Slight Stumble or hesitation

wrenchbender · Post by **wrenchbender** » Mon May 07, 2007 11:06 am

I recently did a tune up on my 02. I used NGK iridium plugs, Nology hotwires, and accel cap and rotor. Everthing ran great when i was done untill this weekend when i finally got around to replacing the Fuel filter and PCV that i missed during the tune up. I noticed a very slight stumble kind of like a cough between 1500 and 3000 RPM. It doesnt happen every time and not at WOT either. I found when i slow pull off from a stop maybe 1/8th of the way down on the pedal it happens, not enough to notice on a bumpy road but just enough to irritate the hell out of me. Ive run an injector cleaner through the tank, cleaned the intake and TB with sea foam, Cleaned MAF and IAT and that has done nothing for it. I think im going to experiment with different gas. Any other ideas or solutions would greatly appreciated

killian96ss · Post by **killian96ss** » Mon May 07, 2007 12:30 pm

I had some misfire problems with the NGK iridiums in my 01 CC.

Some people here have had success with them, but my CC did not like them for some reason.

When I replaced the plugs with Delco platinums the problem immediately went away.

More than half of the iridiums I took out showed signs of carbon tracking.

If it's not your plugs then it's possible that your new wires are arcing occasionally.

I've never really believed in the capacitor design of the Nology wires.

Have you checked for any pending codes?

Steve

wrenchbender · Post by **wrenchbender** » Mon May 07, 2007 1:26 pm

Why would it run beautiful with an old junk fuel filter and then misfire with the new?

It hasnt set an idiot light wouldnt a misfire show up in the computer records?

Whats the price on delco platinums and where'd you you get them? Had any problems with them?

Post by **HenryJ** » Mon May 07, 2007 1:55 pm

wrenchbender wrote:Why would it run beautiful with an old junk fuel filter and then misfire with the new?

Contamination during the replacement is a possibility.

...wouldnt a misfire show up in the computer records?

It might.
You would have to read the count though. It may take a number of misfires and a continuing problem to set the light. The light sets when there is a condition that could affect the vehicle emissions or emissions system. It really does not set for driveability issues.

killian96ss · Post by **killian96ss** » Mon May 07, 2007 6:39 pm

wrenchbender wrote:It hasnt set an idiot light wouldnt a misfire show up in the computer records?

Did you already scan the computer?

Pending codes will not set a light.

The computer will set a light once problem becomes continuous or as HenryJ mentioned a certain # of counts has been recorded.

Whats the price on delco platinums and where'd you you get them? Had any problems with them?

Delco platinums are the same as the OEM plugs and can be found at just about any auto parts store or GM dealership.

I would get the Delco double platinums or Rapid Fire platinums.

I have never had any problems with the Delco's.

Steve

wrenchbender · Post by **wrenchbender** » Tue May 08, 2007 8:37 pm

I finally said screw it and went out and got AC delco platinum plugs and put them in today. I borrowed a OBD II scanner from a buddy of mine and everything was clean, No MIL and no pending codes. I still got the same damn problem. I have sea foam in the tank now but I have never had an injector cleaner cause rough running. I think the nology wires are soon to be workbench weights. As for new wires, which performs better, the Taylor Spiropros or the MSDs? Pros and cons on both?

IAC Sensor is a goner?
Coil starting to take a S__t?
Fuel pump?

Im still stuck on the fact that i didnt have the problem before the new fuel filter? Is it possible i got a junk filter and the correct amount of fuel is not getting to the engine? I got the filter at Auto Zone, where i have never had problems with parts before.

Post by **HenryJ** » Wed May 09, 2007 2:38 am

It may be helpful to get a scan tool that will read the misfire counts.
The Tech II will do this, as will Autotap. I use Autotap.

I use the Taylor SpiroPro wires. I can not say which perform better. I will say they are less expensive. There are some plug wire threads that list the pros and cons.

Did you clean the throttle bore and IAC with a spray type cleaner?

Did you double check the distributor cap, rotor and housing?

Think simple. How about a wire that is not fully seated?

killian96ss · Post by **killian96ss** » Wed May 09, 2007 5:14 am

What brand of fuel filter did you install?

Hopefully it was not a FRAM.

Steve