Hi,

My indy has developed a miss when driving about. Static, it revs fine, but on the road it'll start missing, dies a bit then catches. Typically low revs it's OK, but give it some throttle and it's when it starts playing up.

I was hoping helpful soul could have a look over my MegaLog file and look for obvious problems. From what I can tell from comparing an older file when the car was OK, looks like there is a of of noise in the data, for instance the coolant temp (CLT) is varying by a good 8-10 deg. The TPSacc is probably the best visual indicator of the miss occurring.

MegaLog File

and my current tune file.

Just to clarify, the car has been running great and no changes have been made.

have you checked that there is no blockage in the fuel line or filter, this will cause the symptoms ask me how I know

Go on then, how?

Did wonder about the fuel supply. The pressure regulator on there is a ebay special, but it does have a dial. I took a video of the pressure and it's all over the place, but having never seen it in action can't tell if this behaviour is normal. Need 3 bar, which it kind of gives, but it's very variable.



You know you must be wasting too much time on this forum of you choose to watch the video

If the FPR is dodgy then all bets are off as to how much fuel is actually squirted into the engine compared to what the ECU wants to squirt in.

I had an intermittent misfire on Megajolt and it was a breaking wire in the mini plug to the VR sensor

loose earth somewhere ?

IŽd put my money on the Fuel Pressure Regulator.
Do you have access to one of those In Car Injector Cleaner contraptions? The ones with a pressurized can.
You can warm up the Engine with the Fuel Pump, connect the thingy, and run the test with it, if the engine runs right youŽve locateed the problem..
In the process you will have clean injectors.
HTH

watched the video! I agree FPR, or a leak in the system somewhere which is allowing the pressure/fuel to escape erratically. no leaks around your injectors? the rubbers are all good?

Test the fuel pump, after that its the FPR. Your MS has nothing to do with pressure.

If there is a blockage due to swarf from the tank the car will idle and rev without a problem however under load the blockage will cause an under fuelling we had this on a 2 litre zetec the problem with that one was compounded to a build up of poo and a swirl pot that was too small causing fuel starvation under heavy acceleration.

quote:

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Originally posted by Hodor
Go on then, how?

Did wonder about the fuel supply. The pressure regulator on there is a ebay special, but it does have a dial. I took a video of the pressure and it's all over the place, but having never seen it in action can't tell if this behaviour is normal. Need 3 bar, which it kind of gives, but it's very variable.



You know you must be wasting too much time on this forum of you choose to watch the video

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Thanks for the replies.

I cleaned out my washable glass filter and changed the fuel filter today - no better. I do have a lovely aroma of petrol now though - would have gone up like a roman candle if someone tossed their fag end my direction.

Question about the fuel pump -should it be as loud as this? It always was loud, from when I got it in April, but is that its death rattle or sounds normal?

Think next thing to do I guess is get a new fuel pressure regulator and try that.

Blipping the throttle now makes the miss happen, even at a stand-still (before it was only when I was driving about). Revving the car up slowly is OK, it's just when you need to get fuel NOW that it has trouble. Got to be fueling, right?

Either Pump or Regulator, you need to measure Fuel pressure.
Your pump sounds like dying, so IŽll change my recommended course of action, and suggest you change it, if it is working OK, with all that grinding it wont last long.
When you change the pump, take some time to check for debris on your fuel lines as that may kill a pump. (You donŽt want that to happen to your new pump)
If you find a little too much debris, maybe a tank cleaning wonŽt hurt either.
You say you cleaned your glass filter, I arseume it isss after the pump, and you donŽt say how badly fouled was it.
Some fuel systems have a filter before the pump to prevent damage to the pump in the event of corrosion or foreign matter on the tank. You may want to do this too.
Then, with new pump, verify Fuel pressure at the rail, with a good fuel manometer. Fuel testing/lceaning outfits will have a rasonably good manometer.
If pressure is OK then you already found your problem and avoided more hassle at a future date. Debris may clog a pressure regulator and cause malfunction.
If Pressure is erratic, and lines are clean, FPR would be the last suspect.
Damn.... Sorry for the mess, but I just wrote as I was thinking...
I hope all I wrote makes sense...
At least youŽll be occupied deciphering...

