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Rpm fluctuating by painandgain99
Started on: 10-14-2015 08:16 PM
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Last post by: jscott1 on 10-19-2015 10:38 PM
painandgain99
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Report this Post10-14-2015 08:16 PM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
Hey guys. I asked about this before but just wanted to make sure. When i start my car, the rpms fluctuate between 500 and 2000 back and forth. Its not over a time period, it just goes up and down for a few minutes then idles out at about 2000 which i thought was a bit high. Any help on this ? My grandpa suggested it could be an o2 sensor..

Also, the computer ( i assume) behind the center glove compartment, is making noise. Sounds like a DVD player is playing.

Last thing is twice now, when taking off, i heard a loud squeeling seeming to have come from the passenger side rear.

Im trying to get this car reliable withing a month or two so sorry ive been asking alot of questions!

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Report this Post10-14-2015 08:33 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
A previous owner might have installed a small PC fan or two in the center console, to cool the ECM, and it would make noise if so, especially if it was going bad. You can pop the little plastic vent off the side of the console to see what the noise is.

Any number of things could cause the hunting idle, but the high idle at 2000 RPM is probably a small vacuum leak. The original plastic and rubber vacuum lines will dry out, and could have a break or small leak somewhere, causing the vacuum leak. Another common vacuum leak is the EGR tube that bolts to the bottom of the intake manifold neck behind the throttle body, and the EGR valve at the other end.

Does the idle stay high when the engine warms up?
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painandgain99
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Report this Post10-14-2015 08:43 PM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:

A previous owner might have installed a small PC fan or two in the center console, to cool the ECM, and it would make noise if so, especially if it was going bad. You can pop the little plastic vent off the side of the console to see what the noise is.

Any number of things could cause the hunting idle, but the high idle at 2000 RPM is probably a small vacuum leak. The original plastic and rubber vacuum lines will dry out, and could have a break or small leak somewhere, causing the vacuum leak. Another common vacuum leak is the EGR tube that bolts to the bottom of the intake manifold neck behind the throttle body, and the EGR valve at the other end.

Does the idle stay high when the engine warms up?


My EGR tube heat wrap is wripped but i dont think the tube has a leak, how would i check this? And how do i check the vacuum leak?

I dont drive it much as it currently has no insurance or plates, just start it everyday to keep everything circulating but yes after running for a few minutes on a hot day, it still idles there. Ive seen it idle at 1300-1500. Im not sure what the number should be for this car.
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Report this Post10-14-2015 10:08 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by painandgain99:
My EGR tube heat wrap is wripped but i dont think the tube has a leak, how would i check this? And how do i check the vacuum leak?

I dont drive it much as it currently has no insurance or plates, just start it everyday to keep everything circulating but yes after running for a few minutes on a hot day, it still idles there. Ive seen it idle at 1300-1500. Im not sure what the number should be for this car.


Spray some throttle body/carb cleaner around and see where it gets sucked in or stumbles as a result. If you smoke, you can also hold a cigarette near and watch for the smoke getting sucked in anywhere.

When the coolant temperature hits about 200 degrees, is what I mean by warmed up. The normal idle speed should be around 700 when warm, IIRC. If it's 1300+ then you most likely do have a small vacuum leak somewhere. Also, do the exhaust manifolds glow any? You might need to warm the car up at night to check this. If the exhaust is glowing, the engine is running rich, probably due to the vacuum leak.

Is the check engine light on when the car is running? If so, you need to pull the codes to see which ones are set.
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painandgain99
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Report this Post10-14-2015 10:19 PM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by dobey:


Spray some throttle body/carb cleaner around and see where it gets sucked in or stumbles as a result. If you smoke, you can also hold a cigarette near and watch for the smoke getting sucked in anywhere.

When the coolant temperature hits about 200 degrees, is what I mean by warmed up. The normal idle speed should be around 700 when warm, IIRC. If it's 1300+ then you most likely do have a small vacuum leak somewhere. Also, do the exhaust manifolds glow any? You might need to warm the car up at night to check this. If the exhaust is glowing, the engine is running rich, probably due to the vacuum leak.

Is the check engine light on when the car is running? If so, you need to pull the codes to see which ones are set.


Service engine light is on, only when i turn the key halfway to turn on the electronics. I think thats normal?

I will check the egr tomorrow although i dont have any throttle body cleaner. I have engine foam cleaner? And i might be able to check the exhaust tonight. If its not the egr, how do i check for another vacuum leak?

Dumb question, the car has to be running to checkthe egr leak correct? And the exhaust manifold is where the exhaust connects to the engine?

[This message has been edited by painandgain99 (edited 10-14-2015).]

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Report this Post10-14-2015 11:02 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by painandgain99:
Service engine light is on, only when i turn the key halfway to turn on the electronics. I think thats normal?

I will check the egr tomorrow although i dont have any throttle body cleaner. I have engine foam cleaner? And i might be able to check the exhaust tonight. If its not the egr, how do i check for another vacuum leak?

