Hesitation killing my will to live (SOLVED)

[ExiledWeegie]

tightening the bolts has obviously helped plug the exhaust leak, but hasnt made any difference to the slight hesitation or the fuel trims. honestly have no idea were to go next with it now.

noticing the short term fuel trims bouncing about quite a bit, I was under the impression they should be at or close to 0% ranging from +-1%, mine go to -4.7% to +3.0% and bounce around a lot between that, even at idle its still jumping around a bit.

 

[mty12345]

noticing the short term fuel trims bouncing about quite a bit, I was under the impression they should be at or close to 0% ranging from +-1%, mine go to -4.7% to +3.0% and bounce around a lot between that, even at idle its still jumping around a bit.

That's exactly how short term trims should be mate, oscillating either side of stoichiometric (Air/fuel 14.7:1) at idle. That how the ECU keeps the idle mixture perfect, by going ever so slightly lean, then ever so slighty rich and repeating. While driving short terms can move anywhere from +10/-10 or even more on ocassions. It's not an issue, just the ECU also doing it's thing to get the mixture right.

Your Long term of -7% after a long drive is perfectly normal, and would class as a healthy car rather than running rich. . Even on a brand new standard engine, you will never see 0% in day to day driving, let alone one with a load of mods like yours. Anywhere from +10/-10 is fine, and it's going to move around depending on if you are crusing on the motorway or driving around town. When it says long term, it's only long term relative to the short terms, it will still move around quite a lot, even over the course of a few mins.

As @nd-photo.nl said, no point in carbon cleaning it as it's not a direct injection engine. If the tuner doesn't know that, then i've got to question how good the map is and how well he knows the 1.8t. If i was you i would take the car to a reputable 1.8t tuner with a dyno and get them to live map it to all the mods you've got. They'll look it over at the same time and will probably spot the issue in no time at all, With all the parts you've replaced, you should have a nice solid reliable motor if it's all set up properly.

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[ExiledWeegie]

mate that deffo sets my mind at ease regarding fuel trims thanks for that, i do alot of short runs in the town so that might be why its the way it is.

i'll tell the guy im not going to bother with the carbon clean, no point me wasting another 50 quid if its not needed. regards the tuning i might need to wait until later in the year now, ive thrown money at this constantly and wont get away with any more right now (by SWMBO). the car runs great for the most part and mpg is great, the power is also what i wanted so ive no complaints there.

if i could get rid of this slight hesitation at part throttle id be happy. i think ill just bite the bullet and order a harness repair kit when i can and do it, the only problem there is the last one i bought and sent back had pins for 10 or 12 wires, it seems my loom has 11 wires so i got confused and sent it back.

 

[nd-photo.nl]

[...]If the tuner doesn't know that, then i've got to question how good the map is and how well he knows the 1.8t. If i was you i would take the car to a reputable 1.8t tuner with a dyno and get them to live map it to all the mods you've got. [...]

With the amount of work done by @ExiledWeegie to isolate the issue, it might very well be in the quality of the mapping indeed.

 

[ExiledWeegie]

guys do any of you know if the clutch switch could cause hesitation?

ive noticed that if i dip the clutch when on cruise control the revs increase quite a bit before settling down, also when im giving the car the beans on gear changes the revs increase so makes gear changes sound like ive not let off the throttle. ive also put vcds on it earlier and the brake switch will show on and off, the cruise control will show on and off, but nothing when i use the clutch. ive ordered a febi part as it was only 12 quid, but wondering if its got anything to do with the small hiccups i get.

 

[ExiledWeegie]

I'm at the stage I'm latching onto anything to try find reasons to spend money so yeah its probably not the clutch switch although that needs changed too.

I had it plugged in to VCDS for an hour just monitoring to see if anything jumped out and I am getting some misfires at idle, sometimes goes 10 mins without any which is why I thought I didnt have any, but then it will get 1 or 2 on different cylinders, then it will clear up and then it will randomly throw one here and there, never anymore than 1 on the same cylinder before it clears again. so no doubt the hesitation and small hiccups is most likely misfires randomly when driving under part throttle.

 

[mty12345]

guys do any of you know if the clutch switch could cause hesitation?

ive noticed that if i dip the clutch when on cruise control the revs increase quite a bit before settling down, also when im giving the car the beans on gear changes the revs increase so makes gear changes sound like ive not let off the throttle. ive also put vcds on it earlier and the brake switch will show on and off, the cruise control will show on and off, but nothing when i use the clutch. ive ordered a febi part as it was only 12 quid, but wondering if its got anything to do with the small hiccups i ge don't think it would cause hesitation or anything, but it does cause the revs to 'hang' on gear changes.

