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Sudden burst of power @2500rpm 

 

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Mon Oct 06, 2014 7:46 pm 
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Joined: 16th Oct 2012

Ride: 98 EL Falcon

Location: Brisbane
QLD, Australia

How would I be able to diagnose a leak from that area? The only thing over there is the brake booster and that seems to be leak free. :?

Quote:
It's really noticeable in second gear when keeping a constant throttle opening when it hits 2500 rpm you get this nice push in the back of acceleration.


^^ This is exactly it, I still have no idea why :P

 

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98 EL Falcon Gli - AU II intech - t5 manual - Lowered on king lows - 2.5" custom exhaust - 200cell hi flow cat - 17" Speedy cobalt's powder coated in steel pearl - powerwindows - suede door inserts (classy) - fog lights - (probably other things I can't remember)

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Mon Oct 06, 2014 11:45 pm 
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Ride: Falcon XR6

Location: FTG
VIC, Australia

Toquin wrote:
How would I be able to diagnose a leak from that area? The only thing over there is the brake booster and that seems to be leak free. :?

Quote:
It's really noticeable in second gear when keeping a constant throttle opening when it hits 2500 rpm you get this nice push in the back of acceleration.


^^ This is exactly it, I still have no idea why :P


I would suspect your brake booster is not as fine as you think.
Boosters can leak vacuum through the actuator shaft that goes through the firewall and connects to your brake pedal.
I had to replace my booster due to an air leak from there many moons ago.

Ah you still have the power surge then.
I have no idea what is causing it ... but I like the effect ... LOL

Perhaps the only way of telling is to have the car on a dyno and recreate the effect with a heap of sensors connected to "see" what is going on.
Then maybe the reason can be determined ... does the AF ratio change at 2500rpm or does the EECV advance the ignition ... etc etc ...

 

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95 EF XR6 Manual
Pioneer, Oz Audio, Butler, Image Dynamics, Audison
MEASQ - Aust Champion Intermediate Class 2006
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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Tue Oct 07, 2014 7:23 am 
Getting Side Ways
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Joined: 1st Apr 2005

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Ride: EF XR6 Wagon, AU2 XR6 VCT

Power: 148 rwkw

Location: Auckland
New Zealand

Like Sierra says, it's likely that you have a brake booster leak. The E-series and AU1 were notorious for it. I had it happen a couple weeks ago to my EF. Exhaust heat melts the rubber diaphragm in the brake booster. The atmospheric side of the booster vents under the dash around the actuator shaft, so you won't find a leak in the engine bay. When the leak gets bad enough, your power assist will take a second to kick in when you hit the brakes - not fun. So, don't wait. It's reasonably quick and easy replacement.

As an aside, a brake booster leak has the effect of making the engine run rich(er) at anything less than full throttle. I had tuned my J3 chip about six months ago, and couldn't figure out why it was running about .5 AFR richer than I had set it. Replaced the booster, and the AFR is back to normal.

As for the surge at 2500RPM, the MAP-sensed engines like the Falcon 6 are easily unsettled by any changes to air flow. Perhaps the improved air flow from the new exhaust is interacting with the factory tune to create a "sweet spot". The volumetric efficiency and flame speed of the EF-AU engines are not linear: the ignition timing has to be reduced a lot at about 2500-3000 RPM and moderate throttle (18-27 inHGa) to achieve maximum torque. The factory EF tune pulls out 5-10 degrees of advance in this range, so maybe that suits you new airflow very well and creates a burst of torque. If you like that extra torque, get a TI Performance J3 chip and you can have that everywhere in the range :twisted: .

