I’ve been having a weird problem with my car, a 1986 GT, that I have not been able to figure out.
The car is nearly stock and usually runs very well. Lately, the past six months or so, it has seemed just a little low on power. The past few months, however, it has developed this weird problem. The problem presents when I’m driving steady on the freeway and I want to accelerate. I open the throttle and the engine hesitates, like it’s taking a breath, then it tries to accelerate but there is a loud whine or screech coming from the engine and it feels like something is holding the engine back. When I do close the throttle (which I do right away because of the ugly noise) the car surges forward slightly.
I’m an older guy and I’ve been around vehicles for a long time but I cannot pinpoint exactly what kind on noise it is. Sure wish I could stand over the engine with the mechanics stethoscope at 60 mph.
It feels like it’s electrical. However, just to be sure I checked the fuel pressure following the manuals procedure and it is within specs. I also applied vacuum to the fuel regulator and the pressure dropped as it’s supposed to.
I should also mention that the car recently passed the California smog test, which it usually does.
During this process I have decided to replace any sensors that might be questionable. Then I decided to replace any sensor I had not already replaced. After all, they are 30 years old.
Here is a rundown of what I have tried to solve this problem: replaced the fuel filter, checked the vacuum lines for leaks, replaced the EGR valve and the EGR solenoid, remove and cleaned the throttle body. Installed with new gaskets, replaced the Throttle Position Sensor, replaced the Idle Air Control Valve, replaced the Air Charge Temperature sensor, replaced the O2 Sensor, replaced the Fuel Vapor Canister Filter, replaced the Manifold Absolute Pressure Sensor, replaced the coil, replaced the distributer (the pickup coil went out, in the fast lane, of course), replaced the PROM (apparently died when the pickup coil went out), replaced the PCV Valve, triple checked the timing. and checked the engine grounds (with a multimeter)
Has anyone run across anything like this?
I appreciate any ideas or suggestions. If anyone can help with problem it will be the people here.
------------------ Jim Martin White '86 GT Monterey, California
Sure wish I could stand over the engine with the mechanics stethoscope at 60 mph.
With the unique design of the Fiero, you can do just that. Have a friend help you remove the decklid then you (or he) can stand in the trunk at speed. Just trying to help.
Could be any one of the bearings on the belt. If you take the belt off and spin each pulley, one should feel a little bumpy. Possibly the A/C compressor too.
Check the vacuum lines again, and again, and... I spent nearly $1500 trying to correct a similar problem (new injectors, timing chain, other parts, labor, migraines) before I took it to a specialty shop that worked only on intakes and such. The problem was simply a broken vacuum line that had caused lack of power, back firing, acceleration, and the like. All this for a car for which I purchased for $2900 in '97. Nevertheless, I wouldn't sell my Fiero (86 GT) for any price. Chicks dig it, but I'm 68, so I'll just dig it.
With the unique design of the Fiero, you can do just that. Have a friend help you remove the decklid then you (or he) can stand in the trunk at speed. Just trying to help.
Interesting idea.
I don't need help removing the deck lid, I take it off whenever I work on the engine. However, I hope this idea is tounge-in-cheek. Besides being very dangerous I know we would get stopped by the CHP.
Don't get me wrong, I considered it. I have stood on the skids of a helicopter shooting video footage of wild horses in Nevada for PBS and hung out the side hatch of a Chinook helicopter at 4000 ft shooting a Navy aircraft carrier and support ships. But, that was when I was younger.
------------------ Jim Martin White '86 GT Monterey, California
I was trained in automotive electrical systems by the Navy (ASE-2) and I know the sound of alternator bearings going out. Besides, the alternator is less than two years old.
But thanks,
------------------ Jim Martin White '86 GT Monterey, California
Check the vacuum lines again, and again, and... I spent nearly $1500 trying to correct a similar problem (new injectors, timing chain, other parts, labor, migraines) before I took it to a specialty shop that worked only on intakes and such. The problem was simply a broken vacuum line that had caused lack of power, back firing, acceleration, and the like. All this for a car for which I purchased for $2900 in '97. Nevertheless, I wouldn't sell my Fiero (86 GT) for any price. Chicks dig it, but I'm 68, so I'll just dig it.
