R400 Duratec - Lacking top speed.

[Tomiam]

Hi folks, 
Just wondering if anyone else has experience of this and would care to share some pointers to help me.
I have an R400 Duratec, 2008, with roller barrel throttle bodies.  220 bhp.
Car will fly up to 95 / 100 mph but from then on it's slow to accelerate.  Very slow, maybe 1mph per second.  I do a fair amount of sprints and track days and rarely get past 110 mph.
On Bentley straight at Snetteron Im getting 112 max.   Looking at others videos (R300 / R400) they are getting 120+ with ease.  Corner exit & speed onto Bentley is fine.

BIts of info.
Diff is a 3.62 (60mph = 3400 rpm or very close)
6 speed box
Speedo is verified vs GPS
Checking my videos back Im changing gear at about 7500 rpm

Possible clues.
I've checked the plugs are a couple look like they are running lean.

I've asked about on FB as well, to try and get a wider range of experience.
Fuel pump likely to be struggling?

Any help greatly appreciated :)

 

[SM25T]

Friend had a car that was missing top speed. After we removed the air filter we found the butterfly was not opening fully. It was an ex hire car that had the throttle opening restricted. Might be worth checking that your throttle does open whatever is fitted fully !

[7 wonders of the world]

Check for full throttle as mentioned above,

If your running a cat check this isn't toasted !

[Paul Deslandes]

Check your air filter, especially if yours is buried in the elephant's trunk inlet pipe to an air box.  They can pick up all manner or muck from the road, and clog up, strangling the engine.

[Tomiam]

Thanks for the tips.

Just checked, with aid of 2nd person, and the roller barrels are opening 100% on all 4 inlets.

Air filter looks pretty good tbh although I suspect its the original one from 2008. Its the pipercross foam filter which covers all inlets.

Spark plugs look a little lean if anything. Rather than not enough air.

I dont have a cat on it. Took it off a while ago.

[John Vine]

If the air filter is original, has it ever been cleaned?

Has the car ever been remapped or on a rolling road?

What plugs do you use?

Do you run an aero?

JV

[Tomiam]

Hi John,

Air filter has just been taken out and cleaned. Literally... just as in 1 min ago. Water didnt look that dirty to be fair.

Car was on a rolling road for previous owner. I have dyno print outs from when roller barrel throttle bodies were installed. 193bhp at wheels. Never had it on one myself.

Dont know if its been remapped. Ecu is MBE 38L036A. Can they be remapped? I thought the MBE were locked, unless im wrong.

Plugs. Bosch HR7KPP33 double platinum.

Aero. Yes. Whenever im sprinting or on track its always aero'd. It feels fast at anything sub 80mph. Soon as i get to 100 though its only gaining spped at about 1mph per second or less.

Trying to think of anything else i can say which ive not in opening post that would help.

 

EDIT: reformatted post on my pc as formatting was bad from mobile.

[Tomiam]

..

[Paul Deslandes]

Variation in plug condition would suggest injector flow rate imbalance .  Have them cleaned and flow tested on an ASNU tester.  SBD has one.

Check TPS voltage at idle.  You can see what's going on with Easimap although you can't view or edit the maps but may get some clues by hooking up to a laptop.  Check that ECU is seeing all load sites over the TPS range.

Check fuel pressure at full load/high revs to see if pump is keeping up and/or fuel regulator failing at high demand due to not fully closing.

One or two tuning outfits, e.g. Track n' Road (the two Steves) can remap original CC sourced ECUs and it's well known that the factory map is less than optimised.

After cleaning the filter (not sure that washing with water is going to do the job) it should be re-oiled with correct ITG or other filter oil to help dust to stick.

If all else fails you could get the cam timing checked but leave that and anything equally drastic until you've exhausted everything else!!

Paul

[Tomiam]

Cheers Paul.

Tps is at 4.64v , as close to 4.62v as i could get.

Load sites go from 0.0 to 15.0

 

How do you check fuel pressure under load? Can easimap do this?

[Tomiam]

Oh and air filter was washed in hot soapy water. Will be re-oiled with K&N oil once dry.

[Paul Deslandes]

To measure fuel pressure you need a fuel pressure gauge inserted into the fuel line.  If your car is a factory Duratec you probably have the integrated fuel pump/regulator unit in the tank, rather than a separate regulator somewhere up front near the throttle bodies.  If that's the case there will be just the fuel feed line going to the fuel rail so you'll need a T piece to tap into the fuel line and to connect the pressure gauge on the end of a hose into the cockpit if you're going to test it on the road, rather than on a rolling road.  Not my preferred setup!!