 

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95 EF XR6 wagon, 17" FTRs, DBA, QFM, KYB/Koni, AU block, ported EF head, SS Inductions, Territory intake, MLS gasket, milled, Franklin RH24B cam, Coby headers, no cat, Tickford 2.5", 2800rpm stall, J3 chip

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Tue Oct 07, 2014 12:42 pm 
Stock as a Rock
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Age: 23

Posts: 100

Joined: 16th Oct 2012

Ride: 98 EL Falcon

Location: Brisbane
QLD, Australia

I appreciate the info :)

With regards to the brake booster, if I were to say blow into the booster hose coming from the vacuum tree on the inlet manifold. Should air come out anywhere, or does it have a valve that stops air from entering the booster? I imagine if I were to blow into the booster, I would then be able to pinpoint the leak a little further.

Out of curiosity, how do your brakes feel? Becuase mine aren't necessarily strong. What I mean is my partners little hyundai feels like it has stronger brakes, so does her mothers rav 4 and my fathers verada and so on. Mine feel pretty underwhelming. They work, they just don't feel "brakey".

On the topic of the j3, when I can afford a new cam the plan is to get a j3 from T.I performance. A wade 1502AU should do nicely :)
Then it can be a little lumpy and powerful :D :twisted:

 

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98 EL Falcon Gli - AU II intech - t5 manual - Lowered on king lows - 2.5" custom exhaust - 200cell hi flow cat - 17" Speedy cobalt's powder coated in steel pearl - powerwindows - suede door inserts (classy) - fog lights - (probably other things I can't remember)

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Tue Oct 07, 2014 3:22 pm 
Getting Side Ways
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Joined: 1st Apr 2005

Gallery: 4 images

Ride: EF XR6 Wagon, AU2 XR6 VCT

Power: 148 rwkw

Location: Auckland
New Zealand

The booster is designed to act as a vacuum reservoir, so you will still have brakes if the engine stalls. It does this by using a check valve (white colour, from memory) where the vacuum hose connects to the booster. This allows the manifold vacuum to suck air out, but stops air coming back in. You can test the booster by idling the engine, switching it off, then pulling the check valve out of the booster 10-20 seconds later. There should still be vacuum in the booster. If it doesn't suck air in when you pull the check valve out, you have a leak (or your check valve has failed). You can test the check valve by blowing through it; air should go only one way.

In my view, the EF's single-piston calipers and modest rotors are barely adequate for a 1500-1600kg car. I also have an AU2 XR6 with factory twin-piston calipers, so I can make a direct comparison. Both cars use QFM HPX pads, but the AU2's braking is so much better. The EF's brakes have more pedal travel, less initial bite, feel "mushier" and require more pedal effort for the same braking. I have upgraded the EF's brakes with Safebrake braided stainless lines, DBA slotted and cross-drilled rotors, new master cylinder, Motul RB600 brake fluid, and the excellent HPX pads; but it's still not as good as the factory AU2 setup with the same compound HPX pads. The EF's absolute stopping distance is probably not much longer, but it is much less confidence-inspiring and harder work. I have experienced more responsive braking in run-of-the-mill Japanese hatches. Obviously, better tyres will give better braking. One other point if you want better braking: better shocks (eg, gas shocks) reduce stopping distances significantly - you don't lose as much braking energy in body motion.

The TI Performance J3 chip is the best money I ever spent on my car. And you will absolutely need one if you go for a lumpy cam. But be careful going too lumpy - you will gain top-end power (say, above 4000 rpm) at the cost of losing bottom end (say, below 3000 rpm). A hot cam is not a magic bullet, but can be a disappointing trade-off; though you might be OK with a manual transmission. Unless you spend most of your time racing, you won't get the full benefit of the top-end power of the cam. Check KWIKXR's build thread: he went for a big cam, but replaced it with a tamer one later. He got better performance with the cooler cam - even at the dragstip; but his is an automatic. If in doubt, go with the tamer choice.

