:thumbup:thanks.....i'm sure there's other factors involved.....so i'll try it....see do i get more bhp......

i'll stick the vag com on and see what temp sensor says......:eek:

people seem to put these mods in diff places..ie fuel sensor......coolant sensor.....even air intake sensor....

the one being referred to mostly here seem to be fuel sensor mod....so the ecu would already "know" the coolant was hot but "think" the fuel was hotter than normal so inject little more to make up for loss of mass...??!!!!>>>???:confused:

If it's messing with the coolant temperature, it's just the fleabay resistor mod again, isn't it?

Yep...but in a Wig and a pink dress.

The PD one definitely plugs into the fuel temp sensor. The non-PD one may be different.

Chris

great thread on this mod....Cheapest TDI PD Power Boost - uk-mkivs...

some testing and useful figures

whatever its bu66ering about with , Fuel or coolant, I agree with Blanchie, its the resistor mod in a wig and pink dress.

If your going the resistor 'way;' then its probably the safest way to do the resistor mod [re. warning lights and controllability] and It'll probably give you an extra 15bhp Okay for the £15 it'll cost you to make your self but not if your paying £50 or so from flea-bay. might as well save it towards a remap.

Agreed; that's why I wanted the expansion co-efficient. I could use that to work out how much extra fuel you'd add, and hence how much extra power you could develop (in a diesel, and on part-throttle; on full throttle you may not be in a lean burn any more).

I believe diesels run quite considerably above stoichiometric, even under full load. I don't know whether the Evry mod (or any other overfueller) could potentially push the fuel:air ratio below stoichiometric, though. Certainly, the bumpf for my Dragon box suggests that the top couple of settings could be too high, and I guess it would explain why they can make it look like you're driving a wood-burning car unless you do something to get a bit more air in the cylinders, like fit a PD-daylight-robbery-160 intake!

people seem to put these mods in diff places..ie fuel sensor......coolant sensor.....even air intake sensor....

the one being referred to mostly here seem to be fuel sensor mod....so the ecu would already "know" the coolant was hot but "think" the fuel was hotter than normal so inject little more to make up for loss of mass...??!!!!>>>???:confused:

I wasn't suggesting the Evry mod worked on the air intake sensor (MAF); I was just saying that I understand the need to measure mass-airflow (essentially due to Boyle's Law)

Guys , just going back to the Evry mod ,the idea is that the resistor mod fools the ECU into thinking that the COOLANT[ ie. the engine] is colder NOT the fuel .

The low resistance caused by the presence of the resistor in the 'resistor mod box' fools the ECU into thinking the engine is still cold like at a cold start up and injects fuel for a longer time period [higher vol of fuel] . Measuring / bu66ering around with FUEL temps has nothing to do with this mod.

Well, if it is 'perceived' coolant temperature that the mod affects, I can understand it a lot more easily - it'd all come back to my manual choke analogy...

I believe diesels run quite considerably above stoichiometric, even under full load. I don't know whether the Evry mod (or any other overfueller) could potentially push the fuel:air ratio below stoichiometric, though. Certainly, the bumpf for my Dragon box suggests that the top couple of settings could be too high, and I guess it would explain why they can make it look like you're driving a wood-burning car unless you do something to get a bit more air in the cylinders, like fit a PD-daylight-robbery-160 intake!

I thought that really heavy sooting indicated partial combustion, and hence running below stoichiometric. I've never actually done the sums though.

the fuel sensor method so far is my favourite....since most work seems to be done on this one..[se above thread and others]....and it only seems to work on diesels well...i imagine if overfueling[choke effect].....was happening some of other sensors would throw a light or it would show on m o t

whatever is happening it makes me question cost of remaps

whatever is happening it makes me question cost of remaps

There's oodles of stuff on resistor mod vs. digital tuning box vs. remap, so you should have more than enough info to make up your mind if you do a search.

