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4k Limit with Wide Open Throttle


Tech988

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Hey guys new to the community, hoping I'm posting in the right place. I have a Link ECU and just started working on the fuel maps and all. So far my idle is great, steady with about a 30rpm fluctuation, but I'm having an issue with acceleration. In any gear or in neautral, if I floor the throttle, the RPMs dont go above ~4000 RPM. If I accelerate regularly however, I can hit around 7500 RPM. What numbers should I be looking at to find out what going on?

 

 

I don't yet have access to the ECU through my laptop since I have no idea what cable to buy, so if someone could point me in the right direction I'd appreciate it. 

 

Thanks in advance!

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Hi Tech988, welcome to the forums.

There are a few things that could cause an issue like this. Probably the first thing we'll need to know is what version of firmware you are running in the ECU. 

I see you have posted this in the G1 ECU thread, are you sure this is what you have? Some of the G1 ECUs were PC Tunable, and others could only be programmed with a hand controller. 

If you post a photo of your ECU we can confirm which type it is.

Scott.

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https://imgur.com/a/H1w1f

I'm running on MK-2 03-MAY-01 ... it's the default map for NA with oem injectors. I've only made modifications to master fuel, Cstart, lowered max map to 110 kpa, daily driving with coarse tune, and a few other things, curious as to which can cause the issue.

I have a Link handheld engine management system tuner(6 buttons, green background with black letters)

Edited by Tech988
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If I was to pick one thing to check would be the spark plugs you are using. They MUST be resistive along with resistive HT leads.

The actual unit you have is a MX5 plugin running Flyin Miata firmware.

You can find the manual for it here http://forums.linkecu.com/applications/core/interface/file/attachment.php?id=2535

This might not be an exact match due to the custom flyin miata firmware which they developed themselves (we only supplied the hardware)

You might find more info over at flyinmiata.com

 

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I only use iridium NGK plugs in my car, also I looked at the link you gave me, and was able to find it said 

 

"ACCEL Controls acceleration enrichment during abrupt opening
of the throttle. There are 4 zones each covering a 2000 RPM
span to allow optimum enrichment figures to be set for
varying conditions. Note that ACCEL is only effective during
the actual movement of the throttle to cover any brief flat
spots occurring at that time. The actual zone is selected
automatically, and is shown as Z=x where x = the currently
active zone. e.g. Z=2 indicates transient zone 2 (2000..4000
RPM range)."

 

Now I could see how the above could help with wide open throttle, but even with this, I can't find this acceleration option in the tuning keypad. And I just drove the car, I was in 2nd at 5k, and floored the throttle, and ashe I expected the engine died down to 4k rpm, however slowly. It didn't just go to 4k, it kinda went as if I was engine braking.

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I think the miss match in settings available will be due to the firmware.

If a map is tuned to close I would not expect much accel to be needed at higher RPMs.

I'm assuming the injectors and fuel system are up to the task and its not a simple case of not enough available fuel supply.

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Ok, well I was taking a look at some numbers, and if I open the throttle and get less than 5 in. Of vaccum, I go into the fuel map above F635 (above 4k rpm with the 4 in. vacuum reading) the conditions presents itself.

*this specific fuel map works based off a 3 digit number, 1-6 for the first number and 05-95 for the 2nd and 3rd. Can't recall what the first is for but the 05-95 that goes off 5 digit increments, is based off the RPM (05*100 for 500rpm, 25*100 for 2500rpm).

 

As a side note, I had the factory ECU until this Saturday. The condition was not present before. I did all the re-wiring myself of the few wires that needed to be moved to communicate with the new ecu, including pulling a wire from the maf wiring and the diagnosis box, I soldered and heatshrunk thus new connection. The car turned on without hesitation.

 

 

Can anyone give me a link to find the cable for ecu to laptop? The cable is a female 2x7 pin ribbon cable.

 

Thanks Simon for the continued responses

Edited by Tech988
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Found the issue - during my checking, found IAT sensor showing a reading of 100C, found a power wire not fully installed at the sensor causing system to see a short. After repair, cleared the map to start again from scratch since the lambda, I believe, was making adjustments and caused a high rich fuel content.

Edited by Tech988
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Jeez, I really need to get my hands on a SerialLink. I had a strange acceleration hesitation, saw the fuel maps being used, and saw map 210 @ 102 and 305 @ 67 then 310 @ 97. I really need to look over these maps on my laptop. Does anyone have a Link to a chart I can printout to write down a log of the fuel and ignition map?

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