What pump is it? I remember reading(some time ago) on the Bosch web site that the 044 needs to be fed by another pump, otherwise they can be very noisy and fail prematurely!

Also if it's an 044, thats way overpowered. They are good for 600+bhp.

Hi,

Glass filter is just before the pump, fuel filter is after the pump. The glass filter had a fair amount of crap in it.

i'm leaning to the pump being the problem also, it's an erratic readout I'm getting on the FPR gauge - that is more likely a true output from the pump opposed to the diaphragm in the regulator going bonkers (unless it's split I guess). The fuel line directly out of the pump feels like there is a lot of turbulence going on - a lot of vibration in it.

Pump is a sierra part.

Will try and get my hands on a pressure gauge and measure independently.

Cheers.

With a faulty FPR, it will make the work the pump has to do vary, resulting in a very weird irregular noise and return flow. You could test the FPR with an air compressor to see it if regulates correctly.

Just to close this thread off, my problem is fixed. It was the fuel pump that did it, but I suspect that the pre fuel pump filter was starving the pump of fuel, causing it to overheat and ultimately fail.

I have changed out the whole fuel line from back to front in trying to debug this and eventually fitted a Bosch 044, re-positioning it lower down than it had been - put it in and the fuel pressure at the rail was much better, but could still hear it screech now and again and it was starting to get warm. Removed the pre filter and all good - quiet and cool.

Bought a large disposable diesel filter from ebay, stuck it before the pump and it is magic.

Very nice to get the car back on the road, only saving grace about the summer being pants is that I've not missed out too much.

And petrol stings when you get it in your eyes.

glad to hear you got it sorted

Thanks.

In the course of all this, I paid for the full version of Tunerstudio and I've been messing about with the auto-tune function which seems to be pretty good - it constantly adapts your map to achieve the target AFR ratio. Given enough runs to fine tune the fueling, I wonder how it would stack up against a rolling road session with a tuner? Anybody had experience?

I tried to do this to get my car pretty good before getting up to Baily Performance for a proper map.

I think I got a fairly good map that let me drive off pretty steadily, get to cruising motorway speed. I had one band of drivable area/map.

you would then need to try and level the map out manually as any putting your foot down and if the base map is wrong, ie in my case it was far to rich (scudderfish kindly gave me his RV8 4.6l map as a start for my 3.5) it just bogged down. I was getting extremes on the map.

I think Phil at extra efi says you could maybe use it to fine tune a pretty good map.

I think I would agree with this statement.

However, unless you have an empty road to keep tuning on, I personally don't reckon it will ever be any where near as good as a RR session will get.

However, I am sure there are many who have got their cars pretty good by tuning manually on the road, with a mate at the controls of TS and if you are always tweaking your setup I think it could be very useful, as you wouldn't be going back to the RR every time,


ps I didn't try to tune it myself for very long or very hard either..

[Edited on 6/8/15 by Chris_Xtreme]

My experience with the autotune is "it's OK, if you know, understand and accept its limitations". You need to understand how and where your acceleration transient fueling starts and ends to ensure you set the autotune to not tune "through" the transient. You need long roads and hills to tune higher cells, and you need a car-buddy with an idea about tuning to keep an eye out while you're driving to hit certain cells, or you just end up covering the common cells. That said, with some good intuition and experience you can set a fairly decent map with it and some interpolation. I have to admit though, I must have sunk 150 quids worth of fuel into the process and still not been 100% happy (I'm a bit of a perfectionist) and at the end of the day, with some spare cash these days I'd much rather hand it to someone who can sweep all critical cells in the maps on a RR. Happily use it to get a base map though, but in future I probably wouldn't use it for mapping my 20psi compound boosted 2 litre - a zetec maybe.

[Edited on 17/8/15 by coyoteboy]