Acceleration Problem on Transit 2005 2.3 RWD / LPG

[davebaldwin]

Hi,

Been having trouble for 3 or 4 weeks now with accelerating from idle. When pedal is pressed, a very deep. throaty sound can be heard and it will sometimes backfire in the inlet manifold until the speed picks up a bit. It's drivable, but you have to be very gentle, otherwise it's rough. I've tried everything I can think of and am running out of ideas.

So far, I've stripped off the inlet manifold etc. to get to the EGR which turned out to be fine, check all vacuum hoses, found that one of the components of the MAF sensor had become detached from the wire so replaced that, replaced the MAP sensor and thoroughly tested the TPS which is getting 5v and giving a smooth range from 0 to 5v when rotated.

I've learnt a lot about sensors because of this, but i'm now stumped. The problem exists when running on both petrol and LPG, and it's a bit worse in that it will backfire more on LPG. Oh, and at no time has there been any engine warning light on (no it's not the bulb!).

Any ideas?

Cheers,

Dave

[rikki19]

I had similar symtoms with my 2.3 L petrol only . Turned out it was the front O2 sensor which eventually got so bad it would backfire and not accelerate at all . Did you change the DPFE sensor when you had the EGR valve out ? . I did get codes however , from memory I think they were p0401 for the DPFE and p0135 for the oxygen sensor ( bank 1 sensor 1 )

[Covrender]

Didn't want to start another post sorry to hi jack I have the same problem with my fwd 7 transit when I try to put my foot down it makes a racket until a certain speed is reached unless I graduly acelarate the turbo sounds so loud could the turbo be spooling it's defo from the engine or turbo was thinking of running 2stroke oil but I had the same problem with my mk6 but never knew why unless All transit are like that

[davebaldwin]

Thanks rikki19, I'd never heard of a DPFE sensor until now. That sounds like a probable cause, I'll try disabling the EGR and see what happens and let you know. I take it that it's the thing attached to the 2 small metal pipes coming off the feed pipe to the EGR?

[rikki19]

Yes that's the one

$T2eC16hHJGoE9nuQhobbBRKuRFVtpQ~~60_32.jpg

The original is slightly smaller . It doesn't fasten to anything , it just sits on top of two short lengths of heat/oil resitant silicone tube about 3 inches long . You can reach it from the top if you remove the rocker cover as it's quite far down and a bit of a squeeze . I replaced the tubing at the same time and cut longer lengths so it sits a bit higher . If it goes again I can get to it without removing anything.
http://www.amazon.com/gp/product/B000QU ... PDKIKX0DER
I drove my van for months before I replaced it ..... no ill affects really , maybe ran a bit richer .
I would definitely check your o2 sensor though , a bad one will cause backfiring and screw the performance but I'm surprised you haven't got any engine light

[davebaldwin]

Well, disconnected the EGR, plugged up the vac tube and its running much better now, so it looks like it is the DPFE, thanks a lot for the advice. Any idea where to get a new DPFE sensor in UK? Tried the usual places like amazon and ebay, nobody seems to be selling them.

[rikki19]

Not sure , sorry , I normally get parts from US or UK as not readily available over here . I think the Ford part no. is YF1E-9J460-AD

[davebaldwin]

Update... I've had the egr disconnected for a week now and slowly, the backfire problem has come back, which has lead me to believe it is the oxygen sensor. Correct me if i'm wrong, but I figured with egr disconnected, the mixture would be instantly richer, if O2 sensor not working, computer will gradually make mixture more lean causing the backfire.

[rikki19]

What Are Symptoms of a Bad Oxygen Sensor

An oxygen sensor gone bad impacts your car's engine performance. A bad oxygen sensor can negatively impact an engine's performance in a variety of ways. Because of the important role an oxygen sensor plays in the maintenance of proper air and fuel levels in a running engine, any abnormal or faulty oxygen sensor function can create several abnormal engine symptoms.

Poor Gas Mileage
Oxygen sensors play a huge role in adjusting a vehicle engine's air/fuel ratio, the combination of gas and air an engine burns to produce power. A faulty oxygen sensor may allow too much fuel to be added to the air/fuel ratio, resulting in poor gas mileage.

