Skippr1999 F1 Rookie
    Silver Subscribed

    Dec 22, 2009
    4,209
    FWIW my belt slap sounds like the sounds you have in the video and it does it when cold and clears up in a few minutes. It sounds very metallic at times and can be quite a troubling sound, but it’s just the belt. I’ve been round and round with it and haven’t found a lasting solution. No biggie on that front.
     
  14. sahn44

    sahn44 Rookie

    Aug 29, 2019
    40
    New York City
    Full Name:
    M. Sahn
    Thanks for the info and detail here. I'll try to go through more of these checks piece by piece. Seems like the screw adjustment might be a last resort way to get it idling reliably enough to drive it to a mechanic ultimately which is good to know about.


    Yeah, that startup was from cold. Good to hear that timing for RPM drop isn't so far off from yours. It was definitely longer for me before, at least a minute and half, but I guess the valve is functioning ok to be starting high and dropping low, albeit more quickly than before. Sounds like your RPMs are higher than what mine were, but I could be remembering a little low and I guess each will be set a little different.

    Thanks, I'll look over all the vacuum hoses. That makes sense if some extra air was getting in where it shouldn't that would cause problems.

    Good to hear this. Definitely freaked me out. It's possible it's made that noise before (from the belts) and I just didn't notice being inside the car with the rear closed. This was a rare time when I was up and out of the car right after start with the rear open and with the AC on at idle from cold start. I'm happy to put this one to bed (for now. fingers crossed).
     
  15. Skippr1999

    Skippr1999 F1 Rookie
    Silver Subscribed

    Dec 22, 2009
    4,209
    You will hear it in the cars cabin too. I think turning off the AC stops it. My AC works great, so I usually leave it on which leads to the belt slap all the time.
     
  16. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,626
    Canada
    The belt slap is normal for a cold older belt. A new belt will eliminate that for about 2 or 3 years, appears that heat and age stiffen things up, although it is also possible your belts need re-tensioning, that is part of the factory service a couple of years after new belts, as they can slacken and flap around a bit more with use.
     
  17. thorn

    thorn F1 Rookie
    Silver Subscribed

    Aug 7, 2012
    3,322
    Tallahassee, FL
    If it's AC Belt Slap, you'll probably hear it whether the AC is engaged or not - either way, the pulley is turning.
     
  18. Alfer

    Alfer Formula 3

    Sep 4, 2007
    1,346
    NH/the Netherlands
    Full Name:
    Menno
    The ticking sound is the AC belt. I have heard several now and also mine had it (100% exact same sound). Tipically the sound get less when the motor warms up and likely disappears after some minutes. Just see for more tension of the belt.
     
    Skippr1999 likes this.
  19. sahn44

    sahn44 Rookie

    Aug 29, 2019
    40
    New York City
    Full Name:
    M. Sahn
    Luckily, the ticking sound has yet to return again, so still left with the low idle. I've done some more looking and maybe ruled some things out. For one, it appears the air injection system is working fine (ie, check valves, electrovalve, cutoff value). I checked this by removing the air filter and holding my finger to hole in the airbox while it was idling just after startup. It was sucking air very well and nothing coming back the other way. I did notice soot/dirt there in the hole and coating the bottom part of airbox when I first removed the filter, so thought that was maybe evidence that there would be exhaust coming back in, but it was sucking air in pretty well when I started it. I guess it was just some normal dirt. Then, to see if the cutoff valve was working (ie, closing once temp was up) I revved up to 1500/2000 for a couple mins to get the temps up and then checked the suction again. Once the engine was warm (and now barely not stalling), the hole was no longer sucking air at all and there was nothing coming out, either. So, the cutoff valve must have properly engaged and no more suction. So, seems like I can rule out the air injection system, bad valves, etc.

    the airbox hole feeding air injection:
    Image Unavailable, Please Login

    After reading about frequency valve being a potential issue in some other threads, I wanted to check that, too, since I had not really been able to hear/feel the "buzzing" that people had said to check for. I unplugged the wiring harness from it, started the engine, then checked that there was voltage going to it, which there was. As soon as I plugged it back in, the idle immediately improved considerably, increasing RPM a bit. So, I can rule that out.

    I tried increasing the idle RPM by turning the large idle air bolt as @moysiuan @mike996 suggested to compensate temporarily. It did increase the idle, but I did a full turn and a half and only increased it maybe 150RPM or so to 700/800 (still in cold cycle) and got nervous and put it back where it was. Would it be ok to unscrew it a lot, temporarily, like 3+ full turns to get the idle up enough for testing and maybe drive it to shop that way?

    Generally seems like AAV valve is functioning since I do get the RPM drop once it warms. So, in summary, everything is happening as it's supposed to, just at way lower RPM than it should. When warm it will just barely not stall, maybe 250-300 RPM. Not sure what to check next. Still possible there is extra air leaking in somewhere bypassing the air plate as @conan said. But, tracking down a vacuum leaks seems challenging. At the end, I did notice this one loose clamp on a hose going to the bottom of the throttle body. I think it goes to the WUR, but the hose seemed otherwise pretty solidly on there so I doubt any extra air was actually going in there. I'll get that tightened up next time and try again.

