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Engine stutter at low revs on 97MY GT3 - ECU/Freescan/Espritmon - The Lotus Forums Jump to content
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Engine stutter at low revs on 97MY GT3

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Ok so it's the start of a new year, the car came out for the first time and I want to resolve a problem that has been annoying me since i got the car.

When I go to pull away from idle the car bogs down at about 2000 revs and then picks up again. Same goes for reving the car at a standstill.

If I reset the IAC on Freescan, the car is much better for a while and it gradually gets worse again.

I did replace the IAC with a lotus part but the fault remains.

If I download a log from Espritmon can someone have a look at it and tell me what they think is wrong?

What exactly is required to diagnose this? Espritmon log? Freescan log? Sorry, complete newly to this.

Car has been chipped......#11 I think from memory..... I tried this rechip to cure the fault when I got the car.

I know this has been raised before (pretty sure I started a thread my self at one point) but I have just figured out how to get Espritmon to work so hopefully between Freescan / Espritmon and your help I can get this sorted.

Thanks in advance

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Hi Gordon,


I had a similar problem with my S4s, the idel was erratic but also it would stall & stumble at low revs.

Please find link to my original post.

I sorted it with help from the good people on here & Freescan.

Hope this is some help to you.


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Will do Travis, that would be great if you can help out thanks.

Is this a log from Freescan you want?

Is it a standard log or do i have to set anything up in particular?

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Standard freescan or espritmon log. Just make sure you log from starting the car cold and let it idle till warm at 80C. Don't touch the throttle or do anything. Then once warm, you can take if for a short drive or not.

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Hi Travis


This is a file recorded from FreeScan as requested.

Its pretty cold here tonight (0 Deg) so that may be something that shows up on the results??


As for the way the car is running tonight, i reset the IAC on Sunday and it always runs better for a while after i do that. I have also noticed in the past that its a lot smoother in cold weather and that seems to be the case as well tonight with the stutter almost unnoticable...... not sure if thats a function of the cold or the IAC reset.


Anyway, if you can cast your eye over this and come up with any suggestions i would really appreciate it.


Thanks for your help



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ok, taking a look.


Yep, you IAC counts are high at idle, when the engine is warm.  They are at ~55 and should be between 20-40 at idle, when warm.  This will definitely cause a stalling problem or a hesitation when you initially touch the throttle.  This usually goes away once the engine has been driven a bit, but it is frustrating right when you start the car.


The cause could be a mal-adjustment of the minimum air rate bleed screw, but you'll need to check for manifold air leaks first.


Follow that thread that Philip linked.  Also clean the pintle of the IAC valve and the hole.  Maybe a new o-ring too.


The air leak, if there is one, could also hurt your pulling away performance from a stop sign, even after the car is warmed up.


Your O2 sensor looks ok, and I don't see any obvious lean or rich condition.  You do have a couple cells in the BLM that are on the rich side, and that may be when you are pulling away from a stop.  So you might have a sticky injector or something along those lines.  These cars are getting old enough that it seems like the fuel pumps and injectors are starting to fail.


Go through that thread about the IAC, and then go from there.

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