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Gtir Motorsport club » Tech room » Ecu related section » Another Jam Ecu.

Another Jam Ecu.

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1Another Jam Ecu. Empty Another Jam Ecu. on 30th April 2018, 12:48 pm


Hi, Long time lurker first time poster. I know some of you from FB and have also met some you.

Any how i have a JAM ecu that i got from Japan and have had for a while. Paid about £70 all in so not too bad. On the advert when translating from Japanese it said the ecu needed 550cc injectors but i do not believe this to be true. On the board inside there are two chips and both have stickers on that say RPM550 -4 this is what makes me think that injectors are not needed and it is actually the rpm that has been increase by 550.  

Does anybody agree with this?

Very little information exists about Jam Sport, i believe they went bankrupt but where a very reputable tuning company, so here is what i have managed to dig up using the Wayback machine from the JAM website about the Pulsar GTiR

By exchanging only the muffler, power up of 35 ps or more is possible. The air-fuel ratio is corrected and remains the same as normal, as long as you keep up with the genuine computer as long as you do not boost up even if you are concerned about the fire.
If boost is raised from 1.0 to 1.2 in EVC etc etc, sports computer needs to be replaced.
Even in this case it is not necessary to change the capacity of the injector. When replacing with a large turbine, "Replacing the injector and corresponding computer is necessary.

Boost due to actual running (fully open) and air-fuel ratio · normal vehicle
gear         Boost       Air-fuel ratio
2nd speed  0.7           11.1
3 rd gear    0.7           11.1
4th speed   0.7            11.1
5 speed     0.7 → 0.65 (sauce) 11.2

· JAM Sports muffler fitted car
gear            Boost      Air-fuel ratio
2nd speed     0.85          11.2
3 rd gear 0.88 -> 0.85    11.1
4th speed 0.88 -> 0.85    11.1
5 speed 0.90 → 0.85        11.2

· JAM Sports Muffler + JAM Sports Computer (Boost at 1 o'clock)
gear          Boost      Air-fuel ratio
2nd speed   0.9          11.1
3 rd gear     0.9          11.1
4th speed 0.90 -> 0.95  11.1
5 speed    0.95 → 1.05   11.2

My car still retains the top mount ic. the engine has Tomei gasket and con rod bolts and a full exhaust with one of bogdans elbows and 360deg thrust bearing on the turbo. I also have a forge bov and am currently using a blitz dsbc to control the boost.
i have hooked up the Jam ecu to my car after adjusting my idle to suit it seems to tick over nicely. this changes when starting to drive the car and off boost it feels a bit lumpy and feels as though i have to try to catch the revs as they start to drop when coming to a stop. On boost is a different story. It pulls nice and feels a lot smoother than the standard ecu.  I ave also notice that the little adjuster on the ecu has been messed but am unsure of what this does.

Any ideas what to look at that could cause the lumpy running off boost?



2Another Jam Ecu. Empty Re: Another Jam Ecu. on 30th April 2018, 1:34 pm


I had a Jam sport ECU in my first Pulsar...standard injectors fitted!
I think they're much the same as the likes of Mines ECU's as in they're meant to run about 1.2 bar boost, maybe with a smidge more ignition timing than standard.

The little screw on the side of the ECU is to switch on diagnostic mode which, if you have a paperclip you won't need!

Have you checked for an air leak in one of the many vacuum/boost pipes? Still got the carbon canister fitted to N/S inner wing?

The dropping revs issue is a classic symptom of removing the PCV system from the inlet manifold. Both my current one and last R had this issue and both started doing it shortly after removing the PCV pipework. It doesn't happen all the time, only sometimes and the revs would drop to like 500rpm for a few seconds and then stabilise at 1000rpm.
IMO its because the idle stabilisation valve(s) under the manifold are maybe a bit slow to react (or so it seems!). I'm actually trialling something on my R just now to cure this issue as its getting right on my tits...looks promising at the moment but will post separately later this week if I'm still happy...

3Another Jam Ecu. Empty Re: Another Jam Ecu. on 30th April 2018, 2:22 pm


Hey Mike.

No Carbon canister and pcv all removed without any issues. i will add i have no running issues with the standard ecu and it idles at 950 - 1000 rpm just fine.

Will have a look over the vac pipes but i am pretty confident they are in good shape.

4Another Jam Ecu. Empty Re: Another Jam Ecu. on 30th April 2018, 3:05 pm


hmm, intriguing!
The only other thing I could suggest is check for fault codes on both the standard and JAM ECU's...I seem to recall some aftermarket ECU's can be a little sensitive to certain things and throw a code whereas standard ECU's wouldn't (eg 34 - knock sensor)
Something else maybe to check for is any dry joints or burnt tracks inside the JAM ECU?
Failing that I'm nae sure mate. I'm sure its nothing too serious if it runs well otherwise... Smile

5Another Jam Ecu. Empty Re: Another Jam Ecu. on 1st May 2018, 5:04 am


Yes Intriguing.

I am going to have another play with it today and I will try what you have said.

6Another Jam Ecu. Empty Re: Another Jam Ecu. on 1st May 2018, 6:24 am

johnny gtir

johnny gtir
Welcome to the forum where roughly you from? Do you have a wideband fitted ?

7Another Jam Ecu. Empty Re: Another Jam Ecu. on 1st May 2018, 6:33 am


Morning Johnny.

No wideband at mo.
I am based in North Manchester.

I also have an AEM fuel pump fitted.

8Another Jam Ecu. Empty Re: Another Jam Ecu. on 1st May 2018, 6:39 am

johnny gtir

johnny gtir
I know it’s all money mate but cheaper than a engine is there no where that will do a run on dyno and check it. The fact it’s running on the standard Ecu with no idle or issues off throttle gives a fair indication it’s not split pipes etc

9Another Jam Ecu. Empty Re: Another Jam Ecu. on 1st May 2018, 7:28 am


Yeah fair point Johnny.

I am not that far away from Tuning developments.

10Another Jam Ecu. Empty Re: Another Jam Ecu. on 1st May 2018, 7:17 pm

johnny gtir

johnny gtir
Just thinking be safe rather than sorry and you know exactlly what is doing where across the board. Keeps life in the engine mate

11Another Jam Ecu. Empty Re: Another Jam Ecu. on 1st May 2018, 8:54 pm

Mr B

Mr B
gtir technician
gtir technician
On age of these cars you want be going on rollers for a check as many old components may struggle, add in an unknown map daughter board ecu and it really smart thing do and likely net best end result .
Pretty sure Jam bit like tomei and done several stage tuning maps, piggy back ecu a good cheap option for basic tuning, the later daskek unichips was cheap way tweak fuel and ignition and dirt cheap pick up used .

12Another Jam Ecu. Empty Re: Another Jam Ecu. on 2nd May 2018, 5:36 am


Thanks for the input and the warm welcome, although it feels like I have been on here for years.

So yesterday I ran through a few things as suggested by Mike. Checked over all vacs and did fault code check on standard ecu, none to report, all good.

Switched over to Jam ecu. Ran a fault check and also nothing to report, code 55. Fired it up adjusted idle to spec. seems to have a misfire somewhere that isn't there when standard ecu is on.

Put standard ecu back on and the Jam has gone back into the box until I can either get it checked on a dyno by a professional or go with nistune.

13Another Jam Ecu. Empty Re: Another Jam Ecu. on 2nd May 2018, 5:56 am

johnny gtir

johnny gtir
Good idea something it don’t like on the jam

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