FD2 cams on FN2 - need bigger injectors ?

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Hondata1
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Post by Hondata1 »

Your datalog shows that you hit 100% duty cycle at 6900 rpm. This should not happen on a naturally aspirated 2.0 litre car with stock injectors.

What are your bolt-ons?

Perhaps your fuel pressure is too low. Have you changed anything in this area? What is your fuel pressure?
dinoc
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Joined: Wed May 16, 2007 4:35 am

Post by dinoc »

Hi Hondata,

Thank you for answering me .

My bolt-ons are the ones from my signature :
- Toda exhaust manifold (de-cat),
- Toda catback exhaust
- Gruppe-M intake,
- Hondata heat-shield gasket,
- JDM FD2 RRC intake manifold
- JDM FD2 cams
- FlashPro MAF locked calibration (can't see it or modify it)

I'm not sure how to check the fuel pressure , shouldn't this appear in the datalogs ?
Where should I check this info ?

The history with this 100% duty injectors is like this :
- after changing FD2 cams and did some datalogs, someone pointed me, that my duty cycle was 100% at WOT , never checked this before,
- then checked some older datalogs (with OEM cams and another FP calibration) and noticed the 100% duty cycle also (but only sometimes) ,
with FD2 cams seems to happen all the times at WOT

Who might be responsible for fuel pressure being too low, a failure of the fuel pump, injectors or the calibration or something else ?
Euro Honda Accord CL9
dinoc
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Post by dinoc »

Anyone know how can I check the fuel pressure ?
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joel1188
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Post by joel1188 »

the 100% duty cycle that you are seeing could be a result of the MAF calibration that you are running.

i have tuned quite a few of the FN2 and noticed it happens... send me an email, i should be able to help you.
dinoc
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Post by dinoc »

Hi Joel, I've sent you an email.

Meantime, can someone tell me where do you read that fuel pressure ?
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Spunkster
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Post by Spunkster »

Fuel pressure must be measured using a fuel pressure gauge.
dinoc
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Post by dinoc »

CPL said the fuel pressure should 50 psi ... tough not sure what the real fuel pressure is as I don't have a separate logger/gauge for fuel pressure, I'll see if I can find out one ...

But theoretically is it possible to need bigger injectors just with the bold-ons I have ?
CPL said they have tuned a few cars with similar bolt-ons and they never saw 100%duty cycle ...
Euro Honda Accord CL9
dinoc
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Post by dinoc »

I have found to borrow a fuel pressure gauge so I was thinking to the following plan:

-to take the car to a local dyno and monitor fuel pressure and AFR also, using the dyno's lambda sensor
- at the same time to datalog the car on OBD2 and when I see 100% duty cycle to check the fuel pressure

What do you think about this plan ?

I really want to get sorted out this 100% duty cycle issue,
so please give me some guidance here if I need to check anything else, also ?

- never run a dyno before, I guess I should run this at WOT , right ?
- does it matter which gear, if I run it in the 5th gear at WOT will be ok ?
- any other suggestions ?

many thanks
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Hondata1
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Post by Hondata1 »

Fuel Pressure on a US Civic is 53-54 PSI and doesn't vary by more than 2-3 PSI during a full throttle run on a naturally aspirated car.

90-100 % duty cycle on stock injectors with this 54 PSI naturally aspirated should be 30-40 HP peak over stock. On the Dynapack we test on we see 240-wheel HP at about 95 % duty cycle.

Gear should not matter. Use third gear.

However you should first test fuel pressure at idle. When we tested we taped the fuel pressure gauge to the windscreen and did a 2nd WOT gear run down the road.

A dyno will be able to double check your air fuel ratio and power though.
dinoc
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Post by dinoc »

Thank you Hondata , I'll check this and let you know about the results.

By the way, CPL said (as I wrote above) that fuel pressure is 50 psi , I guess on their tuned cars with the same calibration ...

[LE] well another forum colleague just gave me an idea about that I might have a faulty O2 sensor , he had a similar problem.

quoting him :


What happens is at WOT the ecu is trying to get to 13:1 but your o2 is only going to 13.6:1 so it gives more and more fuel until it cant give anymore.


what do you guys think ?
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nunoctr
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Post by nunoctr »

dinoc, the aswer of hondata is in this topic:

http://www.hondata.com/forum/viewtopic.php?t=10170

You are running a closed loop at WOT - usually this is because the WOT fuel compensation tables are too high or the open loop pressures are too high.

Running closed loop at WOT gives perfect AFs, but if anything goes wrong with the oxygen sensor you'll potentially hurt the engine.
dinoc
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Post by dinoc »

Hi guys,

I've tried today at Honda dealer to install their fuel pressure gauge, but unfortunately we were unable to, their gas pipes are not good for civic so they need to order new pipes ... etc ... so I'll had to postpone this ... I'll do it once they receive the new pipes.

Now something else, I've convinced them to change the primary O2 sensor ( as a fellow suggested me that I might have a faulty sensor).

So I did datalog the car again, and now the duty cycle maximum seen is 85, 86% .

So it looks to me that the replacement of the O2 sensor solved my problem.

Attached are the datalogs , Hondata please tell me your opinion.

The car feels very good to me, and I did a dyno today , here are the results:
http://hondafan.etp.ro/gallery/d/236012 ... type-r.jpg

Many thanks,
Dinu
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