despair at GDI
Hi folks, new to here, I recentely aquired a 2002 pinin with a 2 litre GDI, in the UK. I took it on from a mate of mine with an on going fault, The fault started after he had fueled up (using supermarket fuel!) it has a flashing engine management light, code reads P1221, and is in limp mode. was origionaly told it was Throttle potensionmeter (on pedal) changed but fault still there, then told Throttle Body, had it reconditioned, no joy, next to be replaced was Throttle control unit, guess what, still no joy, its also had tank filter cleaned, had micro filters out of HP fuel pump, new plugs, still only get 3000 revs with no power an drops onto 2 cylinders, wondered if anyone out there as come across similar,
From my understanding ...
It may not be the throttle body that's carboned up, but more the intake manifold, especially around the back of the intake valves ...
Even though I have a GDI engined Pajero iO, I have no particular experience with the GDI systems, but have done a lot of reading - the problem is apparently a two fold one - the use of EGR - Exhaust Gas Recirculation - and the fact that the fuel is introduced to the air stream after the intake valves. From what I understand the source of the carbon is the recirculated exhaust gases, and possibly the crankcase ventilatiion system, and this is to some extent present on all engines tha tuse these systems (which is pretty much all current production), however on a more conventional engine, where the fuel is added before the valves, the fuel washes the carbon into the combustion chamber rather than allowing it to build up in the intake where it eventually restricts the air flow.
Whilst the term GDI - Gasolene Direct Injection - is a Mitsubishi trademark, the technology is in fairly widespread use and has a number of other names, Toyota has D4 Direct Injection, Hyundai has DI (direct injection) and so on, and from what I understand, this "coking" of the intake is an issue common to all brands, although the different manufacturers are adopting different strategies to deal with it - including adding an extra injector upstream from the valves to provide fuel to wash the intake & valves clean - which of course, is not the type of solution available to us as users.
Apparently our options are significantly more limited, and may be even more so depending on the particular vehicle - having a Mitsubishi (or Volvo, since they use the same engines) dealer "decoke" the intake (which they apparently do by blowing crushed wallnut shells through it) is perhaps the first option, and if you are not restricted by an OBD2 compliant ECU, blanking the EGR passage might be one way to prevent a repeat.
In case you're curious as to why blanking the EGR might not be an option on an OBD2 compliant vehicle, apparently the OBD2 system will detect the lack of EGR flow and set the check engine light if the ECU firmware is not modified to prevent it.
Now - although I have been able to get what I will describe as extraordinarily good consumption figures from my iO, the truth is that I can only get that type of figure on a longer "out of the city" run, and "in city" milage is mediocre and if the air conditioner is used will become down right ridiculous, and unfortunately the bulk of my driving is "in city". I continue to use the car on a daily basis because the consumption (without a/c) is better than my other car (a 2.0 Grand Vitara) although if I were to use the a/c (on both vehicles) the situation would be reversed.
I'm currently toying with the idea of pulling the intake manifold to at least take a peep in there, and if it is coked, try to clean it, possibly blank the EGR whilst I'm in there.
TPS
A P1221 code points to a throttle position sensor (TPS) problem, and as far as I know the TPS is located on the throttle body, and can be tested with an ohm meter - I would like to point out that this is not the same as the accelerator pedal position sensor which is what appears to have been changed (was origionaly told it was Throttle potensionmeter (on pedal) changed but fault still there)
There's a service manual that documents the fault codes and tests available for download on this site - I'm willing to assist in any way I can, however, the ECU on an 02 2.0 GDI engined Pajero iO is EOBD compliant and significantly different to that fitted to my 98 1.8 GDI engined Pajero.
One further comment - my statement that a P1221 points to a TPS problem is based on Mitsubishi's service documentation for the Pajero iO, other manufacturers may use this code differently, on a BMW it does point to a pedal position sensor - the garage doing the original diagnosis may have been misled by their EOBD code reader.
Because the Pajero iO uses a "drive-by-wire" electronic throttle, there is no cable or linkage between the throttle pedal & the throttle plate, instead there is a dual channel redundant system (think of it as a control circuit and a back up) so there are potentiometers on the throttle pedal and also at the throttle plate.
Does DHC mean double overhead cam?
Are we talking about the GDI engine here?
If I recall correctly the EGR would/should be behind the cylinder head and almost impossible to see/reach with the engine in the vehicle - go from the right side, find the throttle body and follow the EGR tube.
Thanks
Thanks a lot guys.As a 23 year old, looking for some fun I bought this io about two months ago with a lot of underlying issues. through this forum i have gotten it to work that much better than it was two months ago. still has some quirks like a chocked catylic converter and coked egr. Looking forward to the response on the last question.
Nathan io
I really have no idea...
Having said that - if you have a choked catalytic converter, I would deal with that as a matter of priority - having a restricted exhaust will limit the engine's ability to breathe and to produce power - you're going to have to use more throttle to get the same amount of power, and that might have something to do with the GDI light not coming on.
I don't think a coked EGR will cause the GDI light to not come on, on my vehicle the EGR system was blanked when I got it - I was not aware of this, and was intending to blank it when I took the throttle body & intake apart to clean it, and discovered that someone had installed what appears to be a curved stainless steel plate in the throttle body itself, that covers the EGR ports in the throttle body - I left it where it was.
By the way - have you checked to ensure there is a lamp bulb behind the GDI light and that it is working?
Will check
i will check to see if there is a bulb and that its functional. The mechanic just called saying that the cat converters were not chocked. What then could be causing this loss of power and miss when climbing hills?
He suggested that i clean the transmission strainer. i have serviced the vehcle two months ago when i bought it but it was parked for a while before that. I checked recently and the engine oil is black again. i will have the mechanic to check out the oils and change them.
I will also have it scanned because when it climbs hills the check light comes on. Maybe oxygen sensors. where can i get the oxygen sensors for my 2000 4g94 gdi dhc? Will keep the forum updated.
Nathan io
Syndicate
low quality fuel
GDI's are fantastic punchy engines, they are born and bread for hooning around snow-capped mountains in japan on high-quality high-octante fuel. They carbonise and generally go to crap when you run them on anything less.
I would bank on the low quality fuel screwing up the fuel throttle system, i've heard many many reports in the UK of GDI's needing the throttle body de-coked on a yearly basis. don't give up - the rewards are well worth it! I would go to a mitsi dealership and get them to fault-find and repair with guarantee. Once fixed run the best fuel in it you can afford, the GDI millage when running well will EASILY repay you!
I've lusted after a GDI 1.8 turbo motor, or even the 2.0 GDI NA motor for years. Unfortunatly for us in Australia our fuel is even worse than the UK, sulphur levels are through the roof! as a result the GDI would end up being as slow as the MPI NA motors they sell here and chew just as much juice
Good luck, would love to see how you go!
Bob
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