Hesitation?

[stuarttunstall]

Had my Leon Revo'd on Friday, and on the whole, I am well impressed with the difference in performance, except for one thing.

At around 2.5K rpm, the car seems to hold back when in 98ron performance mode.It does not feel like a missfire, and is not major, it just feels like the car wants to go, then thinks "hang on! I should not do this!", I also noticed a loss of power last night changing from 2 to 3rd at around this revs.
If i change back to stock mode, it disappers. The car is fitted with the standard dump valve, which, I have found out from Richard at Revo is rated at 0.8bar. As my car now puts out 1.2bar, does it sound correct that the turbo is loosing boost at the level set on the dump valve? and would a competion/Forge 007 valve rectify this?

Both Richard and my Dealer say it sound like this, has anyone else had this problem running Revo with a standard dump valve?

Richard has sent me a dump valve to try, and my dealer is fitting it for me Saturday, fingers crossed this will solve the problem.

Thanks for all your advise and help Richard, makes a change to find a VERY HELPFUL company these days.

Any comments would be welcome

Thanks

Stu:cheers:

[le cupra]

mine does this too and I've got a forge dump valve. Think there has been a thread before and also a thread on the golf mk4 site too.
Seems that some Revo'd cars do this while others don't. I've just changed my driving slightly and now very rarely have this problem.

[mark sheerin]

If its a case of some cars doing it and others not could it be just simply a small air leak somewhere..maybe on the inlet pipe for the turbo?
I still have my original DV on and I'm running SUL at 97ron rather than optimax but I had the optimax settings put in when it was installed.
I'll try some optimax in and see if I get the problem..

I must admit but then I'm no expert..I was surprised to find the ignition was advanced for Optimax..I would have thought it would be retarded slightly to allow for the fact that the optimax burns quicker than normal petrol.
I've always had the view that although you get better power at high revs with optimax it seems less happy at low revs.
This was confirmed in practice in a car magazine when an Evo was timed with and without optimax..
Overall the car was quicker when revved hard but slower on some of the in gear times....

[ZBOYD]

Yeh noticed this too Mark. Running my R standard since new on only Optimax, and at low speeds, just normal A-B 30-40mph commuting, it can feel very breathless, and hesitant. But when you open it up, its rapid and pulls and pulls you can really feel the VVT kick in. :)

I think the low speed hesitancy is due to the Optimax fuel.

My old APR Leon however, we think had a MAF fault, as it had problems at the opposite end, ie surging and hesitating higher up the rev band. It also lacked the VVT solenoid the later Leon Cupra's got.

I would certainly try a Forge DV, maybe see if you can replace or swap in a new MAF sensor too.

[Mark_2_go]

When I had the Revo DEMO at silverstone my car was hesitant in high gears and at low revs.

When accelerating it sounded like the turbo was working real hard and I was getting too much boost.

Kev offered to take a luck but since then I was caught speeding!! so decided to put REVO on ICE.

Since the DEMO is over though things have been fine. Kev thought this was to do with the DEMO code.


Mark :D

[coops]

i have driven a family members Revod leon r and it felt the same it pauses for a second and the you can hear the air "gushing really loudly" and for a second nothing seems to happen. in fact on some occasions it seems like its running out of puff. been in high gears at 4k rpm and it seems to suddenly lag??????????????????????????

[Mark_2_go]

Thats it m8 same as what I had.

Mark :cheers:

[mark sheerin]

Fortunately can safely say my car feels fine...
Fine enough to get past a Fiat Coupe turbo last night with a driver who deliberately accelerated to stop me getting past...and failed:D

[Mark_2_go]

Nice one Mark! lol

Mark :D

[Cupramax]

Thats no mean feat in itself... Fiat Coupe's are pretty quick especially if it was the 5cyl 20v Turbo.

[mark sheerin]

It was .. with the hugemungeous exhaust...

I did kind of trick him though..he was driving at 50 and I hung back and near the kerb so he wouldn't think I was going past even after the road split into two lanes...
..and then I just dropped a gear and went for it.
He reacted straight away..but too late..
Thing is though why just because I started overtaking him did he put his foot down?
Under normal circumstances i would have given him the finger but last night I just laughed at him as he had to admit I'd got him.:)

[vern]

:car:
agree with z re. optimamax on low speed running,when i picked up the car it was half full (with s*it low grade 95 ron)car ran better at low speeds with this though even though it had only done 20 miles now at 900miles trying optimax with octane booster (100ron)it ran no better @low revs + speed but mega pick up @ higher revs + speed strange ehhh! think this would alter with higher boost though and would give u a saftey margin, or is it just cos the weather is a lot hotter than when i bought it?????

:cheers:

[stuarttunstall]

Now I am confused:confused: :confused: :confused: :confused: Just be out tonight, done 40 miles, in 98ron setting, and went upto and past the 3.5k rpm, and did not notice the hesitation once! The only thing that I did notice, was at around 3k rpm, and letting my foot off the accelerator, the gearchange was not smooth.

I am having the forged dump valve fitted in the morning, so I am keeping my fingers and everything else crossed that the car has sorted itself out.

I would just like to thank all of you that replied to my question, and I will let you know tommorow what the new dump valve has done

:cheers:

Stu

[stuarttunstall]

Just took the car to the dealer to have the new dump valve fitted, still no signs of the hesitation.....So I can only assume the car has corrected itself?

The car now seems to repond quicker and smoother with the new dump valve.


