Cold start and Idle control issues

Hi everyone!

Stock 2ZZ-GE Engine w/ Stage 2 camshafts

Link G4X Storm

Im new to tuning and I have had the car mapped with a local tuner all ready but there are some issues around cold starting and idle control that I'd like to resolve.

The car runs fine past 2k rpm.

During cold start and warm up process, if I don't touch the throttle the car will idle at the desired target and decrease as operating temp increases which is normal. If I drive the car during the warm up process, the idle shoots right up to about 2.2k rpm and does not settle.

Once the ECT reaches about 50 degrees celcius, it will then proceed to idle at the target rpm.

Once fully warm, the idle will hunt and bounce up and down around 1.5k - 950rpm.

There is also a juddery feeling as if the car is lurching back and forth sometimes in the low rpm zone (under 2k). This seems to be very intermittent and does not happen all the time.

I have played around with the open loop idle control settings but I'm now stuck for ideas.

I have uploaded my map file and a log.

Map file

https://drive.google.com/file/d/1nE5QmH24MLS3K5D5ZNMEirAbZV6Ky8fi/view?usp=sharing

Log file

https://drive.google.com/file/d/1h5gr00gO95DFH2QGMqAJW4iA_6OHcqu3/view?usp=sharing

Hopefully you tuning guru's will be able to help me out! Thanks in advance.

Hello,

I'll take a look at the calibration and see if there's anything obvious.

Make sure the IACV clean and functioning correctly and the throttle is closed with the TPS sensor calibrated correctly.

The symptoms you describe could also be a an air leak, check all the usual culprits vac, PCV hoses,manifold gasket etc.

Cams will have an effect on idle but it should be consistent hunting c.200rpm that reduces with rpm not the big swings you are getting.

**EDIT**

I've taken a look at you map and there nothing that stands out too much, the log shows it idling quite nicely from 10-25 seconds.

Regarding the set up if the IAC valve make sure this is correct and compatible with your IACV as 2-3 wire solenoids require a different set up 2zz's use a 3 wire i believe, the set up notes in PClink are helpful.

Providing the set up and config is correct and the problem persists, you could check to see where the issue is coming from setting parameters to a flat map such as target rpm and ignition.

I can see the revs hanging on from 25-30 seconds; during this time the ignition advance is over 30 degrees and the idle controller duty is still at +70% which could be driving the rpm and looking at it the ignition map is too aggressive in the low load areas so setting the low load areas to a flat value of 5-10 degrees should help, you could also increase control at idle and low load by adjusting the breakpoints to give you better resolution as there is no need to map below 30kPa really.

I'm sure someone form Link can provide more technical answers on IACV configuration if the F1 help function doesn't answer all your questions so it worth dropping the an email.

Hey and thanks for your reply.

IACV is working correctly

I've resolved some of the issue, cold starting and idle control is sorted now. It was a silly mistake that I overlooked which the RPM lockout above target was set too low.

I still have this juddery/jerky feeling under 2k rpm which seems to be more prominent when the engine is cold and not as bad when warm. Do you think this would be due to the aggressive ignition map? If I reduce the ignition advance in the low load areas, will it have an effect on A/F ratios and in what ways will that affect the engine?

Thanks

Can you do a log of the jerking issue, your accel enrichment is set up very sensitive so I suspect that is possibly some of it.

Also, your firmware is old, I suggest you update that as there have been many improvements and fixes since.

Adjusting ignition advance wont effect your air/fuel ratio and there will be no adverse effects to using a flat value across the lower sites, there really is no need to be running 30 degrees advance at low load irrespective of rpm. Smooth interpolation from these low load areas will result in a more measured throttle response giving the driveline an easier time.

To give you an example, on the last bespoke race engine I worked on without and IACV or FBW throttle the bottom 2 sites were set to 5degress giving an idle of 1500rpm, we then used a high idle function of 25degrees giving 2800rpm both set points were for the same given throttle setting.

Hi guys and thanks for your replies

Here is a log file of the jerking happening in a 5 minutes drive from cold.

https://drive.google.com/file/d/1yJwTE0ykdTdkY-LTtyvT2bS1QH1yv-4L/view?usp=sharing.

I would say mostly Ign related, bottom blue trace is advance, you are bouncing between the 20 & 34 deg cells in the ign table. Lambda is a bit on the lean side which will make it more sensitive.

Okay great, I'll have a go at bringing the numbers down at these cells.

Thanks for your help!