    Image Unavailable, Please Login
     
  20. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    3,626
    Canada
    Your main accordian air intake hose from the plenum to the throttle body almost looks a bit cut by the clamp. Maybe that hose has a split underneath where it is hard to see, in the one of the accordian folds. I would take it off and look at it carefully, it is just two hose clamps (it might be a bit stuck on if it has not been removed of late). This hose gets hot, and flexes a lot with the engine moving around quite a bit, which is why it is an accordian design and while it is thick it might harden and split.

    This reminds me to check your throttle position sensor. The TPS is the black triangular thing on the right of the throttle body. This switch is supposed to be adjusted in its position such that just as you open the throttle (just push the throttle cable lever at the throttle body and listen carefully) it will make a click. Do this check with the engine off, the click is very faint. The TPS has a special setting for idle, and if you don't hear the click just off idle, the TPS may need to be adjusted. The two screws that hold it can be loosened, and you slightly twist the unit into a position such that you get the just off throttle click. To be more advanced, you can also test the TPS with an ohm meter at the connector to the wires. It can be done without removing the item, but it is easy to remove (just don't drop the little bolts/washer that hold it on when removing it). https://ferrari.cdyn.com/carl_rose_docs/Ferrari 328 TPS.pdf

    Seeing how your car starts and runs, I would play around with the idle adjustment. Just keep track of the number of turns in the air bypass bolt adjustments you make, such that you can reset things back. It won't hurt anything. Raising the rpm 300 rpm as you would seem to require would be well within its adjustment range to do that. The goal is simply to be able to put it back so if you eventually have to get this looked at at a shop, then the original setting intact will provide the better basis for someone to do the diagnosis. Put a paint or magic market dot on the bolt so you don't loose track of where you started. The air screw is typically (I think, maybe others can chime in) about 1 to 3 turns out from full closed with the throttle plate correctly adjusted.

    Just don't touch or adjust the mixture screw on the fuel injection distribution and plenum unit. That is a really sensitive adjustment and key to the emissions outcome, and really small movements have big changes. In theory one would adjust the fuel mixture after adjusting the air bypass, it is a circular approach using an exhaust gas analyzer to get the correct emissions and optimal drivability fuel mixture setting using both the air bypass and mixture screw adjustments.
     
  21. mike32

    mike32 F1 Veteran

    May 13, 2016
    5,828
    Isle of man- uk
    That would have more effect at speed as the fuel flow increased, not at idle
     
  22. sahn44

    sahn44 Rookie

    Aug 29, 2019
    40
    New York City
    Full Name:
    M. Sahn
    I visually checked it and I don't see anything like a split. The part at the front that looks cut is just impression from the clamp. Might still remove and look closely as you said. Was really hoping this was it as it would be an easy fix at least.

    Checked and it's definitely making the correct slight click sound just off idle.

    Playing with the idle bolt more aggressively this time, it basically did nothing. Letting it out 3 full turns and it didn't make any noticeable difference in idle speed, though this was while it was still in the cold cycle. It was staying there at 650 or so. I guess this would have made more of a difference once auxiliary air shut off, which it didn't even get to tonight as I didn't rev it to get the temp up this time (was idling maybe 5 mins). So, i'm nowhere near 1,000 RPM at idle now during the cold cycle and with the idle screw opened more.

    Looked and felt around other air lines and didn't see anything suspect. Anything else easy I should check? I'm reasonably confident it's drivable (to a shop) with A/C off and giving it some throttle at idle. It's always starting reliably, revs up with throttle, and the clicking/ticking never came back.
     
  23. daynyc

    daynyc Karting
    Silver Subscribed

    Aug 5, 2016
    79
    From your photo, it doesn't look like your butterfly stop screw is doing much. I won't go into all the theories about how much idle should be adjusted by the screw versus the "idle bolt," but if you need a stronger idle, if for no reason other than further diagnosis, will opening the butterfly help? By the way, did you check your spark timing with a light and confirmed that you have no issue there? I now know that your 328 does not have dual ignition boxes and three sensors like my 308, but I do know that these devices do not necessarily fail totally and all at once.
     
  24. ginoBBi512

    ginoBBi512 F1 Rookie
    Rossa Subscribed Silver Subscribed

    Oct 9, 2016
    3,434
    SO CAL
    Full Name:
    GINO RUGGIERO
    I think the shop idea is at hand, you wouldnt believe all the ins and outs that these cars have, I would bet that a shop with 3x8 experience will have you back on the road shortly. This has been my experience with my 20 years and 80,000 miles of ownership . I would venture a guess that being the 3x8s have been the best built Ferraris since the V12s came out in the 50s and 60s, ( I would also include the BB512, Testarossa, 348 F40 ) they are the easiest to repair.While you are at it, I would have the shop replace the throttle cable, caps and rotors, wires, if you have not already.

    Thank you
     
  25. conan

    conan Formula Junior

    Nov 13, 2011
    389
    Air leaks are not easy to see. You need to disconnect the hoses and test for vacuum in each line. You can also see if the hose is cracking.

    Of course, a good shop will more effectively find the root cause, but if you are in for getting the knowledge yourself, take one hose at a time and understand what it is used for and test for vacuum.
     

Share This Page