(noob) Questions re throttle body & MAF

sentient_6

I've had poor power on my sonata crdi the last week or so. Sometimes struggling to get the car out of 1st gear, completely dead on the low end.

For some strange reason it has improved today but still sluggish. Had a mechanic out to run a diagnostics. No fault codes, turbo appears to be working, but after some rooting around/checking sensors etc he took the air hose from the intercooler off the throttle body.

It was fully open no matter what. Whether at idle or reving. Although it would close & open with the ignition. So my question is is this correct? should it be adjusting with the accelerator? Would it being fully open from idle be letting to much air in intially giving me the poor performance on the low end?

Now the MAF, the scanner was telling him the air intake temperature was 28 degs. The outside temp was in the region of 4 or 5 so its obviously miles off, could this be part of my problem potentially?

PADRAIC.M

sentient_6 wrote: »

I've had poor power on my sonata crdi the last week or so. Sometimes struggling to get the car out of 1st gear, completely dead on the low end.

For some strange reason it has improved today but still sluggish. Had a mechanic out to run a diagnostics. No fault codes, turbo appears to be working, but after some rooting around/checking sensors etc he took the air hose from the intercooler off the throttle body.

It was fully open no matter what. Whether at idle or reving. Although it would close & open with the ignition. So my question is is this correct? should it be adjusting with the accelerator? Would it being fully open from idle be letting to much air in intially giving me the poor performance on the low end?

Now the MAF, the scanner was telling him the air intake temperature was 28 degs. The outside temp was in the region of 4 or 5 so its obviously miles off, could this be part of my problem potentially?

First off that throttle is used to shut the engine off, so you turn off ignition, this flap closes in turn air entering engine stops causing a faster shut off than just cutting fuel.
The air temp in the engine bay will effect the intake temp,
I think you should check your fuel pressure and egr valve!

sentient_6

Should've mentioned i had the egr looked at during the week. I had problems with it a year ago & thought it was the same again, but it came up clean.

Ill put the fuel pressure on the list so. With regards the throttle body again though, should i not see it adjust as the engine is revved?

cletus

You should see the valve inside the throttle body open with revving, and closing again when the revs drop off.

enumbers

cletus wrote: »

You should see the valve inside the throttle body open with revving, and closing again when the revs drop off.

Sorry this is not correct as mentioned above this is a shut of valve on this engine open when engine running and shut when ignition is switched of.

dieselbug

The valve open fully is normal also the air temp. The valve is used as a soft stop when you kill the engine, also to aid egr flow. Sounds like your mechanic may be out of his depth.

What is the maf reading for air flow, might be worth disconnecting and see if that makes a difference. Otherwise fuel flow, supply, has the fuel filter been checked. Is it smokey.

cletus

Apologies, my (admitadly basic) understanding of the working of throttle bodies in general is the the internal valve will open according to the revs. My intention wasn't to mislead.

sentient_6

dieselbug wrote: »

The valve open fully is normal also the air temp. The valve is used as a soft stop when you kill the engine, also to aid egr flow. Sounds like your mechanic may be out of his depth.

What is the maf reading for air flow, might be worth disconnecting and see if that makes a difference. Otherwise fuel flow, supply, has the fuel filter been checked. Is it smokey.

The place i had the egr looked said they disconnected the maf & it made a slight improvement & recommended i get one from a breakers & see if it fixes it fully. Another person i talked to dismissed the maf exactly because it didnt make a huge difference disconnecting. So jasus i dunno! My head is wrecked. I've a fuel filter bought & ill get it changed soon as so. Car isn't smokey. The guy who did the diagonostics wanted me to get the dpf checked to see if it was blocked also.

The last thing i need is to pay for full days of labour for lads to stab in the dark throught a list of potential faults, & not knowing if they even have a clue what they're at.

dieselbug

The last thing i need is to pay for full days of labour for lads to stab in the dark throught a list of potential faults, & not knowing if they even have a clue what they're at.

Exactly, if you give your location someone will be able to recommend a good independent equipped with the gear and knowledge to help you out. It will be cheaper in the long run.

sentient_6

I guess anywhere between galway & athlone. Im also thinking of going to kennedy's in birr(hyundai dealer) because they're labour rates are in the region of most indepedents, there very fimilar with that engine & they've sorted me out in the past with little fuss. I'll see.

Reckon i can rule out the MAF, took it for a drive myself there & unplugged it & it didnt make a bit of difference. Ill definately get the fuel filter changed soon.