Dumb question, the car has to be running to checkthe egr leak correct? And the exhaust manifold is where the exhaust connects to the engine?


Yes, the engine light comes on when the key is in the on position and the engine is not running. That is normal.

You can't use foaming degreaser to check for vacuum leaks. You can't check for exhaust leaks that way. You shouldn't spray the cleaner on the exhaust. There are lots of vacuum lines running under the top (red) plenum, you can spray under it. You can follow the vacuum lines around too. They are the black rubber/plastic lines, and there are a few steel hard lines that run partially across the trunk wall and such, for the cruise control vacuum canister. Use that service manual you got. It should have a map of the vacuum lines in it.

Yes, the engine must be running to check for the vacuum leaks. The exhaust manifolds are the parts that attach directly to the heads. The part of the exhaust that goes over top the transmission and connects the two sides together, is the Y pipe. The O2 sensor is at the lower end of the Y-pipe, just before the connection to the lower pipe for the catalytic converter.

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painandgain99
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Report this Post10-15-2015 12:30 AM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thank you so much dobey, will check tomorrow. Anything else i could spray to check for leaks or should i just wait until i get throttle body cleaner?
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Report this Post10-15-2015 07:00 AM Click Here to See the Profile for hyperv6Send a Private Message to hyperv6Edit/Delete MessageReply w/QuoteDirect Link to This Post
It sounds like a EGR tube. Once it breaks off it will idle at 2000 RPM. If not that the valve may be bad.

As for the noise in the console I real doubt there is a fan as it really needs no cooling.

I would putt the top of the console off and see just what is going on. This is the most basic of computers and really does not make noise. To be honest this computer is so basic it is scary today that we even call it a computer. I would try to locate the noise and make sure where it is coming from. the cover is easy to remove.
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Report this Post10-15-2015 10:47 AM Click Here to See the Profile for jscott1Send a Private Message to jscott1Edit/Delete MessageReply w/QuoteDirect Link to This Post
The vacuum line for the brakes runs through a center console. A leak in that line, (which is large in diameter) would cause a sucking sound in the console and could also lead to your idle issues. After 30 years the line can easily rust ,if you ever had a sunroof leak.
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Report this Post10-15-2015 02:59 PM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
Update, pulled the vents by the computer off. The sound isnt really concerning sounding, it sounds like a laptop running. Have to put your ear near it to hear. If this is not regular, i will pull off the center area and check it out so id like if some let me know.

Couldnt check the vacuum leak yet, i figure ill just put an incense stick near it?

Also, the loud squeeling again. Whenever i first start the car i hear a loud squeeling from the passenger side. It sounds like tires spinning. High pitched.

Another thing is i hear what sounds like something flowing, on the bottom of the drivers door, havent checked passenger. I figured this is the coolant tubes? Really wish someone was around me so they could come out and help me diagnose 😧 but ill be at the NIFE event november 14th hopefully i can get some help there
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Report this Post10-15-2015 09:52 PM Click Here to See the Profile for jscott1Send a Private Message to jscott1Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by painandgain99:

Update, pulled the vents by the computer off. The sound isnt really concerning sounding, it sounds like a laptop running. Have to put your ear near it to hear. If this is not regular, i will pull off the center area and check it out so id like if some let me know.

Couldnt check the vacuum leak yet, i figure ill just put an incense stick near it?

Also, the loud squeeling again. Whenever i first start the car i hear a loud squeeling from the passenger side. It sounds like tires spinning. High pitched.

Another thing is i hear what sounds like something flowing, on the bottom of the drivers door, havent checked passenger. I figured this is the coolant tubes? Really wish someone was around me so they could come out and help me diagnose 😧 but ill be at the NIFE event november 14th hopefully i can get some help there


You are hearing things that I've never heard of anyone hearing... (no pun intended).

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Report this Post10-15-2015 10:10 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by painandgain99:

Update, pulled the vents by the computer off. The sound isnt really concerning sounding, it sounds like a laptop running. Have to put your ear near it to hear. If this is not regular, i will pull off the center area and check it out so id like if some let me know.

Couldnt check the vacuum leak yet, i figure ill just put an incense stick near it?

Also, the loud squeeling again. Whenever i first start the car i hear a loud squeeling from the passenger side. It sounds like tires spinning. High pitched.

Another thing is i hear what sounds like something flowing, on the bottom of the drivers door, havent checked passenger. I figured this is the coolant tubes? Really wish someone was around me so they could come out and help me diagnose 😧 but ill be at the NIFE event november 14th hopefully i can get some help there


The sound form the center console area is then almost certainly the fuel pump. They do tend to get noisier toward the end of the life span, but unless you are having fuel issues, yours is probably fine.

Incense might work as well to check for the vacuum leaks. Just try not to get ash everywhere when you do it.

The squealing is almost certainly the belt slipping. Might be time for a new one, or your alternator might need adjusting. Another possibility would be the water pump itself. You'll have to check with a closer ear to see where it's actually coming from. If your car has A/C, could also be the compressor if it's gone bad.

