Flat Performance

[Telf 222 2 Cars]

Hi

Im having a problem with my 205, its performance basically is very flat, it pulls well in 1st/2nd but from 3rd onwards its very flat. My mate has a 205 and the difference between the 2 is massive. His is very revvy with loads of torque-mine isnt. He reckons mine is basically coked up because i never drive it hard - barely over 4000revs. His solution is to get it warmed up on a drive out and basically trash it up to 5/6000 revs through the gears- any thoughts on this? He thinks it will loosen it up.

 

We did have a try with him following behind and it blew alot of garbage out the exhaust.

 

I checked the compression on the cylinders, all ok

The spark plugs are slightly grey.

 

I should add the car is pampered and looked after- well serviced and never stutters or holds back- it just doesnt feel very GTI

The car is standard apart from having a 1.6 gearbox (its a 1.9) and his is the same.

 

Anyway any thoughts or help would be great

 

 

Thanks

Edited May 7, 2013 by Telf

[DamirGTI 327]

If the compression is ok. , and all the ignition/fueling bits in good working order , i can offer you one trick how to "de-choke" the engine which has carbon sediments in the engine internals .

 

It's very simple and works great , i did a lot of cars like that and results where always good/beneficial

 

D

[DamirGTI 327]

Equipment needed :

 

1. Buy an pumping garden spray jar , with an adjustable spray nozzle

http://www.aliexpress.com/store/product/800-ML-Chemical-Sprayer-Portable-Pressure-Garden-Spray-Bottle-Plant-Water/203288_611532848.html

 

2. Fill it up with 60 % water (yes regular tap water ..) and 40 % some shop de-greesing solvent , shake/mix the jar .

 

3. Bring the engine to the full operating temp.

 

4. Hook up an piece of hose on the end of the jar nozzle (adjust nozzle spray pattern to fine cone spray ..) secure with an clip , then hook the other end of the hose on the inlet manifold vaccum fitting (which is used for the brake servo booster ..) , secure with an clip again .

 

5. Pump the jar (with the mixture of water and solvent ..) to create the pressure within the jar .

 

6. Start previously warmed engine - hold the revs higher and simultaneously inject the water/solvent mixture into the inlet manifold

 

7. Do not do this on cold engine by any chance , and during the injecting the mixture start slowly then further add each time a little bit more , and keep the engine running by bleeping it on the throttle .

 

 

What will happened is : when the engine is on the working temp , water/solvent will when injected inside the inlet manifold travel trough all the engine internals (head ports , exhaust ports , valves , piston ring gaps , combustion chambers , exhaust system ..) and will turn from liquid into steam which will break/wash all the carbon deposits/sediments in said areas .

 

How much long you need to do this , well , I usually inject as per looking at the exhaust tail pipe - when cleaning/burning the mixture at idle with holding the revs so that the engine doesn't stall , it'll spit all the carbon so it'll smoke a lot (black smoke ..) .. when it clears - stop , unhook the jar , re-connect the brake booster vacuum hose and go for a blast on some open road for 30min.

 

D

[Telf 222 2 Cars]

ok well i have abit of time on my hands this week so i might as well give it a go.

 

Does anybody think this is likely to be the cause of the poor performance?

 

It was MOT'd last week and the emissions test and the results where HC 128ppm (max allowed 1200ppm) and CO 1.17% (max 3.50%) i dont know if this reveals anything about the state of the engine or not

 

Anyway thanks for the advice- ill report back when complete

[Tom Fenton 1,526]

Clue is in the signature for me, 228k miles, I'm not suprised it is tired, it is probably down on compression due to age.

[Telf 222 2 Cars]

hi Tom

 

So my compression figures where as follows but on a cold engine ( dont know if this matters!)

 

I carried out the test and got the following results, looking at the engine from left to right

1--- 160psi

2--- 155psi

3---170psi

4---170psi

cylinder 1, 3 and 4 shot straight to their respective figures whereas 2 went straight to 130 then afew extra turns took it to 155.

 

I think 190 is respectable on a fully healthy engine......

 

So what should i do with this one?

[DanteICE 72]

Clue is in the signature for me, 228k miles, I'm not suprised it is tired, it is probably down on compression due to age.

 

Is that miles then?

 

Try Terraclean, google it, there is a video of it in use in the UK somewhere. Might be a place near you that'll do it. Can't hurt and less risk than Damir's suggestion (although I don't see much wrong his suggestion).

 

What about something sizeable stuck in the intake? Would explain why below 4000 it's fine.

 

Injector issue maybe?

[welshpug 1,623]

check the throttle cable adjustment, also the AFM flap.

 

I have picked up several cheap 306 gti6's with the previous owners saying its quite nippy, but to a serial XU10J4RS driver they seemed nowhere near....

 

first petrol stop pop the bonnet and yank 2" of play from the throttle cable, YEEEHAAA!

[DanteICE 72]

check the throttle cable adjustment, also the AFM flap.

 

I have picked up several cheap 306 gti6's with the previous owners saying its quite nippy, but to a serial XU10J4RS driver they seemed nowhere near....