Best wishes, bb
This is what has been running through my head. Is one of the vacuum lines under the intake plenum leaking. It must be a very small leak because I have tested the intake with a vacuum gauge and it has very strong vacuum. I even ran a long hose and taped the gauge to the dash and went for a drive. I did not see anything out of the ordinary.
I have also tested the lines running under the plenum (I think I got them all) with a hand vacuum pump. They all held vacuum.
------------------ Jim Martin White '86 GT Monterey, California
Since you did mention nothings been done to it in 30 years you could replace the injectors. I got mine at Rockauto for only $120 and it was a pretty easy job. Worst it could do is improve performance and probably gas mileage.
Since you did mention nothings been done to it in 30 years you could replace the injectors. I got mine at Rockauto for only $120 and it was a pretty easy job. Worst it could do is improve performance and probably gas mileage.
Well, it has had some work done, but not injectors. I have been considering replacing them but have been advised that injectors seldom go bad. The car does run so I don't want to pull them out and send in for testing.
The big question is, would a bad injector make a loud squealing sound?
I agree they don't go bad or you'd know it but they certainly do get dirty and develop bad spray patterns over time. It made a big difference in how well my car runs. No, I can't see them making a big squeal. Good luck I hope you find it!
I agree they don't go bad or you'd know it but they certainly do get dirty and develop bad spray patterns over time. It made a big difference in how well my car runs. No, I can't see them making a big squeal. Good luck I hope you find it!
I only use Chevron gas. It has Techron in it, which is the primary fuel injector cleaner. The car does not miss-fire, does not sputter, and runs fine . . . except for the mentioned problem. Which is one of the reasons this problem is kicking my butt.
Originally posted by Jim_Martin29: I don't need help removing the deck lid, I take it off whenever I work on the engine. However, I hope this idea is tounge-in-cheek. Besides being very dangerous I know we would get stopped by the CHP.
Thank you for your service in the Navy, Jim. Wish I could help but will hope for a speedy resolution.
Your comment above inspired a silly idea for a YouTube video ... one could drive a Fiero w/o the deck lid but with a Dummy rigged up to stand in the trunk, dressed for special holidays and occasions, e.g. for Cinco de Mayo coming up he could be Juan Cabrillo, etc. If that tended to attract benign 'fix it' tickets perhaps one could get a surplus deck lid and cut out an opening for a dummy. This could have the potential to go Viral
Thank you for your service in the Navy, Jim. Wish I could help but will hope for a speedy resolution.
Your comment above inspired a silly idea for a YouTube video ... one could drive a Fiero w/o the deck lid but with a Dummy rigged up to stand in the trunk, dressed for special holidays and occasions, e.g. for Cinco de Mayo coming up he could be Juan Cabrillo, etc. If that tended to attract benign 'fix it' tickets perhaps one could get a surplus deck lid and cut out an opening for a dummy. This could have the potential to go Viral
Lol, that's not a bad idea. I am a defense contractor and I produce video programs for the government. Maybe if I follow this idea, mount a few cameras on the car, and take a drive it might make a great viral video.
Thanks for the idea, but first I have to get it running right. (Yeah, I know. If I wait too long someone will beat me to it.)
The car is nearly stock and usually runs very well. Lately, the past six months or so, it has seemed just a little low on power. The past few months, however, it has developed this weird problem. The problem presents when I’m driving steady on the freeway and I want to accelerate. I open the throttle and the engine hesitates, like it’s taking a breath, then it tries to accelerate but there is a loud whine or screech coming from the engine and it feels like something is holding the engine back.
When reading the first part, I'm thinking - sounds like the Catalytic Convertor is clogged... Then I hear you talking about a screech - and I'm thinking a belt is slipping - A/C compressor clutch??
When reading the first part, I'm thinking - sounds like the Catalytic Convertor is clogged... Then I hear you talking about a screech - and I'm thinking a belt is slipping - A/C compressor clutch??
Just 2 more things to check...
Both good calls.
The catalytic converter is only a couple of years old and is a high-performance Magnaflow converter. I did take the car to the shop that installed it to talk to him about it. The converter is solid, not weak spots and no rattling. I don't think that is the problem.
