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Rough Idle after warming up 92 SSEI

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Old 03-15-2009, 11:41 AM
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Originally Posted by Danthurs
If the O2 is old you should replace it. It might help. But seeing it'* giving you trouble when hot I still think it'* the IAT sensor. Also clean the MAF. Have you done a seafoam top clean? I've seen this do good things in the past.
I'm thinking I will replace the 02 because I think it is stock with ~130k.

is the IAT the same as the IAC? I'll check on that. Yeah I want to clean the MAF as well.

I bought a can of seafoam but I haven't done it yet as I wanted to make sure it was done right. I will post a pic later of which vacuum hose and if you guys can let me know thats the right one.
Old 03-15-2009, 05:49 PM
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IAC is idle air control valve, IAT is intake air temp.

As for the O2, get some penetrating oil on there, you will need it. And get a real heavy duty O2 wrench, the cheap ones are junk
Old 03-17-2009, 01:32 PM
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Thanks for the info Dan.

OK so I just checked for stored codes (grounding AB terminal method). Looks like I do have 34 code stored (MAF). The weird part is it was not lighting up my check engine...

Anyway should I just replace the MAF and see if that fixes it?

I was going through the test procedure and I'm kinda stuck. Here is the page:

Rough Idle after warming up 92 SSEI-code_34-001.jpg

So I'm at number 3 and it says to connect test light between terminals B and C. What is this test? Can i just do a voltage test across the terminals?

Thanks
Old 03-17-2009, 04:14 PM
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There'* a lot of MAF info in teh tech info area, see if that helps. Have you tried unplugging teh MAF and running without it? It wont hurt teh engine but will give a light. If it runs better then the MAF might be bad. If no change the MAF might be good.
Old 03-17-2009, 05:03 PM
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Yeah I unplugged the maf and the car seem to run worse and the check engine was on. I'll try it again though.

Can I clean the MAF with carb cleaner or do I need something special?
Old 03-17-2009, 05:07 PM
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Originally Posted by chantspel
Can I clean the MAF with carb cleaner or do I need something special?
NO! You need to get some special MAF cleaner. Just spray it on and let it dry. Do not touch the wire on the MAF.
Old 03-24-2009, 12:32 PM
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Thanks for the info guys. So I got the MAF clean - no change in idle tho.

OK I'm stupid but I figured out why I got the code for the MAF - it must have been set when I was testing and ran the car with the MAF unplugged. So I'm glad I didn't waste the ~200 bucks on a new one.

Anyways Dan you had mentioned the IAT as a possible cause - is there a way I can test it or should I just replace? I tried unplugging it and nothing changed (didn't run worse or better).
Old 03-26-2009, 07:37 AM
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whats the IAT
Old 03-26-2009, 08:16 AM
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Intake air temp sensor. Should be located inside the air cleaner housing.
Old 03-26-2009, 09:02 AM
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If the IAT fails..what are the symptoms per the FSM?
I only know of it to cause the below.
--more or less timing depending on which way it fails
--check engine light with code stored

Standard checks for an engine that is running rough
Plugs and wires (check)
How did the plugs look when you replaced them, any fouled?
Are any coil posts corroded or rusty looking?
Are any plug wires touching the O2 sensor wiring?
What temp is the PCM coolant temp sensor reading? (the dash is a different sensor and can not be relied upon)
What grade of fuel are you using?
Does the catalytic converter rattle?
Are there any other odd things happening that you believe to be unrelated that you didn't mention?
How much fuel pressure does the vehicle have?
Is the fuel pump excessively loud (aka can you hear it)?
Did you check all vacuum hoses including the ones under the airbox at the charcoal canister?
Do your exhaust manifolds have cracks in them?


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