not running smooth

[GT155]

Hello,

I hope I am allowed to make my first post here about my Twingo GT '08.
It is modified with a cat delete, exhaust, bigger intercooler and mapped on with 98 fuel.
A year ago it made 155bhp and it is quick. :mrgreen:

But 2 weeks ago I got some problems.
The idle was droping sometimes to 600rpm.
And when accelerating the power delivery sometimes has a hickup. Like shifting with an automatic gearbox.

The mapping is set back to original stock values, but the result stays the same.

Anybody got an idea on what to look at?

Thanks.

GT155

 

[oscar]

so you are driving along, you put your foot down and you feel a slight hesitation + a hiccup from the engine like a gentle jolt before the power comes in. like a twitch almost? the idle speed is 650 plus or minus 50 so 600-700 is normal.

the best i can do for you is give you a list of things to look at which can cause this problem.

MAP sensor
Ignition - Intermittent Missfire (enjoy!)
Vacuum Leak (listen for a hissing sound, use a spray bottle of water and washing up liquid - spray around vacuum unions etc)
Blocked Air Filter
Fuel Pump

where do you live? my advice would be that if you do not have proper diagnostic equipment or skills, then get your car to a renaultsport specialist. i can recommend you the best one in your general area of the uk best to get them to diagnose it and then you can carry out the repair yourself should you wish.

 

[GT155]

Thanks Oscar, your comments are spot on.
That is how I feel it.

Where can I find the map sensor on the GT? Can I see anything wrong there or just order a new one?
The spark plugs have been replaced 2 years ago, the spark wires never. So I was planning to do those next week.
Will check the vacuum leak.
Air filter is OK, replaced every year.
Don't know about the fuel pump, should I have it checked on fuel pressure? What does it need to be?

I can work on cars myself, just don't know the GT very well (yet).
And I am not from the UK, here there only is the normal Renault Dealer which don't have a clue about my problem.

 

[oscar]

Thanks Oscar, your comments are spot on.
That is how I feel it.

Where can I find the map sensor on the GT? Can I see anything wrong there or just order a new one?
The spark plugs have been replaced 2 years ago, the spark wires never. So I was planning to do those next week.
Will check the vacuum leak.
Air filter is OK, replaced every year.
Don't know about the fuel pump, should I have it checked on fuel pressure? What does it need to be?

I can work on cars myself, just don't know the GT very well (yet).
And I am not from the UK, here there only is the normal Renault Dealer which don't have a clue about my problem.

on the turbo intake pipe is where you will find the map sensor. hopefully this will help you out a little bit the GT engine code is ''D4F 780'' so you'll see different versions of each section in the same chapter for each of the twingo engine variants (k4m - 133 sport, K9K - DCi diesel 1.5 so on so forth). my advice would be to go on ebay and look for a new coil pack, if i recall correctly you can purchase them for about 20 pounds or 30 euros (around that, not too familiar with currency conversions lol) and some new spark plug wires for your car from ebay to keep prices down.

i would hedge my bets on this being an ignition based problem. your ignition system runs from your ECU > Coil pack > HT Leads (spark wires) > Spark plugs > Ground (earth). first i'd advise that you remove the spark plugs to check their conditions, if you are unsure what overfuelling looks like you can find images of what spark plugs look like with a rich fuel mixture (too much fuel) which could be down to your decat. they may simply need a good clean with some sand paper. also remove the oxygen sensor (the one before the catalytic converter) not the one after (as this is defunct now that you have a decat) and check that it's got a clean head on it. if it hasn't, clean that too. this may be the cause. the carbon deposits may be causing the spark plugs problems, a clean should sort them out! if problems still occur then just replace the coil pack and ht leads! if symptoms still occur then i'd advise finding a renault specialist as close to you as possible or get it to a good garage! trust me, it will be cheaper than replacing parts should the coil pack etc not work