RE: [DML] Idle gradually increased to 1700 RPM during warm up

[<rob@xxxxxxxxxxx>]

 Dennis,

 

If the fuel in your tank happens to be old, or new fuel recently mixed with
old stale fuel, then the fuel injection circuit would be the primary
suspect. Substantially unequal volume delivery by either the fuel
distributor or faulty injectors could easily cause your symptoms. The
increased idle would tend to reinforce this diagnosis.

A second but less likely possibility due to the increased idle speed would
be an ignition problem such as an arcing spark plug, ignition wire or a
cracked distributor cap.

My first suspect would be the fuel system or some other combination of
issues and it couldn't hurt to take a peak into the fuel tank to check for
sour fuel or damaged fuel supply components. Let us know what you find out?

 

Rob Grady,

 

P.J.Grady Inc.

 

  _____  

From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf Of
dmc_5180
Sent: Sunday, May 17, 2009 9:52 PM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: [DML] Idle gradually increased to 1700 RPM during warm up

 






This is a never before seen problem on my car during my 16 years of
ownership. I went to start the car this afternoon , it had not not been
driven since the DMCMW open house weekend 3 weeks ago. The car fired right
up as usual Idle was stable at 775 +/- 25 with a very subtle hunt but
virtually stable. I walk away from the car after 20-30 seconds I'm letting
it warm up. I was getting a few things from the trunk of my other car to put
in the D. While I had my head in the trunk of the other car The RPM starts
to gradually increase on the D. I did not think too much about it Figuring
that the Idle Micro switch might not be tripped. I walk back over the D get
in driver seat to see the IDLE is at a steady 1700 RPM . I tap the Pedal a
few times NO change. OK, I Go back to engine bay to make sure the Micro
switch is depressed. It IS. Then I happen to Look down at the Left EXHAUST
HEADER. This Is a JET-HOT coated system. The header starts GLOWING and IS
increasing rapidly. I do a quick check of the Right Header which appears to
NOT be turning colors at this point. FYI I was in a rather dark building at
the time so it was fairly easy to see the heat GLOW. Well I've never had
this happen before. and As the header starts turning very RED rather quickly
, I Shut it down immediately. While the engine was shutting, down I hear a
woooof sound in the exhaust, almost like I flame igniting. The exhaust
header quickly turns back to normal color. I wait about a minute then start
the engine again. Idle is steady at 1700. The scary part for me was the Left
exhaust appearing to be much hotter than the right. Again I did not notice
the Right side turning color as the left did. This is a STAGE I exhaust.
both sides are independent each with a CAT. I thought about the possibility
of maybe a plugged CAT but I'm not so sure about that. Any thoughts of what
may have caused my idle to increase like that?

Dennis



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