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Rolling Road leans out severely at 4200rpm - Engine/Ancilliaries - The Lotus Forums #ForTheOwners Jump to content


Rolling Road leans out severely at 4200rpm


MikieP

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Hi all,

 

Been a while since being on here. My car was getting a few things done and finally a rolling road test. I have been told that it leans out severely enough that the test was stopped at 4400 rpm. Turbo is larger, and unidentified by WC Engineering, whose kit it was supposedly to be from,but I was swindled by Jamie Goffaux of Yesteryear Motors, but I am using WC Engineering's larger RC injector kit he sold for the Ceramic Turbo upgrade he used to sell. Shop is going to see if the primaries are clogged but the secondaries were checked and were OK. Perhaps these injectors do not have enough fuel delivery for the larger turbo? The fuel pressure was checked at the end of the supply line and was sufficient. Anyone have any ideas as to the cause of this anomaly, please? Exhaust was enlarged to 3" and decat'ed as well. TIA.

Mikie

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Which ECU MEMCAL chip?

Which O2 sensor?

Which MAP sensor?

Are you using an external boost controller?

What is the wastegate set for?

Was the fuel pressure checked at idle only? Or was it checked to rise with boost?  Was the pressure sustained with full engine load?

Any check engine lights?

Did the ECU cut boost due to the lean condition? or was this just reported by the dyno staff?

Travis

Vulcan Grey 89SE

 

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Derek,

This shop does not know about the EspritMon or other software, nor does the rolling road. I have never been able to get laptop to work as well.

 

Travis,

ECU memcal is WC Engineering's S4s +3% chip.

O2 sensor is stock at the moment but shop is looking into a wideband sensorfor the the second bung hole.

MAP sensor. Dunno.

Stock Boost Conroller for now. gets to 1.25 BAR or so.

Wastegate is supposedly stock setting.

Fuel Pressure was done during spirited driving while looking out rear window at the gauge.

No CEL's.

Reported by dyno staff to shop mechanic so I do not know if boost was cut by ECU.

 

MikieP.

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1.25 bar of boost is too high for the OE MAP sensor to measure as it will only read up to about 2.07 bar absolute. Exceeding the pressure the MAP sensor can measure will cause incorrect fuelling as the ecu has no idea of how much air is flowing into the engine.

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I do think you need to add a wideband A:F sensor, since you have modifications, it's good to know when/if something goes wrong.

I agree with Derek.  Stick with the stock boost settings since the MAP sensor is the limiting factor. 

 

There is a fuel pressure test in the Lotus shop manual that can verify whether the fuel system can keep up with the demand of the injectors up to ~60psi.  Which goes beyond just looking at a pressure gauge while driving.

Travis

Vulcan Grey 89SE

 

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Just off the phone with the shop. Seems like I indeed now own a racing turbo set up by John Welch. Issues are not enough fuel from the esprit's ECU to deal with the larger turbo, the enlarged head ports, enlarged exhaust, enlarged intake, etc. Fuel pressure was measured on the road  test and is fine. Just not enough being sent out of the injectors. The primaries also were found to be at around 335 rather than their 370 rating so they have been cleaned. Secondaries were checked and are  fine. Plan now is to check waste gate settings for proper setup as well per earlier suggestion. Also, an HKS EVC Boost controller is being wired in to keep the boost under 15 psi (~1 BAR) thereby restricting air flow to lower levels and then perhaps re-code the Chip if necessary. That is where things stand at this point. Charge Cooler is cooling properly as well. Seems as though this turbo is 500 hp capable as well as onset is much earlier, spool so much faster than stock due to exhaust enlargement, decating, intake enlargement, etc so have more than enough air flowing, just not enough fuel to keep the A/F around 13.5 or so at this point.

MikieP

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with the few modifications i had, the condition Derek describes was norm and system would run lean and cut boost.  To take advantage of the bigger turbo, the solution was to install aftermarket ECU.   I am told that there is a big Tunercat community who can probably mod the GM chip program to utilize a 3 bar MAP sensor, but when i investigated vs an aftermarket ECU conversion (A) the cost was similar (B) i would still be left with ancient tech and would have to shell out same $ each time a tuning was required.  as you discovered, dyno tuners dont know anything about Esprit ECU...

