Any JB4 regrets? Issues? additional thoughts?

chirowolf · Jun 19, 2025

I know there are a couple of threads on the JB4, but would like some specific answers on likely problems.

He is my situation.
Emiria 1st addition SC manual
Purchased my car used with 1500 miles on the clock
Assuming I have about 2 more years of warranty left. Not planning to track anytime soon.
Mild mechanical mods so far with a Milltek Valve controller and GRP down pipe.

With all the hype of this forum I got a major case of FOMO. Ordered the unit a few weeks back. Today my JB4 arrived!

Now my quandary. Do I install it?
I really do not want a CEL or anything that would send me to the dealer. I have not had great results with the local dealer. I have not been to the dealer in years and would like to keep it that way.
I used to tell myself my Evora with 300hp was more than enough. The Emira with 400hp is absolutely insane compared to my Evora.
I should be happy. right?
Can't help but feel I'm leaving hp on the table and just a bit more would be great.

I know with more power I will have to balance the risk/reward. I'm thinking If I go conservative, let's say, Map2 with 93 octane. I will get a nice boost without stressing the car and minimizing risk.

Thoughts?
Criticism?
Opinions?

Eagle7 · Jun 19, 2025

I think as long as you log your car's performance with it, and send the logs to them so they can see how everything looks, you should be good (that's what I'm going to do). I'm going to run the first 100 miles using only Map1 (not Map0 or anything else), and then take it to the dyno shop to get a comparison to my last dyno. I'm guessing after the ECU adjusts to it, Map1 might be pretty decent as an all-the-time option. Map1 looks pretty mild, and basically what Lotus would have done if it weren't for the overly restrictive CARB requirements (which are now no longer valid). It's not going to stress anything. You could run Map2 or 3 for those occasions when you want to, but keep it on Map1 for normal driving.

My main concern from what I'm reading, is Map3 might be adding more heat that could possibly be a problem. So far I haven't been able to find any stations with 93 where I live, so Map3 may not be an issue for me lol, but I'm going to look into possible cooling enhancements for it anyways.

chirowolf · Jun 19, 2025

Lucky for me 93 is readily available in the midwest
Even Walmart has 93
Most station at 87,91 and 93

Thanks for the input

David s · Jun 19, 2025

I fitted my JB4 2 weeks ago. I also have the GRP cold air, miltek cat delete and exhaust. The result has been astonishing. No CELs, very smooth and strong power delivery. Iv`e been daily driving the car with no problems. I run map 2 continually with no problems. This is how a car that looks like this should go. I`m happy to hear anyone elses experience. Iv`e discussed the upgrade with my trusted Lotus dealer, and he says the car runs safe with the upgrade as the ECU is still in command to protect the engine from any unforeseen events.

FST · Friday at 2:49 AM

David s said:
I fitted my JB4 2 weeks ago. I also have the GRP cold air, miltek cat delete and exhaust. The result has been astonishing. No CELs, very smooth and strong power delivery. Iv`e been daily driving the car with no problems. I run map 2 continually with no problems. This is how a car that looks like this should go. I`m happy to hear anyone elses experience. Iv`e discussed the upgrade with my trusted Lotus dealer, and he says the car runs safe with the upgrade as the ECU is still in command to protect the engine from any unforeseen events.

Please check my post on the jb4 tread… please do a side by side comparison video for the sake of the group like I did so we can see the difference of your claim.

chirowolf · Friday at 8:21 AM

It is encouraging that I have not seen any horror stories with the tune. I did a YouTube search and found most people were quite pleased with the tune (mostly BMW guys). Some had removed the tune due to some minor problems, but OfCourse they had other modes that may be the source of the problem.
A major heatwave hit my part of the US which may delay my install for a week or two.
I have never had a car with a tune (piggyback or otherwise) and am a bit cautious.
I appreciate the feedback.

chirowolf · Friday at 9:14 AM

Another question I have is:
I do not believe my car has had any Lotus software updates. I have no issues.
Should I get a software update?
Get update then do the tune?
Skip update since I have no problems?

Eagle7 · Friday at 11:27 AM

chirowolf said:
Another question I have is:
I do not believe my car has had any Lotus software updates. I have no issues.
Should I get a software update?
Get update then do the tune?
Skip update since I have no problems?