 

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95 EF XR6 wagon, 17" FTRs, DBA, QFM, KYB/Koni, AU block, ported EF head, SS Inductions, Territory intake, MLS gasket, milled, Franklin RH24B cam, Coby headers, no cat, Tickford 2.5", 2800rpm stall, J3 chip

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Tue Oct 07, 2014 6:39 pm 
Stock as a Rock
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Age: 23

Posts: 100

Joined: 16th Oct 2012

Ride: 98 EL Falcon

Location: Brisbane
QLD, Australia

I definitely have good tyres, and good gas shocks, so I should be fine on that front. As well as adb drilled and slotted rotors:)
The 1502AU is apparently the equivalent of an 1636 cam for an el, so it is still pretty mild. My engine doesn't really seem like it likes revving very much. I usually shift at 2~2.5k. I guess it is just old, but I have never driven another el, so I don't know if that is how they're meant to be :(
Did you get your j3 tuned on a dyno, or just get a pre-done tune?

This check valve, does it come out of the booster, or do you just pull the vacuum line off it whilst it stays in the booster? I thought I would brake the valve if I removed it from the booster. :/

How do you find the qfm hpx pads? Also, where did you get them from if you don't mind me asking? I'm actually chasing a set right now :P I'm tempted to just go to them. Apparently they are in QLD somewhere :)

 

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98 EL Falcon Gli - AU II intech - t5 manual - Lowered on king lows - 2.5" custom exhaust - 200cell hi flow cat - 17" Speedy cobalt's powder coated in steel pearl - powerwindows - suede door inserts (classy) - fog lights - (probably other things I can't remember)

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Wed Oct 08, 2014 1:12 pm 
Getting Side Ways
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Posts: 836

Joined: 1st Apr 2005

Gallery: 4 images

Ride: EF XR6 Wagon, AU2 XR6 VCT

Power: 148 rwkw

Location: Auckland
New Zealand

My cam is a mild Franklin RH24B regrind - basically one step hotter than an XR6 cam. With decent engine breathing in and out, I'm doing the 1-2 shift at 5800-5900rpm at the drags. It has run out of puff at that point. Also, with 317,000kms on the engine, anything above that would be seriously tempting fate.

I got a custom pre-programmed chip from TI Perf, which was a big improvement. I supplied a dynoplot with AFR on it, along with a list of my mods, and Jason created a good tune from that. Then I got the bug, bought the full-house tuning pack, and have been tuning it myself since on the "road dyno" :D . There is a lot of performance untapped in the stock tune - even the XR6 one.

The QFM HPX are the best I have used; not to say there aren't better ones out there. They outperformed the EBC Redstuff and Greenstuff I had previously: shorter stopping and better initial bite. They last a long time, produce less dust than most, and are reasonably gentle on rotors. I don't do circuit racing, so I can't comment on their fade resistance, but they have always worked very on the road. I buy them from GSL Rallysport (www.gslrallysport.com).

 

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95 EF XR6 wagon, 17" FTRs, DBA, QFM, KYB/Koni, AU block, ported EF head, SS Inductions, Territory intake, MLS gasket, milled, Franklin RH24B cam, Coby headers, no cat, Tickford 2.5", 2800rpm stall, J3 chip

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Thu Oct 09, 2014 6:30 am 
Getting Side Ways
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Posts: 836

Joined: 1st Apr 2005

Gallery: 4 images

Ride: EF XR6 Wagon, AU2 XR6 VCT

Power: 148 rwkw

Location: Auckland
New Zealand

The check valve can take a bit of effort to remove, but it's just held in by friction against its rubber grommet (and by vacuum, hopefully). I found that mine came out easier by pulling at a slight angle toward the driver's side of the car, rather than straight out. I'm sure there is a better method, but that's what worked for me.

