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How to lower the onset of Secondary Injectors to 3000 RPM???? - Engine/Ancilliaries - The Lotus Forums #ForTheOwners Jump to content


How to lower the onset of Secondary Injectors to 3000 RPM????


MikieP

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Hi all,

Need to find a way to bring in secondaries at much lower than factor's 4800 rpm as the new larger unidentified turbo wants much more gas! Lowered the boost to 1 bar max from 1.25 BAR using an AEM boost controller but still gets 15.7 A/F above about 3800 rpm so need to bring the secondaries much earlier than the 4800 rpm the stock ECU seems to be set to. Or perhaps anyone know the blocks of code in the ECU that can be changed to lower than 4800 rpm? This is a repeated post as the first seems to not be available when clicked on....

 

MikieP

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You would be better off adjusting the VE tables first and monitoring the primary injector dutycycle before using the secondary injectors to provide any additional fuelling. Also, the the secondary injectors aren't simply on or off, they have a mapped duty cycle too and this duttycycle gets further adjusted for things like throttle position and battery voltage.

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The secondary injectors on my car operated at 4000rpm or maybe a litter lower with PUK#6 while the throttle position was 100

But after replacing the OEM ones with RC ones, it seems that they operated around 4800rpm, but the throttle position is between 60 to 80, rather than 100 at that time

is it normal?

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hard to believe your primary injectors would be maxed on duty cycle so soon, esp at only 1 bar boost.  What is the condition of your injectors?   are you reading 15.7 AFR from an aftermarket wideband setup?

John Welch is credited with reverse engineering the code and may be able to help with a custom chip.  There is also a large TunerCat community that may be able to assist.

chris

90SE

just because I don't CARE doesn't mean I don't UNDERDSTAND

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Yes, they are the 270's from Mr. Welch. They were cleaned and tested to be at 269, 267, 268 and 270 flow.  Using his S4s chip that he said would bring the secondaries on at 3600 but it is apparently not doing that as they are not coming on until around 4800. Shop is waiting to talk to ham about perhaps it is bad??? Dunno. Running out of fuel at around 3200 rpm per wideband installed and need a fix or will have to go aftermarket at high cost or go back to the factory turbo which I really do not want to do, ever. lol.

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pan without knowing how the PUK#6 chip is programmed it's impossible to say whether you behaviour you see is normal or not.

MikieP, the secondary injectors do not operate according to engine speed alone; MAP, battery voltage and throttle position all effect their use.

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wait you have 4 270s? the stock setup is primaries 360 and secondaries 190 i believe.  Dermot increased his secondaries to 270 but that is not necessary.  maybe just change them back to stock (i have a new set of RC injectors i cant use anymore.  if interested, PM me with offer)

 

chris

90SE

just because I don't CARE doesn't mean I don't UNDERDSTAND

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I could be wrong about size, just remember that they were putting out significantly less than rated so were cleaned and came back to numbers representing the stated rating... Will call shop tomorrow to make certain I have correct sizes! lol. thought I was told 269, but could have been 359, etc. If they are actually 270, I have a big problem.

 

Also, see this thread....

MikeP

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I have covered this point with people before, the answer is always the same... The stock ECU is designed to work with the stock injectors, boost and timing etc.. Play with anything and you start  to upset the equilibrium . This is where your problems start... As for the PUK chips..  They boast performance figures but have no dyno data or spec to back them up.. Each chip should have component spec to match its new parameters... But even then still has no way of fully integrating the tuning of components and chip.. The standard ECU will always limit the width you can work with on your tuning requirements..  As always it comes down to cost..  All the component costs are wasted or poorly represented until you change to a stand alone ECU.  By doing this, all the mods you are trying to do can be first analysed then balanced to format a performance engine spec.  Anything else is just pure guess work..   However this does require a good tuning technician with an understanding of how it needs to be set up , not just any basic dyno man.. Also be prepared to change components to balance the outcome..  This has never been ABC otherwise 400 bhp would be a walk in the park for everyone..       

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^ he's right...... And Daves been there and done that !!

but on balance - I'd enjoy the car for what it is - it gets to the point that adding extra HP at the top end doesn't achieve much. 

Read his thread - it's amazing in terms of engineering - and the cars stunning.

I have heard all sorts of stuff about puk chips - nothing has ever been near a dyno by them to back up the claims, I looked !! - you may as well by a tuning resistor from eBay for £30 !!

Only here once

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i found the PUK 6 chip to be exactly what i was looking for at the time.  It appeared to work fairly well on a stock SE as the stock turbo struggled to achieve the 1.25 bar allowance and stay within the IAT window (ie it was self limiting).  But the modified wastegate duty cycle limits at lower RPM made the car much more lively and thrilling.  If this is what you are expecting, the PUK chips deliver.   

chris

90SE

just because I don't CARE doesn't mean I don't UNDERDSTAND

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I've driven an SE with the #3 Hi Torque and can too attest that it brings with it some tangible improvements - without knowing exactly what it does I did notice that the car had a LOT more low end torque than my stock SE. 

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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It provided a good increase in mid-range torque, and got rid of the annoying stumble, so I'm very pleased with it.

 

Reference the stock injectors, I wonder if there may be a benefit in having them professionally cleaned before going to the expense of replacing them?

Margate Exotics.

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I'm also coming to the end of a full standalone install, so I completely agree with Dave. I looked at the available chips but decided against them for various reasons.

The stock MAP sensor won't read more than a bar of boost, so If you try and run more than that, your ECU doesn't know about it. Not good. Another issue is that as soon as you start changing the way the engine breathes, any map that wasn't developed on your car is guess work. That's not to say that chips don't have a place, but in my opinion they should be used on mostly stock cars. Once you start changing how your engine breathes or the fuel delivery, you really want something that can easily deal with those changes through a settings change and perhaps a trip back to the dyno if you're expecting more power. Standalone setups also open up a plethora of new features you can use.

