Diagnose this please

[ja3142]

If I blip the accelerator pedal there is a short delay before the revs rise on the dial. Then as the revs fall I can hear a slight cough in the exhaust. The revs also seem slow to fall back.

I recently took the throttle body off for a clean and replaced the throttle cable.

Anything to worry about?

[Bernard LPG]

If I blip the accelerator pedal there is a short delay before the revs rise on the dial. Then as the revs fall I can hear a slight cough in the exhaust. The revs also seem slow to fall back.

I recently took the throttle body off for a clean and replaced the throttle cable.

Anything to worry about?

How old are the spark plugs? They would be my first guess.

[ja3142]

Relatively new I believe. But I will check them tomorrow.

Why do you think spark plugs?

I changed the coil packs at the same time.

[Bernard LPG]

Relatively new I believe. But I will check them tomorrow.

Why do you think spark plugs?

I changed the coil packs at the same time.

Well, from the symptoms really, especially the popping suggests unignited fuel in a cylinder.

Plugs are so simple to check anway to eliminate them that it's always worth doing.

[chrissyboy]

just had a thought it may be air related ,if when you press throttle it might stall , it may not getting enough air have you replaced the hoses back tightly .

[T-Cut]

Assuming this didn't happen before you worked on the throttle system, it seems likely that it's the cause. Have you checked what Haynes says about it?

TC

[SD1too]

I'm not 100% sure on this but I have read that the throttle body has to be reset once taken off the car...
I don't think that's true Chris. I've removed and replaced mine with no problems.

Simon.

[Phil]

that is what i wastold by the experts on here ... reset it sort of by pressing the throttle about 10 times ,but that is not 100% needs o be on a machine to reset 100%

Hi Chris, I said if you replace it then you need to reset it. Removing and refitting the same one shouldn't matter.

[chrissyboy]

Hi Chris, I said if you replace it then you need to reset it. Removing and refitting the same one shouldn't matter.


hi phil thanks for clearing that up ,, was a while ago and i didnt remember word for word ... well misunderstood really .

[Phil]

hi phil thanks for clearing that up ,, was a while ago and i didnt remember word for word ... well misunderstood really .

No probs, thats more for idle issues anyway. :)

[ja3142]

Taking the throttle body off and giving it and the inlet a good clean was part of getting to the bottom of a slightly lump idle, as was changing the coil packs. Still haven't fixed that.

I did wonder if it needed some sort of re-set as its quite weird to press the pedal and then something happens (the revs climb) a moment later. I did not notice it driving about, this was revving it stationary in the drive.

I did also wonder about an air leak somewhere.

I'll have a look at the plugs tomorrow and see what that tells me.

I take it that a re-set needs a T4?

keep the ideas coming guys and thanks!

[marinabrian]

Taking the throttle body off and giving it and the inlet a good clean was part of getting to the bottom of a slightly lump idle, as was changing the coil packs. Still haven't fixed that.

I did wonder if it needed some sort of re-set as its quite weird to press the pedal and then something happens (the revs climb) a moment later. I did not notice it driving about, this was revving it stationary in the drive.

I did also wonder about an air leak somewhere.

I'll have a look at the plugs tomorrow and see what that tells me.

I take it that a re-set needs a T4?

keep the ideas coming guys and thanks!

Yes T4 is the way to go for setting up correctly, air bypass set is the only way to ensure the iac valve is set correctly, at idle, the ideal is 15 to 20 steps on the iac valve. I've quite often seen cars where the stepper is jacked right out by the ecu, when it's trying to compensate for badly set up throttle bodies, the results are predictably slow return to idle/ uneven/high/low idle etc.
Hope this helps
Brian.

[marinabrian]

You could always build your own "TestBook":drool4:
http://i250.photobucket.com/albums/gg279/marinabrian/PICT0047.jpg
I have to say, not that convenient for test drives :)
Brian.

[ja3142]

OK folks, plugs checked out...nice light brown colour.


but, the new throttle cable had not been fitted fully home - refit, spray with silicone and then done a throttle cable reset.

So far, that seems to have cured things...

[chrissyboy]

OK folks, plugs checked out...nice light brown colour.


but, the new throttle cable had not been fitted fully home - refit, spray with silicone and then done a throttle cable reset.

So far, that seems to have cured things...

well done.im glad you was able to sort it ... its a lesson to us all ,that if the car wasnt doing it before we worked on it ,then re check the work that we just did ,as in your case you found the problem .