Thanks

Stu

[junior munky]

I have noticed this hesitation problem since I had my Revo demo.

I think I have worked out what the problem is, at least for me...

:)

I couldn't work out any pattern except that it was definately worse when the engine was only just warming up. I convinced myself it only happened on the motorway after cruising at a constant speed for a while, then disproved that.

Finally over the last couple of months I twigged. I fill up at primarily 2 shell petrol stations in central Herts. If I fill up at one of them (let's call it station A to protect the not yet proven guilty) from an almost empty tank the problem was LOADS worse. Conversely if I fill up at station B from an empty tank the problem just goes away.

Now whether station A has fuel that has been sitting around for a while, whether the petrol comes from a different distillery, or it has been mixed with 95RON (presumably deliberately for somebody to make some cash) I don't know.

I have raised the issue with Shell (about a week ago) but have yet to get a reply.

It may not be the solution for the rest of you before you flame me, but since I stopped using station A I have not had the problem at all.

Before I twigged the fuel thing I had spoken to Revo Kev about it, and funnily enough I was mailing him on this very subject when the mail bounced and I started the "Revo dropped off the Internet" thread. I forgot to resend it.

Oh, and I had the Forge piston DV fitted with the Revo.

:cheers:

Olly..
.

[mpkayeuk]

I must admit but then I'm no expert..I was surprised to find the ignition was advanced for Optimax..I would have thought it would be retarded slightly to allow for the fact that the optimax burns quicker than normal petrol.

Nooooooooo :) Higher RON fuel does not burn faster than lower RON fuels. RON is basically a measure of the ability of a fuel to resist detonation, that is the uncontrolled burning of the fuel/air mixture after a spark has ignited it. Detonation can be caused by many things; high compression (turbo boost, high compression atmospheric engine), high cylinder head temperatures, etc, etc.

Technically, detonation (or det/detting) happens under such conditions whereby, after the spark has ignited the mixture, the flame front advances in a controlled manner but is then met by another flame front which was not ignited by the spark. The two flame fronts then collide prior to TDC (because combustion rate has effectively doubled and therefore completes early) causing massive pressure spikes to travel through the piston, down the con-rod and onto the crank. If you're unlucky this pressure spike can break down the oil film lubricating the big-end!

The higher the RON, the greater the resistance to this detonation. So, this allows you to run more advanced ignition/higher cylinder head temperatures or higher boost.

[Leon20VT_GR]

I would like to also add that here in Greece were we all 18T drivers use SuperPlus fuel with 98 octanes, no such issue of hesitation in low-mid range revs has risen over the Revoed Leon comunities.

Even better, from last month most of us use the BPs new fuel "Ultimate" with 100 octanes, and I believe we are all happier than using the Shell's racing 99+ fuel, (mostly due to is higher price).

The car feels ready to rock and roll even from 2000 revs.:cheers:

[Red Myrtle]

Just had the free 5 hour trial and was well impressed! However, I did find that there was some hesitation especially when accelerating hard (which , let's face it, is most of the time when you're Revo'd!)and it almost felt as though there was a sudden drop in power occasionaly as I went to change gear.

However, the outside temperauture was in the mid 20's so that probably didn't help.

Overall though well impressed and definately on my shopping list!

[Neanderthal]

Same here!
Just got home after having the REVO trial uploaded to the car. First impressions are that it's fantastic, the car is SO much quicker :)
BUT if I put my foot right down in say 3rd, at 2k revs, when it gets to 3k revs it's like hitting a brick wall! it lingers there for a second or so then takes off like a rocket up to red line! The only other time I've felt the "brick wall" thing is on my Scooby, it was the ECU fuel cut saftey method. It happened when the boost was too high for the amount of fuel it could pump in. Is this purely something that happens with the trial or does the full REVO software have this characteristic? :confused:

[Mark_2_go]

When I spoke to Kev from REVO he was V helpful on this.

Kev told me it was just the Demo software that did this and the full software was fine.

I would give them a ring at daventry. It is well worth the chat. I was going to get mine done straight after the DEMO but got caught speeding just before having the demo.

I have decided to wait for some of my points to drop off. (1 more speeding ticket and I lose my licence) ouch!

Mark :cheers:

[FastShow]

Originally posted by Mark_2_go
Kev told me it was just the Demo software that did this and the full software was fine. This is the line I've often heard and isn't at all true - the full software definitely still hesitates on occasion and it's very, very annoying when it does.

[junior munky]

Yes, it is very annoying. And worrying if detonation is the cause. Shell were totally unhelpful when I mentioned it to them. The conversation went something like:

Shell: We are totally confident that the Optimax at xxxx filling station is unadulterated.

Me: Did you test it ?

Shell: No, we asked them

Me: And you think they were likely to tell you if they had been mixing in RON95 ???

Shell: If you want to take it further, speak to Mr blah blah who owns the filling station. :confused:

Anyhow, I may have been wrong in the first place as I filled up at the station in question a few days ago and it has been fine since. In fact in general the problem has got a lot better. Only happened once or twice in the last 6 weeks or so. I have no idea what has happened to reduce the problem.

Come on Revo peeps, have you any ideas ?

:cheers:

[Mark_2_go]

This is the line I've often heard and isn't at all true - the full software definitely still hesitates on occasion and it's very, very annoying when it does.

Point taken then. Nobody has ever mentioned this to me in the past that the full software still suffers from hesitation hense my quote.

Interesting that it still happens though.???????

Mark :cheers: