exhaust manifold red hot

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  #1  
Old 07-04-02, 09:14 AM
tom_NC
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Question exhaust manifold red hot

I have a 1988 Mustang with a 2.3L 4-cyl fuel injection. After only a short drive (say 20 miles) the exhaust manifold is glowing red hot. The engine also idles high (1800 rpm) when warmed up. New sensors include throttle position, MAP sensor, engine temp sensor. Full recent tune up - plugs, wires, distributor cap, rotor, air and gas filters.

Update 7/5/02 - Timing belt was changed... I'm almost sure it was set correctly (worry...). Can this be adjusted out at the distributor?

Engine is out of a wrecked 1989 with 50K miles. Changed everthing before running it.

Car is at 124K miles...
 

Last edited by tom_NC; 07-05-02 at 08:09 AM.
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  #2  
Old 07-04-02, 10:08 AM
tstokka
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sounds to me like your timing is off. causing the increased rpm. and the burning of the fuel in the manifold.
 
  #3  
Old 07-05-02, 05:58 AM
Joe_F
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I agree. That is not a good thing and will ruin the engine over time.

You might have a stretched timing belt or a worn tensioner that is causing it to slack or run loose.

You don't mention the mileage of the Rustang, I mean Mustang
 
  #4  
Old 07-05-02, 08:14 AM
tom_NC
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exhaust manifold red hot

Originally posted by Joe_F
I agree. That is not a good thing and will ruin the engine over time.

You might have a stretched timing belt or a worn tensioner that is causing it to slack or run loose.

You don't mention the mileage of the Rustang, I mean Mustang
Timing belt was changed. I'm almost sure it was set correctly (worry). Can this be adjusted at the distributor? Car seems to run well otherwise...
 
  #5  
Old 07-05-02, 10:52 AM
Joe_F
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Make sure it's at the factory setting. Consult a service manual or the autolibary link I have in below in my signature file to set the timing. Follow the mfgr's specs and procedures.
 
  #6  
Old 07-06-02, 07:02 AM
tom_NC
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exhaust manifold red hot

Update 7/6/02 Rechecked the timing marks at the belt and they looked right. I'm going to pull distributor cap and see if it's pointing at no. 1 using the calibrated eyeball tool. Everything I've read says you can't set timing with electronic engine controls... I'll try a timing light anyway.
 
  #7  
Old 07-06-02, 01:31 PM
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Don't believe a lot of what you hear! Timing, if it has a distributor, must be set. On your car you have to pull the spout connector to set the timing;If you don't your timing will be way off which will cause your concern.If your not familiar with the spout connector, it's a small square shaped plug that just pulls out of the harness usually near the distributor.If the car starts normal and runs decent then the belt is probably ok.
Also make sure you don't have any vacuum leaks.I've seen small vaccuum leaks turn a manifold cherry red!!!
 
  #8  
Old 07-06-02, 01:34 PM
Joe_F
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Thumbs up

I agree with Fordtech and he's right on.

By disconnecting the spout connector, you are setting BASE timing. This takes the computer out of the picture and allows you to set base timing...quite important.

Do that and tell us what you find. Generally, if a car is timed correctly to base timing, no other timing adjustments are needed because as you alluded to, the computer controls the timing with the spout connector connected.
 
  #9  
Old 07-06-02, 07:45 PM
tom_NC
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Ignition module and throttle position sensor

Haven't got the timing light on it yet (couldn't find the pigtail - old timey model before inductive pickup) Read out the computer codes and it complained about ignition pickup erratic and throttle position sensor. I traded distributors with the old one and the ignition code went away. Power seemed to improve. Haven't drove it far enough to see if manifold is still overheating.

It's still complaining about throttle position sensor though (That was one of the first things replaced!) Idle is normal when cold but when warm is anywhere from 1800 to 2000. Noticed when first started is normal (1200) but quickly jumps to 1800 or so. Reading the Hayes book it says "Do not attempt replacement of the throttle position sensor. Calibration is beyond the scope of the home mechanic." Screw holes were not slotted so I couldn't see anyway to adjust it anyway... Whats up with that?
 
  #10  
Old 07-07-02, 03:31 AM
Joe_F
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Usually, idle racing/fluctuation is with the idle air control valve before the TPS.

You could have dirt in the throttle body or a faulty IAC. Common problem on many Fords. Go to Ford, get the approved throttle body cleaner, take the IAC off and clean it out. If there's no improvement, change the IAC.

Looks like a cigar with a rectangular base and two bolts. Right up top or bolted to the throttle body. '

Are you stating you get trouble codes for the TPS? Try disconnecting the battery and wiping out the codes and then checking again to see if they reappear.
 
  #11  
Old 07-10-02, 04:41 PM
tom_NC
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Smile red hot manifold resolved

Well it seems when all else fails read out the computer codes...
Replacing the distributor ignition module has resolved the over heated manifold. Improved power also. I'm still getting the throttle position sensor code after resetting computer.
Engine idle is normal when cold (steady 1100 pm) but when engine is wamed up to operating temp idles at a steady 1700. even faster when good and hot. Cleaned idle speed sensor mechanical portion and traded electonic portion with the one from the old engine with no change. I am starting another post looking for info on checking the TPS (It was one of the first things replaced).
 
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