| Author | Message | ||
     Brian Vogel Grand Master Username: guyslp Post Number: 2415 Registered: 6-2009 |
Has anyone got recommendations for product(s) that seem to work [if any of them do - they may not]. I have a recalcitrant misfire on cylinder 7 on my Buick and all of the usual "easy fixes" have been attempted. My next guess is a bad fuel injector, but it could be dirty. The problem most often is severe when the car is first started and running cold for several miles but then generally stops happening. I'd rather try the next "possible simple fix" if I have a single dirty injector that would not require me to take the car to another shop for extensive computer diagnostics and, likely, replacement of parts in a "throw parts at it" attempt to fix it (which seems to be the way with hard to diagnose things these days). Brian | ||
| Mark Aldridge Grand Master Username: mark_aldridge Post Number: 460 Registered: 10-2008 |
Brian, I use Valvoline SynPower in our cars periodically, whether it does any good or just makes me feel good is questionable. Mark | ||
| Omar M. Shams Grand Master Username: omar Post Number: 1326 Registered: 4-2009 |
I wish I could suggest something Brian. Unfortunately I have never had any luck with any kind of additive for anything - power steering - injectors - piston ring wear - radiator cleaner...... no matter what i have tried in the past has not worked for me. I have become an additive non-believer now... | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1795 Registered: 5-2012 |
Hi Brian - Like Omar, I have never had any luck with additives. Have you thought about taking the injector off and cleaning it. There are plenty of videos on youtube and the methods look simple, low cost and effective. Geoff | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1524 Registered: 9-2004 |
I also don't have much time for this type of products but one that worked for me with twin Volvo Penta that suffered with fuelling probs was Wynns. https://www.amazon.co.uk/Wynns-55964-Injector-Cleaner-Petrol/dp/B004RP3AEM | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2416 Registered: 6-2009 |
Thanks to all. I am, as a general rule, and additive non-believer. That being said, in this instance I figure it can't hurt and the expense is minimal. I need to pick up the car later tonight. Brian | ||
| ross kowalski Grand Master Username: cdfpw Post Number: 552 Registered: 11-2015 |
Brian, did you listen to the injector? | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2418 Registered: 6-2009 |
Ross, No. And since I have absolutely no idea what I'd be listening for or where to listen I doubt this would help me much. Also, since my "regular guy" who generally fixes what can be fixed without tons of computer diagnostics beyond OBD (and who's also a long time mechanic with decades of experience) gave up after almost a week of tweaking the usual bits. His next suggestions were either an injector problem (which I suspect is preferable) or, possibly, some weird problem with the distributor which, in this car, is located behind the water pump (oddest and most inaccessible location for this device, really). He also didn't feel confident going further without more advanced diagnostic equipment than he owns. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1798 Registered: 5-2012 |
Brian Re: No. And since I have absolutely no idea what I'd be listening for or where to listen I doubt this would help me much. Here's a very good 3 minute video that shows how to use a screwdriver as a stethoscope and also includes the audio of the sound of the injector. https://www.youtube.com/watch?v=tA_E6X4ISgQ This will of course only tell you if there's an electrical fault causing erratic firing of the injector. It will not tell you if the jet is partially blocked or whether there is an incorrect spray pattern. It's certainly worth checking. I guess what your mechanic is alluding to in mentioning the distributor is the fault on your engine could also be caused by an HT problem on cylinder 7 - distributor contact, spark plug lead or even a faulty spark plug. Geoff | ||
| michael vass Grand Master Username: mikebentleyturbo2 Post Number: 366 Registered: 7-2015 |
Hi Brian ,I wonder if a colour tune plug would show up the fault? Mike | ||
| michael vass Grand Master Username: mikebentleyturbo2 Post Number: 367 Registered: 7-2015 |
Hi again Brian This is a good video https://www.youtube.com/watch?v=RnegCu5-i9M Mike | ||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 1529 Registered: 5-2015 |
swap the suspect injector with another and see if the fault follows the suspect injector. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2419 Registered: 6-2009 |
Another thank you to all who have been offering suggestions. Some of you are actually getting ahead of me by several steps. Geoff, you wrote, in part: "I guess what your mechanic is alluding to in mentioning the distributor is the fault on your engine could also be caused by an HT problem on cylinder 7 - distributor contact, spark plug lead or even a faulty spark plug." For the sake of clarity we've already: 1. Replaced all spark plugs. 2. Swapped spark plugs to determine if we might have had a bad one. We don't. 3. Tried a different spark plug wire (HT lead) This is why we're left at the next two most likely culprits being an issue with one of the the classic two: fuel or spark. I will report as events progress. I can only say that I'm very happy that this is occurring on the left bank on this engine. Cylinder 7 is a PITA to get at on this side to begin with, but the even numbered cylinders on the right are sheer hell. That's one of the reasons why the car went to the shop. I cannot fit my hands/fingers into the space available to deal with the plugs on that side of the car!! Brian | ||