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chris

90SE

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

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What  ragingfool35 said is spot on ...  I covered most of this in the early parts of the 412 thread saying the same about the std ECU.  There is very little you can do with this, even then not really calibrated or financially viable..     If you want to move forward with your mod's you need to go stand alone ECU... This can be as expensive as you wish to make it.  Also be aware certain sensors used with the std ECU will not be compatible with modern technology.  This will open the door to endless possibilities for tuning the 910 unit , most of which are covered in the 412 thread. Also in there is mentioned some of the pit falls..  Tuning an engine is an art, combining many facets.  Just bolting on bits can be more negative than positive , These tuning parts need to be calibrated harmoniously with the engines overall dynamic otherwise serve no purpose.  A stand alone ECU will help do this..  The fueling issue a pressures was also covered , at a more extreme level, but same format..

          

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Chris and Dave,
 

You are both correct. We were thinking about just reducing the boost back to 1.0 or so via the waste gate / AEM / HKS units, per the S4s ECU parameters and go from there into checking fuel flow, larger injectors, etc. Probably might still need to go to larger primaries in any case. Should the S4s ECU not handle the air-fuel at 1.0 bar and lower OK? Additionally, I do have the AEM Boost Controller setup in the car (previous shop - Treasured Motors) could not get it working) and the new shop is going to get it running and see how that goes as well. It is possible for the S4s (+3% fueling - WC Engineering's chip) to deal with 1.0 BAR, is it not? That is the chip I am running now. I also have the HKS V setup if that might help if the AEM will not do the job. Waiting for all this to gel and then add the plenum 1" spacer as well. Could that be an no-no? I am not wanting to get 412 HP or anything like it, just want it to run at 1.0 BAR ok without cutting fueling. No track for this car. Or should I go back to the stock turbo, ech!? After market ECU out of the question financially at this time. Cheers and beers to all.

 

MikieP

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as long as you limit the boost to what the MAP sensor can read, the stock ECU and your existing components will be fine, just not optimal.  My Delco ECU with PUK 6 chip showed slightly enriching compensation for the different turbo (30 to 40 points out of available 128).  from my engine data, there was plenty of wiggle room in both fuel map and injector duty cycle with the bigger turbo (and other changes) if the ECU could have accepted a 3 bar MAP sensor.

the super fast spool of the new turbo also caused entire cells to be skipped on stock fuel map during rapid transition form light to heavy load.  you may experience same.  Not optimal, but you wouldnt know unless looking for it.

chris

90SE

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

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Hi Chris,

Good to know. Yes, shop told me that the timing of the old ECU is too slow to pick up on the rapid changes due to the sub-routines being so nested, and then again, it all depends on the way the ECU starts to prioritize the routines... Hopefully more info this coming week. Not sure how a wide band O2 will help / alter the current situation but here's hoping. I think the key is to stop the turbo from exceeding 1.0 BAR (all the above 1.0 wasted power gone!!!! lol) at the moment and see what happens. Not too worried about the tranny as I have learned not to do any pedal movement in 5th now. Wish the group buy on the charge cooler had gone forward but perhaps better money spent on the current issues instead.
 

MikieP

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reduce the boost and you wont need a wide band oxygen sensor, but it is always comforting to have  AFR displayed on your instrument panel for a modified car (the stock ECU wont use the wideband, it is just a gage for the driver to monitor)

chris

90SE

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

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Hi Chris,

 

Good to hear. That is what am hoping will happen, as I can not afford what appears to be a monstrous cost to go to another ECU system now or in the near future. Perhaps the next owner might care to do that, if there is one. lol.

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  • 1 month later...

Just be aware that even though you're limiting the boost to what the std sensor can read, it sounds like your engine is now breathing much better than when it left the factory. You'll need to make sure that it's injecting enough fuel as you'll be consuming more air even though boost is the same.

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