Another new scan

[tomatcbl]

LECers,

I finally got my elanscan hooked up and wonder if someone could review it. My main issue is a high initial rev count, usually around 2k - and it then declines, oscillating all the way down to about 0.9k. I have looked at several of the posted clean scans and can't see any obvious differences - or at least none I can understand. Background, this is a Federal elan. The scan goes from cold start up, through the thermostat opening an the fan kicking on twice. I then took it for a short spin down the road. Shortly before I bought it in Oct 2010, the prior owner had the O2 sensor replaced. Any comments on whether the behaviour at start up is normal or indicative of a sensor problem of some kind would be appreciated.

Cheers, Tom

[tigerdog]

Hi Tom,
First thing I checked when I opened the scan was the throttle position sensor. I assume when you started the car, you kept your foot off the accelerator as the scan progressed. If this is the case, then either something is binding so your throttle is not closing fully, or you need to adjust the TPS. It reads 14.9% right at the start of the scan and stays that way up to about 500 seconds. Compare this to the scan I attached from Smaug and you'll see what I mean. I imagine it's difficult for the ECU to adjust the idle if it thinks the throttle is partly open.

Setting the TPS is very simple and incredibly so with Elanscan. First, make sure the throttle actually is closing against its stop instead of being held open by a stiff or misadjusted throttle cable. Here's how I did it:

Entire procedure done with engine OFF and ignition key in the "run" position.

• Start Elanscan and "Start talking" Make a note of the "Throttle" percentage in real time on the display.
• From the engine bay, work the throttle by hand and make sure the percentage goes up as you open the throttle.
• Gently push the throttle closed to make sure it's not hanging on something. If the percentage goes to zero, diagnose the mechanical binding/linkage first. Once you're sure the throttle is closed,
• Loosen the adjusting screw and gently rotate the TPS until Elanscan reads 0% throttle, then tighten the screw just a bit to keep the TPS from slipping.
• Still watching Elanscan, work the throttle to wide open position and make sure Elanscan shows 100%. If it doesn't, hold the throttle full open and rotate the TPS just until ES shows 100% throttle.
• Release the throttle and make sure ES still shows 0% when fully closed.
  Tighten the adjustor. That's it!

While you're back there, you might even consider replacing the retaining screw with a socket head cap screw. The gent who spec'd a phillips head screw for that location needs to be forced to work on the TPS for about a month. This should have a couple of benefits. If my hunch is right, it'll solve the idle problem. It may also smooth out your boost/throttle behavior a bit and insure you reach maximum boost. The ECU regulates boost so full pressure is only produced at 100% throttle. The TPS is used as an input to the boost control algorithm.

[tomatcbl]

Thanks for the detailed "how to" Tigerdog. It was the TPS and not anything mechanical - loosening the screw and adjusting its position to give a zero opening fixed all of the idling issues - it not starts at 1250 rpm, holds steady and then gradually declines to around 1000.

Thanks for your help.

Cheers, Tom

[tigerdog]

See? So easy even a (Tiger)dog can do it.