FD Engine cutting out/ limp mode.

[The dutchman]

Hi guys.
Havving some problems with my RX 7 FD
First some information off my car.
\'92 FD Touring. Jap import.
51000 km on the clocks and engine is standart. It only has a other rear muffler.

Never had any probles with it on the 2 years i own it. Untill a few weeks ago.

We where going to a meet nearby. Started the car and drove it to the highway slowly as always. (10 mins drive)
When going on the highway shifted slowly) up and in the 3rd gear on about 2200-2500 rpm the engine started cutting out..... time after time.. So looked under the bonnet of there was something lose but coulded see anything.
The engine didnt sound weird and drove good.
So treid it again.
First and 2nd gear no problems. At the 3rd the same cut. And around the 4500-5000 rpm it does the same in 4th and 5th gear.
The engine just cuts out and i a can push the gaspedal to the floor but nothings happens until it drops about 500rpm and then it revs up.
If i rev it up in 2nd gear to lets say 4500 rpm and then put it in the 3rd then there is no problem. As long as it is above the 2500 rpm and above the 5000 rpm.

Brought it to the dealer and they checked it. They maybe thougt it was the ECU. Putted a other ECU in and the problems where gone.... But that ECU was a european ECU.
So i order a JDM ecu with a guy here in holland. Putted it in and the same problems.....
Now i have tested other JDM ecu\'s and with all the ecu\'s there are the same problems....
So i think it is not the ECU.
But what can it be?
Maybe you guys have a sollution?
Maybe vacuum?

Oh yeah on the same thime the problems started my odo meter stopt working on the dash. Maybe a coincidence??

Long story sorry and i hope you understand it ( my englisch write isnt that good. ) :Giggle

[boosted]

Any recent works on the car...disturbed something? round coil packs ?
Sounds like a bad earth? or coil failure.....put could be a multitude of issues but really strange odo going off at same time which is why i\'m thinking electrical....

More info needed....
Cuts under boost? hook up at gauge and see what boost running.
All of odometer goes off or mileage indicator drops to zero? or rev gauge? or whole display?

As much info as possible ?

[The dutchman]

No works done lately.
No boost gauge fitted yet. Have one but not installed yet. :o

It\'s boosting fine i think . But untill it hits the 2500 and 5000 RPM. Before and after that rpm is pulls strong.And it\'s only in 3rd ,4rd and 5th gear.
And the 2500rpm and 5000 rpm are the moments the turbo\'s kick in.

Will hook the boost gauge as soon as possible.

The odo moter is lighting up. But no numbers on it. The rest off the instruments work fine.
Its a common problem with fd that the display stopt working as i searched it. A little electric shock(or something) can cause it to faillure.
But when it happend at the same time that\'s strange yes.

Thanks for the repley Boosted :Thumbs-up

[clive]

Have a look at the Map sensor pipe, its a possible as the ECU won\'t get info plus a vacuum leak

[The dutchman]

Thanks for the reply Clive. We will have a look.

What i also thought was strange that on the european ecu the problem was gone......
Its only on the jdm ecu..... now i can put the eu ecu in but then the problem is not solved.

[clive]

If the problem was gone by changing the ECU then you have answered your own question.

I\'m sure somebody here will have a JDM ECU for you.

[rx7boy]

When your swapping the ecu you are effectively resetting the error code so this will not give you an accurate reading to why the the car is going in limp mode.

From what you have described I would think it\'s an earth issue. The dash oddly earth\'s through the emission harness so you need to check under the upper inlet manifold UIM  earth\'s

You need to go back to basics and use the service manual error code checker on this, clear the fault codes by draining the system power (remove battery + and press brake 10x) then use an led across the diagnostic port.

[The dutchman]

If the problem was gone by changing the ECU then you have answered your own question.

I\'m sure somebody here will have a JDM ECU for you.

No. I fitted a few jdm ecu\'s and they all give the same problem.
Only the eu spec ecu works.

[boosted]

If my memory serves me correctly there are 3 different ecu types for model years and 8 and 16 bit so whatever revisions are in these ecus like turbo crossover, boost settings maps for different fuel octane ratings from different countries etc ( assuming your still on twins and sequential).
You may be playing with fire here. And risking your engine.

Why are you changing ecu types? The most logical choice would be an apexi fc of the correct revision for your year.

We need all the info mate.

[The dutchman]

No i only fitted a few jdm N3A7 ecu\'s. That where the same as my original ecu.

The european ecu was also a 8 bit computer. But on that ecu all de problems where gone.... but on all the jdm ecu\'s i fitted the engine was cutting out.
I think the european ecu overwrites the problem. I heard that the european fd\'s doesnt have the strong rules that the jdm ecu\'s/fd\'s have.
I would never place an 16bitts ecu in a 8bitts FD.  :Nono!

So offcourse i can buy a european 8bitts ecu and ignore it but that doesnt solve the problems imo.

And yes my engine is complete stock.

And the reason why i have fitted a few other ecu\'s because the dealer thought that was the problem.
Now he is the rx specialst here in the netherlands. But i thought ill ask it here if someone maybe had the same problem. So we can d a better search.

[boosted]

If and a big IF the ecus use different harnesses and pick up earth points from elsewhere maybe your prob being masked by the eu ecu.....check all earths and make up your own grounding kit as a diagnosis tool?

[The dutchman]

Allright we will do that.  I hope that is the sollution :Thumbs-up
But its never bad to do it. I saw that it can cause many problems.....
Thanks for the info and help.
Will also go trought the others options they gave here. :Thumbs-up

Where can i buy a good grounding kit? Or can i use a universal kit?

[boosted]

As Rx7boy said there is a mass of earths under the uim check them for security..check your battery connections and follow the negative from there and check tightenss of connections....at this stage as only a possibilty can you make up some of your own i.e ground from the bulk head to the uim with a cable crimped with eyelets before you buy a kit...ebay i think.

Easy earths to get to undue clean up contact surfaces with emery cloth or such like.