How about some help on diagnosing this issue.
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Drifting
Joined: Feb 2008
Posts: 3,029
Likes: 10
From: Columbus, Mississippi
How about some help on diagnosing this issue.
Friend has a 1982 5 speed. The car has had a ton of new parts added. It idles rather ruff. ( not sure how much extra noise is added when the TB covers are not on the car ).
Things that we now are good.
Plugs, wires, all vacuum, ground points, rebuilt injectors, coil and timing belt marks are good too. Have tried several timings with no real change.
Car has a surge at 2600 to 3000 rpm only under load. Below that and above the car pulls just fine. At 4000 rpm there is a massive valve clatter or detonation ( can't really hear with my old ears).
Anyone have any clues??
First video shows sound at idle.
Second video shows sound at clatter or detonation.
Third video shows surge.
Things that we now are good.
Plugs, wires, all vacuum, ground points, rebuilt injectors, coil and timing belt marks are good too. Have tried several timings with no real change.
Car has a surge at 2600 to 3000 rpm only under load. Below that and above the car pulls just fine. At 4000 rpm there is a massive valve clatter or detonation ( can't really hear with my old ears).
Anyone have any clues??
First video shows sound at idle.
Second video shows sound at clatter or detonation.
Third video shows surge.
Last edited by Dean_Fuller; Mar 14, 2012 at 11:24 PM.
Under the Lift
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From: Buckeye, AZ
I can't make out anything very clearly. The idle seems regular, just a lot of tinkly mechanical noise, but not rough or uneven. Not clearly lifter clatter or anything I can identify. During the drive I don't hear anything dramatic. Could just be heatshield vibrations from what I can hear. Sorry, nothing jumps out at me.
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Dean, what did you find about TDC?
It sounds like it is pinging to death at mid range but don't know why it would clear up in the later RPM's.
One thing we didn't talk about was making sure the vacuum lines coming off the throttle body were in the correct spots. Each one has different purpose. Some only are open when the throttle plate is at certain positions, some have vacuum at idle, some don't etc. Rechecking those and making sure they go where they are supposed to might make a difference.
It sounds like it is pinging to death at mid range but don't know why it would clear up in the later RPM's.
One thing we didn't talk about was making sure the vacuum lines coming off the throttle body were in the correct spots. Each one has different purpose. Some only are open when the throttle plate is at certain positions, some have vacuum at idle, some don't etc. Rechecking those and making sure they go where they are supposed to might make a difference.
Thread Starter
Drifting
Joined: Feb 2008
Posts: 3,029
Likes: 10
From: Columbus, Mississippi
We have double checked the TDC with cam marks and all lines up well.
We also ( because I thought some vac lines may be routed incorrectly) verified all the vac is routed correctly.
I can't think of anything that makes sense with the rpm differences. A damaged internal part would not really be rpm sensitive. ? It may indeed be 2 problems. ?
Just now uploaded the last video...look way too long.
We also ( because I thought some vac lines may be routed incorrectly) verified all the vac is routed correctly.
I can't think of anything that makes sense with the rpm differences. A damaged internal part would not really be rpm sensitive. ? It may indeed be 2 problems. ?
Just now uploaded the last video...look way too long.
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From: Puyallup, WA
Can't explain all the noise at idle, but could the detonation and surge be from a messed up distributor? Maybe giving too much advance in the 4K zone, and not providing consistent advance causing the motor to surge?
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Pro
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From: 3rd Rock From The Sun
This is my car - my thanks to Dean for posting this. I unfortunately didn't have internet access for the last several days to follow up.
It seems like two distinct problems to me, but they may be related:
-Surge: Mostly under light load (constant throttle cruising). Disappears under almost any acceleration (doesn't have to be a hard acceleration), and is not really noticeable under deceleration. Its most noticeable about 2.5k - 3k, but with the exhaust leak fixed I seem to be noticing it more outside of this range.
-Pinging/Chatter: RPM specific, 4k - 5k and predictable in its occurence
Vacuum lines have been verified correct when compared to the hood line diagram. The only differences from stock are my air pump control delete (capped) and a bypass of the thermo-time valve.
82 is vane type.
I was suspicious of this from reading the 944 pages on their AFMs. We swapped in the meter from Dean's son's car. Now that I think of it though, we didn't get much of a chance to test it as we ran into a leak problem at the o-ring.
Could this clear up at higher RPMs?
It seems like two distinct problems to me, but they may be related:
-Surge: Mostly under light load (constant throttle cruising). Disappears under almost any acceleration (doesn't have to be a hard acceleration), and is not really noticeable under deceleration. Its most noticeable about 2.5k - 3k, but with the exhaust leak fixed I seem to be noticing it more outside of this range.
-Pinging/Chatter: RPM specific, 4k - 5k and predictable in its occurence
Dean, what did you find about TDC?
It sounds like it is pinging to death at mid range but don't know why it would clear up in the later RPM's.
One thing we didn't talk about was making sure the vacuum lines coming off the throttle body were in the correct spots. Each one has different purpose. Some only are open when the throttle plate is at certain positions, some have vacuum at idle, some don't etc. Rechecking those and making sure they go where they are supposed to might make a difference.
It sounds like it is pinging to death at mid range but don't know why it would clear up in the later RPM's.
One thing we didn't talk about was making sure the vacuum lines coming off the throttle body were in the correct spots. Each one has different purpose. Some only are open when the throttle plate is at certain positions, some have vacuum at idle, some don't etc. Rechecking those and making sure they go where they are supposed to might make a difference.
Is it possible to get a known good air flow meter or hot wire sensor to plug into the car(which ever one the '82 model year uses)?
I was suspicious of this from reading the 944 pages on their AFMs. We swapped in the meter from Dean's son's car. Now that I think of it though, we didn't get much of a chance to test it as we ran into a leak problem at the o-ring.
Can't explain all the noise at idle, but could the detonation and surge be from a messed up distributor? Maybe giving too much advance in the 4K zone, and not providing consistent advance causing the motor to surge?
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