I live in the Monterey, Ca area. It never gets hot here. I don't use the AC and took AC belt off.
However, the alternator belt does slip a little on a cold start or when water gets on it. But the belt noise is short lived and stops as soon as the belt warms up or dries off.
I also monitor the gauges and the alternator puts out plenty of voltage. When I hear the noise I check the gauges and nothing is wrong. It's charging well, the tachometer is working, it's not overheating, and there is good oil pressure.
Thanks everyone. All good suggestions. But still no winner.
As far as the screech is concerned, I've had the same problem. Replaced alt and water pump, removed a/c belt, still screeched like hell at times. Sometime just stopping and starting the engine was enough to make it go away, sometime pumping the clutch worked. In the end I have installed Rodney's idler pulley kit. Not driven it any yet and only started it once (no screech) so no idea if it has fixed the issue or not. The only thing I have not replaced is the engine pulley. The only thing I can think of is that the pulley's are out of alignment slightly or there's a slight end play in the crank that is enough to cause the pulleys to get out of alignment at times which might explain why pressing the clutch sometimes helps (or it might be totally bogus, who knows!)
PS. My cat did not rattle but that is because it was totally melted inside! Mind you, the car hardly ran either at that point!
------------------ Anything I might say is probably worth what you paid for it, so treat it accordingly!
Don't dismiss anything until you have proved that it is not the source. A slipping belt doesn't necessarily cause a visible symptom on your gauges. I would definitely take the belt off and re-inspect every pulley. Also check the tension once it goes back on. Have you added any injector cleaner to your tank? That frequently fixes stumbling.
Don't dismiss anything until you have proved that it is not the source. A slipping belt doesn't necessarily cause a visible symptom on your gauges. I would definitely take the belt off and re-inspect every pulley. Also check the tension once it goes back on.
Would the harmonic balancer cause any of these symptoms? I replaced mine just before it literally split into pieces. 30 years can really hide a lot of worn parts that go unnoticed until they finally give out
Don't dismiss anything until you have proved that it is not the source. A slipping belt doesn't necessarily cause a visible symptom on your gauges. I would definitely take the belt off and re-inspect every pulley. Also check the tension once it goes back on. Have you added any injector cleaner to your tank? That frequently fixes stumbling.
As I said earlier I use Chevron gasoline so I have injector cleaner in the gas at every fill up. Besides it's not a stumble. I runs smoothly with no misses or sputtering. The noise is only during WOT above 3500 rpm. And there is a hesitation when I open the throttle above 3500 rpm that is not there at lower rpms.
And, yes, if the belt slips you will see a slight drop in the charging voltage. I have noticed it when it does slip and on other cars. I have inspected the belt and it looks good, it's not that old.
And, to be honest, it does not sound like a slipping belt or squealing bearings. The sound seems to have a fluctuation to it. It sounds to me more like some kind of very rapidly vibrating valve or reed. I think I need to record the sound and post it.
And, to be honest, it does not sound like a slipping belt or squealing bearings. The sound seems to have a fluctuation to it. It sounds to me more like some kind of very rapidly vibrating valve or reed. I think I need to record the sound and post it.
Thanks for the suggestions.
I had a similar sound. Everyone figured it was a problem with the valve train (loose bolt on one of the rockers). The sound seemed to come from a certain spot on the head that was nowhere near where the actual problem was. Turned out to be a spark plug wire had come off the spark plug and was arcing. Cylinder wasn't firing properly.
I had a similar sound. Everyone figured it was a problem with the valve train (loose bolt on one of the rockers). The sound seemed to come from a certain spot on the head that was nowhere near where the actual problem was. Turned out to be a spark plug wire had come off the spark plug and was arcing. Cylinder wasn't firing properly.
Yeah, I thought about this. It did sound more like an electrical arc of some kind and I suspected one of the plug wires. Unfortunately I have now replaced the entire ignition system, new coil, distributor, wires, and plugs. No change.
When I read the plugs, while changing them, they were in good shape with a light-brown to gray color. No sign of poor combustion or oil.