| David Gore Moderator Username: david_gore Post Number: 2674 Registered: 4-2003 |
Brian, Have you overlooked the use of a short length of garden hose slipped over the spark plug insulator when removing/replacing the plugs? Helps minimise cross-threading when re-installing plugs and bruised fingers plus avoiding the dreaded "plug drop" when your fingers lose their grip and the plug ends up in the most-difficult-to -access locations in the engine bay. Worked a treat for me and my oft-abused large fingers and hands. . | ||
| Jeff Cheng Prolific User Username: makeshift Post Number: 103 Registered: 2-2016 |
OK, I'll be 'that guy' and say I've had success with FI cleaner additives. Here in Aust, we have a lot of LPG converted vehicles. Since it's cheaper of run on LPG, a lot of them have neglected/gummed up fuel injectors from lack of use. I've owned 3 LPG vehicles which ran pretty poorly on petrol when I first got them. I added FI cleaner additive to 3 consecutive tanks of petrol with noticeable improvements in running. Maybe the additive did nothing and they just needed to be run, who knows, but that's my experience. | ||
| ross kowalski Grand Master Username: cdfpw Post Number: 555 Registered: 11-2015 |
Brian, You don't have to know what the injectors are supposed to sound like. You just listen to them all and if 7 sounds different (it would be quieter) replace it. It won't be a subtle difference if it is bad. Also, a hardened / leaky o-ring will cause a miss too. Soak the offending injector in non-chlorinated carb cleaner externally and see if it does anything. If you have a timing light you can clip it on the #7 wire and see if it is a consistent flash. If that is irregular, then suspect the dizzy. A scope would do a better job but garages don't have them any more. My money on that engine ... dizzy. | ||
| Jean-Pierre 'JP' Hilbert Prolific User Username: jphilbert Post Number: 170 Registered: 9-2013 |
Brian, Here's my story that really, really made me believe in fuel injector cleaning additives: in my quest to solve a rough idle, I added Chevron Techron to the fuel tank. Next morning, there was an intense smell of fuel in the garage, and investigation revealed that the Techron has dissolved all the gunk that ''helped'' to seal the perished rubber o-ring at the bottom of the fuel tank, and fuel was dripping out it. That convinced me of the power of such additives! | ||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 1530 Registered: 5-2015 |
Fuel injection systems are usually batch injected meaning that a V8 will have paired injectors that inject at the same time. It means that the injector plugs can be swapped around. If no 7 injector is swapped with the next injector plug and the fault follows the injector plug swap then you have a loom fault and the best place to look is where the loom plugs into the ecu, maybe give it a wiggle while fault present. My jeep has sequential injection. no 5 started to misfire and the engine fault lite came on. After 4 hours of poking around I found no 5 wire at the ecu about fall out so I stuck a piece of foil in alongside the wire and misfire went. 4 years later the engine runs smooth all the time. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2420 Registered: 6-2009 |
Again, thanks for the additional ideas. The pickup of the car has been delayed until sometime today. The fact that it's got over 200K on it means that there will be occasions such as this when problems crop up. It has been a remarkably reliable car with the exception of the transmission, which has been a horror show several times over the time I've owned it. Brian | ||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 1531 Registered: 5-2015 |
What about a good thrashing of the engine flat out up the free way cops permitting. Also if you dribble water into the inlet manifold at 1500 rpm the water the steam might clean the internals up a bit. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2421 Registered: 6-2009 |
Today, upon picking up the car, it would *not* misfire, at least at low speed on the way home. Gads how I hate intermittent problems!! That being said, I thought, well, given what I've experienced with corrosion, sometimes very slight, on electrical connections I had ought to dig in and at least do a Caig DeOxIt-ing on the fuel injection connections. And that's what I think I did. These photos show what I found when I took the "mystery thing" (photos further down) off the top of the engine and could see what was underneath. These are clearly linked to the cylinders in some way, given that they have the cylinder numbers on them, and they have no relationship to the spark plugs at all. I took off each and every one, as well as other connections in the environs, and treated each.   If these aren't somehow related to fuel injection I have no idea what they are. The "mystery thing" on top of the engine clearly serves some purpose in the air intake. The engine wouldn't even start if it was off, but it's nothing but a huge plastic cavern that sits above the main air intake tube after the air filter and before the intake butterfly valve.   