The coolant tube is under where the door sill is, but you really shouldn't hear the coolant flowing through it.
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Report this Post10-15-2015 11:43 PM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks again dobey, anyone around frankfort that could help me diagnose it? Or should i start looking for a mechanic to help me out
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Report this Post10-17-2015 02:34 AM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jscott1:

You are hearing things that I've never heard of anyone hearing...



 
quote
Originally posted by painandgain99:

should i start looking for an mechanic exorcist to help me out?


Fixed that for you.

[This message has been edited by Patrick (edited 10-17-2015).]

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Report this Post10-17-2015 10:06 PM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
very funny patrick.

So the squeeling hasnt stopped, kind of random then goes away after a few seconds. High idle and fluctuation hasnt stopped. The sound coming from near the side vent hasnt stopped but i captured that in a video here In the video i also showed how high it idles and tried to show the sound of the computer, but i dont think the computer has anything wrong.

I havent mentioned that i havent changed the oil in it yet.. or any of the fluids that have been it it for 4-5 years. i know thats bad but could it be causing these problems?

Also, The clutch is odd sometimes. No matter how slow i let off, it will die or rev very high rpms when i give it enough gas to get going. I have enough experience driving manual to know this isnt my fault, could it possibly be because i havent bleed the line yet?

will post vid of the squeeling soon. Would appreciate any help guys!
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Report this Post10-18-2015 03:26 AM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by painandgain99:

The sound coming from near the side vent hasnt stopped but i captured that in a video here


Are you talking about that suction sound? If so, that's normal.

Your idle is awfully high. I'd be willing to bet your EGR tube is cracked. I replaced mine with one from a Camaro as discussed HERE. Much more durable.
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Report this Post10-18-2015 09:05 AM Click Here to See the Profile for css9450Click Here to Email css9450Send a Private Message to css9450Edit/Delete MessageReply w/QuoteDirect Link to This Post
Is the squealing possibly just the belt slipping?

Re: the high idle. Its also possible the tach just reads high. Or a vacuum leak PLUS a tach that reads too high. Lots of 70s and 80s cars have tachs that read too high due to a resistor in the gauge cluster that deteriorates over many years. Fortunately, like the vacuum leak, its fixable.

It would be useful to get a scan tool on it and see what the actual RPMs are.
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Report this Post10-18-2015 11:14 AM Click Here to See the Profile for hyperv6Send a Private Message to hyperv6Edit/Delete MessageReply w/QuoteDirect Link to This Post
I agree fuel pump is the sound inside.

I would wager the door drain is plugged and there is water inside the door that has not drained out.
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Report this Post10-18-2015 11:32 AM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by hyperv6:

I agree fuel pump is the sound inside.

I would wager the door drain is plugged and there is water inside the door that has not drained out.


How can i check/fix this?

And patrick, i believe it was a post of yours i read a while back but i could be wrong, someones egr tube cracked and the heat wrap had gunk all over it. My heat wrap doesnt. Has some grey powder/ash but before i cleaned the engine, everything had a soot like substance on it.
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Report this Post10-18-2015 01:50 PM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
EGR wrap "soot" like powder in the wrap


heres the belt, theres a package in the car that the belt came in. god knows when it was replaced though.

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Report this Post10-18-2015 02:00 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by painandgain99:

And patrick, i believe it was a post of yours i read a while back but i could be wrong, someones egr tube cracked and the heat wrap had gunk all over it. My heat wrap doesnt. Has some grey powder/ash but before i cleaned the engine, everything had a soot like substance on it.


I obviously don't know for sure that your EGR tube is cracked, but it's such a common reason for a high idle on the 2.8 engine in a Fiero. I also want to make it clear that a cracked EGR tube is often not identified by any type of discoloration of its insulating jacket on the '85-'87 models or of the insulating metal tube on an '88.

[EDIT] I now see your image, but checking a short section of the EGR tube unfortunately won't indicate what the condition might be of the rest of the tube.

[This message has been edited by Patrick (edited 10-18-2015).]

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Report this Post10-19-2015 01:58 PM Click Here to See the Profile for painandgain99Click Here to Email painandgain99Send a Private Message to painandgain99Edit/Delete MessageReply w/QuoteDirect Link to This Post
Hey guys. I managed to get a Video of the squeeling ive been talking about. It happens at about 25 seconds in the video and 45 i believe. And yes, i killed it twice. Oops. With the rpms so high i feel its very hard to drive, i feel like im driving our turbo genisis coupe which.. i have trouble driving.

Anyways.. i felt the steering wheel get more loose when i was driving. Maybe one of the bolts came out.. im going to try to fix that today but i dont have a wheel puller or lock plate compressor so i dont know how far ill get.
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Report this Post10-19-2015 10:38 PM Click Here to See the Profile for jscott1Send a Private Message to jscott1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Sounds for sure like a belt squealing. A very common problem on all Fieros because there are open vents right above the belt. An aftermarket idler pulley will usually cure that. It's virtually impossible to tighten the belt enough to stop that without breaking your alternator mount.
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