Removing Revlimiter on Weber Marelli IAW ECU

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torkil
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Removing Revlimiter on Weber Marelli IAW ECU

Post by torkil »

Hi Mr Croft , I have 2,0 16 V tipo motor in my X 1/9. The rew limiter stop att 7000 rews. Have you any cure for removing this in the ECU. ? Any type off solution welcome.

The con rods and piston are all special made for higher revs.

Regards from Ove Thorkildsen Oslo Norway
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petarn_vx
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by petarn_vx »

Hi Ove,

Which ECU do you have exactly?
Can read out the eprom from the ECU end send the code?
I am quite sure I can find the limiter.

wbr
Peter
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torkil
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by torkil »

Thank you for answer, i will read out the number and sen you it , but it is about 1990 modell witch have a single coil and a distributor just for sending the spark to the spark plugs.
It has just 2 or 3 wires for test instrument . Will send you the number and type .
Thanks OVE
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Honza
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by Honza »

other mods done to engine?

I have now 2 wery heavily modded 2.0 16v engines running on standart (mapped ECUs, but with certain limitations, so power would be better) with kappa 16vt intake manifold and both runs up to 8000 rpm... where is the limiter set.
First ecu is 4Q4 P8 (coupe 16v) and the second is from 107kW tipo (cannot remeber the code)

It doesn´t make sesne to run higher with single throtle-plenum chamber intake system... there is a significant power loss past 7700rpm. With ITBs it would be better - the power loss could occur somewhere around 8500 with right cams.

I wouldn´t remove the rev. limiter, only move it higher... it is safety feature...

here are few specialist wich deals with these ecu and their conversions - NickRP is one of them...
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WhizzMan
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by WhizzMan »

If your con rods and pistons are made for higher revs, that doesn't mean your cam profile, valves and valve springs are. Just taking out the limiter will take the ECU in ranges it has no mapping for, and you could be leaning out your engine, or ignition timing could be off, causing knocking. You will need a full remap with new RPM ranges just to make sure your ECU will give the correct mixture and spark advance. Even if you do that, you won't gain a lot of power, since your cam profiles will max the power out at less than 7000 rpm.

I'd just leave it as it is, or get the valves, springs and cam profile changed to match your pistons and con rods. Then get a full remap to get the ECU adjusted for the "new" engine.
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torkil
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by torkil »

Thank you for repliing .On my question Revlimiter.

The engine is modified with 12 to 1 pistons .Italian fast road cams ,slightly modified head . Have now also a straight intake manufold with thottle bodies . 40mm. These are 600cc motorbike carburetters ,Modified an just used as throttlebodies , It feels that the engine is strong between 6000 and 7000 rpm ,but stops att 7000. I want to try to let it rev at least 7500 and see if that will help. Have tried sevral injectors and fuel pressures.

There is a fact that i have slight detonation on 4000 revs but i pas that rew always quickly. later i will reduse the compression a little in order to get quit the detonation . This is a low cost car and i will keep it that way.

Regards OVE
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Honza
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by Honza »

Your specs are interesting, I think that the best was is contact NickRP (or i think Alex RP also) and they are able to convert your ECU to fully mappable device, wich is one of the better option for you/your engine...then you can alter whatever you want..

there was also some disccusion thread about this converion on this site.
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torkil
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by torkil »

Hi My ECU number is, Weber IAW 4Q1
WF4Q1. 08/AQLAF

Regards OVE
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torkil
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by torkil »

Mr >Honza i have tried to serch for your links with no luck so far.
If adresses or links are a problem on this site i understand

OVE
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petarn_vx
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by petarn_vx »

Hi Ove,

Rev-limiter is set in the eprom (chip) of the ecu. Without eprom-programmer you can not read out the eprom. With all the changes you have done I would change to a fully mappable device, or get full remaping for the orginal ECU.

wbr
Peter
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WhizzMan
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by WhizzMan »

So you did change the cam profile as well. In that case, you should get a full remap, including the ignition timing seriously redone. With 12:1 compression and different cams, igniting too early will most likely be the cause of your detonation at 4000rpm. Just changing the rev limit will not even be close to profiting effectively from all your modifications.

