Faulty Fuel Pressure Relay?

[Westy]

Hi all,

I'd like to inspect my FPR due to it possibly being the cause of my non-existent kickdown.

However, the FPR on my vehicle (a 1996 E230 W210) is integrated into a 'Relay Module' (K40) within the 'Combination Control Module', located at the passenger side bulkhead. See pics below.

My question is, can i just pull this part without causing any other issues?

Also, is it advisable to disconnect the battery before doing so?

Thanks in advance.

 

[BlackC55]

I very much doubt that the fuel pump relay is affecting your kickdown.

 

[Westy]

Hi BlackC55.

Not wanting to contradict or upset anyone in the forum, but Television advised that no kick-down is commonly caused by a faulty FPR.

Sorry, I'm a complete newb to MB's and am gratefully in all of your good hands!

HELP!

 

[BlackC55]

Describe the fault to me in more detail.

I may not be able to help right now but maybe able to tomorrow.

 

[Westy]

Essentially, there is no kick-down at all.

Manually downshifting to 3rd is the only way I can approximate kick-down.

I've also got an erratic idle, but that is probably something else alltogether - maybe?

Other than that the car runs fine, seems to change up and down the gears fine (but without KD)!?

 

[Alps]

Westy,

possible problems

- faulty MAS
- Kickdown switch (either faulty or comehow disconnected)

others may have other suggestions

 

[BenzComander]

Being logical, I would start with the kickdown switch as well.

 

[television]

Auto Data sent out a leaflet earlier this year on this subject and it said.

No kick down = fuel pump relay PCB track goes open circuit = MBs all

Of coarse this can be anything else.

 

[Westy]

Thanks Alps & Benzcomander.

Looking at the kickdown switch in the diagram below, it's located below the accelerator pedal. I guess this means that the switch only comes into play at full throttle. Surely this doesn't mean that you have to max the loud pedal in order to get KD?

Excuse my ignorance, but on the prvious two Auto vehicles I owned (both Mitsubishi Pajero's) KD would engage on sharp acceleration?

If that's not the case, what's the purpose of the switch and how could a fault within it affect KD lower down the acceleration range (if that makes sense)?

Other than disconnecting the MAS/MAF are there any tests that can be performed on it with a multimeter. If so what's the procedure and ranges?

Sorry for more questions!

 

[grober]

Looking at the kickdown switch in the diagram below, it's located below the accelerator pedal. I guess this means that the switch only comes into play at full throttle. Surely this doesn't mean that you have to max the loud pedal in order to get KD?
Excuse my ignorance, but on the prvious two Auto vehicles I owned (both Mitsubishi Pajero's) KD would engage on sharp acceleration.
If that's not the case, what's the purpose of the switch and how could a fault within it affect KD lower down the acceleration range (if that makes sense)?
Sorry for more questions!

The answer is yes to your question you have to physically operate the "kickdown" switch by applying full throttle which forceably causes the gear box to change down a gear/gears simmultaneously raising the engine revs to facilitate this. You must also remember that "on the way" to full throttle depressing the accelerator pedal will alter lots of ECU control inputs on the engine and gearbox --- the throttle position sensor will sense a new more open position---- the crankshaft sensor will indicate RPM----the engine temperature sensor will indicate if the engine is warmed up------ there will be a sensor supplying road speed------ the gearbox will indicate the present gear thats engaged------ etc etc THEN the gearbox ECU will be communicating with the engine ECU and together they will decide whether to change down a gear or gears---leading to what you describe on your Pajero's as "kickdown" more accurately described as "changedown" The "KICKDOWN" switch is really an emergency OVERRIDE to force a gear change despite all these other signals described above.

 

[Westy]

mee no speaky eenglish!

Woah, you dude!

That's a great explanation, thanks grober.

Just so my often absent brain has this chrystal: no pressy kickdown/changedown switch - no kickdown/changedown?

Cheers

 

[pammy]

Exactly. You only get kickdown if you floor your accelerator pedal and then press that bit further so you feel the kickdown switch give. I did wonder if this might be your problem actually but the techy guys thought a mechanical/leccy prob. It's not uncommon among new MB owners.

Try it without having the car switched on so you can feel the switch give. Then you can try it on the road I love my kickdown

 

[Westy]

Oops, there's one for the 'How do you feel now?' gallery!

Thanks Pammy, I guess I was thinking that all Auto boxes would work in the same manner. On the Mitsi you didn't have to floor it to get the box to change down - just blip the pedal.

My old beast was a 3.5 V6 DOHC 24V - The auto box 'PWR' mode was awesome. Use to wipe the smile of the Barry boys faces at lights !
Quite a feat for something as heavy and aerodynamic as a block of flats!

However, I am now a reformed driver and have joined the ranks of the more refined and elite MB owners. (I just need to find out how to work it,...........obviously! !

Thanks all and soz for leading you all up the proverbial garden path......my bad!

 

[Glenn Smith]

Oops, there's one for the 'How do you feel now?' gallery!

Thanks Pammy, I guess I was thinking that all Auto boxes would work in the same manner. On the Mitsi you didn't have to floor it to get the box to change down - just blip the pedal.

My old beast was a 3.5 V6 DOHC 24V - The auto box 'PWR' mode was awesome. Use to wipe the smile of the Barry boys faces at lights !
Quite a feat for something as heavy and aerodynamic as a block of flats!

However, I am now a reformed driver and have joined the ranks of the more refined and elite MB owners. (I just need to find out how to work it,...........obviously! !

Thanks all and soz for leading you all up the proverbial garden path......my bad!

Down changes can occur at pedal positions other than kick down, kick down simply changes to the lowest gear possible for the road speed at the time. so you are correct, you should get down changes without using kick down, depending upon gear and road speed at the time.

 

[mw2510]

have you got a standard and economy switch next to your gear stick? i made the mistake of leaving it in economy and it took me ages to realise that was the problem. as soon as i switched it to standard kick down was back and working.

 

[Westy]

mw2510,

Yeah I've tried both E & S settings.

The kickdown does work when you are absolutely, definately & positively sure, without question, that you want to go faster by putting the pedal through the floor

Seems a little odd though, if you just wanted to briskly, but calmly overtake a little old lady doing 30 - you got to tell the car that you want no holds barred, full on, maxed out 120MPH speed! If you get my drift.

Can't I just pop the throttle half way and quickly accelerate past at a modest 50/60 ish, without the injection system dumping the entire contents of the fuel tank through the engine in two seconds flat

 

[pammy]

You just need to get used to it that's all . I rarely engage kickdown when overtaking, usually only when it's one of those now or never moments.

But when I'm at the bottom of a certain bypass hill near to me - the kickdown will almost always be engaged. Be rude not to