Increased Vehicle Emissions
Oxygen sensors monitor and adjust an engine's air/fuel mixture to ensure proper engine combustion, vehicle emissions and performance. A bad oxygen sensor can result in poor air/fuel mixtures or lean or rich fuel-injection delivery, all of which can cause improper or inefficient engine combustion and increased vehicle emissions.

Rough Engine Idle
Proper engine combustion is crucial for maximizing engine performance. A bad oxygen sensor can cause a car's engine to idle in a choppy, rough manner. This is caused by the less-than-optimum engine combustion firings that result in poor engine performance.

Engine Missing
If a bad oxygen sensor causes an engine's air/fuel mixture to become too lean or restricted, the explosions within an engine's cylinders (engine combustion) will be altered. Normally, an air/fuel mixture that is too lean (too much air, not enough fuel) will cause an engine to miss, or misfire, especially when an engine is idling.

Engine Hesitation
Engine hesitation is similar to engine missing. However, engine hesitation is experienced only during acceleration, while an engine miss can be experienced both during engine acceleration and idle. A bad oxygen sensor may misread or misinterpret an engine's air/fuel mixture or air/fuel requirements and cause too little or too much air and/or fuel to enter an engine's cylinders, especially during acceleration. This can cause an engine to hesitate, or stumble

More than likely the Check Engine Light will come on.

Found this on a US site

[davebaldwin]

Fitted a new oxygen sensor which made no difference, so back to the DPFE... On the plus side, I managed to remove it very easily with removing any other parts. I just reached around the back of the head from the right, felt around for the 2 rubber hoses and eased them upwards. Once off, there's enough cable to move it into view where it can be disconnected. Putting it back was fairly easy too, although I couldn't quite exert enough down force to push it back on properly. Got round this by crawling under the van and reaching up from just behind the near side wheel (DPFE is easily visible from here), putting a couple of fingers on top of the valve and pulling down. Took no longer than 5 minutes.

[davebaldwin]

That should have been 'without removing any other parts.'

[rikki19]

Glad you managed to remove it so easily , your arms must be 6" longer than mine ... lol , or maybe the location was modified from the earlier mk 6's . Apparently the manual starts off with " remove intake manifold " and removing the pipe that runs around the back from the exhaust . Did you get the part no. from the DPFE ?

[rogerw]

Have you tried this from Frag? Its easy and free.

Should tickover around the 850 (+/- 50 rpm) mark i'd think.....

Something you've done has made a difference,so now i'd be tempted to try and re-learn the values in PCM.

Ideally you would reset these with diag tool,but same can be done by pulling the memory feed fuse for engine management.
(Should be a 3A fuse,looks to be fuse no.40 in Aux fusebox,underbonnet i assume)

When you have half an hr 'spare'....
Pull fuse for say 5 mins,or failing that disconnect battery,
Then refit / re-connect.
Start it up from flat cold and let it idle untouched for 2 mins,
Then hold revs at 2000 rpm for 2 mins,
Then go on at least a 5 miles roadtest with varying speeds and loads,hitting full throttle at least once.

This should set a base map for running parameters,it will then start to learn every 'drive cycle'
This is classed as from cold to above 70 degrees coolant temp (just above white on temp guage).

See if it improves the running

[davebaldwin]

Rikki, I got the number off it. It's part number is 2F1E-9J460-AB, could not find anyone in UK that sells them so ordered one from US. If there's nothing wrong with that either, at least I've got spares.

Thanks Roger, I'll try that.

[davebaldwin]

Glad you managed to remove it so easily , your arms must be 6" longer than mine ... lol , or maybe the location was modified from the earlier mk 6's . Apparently the manual starts off with " remove intake manifold " and removing the pipe that runs around the back from the exhaust . Did you get the part no. from the DPFE ?

Guess my arms must be longer. It did hurt a bit, lol, but I think it's pretty much where it should be; roughly in the middle of the back of the head a couple of inches down from the top, tubes were about 4-5cm and 7-8cm long.