Is your car a 4/5 speed? Perhaps the clutch is slipping under heavy load (you mention 3500 rpm and WOT). I had a similar problem in a different beast, my trans am's 406 bogged down under WOT, but it turned out to be vapor lock resulting in fuel starvation. No screeching and not likely in a fiero. Slipping clutch would explain the surge once you let off the gas, but I would expect you would notice the increase in engine speed with a lack of increase in vehicle speed. And the telltale smell of the clutch burning.
Is your car a 4/5 speed? Perhaps the clutch is slipping under heavy load (you mention 3500 rpm and WOT). I had a similar problem in a different beast, my trans am's 406 bogged down under WOT, but it turned out to be vapor lock resulting in fuel starvation. No screeching and not likely in a fiero. Slipping clutch would explain the surge once you let off the gas, but I would expect you would notice the increase in engine speed with a lack of increase in vehicle speed. And the telltale smell of the clutch burning.
Another good suggestion.
However, as you noted, I would see the RPM increase, as I watch the tach closely in case it is ignition or tach filter related, and I'm sure I would smell it. Also, I would think it would slip off the line but I have very good accelleration from a standing star, will even chirp the tires occationally.
Would the IAC cause that sound if it wasn't fully seating like it should. Kind of a vibrational harmonic thing? Would it cause the surge? Just thinking out loud. Also, didn't notice if you checked the EGR tube for leaks.
[This message has been edited by JohnnyBones (edited 05-05-2015).]
Would the IAC cause that sound if it wasn't fully seating like it should. Kind of a vibrational harmonic thing? Would it cause the surge? Just thinking out loud. Also, didn't notice if you checked the EGR tube for leaks.
Excellent suggestion. I had that same thought, especially the harmonics caused by rapid vibrations.
I did replace the IAC near the beginning of all this, however, last week I decided to unplug the IAC and go for a drive. Just in case I screwed up the IAC adjustment before installation. Of course the idle hunted a bit but the car drove the same with the same noise.
I think this may be the correct cause but the wrong component.
Have you checked the cruise control for a leaking diaphragm or maybe the coffee can? Air box snorkel maybe? That's about all I have for right now. Trying to think of anything that can give of a squealing buzz.
I apologize in advance, but my next suggestion is based solely on the performance symptoms and not the noise symptom (I'm nearly deaf and cannot diagnose an engine based on sound since I can't tell one noise from the next). You seem to describe a condition that valve float produces. Or maybe a lifter has collapsed and valve lash is off just enough to let it run (weaker) but never pumps up with oil and becomes very evident over 3500 rpm. I would suspect the failed lifter first, considering valve float is usually way up in the rpm range. I know float produces a sound, so maybe someone with better ears could chime in. Have you had the valve covers off at all? I'd watch the full opening and closing sequence per side with 720° of engine rotation, or even momentarily run the car with the cover off (on the easy side haha). Also, you mentioned the distributor and coil replacement was for actual failure of the prom and coil, but you list it as part of your effort to diagnose the bigger problem. I assume that means you suffered ignition problems in the midst of this elusive issue? Or are you just stating that those parts happen to be new and "shouldn't" be the problem? I ask because distributors and ignition components are well known to be faulty straight out of their Chinese boxes. I look forward to the real resolution behind your car's trouble, it has my interest piqued!
Have you gone over the engine with a mechanics stethoscope? The sound may show up with the stethoscope at higher rpm, even though it isn't under a load.
I'm inclined to agree with the plugged cat theory, or possibly even a plugged muffler. Why did you replace the cat 2 yrs. ago? Could some of the material from the old cat have gotten lodged in the muffler? An easy test is to connect a vacuum gauge to a live vacuum port. Slowly rev engine to 3000 rpm. If the vacuum drops off at higher rpms you have a blockage in the exhaust.
Could be the fuel pump going? Or maybe a leak on the old hose coming off the pump?
I had an '84 that would run fine, but would bog down when under heavy load.. Sometimes just slightly, other times horribly. I changed all kinds of sensors and nothing fixed it. I finally dropped the tank and pulled the fuel pump. It was the original rubber hose coming off the fuel pump had a small crack in it.. At idle and under a small load it would run ok, but under full throttle it would bog down and hesitate. I know you have a V6 and it has much more psi than the 4 cyl but hey, ya never know? You've changed and looked in to just about everything else, might be worth looking in to? Just my $.02.