 

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95 EF XR6 wagon, 17" FTRs, DBA, QFM, KYB/Koni, AU block, ported EF head, SS Inductions, Territory intake, MLS gasket, milled, Franklin RH24B cam, Coby headers, no cat, Tickford 2.5", 2800rpm stall, J3 chip

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Fri Oct 10, 2014 12:28 am 
Stock as a Rock
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Age: 23

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Joined: 16th Oct 2012

Ride: 98 EL Falcon

Location: Brisbane
QLD, Australia

Unfortunately I won't have the chance to do any real car work until at least sunday, so I'll have to try the brake booster then. But, I do have a query for you. This sound I was hearing while driving, the "sucking air sound". After a more careful listen, it definitely sounds like it is coming from in between my legs as I'm driving. Basically right where the booster plunger comes through the firewall. Obviously this is only a guess as to where the sound is coming from as there is no way I can get my head down there while I'm driving. Anyway, this sound is only apparent under acceleration. It is a moderately soft sound that can be heard by the passenger when the radio is off, and it is definitely a distinct air sucking sound from down there. Does this suggest anything to you? I'm no expert, but it sounds to me as if that is the opposite of a vacuum leak? :/

On the topic of J3's though. I'm possibly persuading my partner into getting me one for my birthday (she lets me play with cars - winning!). But, this would mean putting the car on the dyno to get an afr readout. Now, I don't have a lot of confidence in my motor, I feel as if I may be picking its guts up off a workshop floor if I don't get its issues sorted out. I know it is running pretty rich, but how rich I'm not sure.
Everyone I know says the car smells fairly rich, but I'm not sure if it is overfuelling due to the AU injectors or some vacuum issues. Or if it is just my hi flow cat being half the cell count of the stock item. $20 of shell v-power is around 12L of fuel and that gets me around a max of 120km on average sometimes less. 10L/100km doesn't seem that bad for a falcon, but it hurts a bit when you have been driving your partners lantra for the last 6 weeks and it is doing 5L/100km.

What did you do to prep your car for its dyno run? Any things to check over?

So I'm confused, it smells rich, blows greyish smoke in the mornings until it is properly warm, uses a lot of fuel, but yet seems rather economical according to the numbers, seems under powered, yet pulls along happily in 5th@55km/h, but has no go when you put your foot down. oh, and it idles like it has a vacuum leak that I can't find.. :evil:
Possibly worth noting that when I compression checked the cylinders earlier this year, the numbers seemed okay. They were on the lower end at around 120~145 psi from memory - I should do it again..If I could find where I put the damn kit :/

 

_________________

98 EL Falcon Gli - AU II intech - t5 manual - Lowered on king lows - 2.5" custom exhaust - 200cell hi flow cat - 17" Speedy cobalt's powder coated in steel pearl - powerwindows - suede door inserts (classy) - fog lights - (probably other things I can't remember)

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Fri Oct 10, 2014 1:01 pm 
Getting Side Ways
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Posts: 836

Joined: 1st Apr 2005

Gallery: 4 images

Ride: EF XR6 Wagon, AU2 XR6 VCT

Power: 148 rwkw

Location: Auckland
New Zealand

Yes, you would expect a louder sucking sound at idle and cruise, when vacuum is high, and less under acceleration when vacuum is low. I can't say I noticed much sound when my booster failed, but it was definitely pulling in air from around the brake actuator shaft.

You definitely want your basic maintenance issues sorted before getting a J3, or you're just going to be trying to tune around the problems. Make sure:
- that you're showing no fault codes (ie, at least all your sensors are working properly),
- that your breathing is unrestricted (good air filter and cat),
- your injectors are clean-ish (run a bottle of injector cleaner through your fuel first),
- your ignition is good,
- and that you have done any mods you are planning for the near future.
MAP-sensed engines like the Falcon 6 are sensitive to any changes in air flow, so any mods that affect air flow will throw the tune out: cam, exhaust, CAI, porting, etc. So, do the other mods first, then the J3, or expect to have to retune the J3.

Falcons do tend to be tuned rich from the factory, and this doesn't improve with age. A vacuum leak can make it worse - my brake booster leak made it run richer by .5 AFR at anything below full throttle. AU injectors should not have made much difference to your AFR. Running over-rich is not dangerous unless it is WAY over-rich - ie, pushing black smoke all the time. Slightly over-rich is actually safer - it cools the combustion, so detonation is less likely. But it does give away a tiny amount of power.