What on earth is the actual function of this thing? It's got to have one. After the treatment I took the car out for a while and it behaved just fine at low to moderate speed. I had the OBD-II reader connected the entire trip and on the way home I tried the flat out throttle for a short period of time to launch me from low speed to 70 MPH and keep me there. I could have sworn that I felt an occasional miss during this process, but the check engine light never illuminated. I have never seen it fail to illuminate if you have a misfire, but perhaps it has to be "persistent enough" and it wasn't like it was before. When the weather was a bit cooler and this misbehavior was more consistent it would kick in like clockwork on a cold start and during cold engine driving. As my partner so colorfully put it, "This thing is running as rough as a ten-dollar whore!," and that about described it. Today, other than the occasional blip (which could have been me looking for one, since I got no codes thrown) during the heavy acceleration phase she was running smooth as a baby's bottom. Brian | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2422 Registered: 6-2009 |
For "lay of the land" purposes, someone else's shot of the engine bay from the top. It's just like mine. It's a bit too dark now to get a decent photo of my own:  | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1525 Registered: 9-2004 |
"What on earth is the actual function of this thing? It's got to have one." If your engine has a sneeze then you will be glad you had this device and it will have other balanced use! | ||
| gary webb Experienced User Username: webbgw Post Number: 18 Registered: 6-2014 |
hi Patrick it is a muffler for intake noise gary | ||
| Mark Luft Prolific User Username: bentleyman1993 Post Number: 106 Registered: 10-2016 |
Brian, when I bought my Bentley, it had been sitting for years with little movement. When started, it would run rough. I started using Chevron Techron and by the third tank of gas the old girl was running smooth again. I believe Consumers Report did a test on fuel additives some years ago and Techron was the only one that they recommended. | ||
| ross kowalski Grand Master Username: cdfpw Post Number: 562 Registered: 11-2015 |
Brian, That resonator could come out, you'd just have to plug the hole, but it probably does a lot to quiet things down under the hood. Having it out would make listening to the injectors a snap. If an injector wasn't flowing properly, it might be borderline when warm idling, run lean on WOT and cold start and cause missing. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2423 Registered: 6-2009 |
Well, at this point I am now unable to get the car to do anything out of the ordinary. Perhaps it was an issue with corrosion or something else with an electrical connector for the injectors (or, most likely, the one for cylinder 7). I am going to use the car as the true daily driver for at least a few days to see if I can get the issue to recur. I'm not quite satisfied that it's cured. I never am when the work I have to do is just too easy! Brian | ||
| ross kowalski Grand Master Username: cdfpw Post Number: 566 Registered: 11-2015 |
Brian, I agree, rather find a bad wire and know it's fixed then kind of wonder if it's fixed. Fingers crossed here. | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1528 Registered: 9-2004 |
To conclude the engines use of the resonator as a not so much of a silencer but more for the pressure wave harmonics, ie my comment on an engine sneeze, without it the blow back can damage the Maf if fitted and blow the inlet track ducting apart, but more details below: The Common Misconception Most hot-rodders and car enthusiasts think of intake resonators as simple mufflers in the intake tube, devices designed to siphon all the awesomeness out of a car's sound track to appease soccer moms and senior citizens. That makes it a prime candidate for the "chuck-it" school of auto modification. After all, it's basically just a plastic tumor growing off of a tube that should by definition be as smooth and blemish free as possible. While sound control is indeed part of the resonator's job, the sound control itself is really more of a side effect of its primary purpose. Pressure Wave Harmonics Air flowing into your cylinder head's intake port doesn't move in a straight line while the valve is open, then politely stop in its tracks to await another valve opening. When the valve closes, the moving column of air slams into it, then compresses and bounces back like a spring. This pressure wave travels backward at the speed of sound until the intake runner opens up or it hits something, and then it bounces back toward the cylinder. This is the "first harmonic." The pressure wave actually bounces back and forth two or three more times before the intake valve opens again. Intake Tube Pulses The resonator in your intake is technically known as a Helmholz resonator, an acoustic device used to control pressure wave harmonics. Air bouncing back out of your engine and into the intake tube doesn't do it in a single pulse the way it would in a single intake runner; the multiple pistons put out pressure waves at their own intervals, and some of those are going to try to bounce back in while others are going out. The result is a "clog" or high pressure area in your intake tube that ultimately limits airflow through almost the entire rpm spectrum. The Resonator Adding an expansion chamber to the intake tube forces air coming back out of the engine to slow down to fill the cavity, thus expending a great deal of its energy and slowing the pressure wave reversion. This slowdown allows fresh air to flow toward the engine without fighting pressure reversion waves the entire way, thus aiding in cylinder filling. Since these pressure waves are essentially sound, giving them a place to expend their energy before exiting the air filter box ends up dampening the intake noise and quieting the engine. Thus, the resonator helps to make the engine paradoxically quieter and more powerful. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1802 Registered: 5-2012 |
