Lumpy idle

[Leung]

I have just upgraded to a 9930 Everest chip and I think I am getting lumpy idleling(uneven note from the exchaust on idle).Do I really have to adjust the CO pot or can I leave it as it is ?Will it cause problems further down the line?because apart from the idle the car runs fine.

[johnbenk]

Hi

What is the rpm at tickover?

Uneven tickover can be other faults. Erratic voltage will cause the IAC valve to change its position resulting in poor idle quality. You need to adjust tickover if you mess with the CO Pot you also need a Exhaust gas
reader (from Halfords) to check readings Could also be Map sensor output,
faulty ground on ECM. Faulty ESM, Faulty TPS. Idle air control system, vacuum leaks ETC. Fuel injectors for leakage?

You could remove chip if non of the above have faults, check if still present. If so look elswhere for problem

Good luck


chip would not necessary alter tickover?

[Candles]

As the new chip is different software to the oldest chips, the CO pot probably needs setting up. The CO pot defines the mixture baseline, which if incorrect would result in a lumpy idle. Sounds like what you have.

I agree with John above, pop the old chip back in and see if it is lumpy. If not then you need to put the new chip back in and set the CO pot with an exhaust gas analyser. How to do it is in the manual and is an easy job with one small screwdriver and a paperclip as well as the exhaust gas analyser needed.

Candles.

[Leung]

The RPM is normal, ie just above 1000 when cold and just below 1000 when the car has warmed up.the needle does not jump about just the note from the exhaust sounded uneven.I am not sure if this is the same without the chip because I never really paid much attention to it .I will try and remove the chip to see if it is the same.

My main concern is future problems caused by the upgrade,eg ignition and engine problems.

[Doug]

The ESM chip is the exact same parameters at idle and low boost, so it is the exact chip until you hit the upper boost area! The ONLY difference could be that you must have been using the 9929 in your SE and then the 9930 requires the above detailed CO pot adjustment because it is a better program for the CO pot and a newer chip release from Lotus.