But in summary:

RESISTOR MOD

Pros: Highest bang:buck ratio; very easy to install / remove if you go the Ebay box route; extremely stealthy if you go the bury-it-in-the-loom route; using one with a potentiometer rather than a resistor allows a degree of tuning (but always more power than standard).

Cons: Overfuels at all throttle levels, meaning an awful lot of smoke; will throw up warning lights on newer cars.

DIGITAL TUNING BOX

Pros: Cheaper than a remap; still a DIY install; fully adjustable - can even be tuned to reduce power if economy's your thing (see Ken's caveat, however); only overfuels at higher revs, therefore a lot less smokey (except at full-whack with a normal intake!); good second-hand value if you decide to get rid.

Cons: May not produce all that much power than the resistor mod, so if ultimate power's your only consideration, may not be worth the extra.

REMAP

Pros: Alters boost and fuelling levels, allowing a higher power output than overfuelling alone; will allow the smoothest power delivery of the lot; can be custom-coded to make the most of any other mods you might have; certain types can be switched on and off for servicing etc.

Cons: Most expensive; some are permanent (problems in case of warranty claim or other problem); even lower bang:buck ratio than the tuning box.

...As I say, there's loads more on here (including more than one warning regarding declaring any mod to your insurer!) so if you're having trouble making up your mind, just have a go on Search!

The other point about a good custom remap is that it will probably include a couple of hours of rolling road plus RR op's time, so that's about £200 + Darling's Dosh there alone!

:thumbup:nice summary of pros and cons!!!

tried it ....and vag com..test....temperature definitely shows increase with decreasing resistance

interestingly...vag com shows decreasig injection rates as i set the temp higher with my variable resistor.....and when i drop the temp with the resistor the fuel injection rate increases.....so now i'm really confused since most are saying increasing the temp fools the ecu into injecting more!!!!????

I think that indicates that you're spoofing the engine temperature, not the fuel temperature.

i have the resistor on fuel temp side and vag com shows fuel temp rising or falling as i turn variable resistor ****.....fuel temp can be "changed " from 25degc to 129deg c......at 129deg for example vag com shows almost 1 1/2 times less fuel injecting than at 25degree.....

As UK temperatures are almost always below 25C, this mod should do nothing worthwhile then?

you've lost me!!!??/.....the outside temp not connected to this mod....this mod make the ecu think the fuel is either hotter than it is or colder than it is....depending on how you set it up....

the original question on this thread was did the mod make ecu "think" fuel hotter or colder.

once that was established......next question is how does it effect performance?

i tested it with vag com and lower resistance shows ecu thinks it's hotter and injects less fuel....i tested this at idle only...soon i will test it at higher speeds and see if there's a difference

the reason i asked question was because some said more fuel is injected and fuel is reading to ecu as colder

test at idle shows more heat/less fuel.....colder /more fuel...at least that's what the ecu "thinks"....reality is temp is as per normal...but tell tell the ecu that!

Yeah, I got all that. What I meant was that, since you've established that the fuel injected is inversely proportional to temperature (and I read #66 as meaning that the min fuel temp you can set is 25C, which is "warm Summer day" for most of the UK) it won't normally allow a power increase in the UK. It might offer potential increases in the warmer states of the USA though.

Also fuel temperature is not the same as outside temperature, the fuel temperature goes up to about 70ish degrees C

Fuel temp gets that high! How/where? Surely there's not that much of an overflow rate though the engine pump, to supply pump cooling?

yeah fuel temps coming out of the engine[unused ..and back to filter] can be as high as 70c.....although usually from my vag com reading it's about 55c to 65c

o yeah your right ....my setup only brings it down to 25c....so may be i need another resistor thrown in to bring it down more:)

Not sure whereabouts in the system the fuel temperature measures temperature (I'm guessing just before injection?) but apparently the extremely high pressures used in the PD systems mean that the temperature of the fuel can easily be 60 deg C.

Chris

If the fuel temp is a result of fuel pressure, spoofing it down seems like a very bad idea to me.