I don't think it would cause your issues, but it does cause the revs to 'hang' on gear changes.

 

[ExiledWeegie]

I don't think it would cause your issues, but it does cause the revs to 'hang' on gear changes.

switch comes tomorrow so I'll get it fitted and hopefully cure that problem at least.

 

[ExiledWeegie]

well the switch that turned up was the wrong part so need to send that back and order the correct one

but... a new developement in the long running saga of hesitation.

It has been the MAF sensor all along. When I got the car last June the EML and EPC light were on and it was showing MAF codes so I bought a new Bosch MAF and put it on, then obviously since Ive had the hesitation problems I bought another a couple of weeks back and tried it and it made no difference, so I got to thinking that even though I am buying what I think are genuine Bosch parts from Ebay, could I not be actually getting genuine Bosch parts? so 3 days ago I bit the bullet and got a MAF from my local Motor factors, again Bosch, now the car feels great, no hesitation or flatspots all through the rev range.

so basically thats 2 genuine? Bosch MAF sensors since last June, one lasted a few months, the other didnt make any difference on arrival, so am I crazy unlucky or is there something killing MAF sensors on the car?. all I know is now with this 3rd MAF all the problems seem to be gone (hopefully for good)

now to get the right bloody clutch switch and start enjoying driving the car

 

[nd-photo.nl]

Glad its solved!

I had my Leon mapped to stage 2 and had the MAF sensor mapped out. It will then rely on MAP sensor etc. This has the advantage that the sensitive (and expensive) MAF sensor is out of the equation and that you can use a BOV instead of DV, but you will lose TCS as that relies on MAF input.

 

[mty12345]

well the switch that turned up was the wrong part so need to send that back and order the correct one

but... a new developement in the long running saga of hesitation.

It has been the MAF sensor all along. When I got the car last June the EML and EPC light were on and it was showing MAF codes so I bought a new Bosch MAF and put it on, then obviously since Ive had the hesitation problems I bought another a couple of weeks back and tried it and it made no difference, so I got to thinking that even though I am buying what I think are genuine Bosch parts from Ebay, could I not be actually getting genuine Bosch parts? so 3 days ago I bit the bullet and got a MAF from my local Motor factors, again Bosch, now the car feels great, no hesitation or flatspots all through the rev range.

so basically thats 2 genuine? Bosch MAF sensors since last June, one lasted a few months, the other didnt make any difference on arrival, so am I crazy unlucky or is there something killing MAF sensors on the car?. all I know is now with this 3rd MAF all the problems seem to be gone (hopefully for good)

now to get the right bloody clutch switch and start enjoying driving the car

I'd say the most likely explaination is that they were counterfeit. Seen plenty of fake spark plugs and MAFs are easy to manufacture, just not properly

 

[ExiledWeegie]

its got to have been something like that, both the Bosch ones that failed (or didnt work to begin with) had genuine boxes and security stickers although I suppose in this day and age faking anything is easy. If this ever happens again I'll be sure to get the parts from somewhere more reliable, deffo more expensive that way but if it works....

Thanks for your help guys its much appreciated

 

[sol_j]

its got to have been something like that, both the Bosch ones that failed (or didnt work to begin with) had genuine boxes and security stickers although I suppose in this day and age faking anything is easy. If this ever happens again I'll be sure to get the parts from somewhere more reliable, deffo more expensive that way but if it works....

Thanks for your help guys its much appreciated

Unlucky. I replaced the maf on mine as I had an engine light last year. I bought mine from parts in motion on eBay and so far it’s been solid. Great to hear it’s been fixed

 

[ExiledWeegie]

same place I got the MAF that had been on it since last June, it lasted 6 months before the problems started. I use them for loads of parts and very rarely do they let me down and always come quick.

unrelated to the MAF and back onto fuel trims...

anybody watch Eric O on youtube? he mentioned something in his latest vid about fuel trims still being high after replacing injectors and what not, he says that because a car is running rich that some fuel will get down into the oil diluting it and the vapour will from this ends up back in the inlet tract due to the PCV so sets the fuel trims high from that. deffo something to keep in mind, I'm gonna do an oil and filter change now as my oil does have a very distinct smell of fuel to it.