That's kind of a mixed bag. Some believe if it ain't broke, don't try to fix it (which has some merit), others believe it's best to have the latest updates which in addition to fixing known issues (even if you haven't experienced them), also can add or improve features that have been requested. Depends on how convenient it is to get to your dealer, and how good/efficient they are. If they're a long ways away, and your car's running fine, I'd say save up getting updates until you have to make the trip for service or something. If they're close to you, go ahead and keep the updates current.

ADC · Friday at 11:32 AM

chirowolf said:
Another question I have is:
I do not believe my car has had any Lotus software updates. I have no issues.
Should I get a software update?
Get update then do the tune?
Skip update since I have no problems?

If it were me, I'd be inclined to get the updates first (I also had zero issues, but had all updates applied at my recent service). They tend to solve more problems than they cause. That said, I was also a bit twitchy about the idea of going in with a perfectly working car and leaving with a new gremlin, so I know where your head is at

David s · Friday at 7:22 PM

chirowolf said:
Another question I have is:
I do not believe my car has had any Lotus software updates. I have no issues.
Should I get a software update?
Get update then do the tune?
Skip update since I have no problems?

Don`t know about you. But everytime I update the software on my Iphone it runs like crap. JB4 it ASAP. You never get the hours and days back before the Jb.

675430VME · Saturday at 1:40 AM

chirowolf said:
Another question I have is:
I do not believe my car has had any Lotus software updates. I have no issues.
Should I get a software update?
Get update then do the tune?
Skip update since I have no problems?

Do not update any engine management software if your car is fine as is. Our experience in China is the car gets slower for each update, for the turbo anyway.

fcajr · Monday at 12:44 PM

Eagle7 said:
That's kind of a mixed bag. Some believe if it ain't broke, don't try to fix it (which has some merit), others believe it's best to have the latest updates which in addition to fixing known issues (even if you haven't experienced them), also can add or improve features that have been requested. Depends on how convenient it is to get to your dealer, and how good/efficient they are. If they're a long ways away, and your car's running fine, I'd say save up getting updates until you have to make the trip for service or something. If they're close to you, go ahead and keep the updates current.

I'm with you! Two weeks ago I had my software updated and lost the drivers display. Went back last Friday to reload it, and still no display. Lotus currently has no answer and mean while, I have no speedo, tach, fuel gauge, etc. Drove in with no issues, drove out with a big problem.

PatrickJS · Monday at 2:18 PM

yeah I might just sell my JB4 and stick with ECU tunes

chirowolf · Monday at 4:01 PM

fcajr said:
I'm with you! Two weeks ago I had my software updated and lost the drivers display. Went back last Friday to reload it, and still no display. Lotus currently has no answer and mean while, I have no speedo, tach, fuel gauge, etc. Drove in with no issues, drove out with a big problem.

I've had issues with Lotus service in the past. The car would be returned with additional problems and the problem the car was in for was not fixed. Luckily for me my Evora had only minor fit and finish issues.
"Knock on wood" my Emira has been flawless over its 2500 miles. I guess I will not mess with success

chirowolf · Monday at 4:02 PM

PatrickJS said:
yeah I might just sell my JB4 and stick with ECU tunes

Are you having issues? I have not been following all the treads lately so I'm a bit out of the loop.

David s · Monday at 4:08 PM

PatrickJS said:
yeah I might just sell my JB4 and stick with ECU tunes

And who would you sell it to Patrick. Certainly no one on this site would buy it after hearing all the negativity.

Vampyre · Monday at 5:24 PM

Installed the JB4 in my V6 M and love it, Map 1 was about 10 minutes of use and then I moved right to map2 93 and it is amazing difference, no concern for heat or anything as this is not a track car, and if you are looking for a track car there are better choices in the 100K price range than either the V6 or i4 Emira.

PatrickJS · Monday at 7:28 PM

chirowolf said:
Are you having issues? I have not been following all the treads lately so I'm a bit out of the loop.

i haven't been keeping up any other feedback just my experience was bad soon after installing it

Tomwa · Monday at 10:19 PM

PatrickJS said:
i haven't been keeping up any other feedback just my experience was bad soon after installing it

Given this is a feedback thread, can you be more specific?

I don't know if you stated somewhere else what you were not happy with. But just saying your experience was bad and you are maybe going to sell doesn't really say what was bad and why.

FST · Monday at 11:05 PM

Today me and my friend are planning to do more tests with the jb4 as last one was a bit disappointing. Will have the logs send over them and analyse.. also will install draggy today before the test and will do map0/1/2 runs