 

first petrol stop pop the bonnet and yank 2" of play from the throttle cable, YEEEHAAA!

 

Oh god yes! So obvious when you think about it. Certainly a good check.

[Anthony 1,000]

The problem with this sort of "fault" is that it's nearly impossible to diagnose on a forum.

 

The difference between a "quick" and "mediocre" 1.9 engine is massive, so it's possible that you've just got a distinctly middling one, even if it is otherwise healthy.

 

As Tom says, the mileage probably won't help, although if it's still got good equal compression then it should still be reasonably perky.

 

Plenty of things can make 1.9's feel flat though, even though it otherwise appears to run fine.

 

• Ignition timing - has this been retarded to allow it to run on 95 RON? This makes them feel quite flat and loses a bit of power and response. A tired dizzy won't help either.
  
• TPS - is the TPS working properly and completing the circuit at WOT? If not, they feel very flat as it doesn't get the full throttle fuel enrichment.
  
• Fuel pump - I've not seen it so much on 8v's, but I've seen a few Mi16's feeling very flat and down on power, and it's been a dying fuel pump causing it to run lean at top end
  
• AFM - could be dying or messed with, making it again lean and flat. Recently bought a spare from someone on here that drove fine up to 3000rpm or so, and was completely gutless above that and barely able to accelerate, presumably because it was super lean.
  
• Exhaust - clogged or blocked system, especially if it's the one with the split in the downpipe as these can fall apart and block the system
  
• Injectors - 228k miles on original injectors probably means they're long overdue a service/clean, likely suffering a poor spray pattern and flow by now.
  
• FPR - might not be holding full fuel pressure - again, seen this where one was only holding 2.6 bar or so, and improved noticeably when replaced and holding the full 3 bar

 

You've general servicing and consumables on top of that too - tired ignition parts can often give subtle misfires that you can barely notice, but that noticeably knock back performance. You tend to notice this on GTi-6 coilpacks shortly before they die completely for example.

 

An Italian tune up to blow the cobwebs out won't hurt of course, but isn't going to achieve much if there's an underlying problem.

 

To be honest, your best bet, after checking some basics, might be to get the car to a rolling road and see how badly down on power it is, and see if that points you in the right direction (eg lambda trace showing it running lean) and whether adjusting ignition timing etc improves matters.

[Telf 222 2 Cars]

Throttle cable-- now that seems worth a go-- ill do it now-- the AFM flap seems to move fine- ive checked the air side when i serviced it last week- all good no leaks etc

 

I dont actually know how to adjust the throttle but i imagine my workshop manual might help me out! im off into the rain to tinker

[Telf 222 2 Cars]

Hi Anthony

■TPS - is the TPS working properly and completing the circuit at WOT? If not, they feel very flat as it doesn't get the full throttle fuel enrichment.

 

So I dont Know what the TPS or WOT is! Can you enlighten me further please? I was going to take it to a local garage witha rolling road but was put off by my mate who reckoned i should run it abit harder for afew weeks and see if it improves

 

Back shortly im just going to look at the throttle cable...

[Telf 222 2 Cars]

Just had a look at the throttle cable - is it supposed to be like this or much tighter? it does seem a little slack to me but i think its always looked like this!

[welshpug 1,623]

stick a brick on the pedal and check if there's any more movement.

[Anthony 1,000]

TPS - throttle position switch

WOT - wide open throttle

 

Basically, if the TPS is working properly, it should complete a circuit on 2 pins with the throttle closed (which activates the fuel cut on overrun, aiding economy) and complete a circuit on 2 pins with the throttle fully open (which activates the fully throttle fuel enrichment, improving performance).

 

With regards the throttle cable, as above, get a willing helper (or a brick) to fully depress the accelerator and make sure that the throttle is fully open (ie it won't move any more by hand). It doesn't look excessively slack in the photo though, but it's not really easy to tell.

[Telf 222 2 Cars]

with the pedal fully depressed its no exactly tight- i can still move it fairly easily with my finger

[Telf 222 2 Cars]

ok sorry i get it now, so with 4 bricks on the pedal there is absolutely no more movement in the throttle switch

[Telf 222 2 Cars]

Anthony with regard to lean running the sparks are quite white- i wonder if it is actually too lean?

 

If so i would need to advance the timing a little? Which would be turning the dizzy clockwise? Sorry Im trying to remember havent done it for awhile

Edited May 8, 2013 by Telf

[Telf 222 2 Cars]

a little update,

 

I removed all the sparks - all completely white so i decided to play with the timing abit.

 

I think ive advanced the timing - turned the dizzy clockwise as you look at it from left hand side-by about 3mm, took the car for a run and it now picks up much quicker than it did.

 

However it now doesnt seem as smooth or settled when it is idling on the drive - its not bad just not as good as before- anything else i can do?

[Teacher 0]

dizzy vacuum advance unit?

[Mikey S 29 1 Cars]

Whip the distributor to bits and check the advance weights aren't seized up. If they are it will really blunt the performance.

 

Mike

[Telf 222 2 Cars]

ok will try take it apart tomorrow, and will report back, also checking the AFM and trying to get the injectors cleaned