Beautifully explained Patrick. | ||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 1535 Registered: 5-2015 |
Also they tune the intake to make the right sound. The Honda VRF 800 Vtec bike has velocity stacks in side the airbox which by changing moves the the peak torque around the rev range. Some Porsches cars have servo motors that expand the velocity stacks as required by the ecu. | ||
| ross kowalski Grand Master Username: cdfpw Post Number: 569 Registered: 11-2015 |
Patrick, Maybe those resonators produced so much power that they were afraid to add them to "the same' lump when fitted to the corvette. http://gtcarlot.com/data/Chevrolet/Corvette/1995/3333546/Engine-49578595.html Not to get too much into it (FYI, if you do ... Dave Walker) but the pressure wave we care about in an LT1 occurs when the wave in the intake tubes meet the common plenum space behind the throttle body . After that, wave interference and resonance occur, but don't change the pressure at the intake port in any meaningful way. Pretty sure that resonator is there to lower NVH levels for the passengers. It's a Buick. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2424 Registered: 6-2009 |
Ross, I would have to agree with your perspective on the reason in the Buick. The LT1 engine as tuned for the Roadmaster was not "the same" LT1 as tuned for the Corvette. Until testing things out over the last several days I had never floored this car to get to wide open throttle. It had probably never been floored prior to this time. I always knew that the power was, in the words of another famous marque, "adequate," from the way I drive it on the highway. I never knew just how "adequate" it could be. It's odd to feel just how quick a car of this size can be when pushed to its limit. I can only imagine what the 'Vette is like! Brian, who is now willing to declare my issue fixed, at least for the moment | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1530 Registered: 9-2004 |
And as for the Corvette different and more efficient design [PIX above] the use of venturi effect. The speed of the airflow is increased by directing the air through a path with limited capacity. The Porsche 968 go's further with a vario inlet cam together with the inlet manifold by design that gave low pressure supercharging effect that forced more air into each cylinder [BMEP] this system increased the pressure on top of the combustion stroke by 4psi. clever stuff. Brian's car may be suffering from changing weather conditions if electrical prob is present. | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 1700 Registered: 4-2016 |
I understand that the V12 used in the Ghost & PVII utilises the BMW Double Vanos system of variable inlet manifold. But I don't think it is mentioned anywhere. Also I am not sure about PVIII due to it now having 2 hair dryers attached?? | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2425 Registered: 6-2009 |
Just as a follow-up, either my issue with missing is not 100% gone or I've uncovered something else. I cannot get the car to throw any code that triggers the check engine light, which I would have thought would happen if even a very few misfires were detected within a few seconds. Now she's generally purring along like she always did, but if I'm at highway speed and need to remove my foot from the gas pedal to either cease accelerating or slow down, sometimes when I try to speed up again I will get these very brief and very noticeable jerking sensations that really strike me as what a miss should (and often does) feel like but the OBD is not throwing any code. It's typically one or two of these, sometimes three, over the course of about as many seconds, so that would seem to be enough to cause a code to be thrown if it were actually a miss. Given that the car has had transmission issues in the past (the only car I've ever owned where a full transmission replacement has been needed) I am wondering if it could be transmission related, like a very quick slip and grab. I'll probably take her in for a check-up at the transmission shop simply as a preventive measure at this point. That's a replacement I don't want to have to go through again (particularly since no one could explain the genesis of the failure the first time). Brian | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1531 Registered: 9-2004 |
Patrick, I had forgot the probs with the Vanos BMW N55 engines ie carbon under inlet valves, needing removal of the manifolds for cleaning every 40000 miles, costly. The N74 V12 engine configuration is two N55s in one crankcase. Yes two large Garrett turbo's.  | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 1532 Registered: 9-2004 |
Brian FYI the difference in testing the jerking whether engine or transmission etc failing is speed related under power torque. Maybe when you slow down and power up you get dynamic out of balance that jerks your seat. This may be caused by some foreign body left in a rear tyre etc! |