With the mid-range torque, I believe the stock ECU does boost vs RPM/Gear to reduce stress on the drive train. The chips are probably winding up the boost faster.

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Shop is on vacation until next week so can not be sure of what I am saying here, but if my memory serves, according to boost gauge car is getting full, though now very limited, 1 bar at around 2200 and air to fuel is fine until around 4200. Then is starts to run lean as the secondaries do not come on until 4800.... All have been removed and professionally cleaned. Yes, most do agree a stand alone ECU is the way to go but $2K seems to be the starting point whereas getting the secondaries to come in earlier might cure the issue or at least make it driveable on the road. This car will never see a track, though perhaps a growl or two at a mustang may occur, Given that some estimates of this turbo are 450+ HP capable, I have no intention of attempting that number, just wanted it to be a bit better than it was originally. A bit over zealous race mechanic started this upgrade down the slippery slope, a little fraud here, a little incompetence there and we are now where it is. Sort of hard to go backwards after all this.... Chip is not stock SE. It is the S4s from John Welch. Is the S4s not able to see and use up to 1.2x BAR or is it just the MAP sensor that is the limiting device here and could this be remedied? My rpm numbers could be off here and if so, will post corrected ones when shop comes back from vacation next week....

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21 hours ago, ian29gte said:

It provided a good increase in mid-range torque, and got rid of the annoying stumble, so I'm very pleased with it.

I've never felt that stumble - what exactly is it? Is it like a dip in the torque curve at 3k? Only car I've felt that on was the GT86/BRZ where it gets going then dies somewhere around there before recovering due to a stupid engine management calibration. My SE on the other hand is completely dead before 2300 rpm - then it gets going and doesn't let up.

Vanya Stanisavljevic '91 Esprit SE | '97 XK8

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19 hours ago, cammmy said:

I believe the stock ECU does boost vs RPM/Gear to reduce stress on the drive train.

The 4 cylinder ecu doesn't know what gear you are in (the V8 ecu does though from the vehicle speed and engine speed).

15 hours ago, MikieP said:

Is the S4s not able to see and use up to 1.2x BAR or is it just the MAP sensor that is the limiting device here

No, neither coding or MAP sensor allows it.

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2 hours ago, Vanya said:

I've never felt that stumble - what exactly is it? Is it like a dip in the torque curve at 3k? Only car I've felt that on was the GT86/BRZ where it gets going then dies somewhere around there before recovering due to a stupid engine management calibration. My SE on the other hand is completely dead before 2300 rpm - then it gets going and doesn't let up.

 

In my case, it felt like a minor misfire, surging, or hesitation on part-throttle, which occurred around 2,750 - 3,000. It also happened on light acceleration. I must stress that it was minor, and there was never any such issue at full throttle.

The replacement MEMCAL eradicated my problem, but I also read somewhere that not all Esprits suffered from it. I should at this point give a thanks to @sailorbob who was instrumental in the process. I chose not to exceed the standard MAP limits.

Margate Exotics.

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18 hours ago, MikieP said:

Yes, most do agree a stand alone ECU is the way to go but $2K seems to be the starting point whereas getting the secondaries to come in earlier might cure the issue or at least make it driveable on the road. This car will never see a track, though perhaps a growl or two at a mustang may occur, Given that some estimates of this turbo are 450+ HP capable, I have no intention of attempting that number, just wanted it to be a bit better than it was originally. A bit over zealous race mechanic started this upgrade down the slippery slope, a little fraud here, a little incompetence there and we are now where it is. Sort of hard to go backwards after all this....

Sorry to hear that.

That's not so say a chip won't work for you if you're not deviating far from stock. I just believe that it's worth the extra time and money to go full standalone. I used an MS3/X. It has pretty much all of the features of any other ECU but they're much cheaper. The only issues are that you rely on the community for support (although I have to say the forums are excellent) and that a number of tuners won't work with them as apparently the older models had issues. I've not had any trouble with mine thus far though. If you've got some fancy bits on there then standalone is the only way to make the most of them.

Getting back to the issue, how do you know when the secondaries are coming online? As mentioned previously, I don't think it's a static number. Also, have you been able to check fuel pressure? I had to stop on dyno day as I was going lean at 5,300rpm at only .45 bar. I've got an aftermarket regulator with sight gauge installed, so I was able to verify that the pressure was dropping off. I've since installed a new fuel pump and will be changing the filter before heading back.

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Rolling road tests indicated 4800 kick in and too lean to continue the testing above about 3600 rpm. Fuel pressure tested while driving and watching pressure gauge and did not seem to be a cause of leaning out. Bringing in the other two injectors earlier would / should help but still may not be enough for a cure. Waiting to hear back from Mr. Welch on his thoughts on why his chip still waiting till 4800 to kick them in. It apparently is breathing far better than original, now with decat, 3" turbo back, reworked head, larger turbo and soon to be installed 1" plenum spacer. Looks as though there is no way out of the 3rd party ecu then.... Just wish I could get the secondaries to come in around 3600 just to see if that would make it streetable (sic).... lol

 

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Wait and see what he comes back with. If you do go down the standalone route, I can give you a wealth of information on exactly what you need to do for an MS and can also give you a base map that includes all the settings I had to work out. This would get you started and to a dyno.

Ragingfool has also gone standalone from a different manufacturer and gave me a load of very useful info, so would be a good person to talk to if you're interested.

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If you are not exceeding 1 bar of boost then a standalone management system is not required. As I said above, you would be better off adjusting the VE tables first and monitoring the primary injector dutycycle before using the secondary injectors to provide any additional fuelling.

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