As for dyno prep: lubrication and cooling have to be right. Oil and filter should be fairly fresh, oil level at max on the dipstick. If you are doing an oil change, spend a bit more and get decent oil, preferably synthetic or semi-synthetic: Nulon, Royal Purple, Redline, Amsoil, Valvoline Durablend, etc. Make sure your cooling system is working well - no issues with temps climbing - coolant level at max, and coolant concentration adequate (never straight water). Tyre pressures checked OK (I go 34-36 psi). With the car strapped on the dyno, immediately before the run, disconnect the ECU for one minute to clear the fuel trims, so they don't affect your AFR readings. Have the tank at least half full of fuel, and of the grade (eg V-Power) that you expect to use normally.

10L/km for a Falcon I think would be typical on the highway, but excellent around town. So, you are probably running no richer than a normal Falcon.

When you order your J3 chip, let TI Performance know your mods, and they will tailor a tune to suit. They adjust the fueling based on your dyno AFR results. They also adjust the ignition advance - this is where the biggest gains are made. Let them know the fuel you will be using, and they will optimise the advance to make the most of the available octane. If you are using 98 octane, you will find quite a boost in performance from the extra advance.

My EF also runs rich on cold start. Part of this is what it's supposed to do, like the choke on the old carbureted cars. This can be adjusted if you have the tuning pack, but it takes ages, as you can do it for only a few minutes a couple times a day - until it warms up.

As long as your compression is pretty consistent across the cylinders, and the engine's not burning oil or smoking blue on deceleration, the actual number is probably not too important. To get more compression is at least a head off job, or even a full rebuild if your rings are gone.

 

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95 EF XR6 wagon, 17" FTRs, DBA, QFM, KYB/Koni, AU block, ported EF head, SS Inductions, Territory intake, MLS gasket, milled, Franklin RH24B cam, Coby headers, no cat, Tickford 2.5", 2800rpm stall, J3 chip

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 Post subject: Re: Sudden burst of power @2500rpm
Posted: Fri Oct 10, 2014 6:27 pm 
Stock as a Rock
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Age: 23

Posts: 100

Joined: 16th Oct 2012

Ride: 98 EL Falcon

Location: Brisbane
QLD, Australia

So it would definitely seem to you that there is at least a small issue with my brake booster? I can polish the exhaust tips in the morning and come home from tafe in the afternoon and have them covered in carbon deposits thick enough to hide the stainless below. I don't think it should be that extreme for 40km of driving?

Coming from shell hx-7 high mileage, I now use penrite everyday plus 15-40 semi syn engine oil and nulon green concentrate coolant. The cat is only around 9 months old so I think it is still okay. The only error codes I get are for a powersteering fault even though it works and the switch is new (the error says the switch is opening or something like that) and an ISC fault (obvious because it is blocked off so it can't do anything).

I have never seen black smoke come out of the car, or blue smoke - just grey. It does use a small amount of oil, however it doesn't blow smoke or leak. So I don't know where it is going. It doesn't use any coolant whatsoever so I know the head gasket is fine on that side of the engine and there is never any water in the oil when I change it.

When I have a job again and can afford too, it will be getting a proper service instead of an oil change. So I'll be doing things like trans fluid, diff oil, p/s fluid and pump (I have a reco'd one I pulled from a wreck. Metal pulley and all :D ), spark plugs and all that jazz, as well as a K & N panel filter (heard good things about these - your opinion?).

So with all that said, do you think there is anything else that would need going over? Apart from sensors? I have three used MAP sensors to play with as well as four used oxy sensors too, and the IAT was replaced a couple of months ago as well as the intake manifold gasket.

I do want to do a cam, but I'm nervous I'll have valves meeting pistons, despite the fact I just successfully last weekend did a timing kit and had no dramas then :P

 

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98 EL Falcon Gli - AU II intech - t5 manual - Lowered on king lows - 2.5" custom exhaust - 200cell hi flow cat - 17" Speedy cobalt's powder coated in steel pearl - powerwindows - suede door inserts (classy) - fog lights - (probably other things I can't remember)

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