I have no idea about the max revs stock valves and springs can handle. Maybe someone else has these details? I would be cautious to go over 7500 without an answer to this question.
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torkil
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by torkil »

Hi i just fund out that my ECU weber IAW 4Q1 is an US version ,and now i know why there is an REW limiterin there, Well i suppose that there is a lot more limitasjons there also, This X 19 car is not mutch faster than my 124 Sport Coupe 2,0 8V ,

Now i know what to doo , I have an old DTA e 48 , that i will try to slot in . I have waiting a long time with doing thes , Due off the yonger gyes dont like a non window based ,and non live programming divice .

I will try Reg OVE
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WhizzMan
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by WhizzMan »

You may find some interesting information in this earlier thread:

http://guy-croft.com/viewtopic.php?f=13&t=380

Nikola (NickRP on this forum) supposedly can modify your ECU so it is programmable. There is more interesting information on your engine and ECU in that topic that may interest you.
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Alex RP
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by Alex RP »

@torkil:
Could you please post a photo or two of your engine bay, with throttle bodies etc? How long are the intake runners (from valve to butterfly and from valve to trumpet)?

IAW 4Q1 is not a US ECU version, by the "US" suffix (in EPER, for example) it is only noted that it is catted and fulfills certain US exhaust gas norms, which are more or less the same with European Euro-1 exhaust gas norm. All pre-facelift Tipos 2.0 16v were equipped with the 4Q1 ECU, and none of them were ever imported to the states.

With throttle bodies and upgraded cams I would expect issues on low revs with speed/density indexed fuel map, as the vacuum signal will be quite weak, and pulsate a lot. So my suggestion would be to use speed/alpha indexing, where load would be indicated by throttle position sensor.

Back to your question: given the amount of modification, it is almost amazing that the car is running at all with the OE map. However, I would expect it to be quite rich at low end (so rich that bore washout will occur) and dangerously lean at higher revs. Ignition map would ABSOLUTELY need attention. OE one is (luckily for you) very conservative, otherwise one could most probably do some oil pan inspection through spark plug holes! :) So, you need a special firmware to run speed/alpha indexing and a full remap.

For sake of completeness: we can fix rev limiter for you, it goes quick, but this would only open Pandora's box wider. Also note Guy Croft recommendation on rev limit with cast iron flywheel:
Guy Croft wrote:... but the highest rpm I recommend on a cast iron fw (all of them are cast on OE units) is say 7500 on the 2 liter... Over 7200 I definitely recommend dowelling to stake the shear stress off the bolts alone.
Taken from http://guy-croft.com/viewtopic.php?f=3&t=570. Be sure there is a reason behind this!

Should you need any further assistance with this type of ECU, diagnostic software, reprogramming etc, let me know. But make sure the mechanical side is sound first.

Best regards,
Alex
A. Petri
rp-lab.com
torkil
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Re: Removing Revlimiter on Weber Marelli IAW ECU

Post by torkil »

Thank you Alex for wey important , informations! I have a hard time getting it so far but now you opened it up.

The intake with bodys trumpets is 30 cm. long. have 40 mm KIE HIN carburetters just used for TH bodys. Modyfiing these is just to solder all fulingsystems and lock the vacum operated butterflies in top posisjon,and fit the TPC. these are wery adjustable between carbs an easy to adjust. And can be whatched on my picassa web, under my name ove thorkildsen. The will also soon be out a new video on the tube.
You are exactly right whenn it coms to fueling, Rich in the bottom. yes , but i ran bigger jets from croma turbo, have also tested some green boesch 430 jets ,(too Ritch in the bottom) witch is fine on the top revs, at least almost.

I hope that you can give mee a price to lift the rev limiter 7600. This car also serve as a sunchine chopper an is just registrated for 145 horsepover with OE ECU clearly stated in the title, But i use it on trackday also then i make it a little diferent . I am fully avare off MR Croft advice on 7500 revs , he has right in that .

I hope that i have gone to far on mr Croft forum . But i think i am fine this time.

Regards OVE Oslo
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