93 Olds Cutlass Supreme runs rough

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  #1  
Old 11-02-15, 07:33 PM
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93 Olds Cutlass Supreme runs rough

93 olds cutlass supreme 3.1L - vin letter T

My problem is it runs fine after it sits for a few hours, after that it lacks power and idles rough. I have replaced the map sensor, idle control sensor, ran test on throttle control sensor and it checked out good also tested coils they seem to be fine, replaces PVC valve amd new spark plugs and wires.
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Last edited by PJmax; 11-02-15 at 09:03 PM. Reason: put vehicle info in text
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  #2  
Old 11-02-15, 08:14 PM
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So, after it gets hot, it runs rough, correct? That could mean that something is expanding & letting air in where it's not supposed to go. Look at vacuum hoses & lose bolts, on the manifold, etc....
 
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Old 11-02-15, 08:42 PM
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I checked all the vacuum connections they are fine, put new intake gasets on but I am thinking maybe its warped? I don't know
 
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Old 11-02-15, 08:58 PM
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Welcome to the forums.

The EGR (exhaust gas recirculation) valve can also cause problems like that especially if it doesn't close properly.

If you think you have an air leak in the intake manifold.... take a can of starting fluid and very carefully spray a small amount where the manifold joins the block. The idle will increase if a leak is present. A basic vacuum meter could also be helpful here.
 
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Old 11-02-15, 09:35 PM
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sorry I for got to mention I also replaced the EGR valve and cleaned what I could with carberator fluid, I'll try what you suggested for finding a leak and get back to you to you tomorrow, thanks
 
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Old 11-03-15, 02:49 AM
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so it does run ok cold but runs rough and loss of power when warm?
would probably check fuel pressure also might check resistance of injectors they should all be very close to the same resistance.
 
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Old 11-03-15, 08:51 AM
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No check engine light?

Did you clean the passages below the EGR when you had it off?
How about the IAC valve--have you tested/cleaned that and below?

Those 2 things cause problems that show up as heat-related. Rough idle, uneven idle, surging idle. Unplug the IAC harness while the engine is running cold, then hot. In both instances the idle should get worse with the IAC unplugged.
 
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Old 11-03-15, 09:48 AM
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1. do vacuum leak test with brake cleaner spray. That tubes look Ok means nothing. Esp test around head gasket and throttle body
2. do plug wires leak test with soapy water
3. when were plugs and wires replaced?
4. my wild guess is you have, otherwise, leaking injectors, flooding spark plugs. Pull plug or 2 out and check for deposits or dampness from petrol.
 
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Old 11-03-15, 11:08 AM
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I began this project because it started running bad so the first thing I did was replace the plugs and wires with new ones , I am sure my vacuum lines are all well sealed.
I replaced the intake gaskets and sealed them, but because it ran well until it warms up I was thinking the intake ny be warped, today I will run a test for leaks around the intake.

I am smelling fuel after I shut it down.

you guys have given me a lot to do, thanks
 
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Old 11-03-15, 03:58 PM
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I am smelling fuel after I shut it down.
That is probably the clue, to the problem. How many fuel pumps does the car have?
 
  #11  
Old 11-03-15, 09:04 PM
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I did a leak test on the intake manifold today, there is a leak around one of the bolts, you were right that is moslt likely the issue, thanks for the help.....
 
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