Another way of doing it would be to fit a wideband lambda sensor into the exhaust and log the lambda at maximum load.  Significant increase in lambda/decrease in fuel-air ratio would point towards lack of fuel getting through the injectors.  An Innovate LC1 can do this for you and you can use a laptop to monitor lambda in real time.

Whereabouts are you in the country?

Paul

[ChrisC]

I would say easymap could help you with this, but indirectly.    I would log the injection pulse and lambda, and see if its getting to 100% duty cycle, before full throttle / max speed.    If it is then maybe fuel pressure is not enough to keep up with demand. 

I once used this to detect a fuel supply problem on a mates car,   It would die for no reason.  Eventually we logged it dying, and you could see it getting leaner and leaner (from the lambda value) but you could also see the fuel pulse getting longer and longer as the ECU tried to solve the lean problem.   This indicated a fuel supply problem, all be it intermittent and at idle.   Thankfully it was a simple inertia switch that fixed that one, but the ECU logging pointed us to the fuel system. 

Good luck. 

[Tomiam]

Thank you very much. Thats information i can definately understand.

I'll plug the laptop in and log it. I know a stretch of private road.

 

Im located just outside Bristol. Bit of a drive to the two steves but im not opposed to it.

[ScottR400D]

Just for info, I had my RBTBs fitted by Luke Stevens and it was mapped there by one of the two Steves. 

With an aero, two up, at Snet it will indicate well over 120 on Bentley Straight. 

If you go to Snet often, perhaps book it in with Luke and Steve for a remap beforehand. 

[Tomiam]

Thanks for that Scott. Gives me a bit of reassurance im not imagining it. :)

[Tomiam]

In case anyone else needs this info in the future.

 

run a logging session tonight.  friend and laptop in passenger seat with laptop plugged in with easimap 6 running.

lambda fluctuating up / down around 1.0 mark.  at full throttle lambda was ignored, engine ran rich at this point.

throttle sites moving smoothly from 0.0 at idle to 15.1 full throttle.  consistently smooth readings.

tps from 4.64v at idle to 0.8v at full throttle.   again, consistently smooth readings

duty cycle never higher than 50% even at throttle site 15 (full throttle)  (not sure this is too low?)

spoken to two steves at track n road.  getting it booked in for a session with them,

 

other than the duty cycle, which only appears low to me but i dont know if this is normal (green injectors), im struggling to see anything immediately wrong.

[Paul Deslandes]

Unless they are high delivery injectors or they're running at very high pressure, 50% does seem somewhat low at full chat.  You'd expect them to be at closer to 85%.  The ecu can struggle to control fuelling with very low duty cycles at idle if the injectors want to flow too much fuel. 

Unfortunately the standard narrow band lambda is really only intended to monitor and correct lambda at idle or thereabouts.  A wideband would have shown whether the fuelling was running lean at 50% duty. Steve will put in a wideband so he'll really be able to see what's going on.  Please keep us posted when you get to the bottom of it.

Good luck

Paul

[Tomiam]

Yep.  I will definately keep you posted :)

[Ian Mackenzie]

Hi there

The normal recommendation for maximum duty cycle is normally around 80%, max at 85%. If the duty cycle was at 100% this would mean the injector would be open 100% of the time.

cheers Ian

[Tomiam]

As promised, latest update is that its going up to two steves at track n road for mapping.

Likely to be about a month before I update this thread again unless i find something new.

[Tomiam]

As promised... here is the update.

Took the R400D to the two steves at TracknRoad tk have it remapped.

Prior to arrival I fitted a new set of BR7 spark plugs gapped at 0.9mm (I found a post on here saying Steve G recommended them. Also found one from Aerobod with loads of good info).

 

After remapping its like Ive got a different car.

Massive increase in throttle response. Like.. night & dsy levels of difference. Loads more urgency and pull from the engine when you squeeze the throttle.

On RR it hit 140mph so I know the gearing is capable.

Ive not been able to test top speed on circuit yet but I have absolutely zero doubts its going to be much higher than before given the new sense of power.

 

All credit to the two Steves. They know their stuff and as far as Im concerned... money well spent.

 

[L777JDP]

Just in case this is something you've overlooked... have you changed the fuel filter? Not necessarily the most obvious cause, but very cheap to eliminate as a cause.
 

[L777JDP]

Scratch that. Didn't read the last post.

[R400CAT]

Where is the fuel filter located on the R400 Dura?  Is it in the tank?

 

Good result on the remap.  I am thinking of going down the same route.  My R400 same set up as your car has been having issue since I got it.  Its pulling really well, and defo does not run out of puff, but its the low speed running of mine that is frustrating, which will drive me eventually a trip down south.