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Momentary shuddering throttle at low revs... Fuel issue??

Posted: Wed Jul 16, 2008 9:23 am
by pjeadie
Hi guys,

Went to garage on Friday to fill car, which had just popped up with refill. Went back after paying and car wouldnt start - sounded like it was dying due to a lack of fuel... managed to get it started by getting a mate to turn the ignition as I manually opened the throttle switch next to the engine..

It has been starting fine since, but has picked up a shuddering around 2500-3000 rpm. It can be quite severe, and feels like there is a sudden stuttering in the power out put.

It tends not to happen when the engine is colder ie first few miles of journey. The exhaust (im told) was quite sooty when I started it last night having not driven it for 24hrs.

This is obviously a fuel issue, but Im not sure exactly what. Is there a manual way to alter the air to fuel ratio?

Any help / advice would be greatly appreciated.

Cheers guys,
James

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Wed Jul 16, 2008 9:28 am
by Shug
What car is it? S1 S2, Toyota engine, Rover engine?

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Wed Jul 16, 2008 9:30 am
by pjeadie
Sorry, its a s2 Honda engine...51 plate.

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Wed Jul 16, 2008 9:48 am
by Shug
Hmmm,

Don't suppose you know which install it is? Link-up or Sinclaires, or something else?

Might be duff sensor, might be pressure regulator set wrong (if it's adjustable) but I'm not really up on the Honda installs, so will shut up now and leave it to someone who knows better 8)

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Wed Jul 16, 2008 11:05 am
by Rich H
Are you sure its a Honda? Fly by wire throttle sounds like a Yota...

I would be looking at the ignition to be honest. But I know cock all about honda's/yota's too.

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Wed Jul 16, 2008 11:18 am
by pjeadie
Sorry, heads not on. Its a Rover engine. Was talking about a mates Rover at the time...

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Wed Jul 16, 2008 11:21 am
by Shug
Ah so - no fly by wire either - red herring there (wondering why you were in the engine bay blipping)

Yup - remove and clean up the leads, take out the plugs and see if any one is sootier than the others. I'm with Rich - sounds ignition-y.

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Thu Jul 17, 2008 8:38 am
by pjeadie
Cheers for the response guys. Unfortunately it happened again last night when I filled the car. Just kept dying after kicking in for a spilt second. Had to do the same as last time and push the small throttle level on the engine to get it started. Might give Ali through in Dalkeith a call and see if he knows.

Will clean leads / plugs this weekend and see if that helps....

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Thu Jul 17, 2008 8:56 am
by Shug
pjeadie wrote:Cheers for the response guys. Unfortunately it happened again last night when I filled the car. Just kept dying after kicking in for a spilt second. Had to do the same as last time and push the small throttle level on the engine to get it started. Might give Ali through in Dalkeith a call and see if he knows.

Will clean leads / plugs this weekend and see if that helps....
Pushing the pedal will do exactly the same thing mate. The TPS is on the throttle body, so it's not reading closed throttle, even if the pedal is up.

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Thu Jul 17, 2008 9:34 am
by pjeadie
Next time it happens (if I dont get it sorted before hand) I'll try it again, but I did start by pushing the pedal a few times before I resorted to the back..

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Thu Jul 17, 2008 9:51 am
by Rich H
Sounds odd. The throttle pedal #Should# be conected directly to the throttle body. Is there any slack in the cable?

Sounds like a couple of problems, starting will probably be IACV related the shudder sounds like spark problems.

Clean the IACV and throttle body out for good measure with carb cleaner and reset the MEMS. (Door open, ignition on, throttle open 5 times or more, ignition off, then go for start, should start and run like a POS but will recover quickly and get better, just leave it to do its thing)

Clean plugs but not until you have compared them to each other to ensure you don't have a problem on one cylinder.

Rich

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Thu Jul 17, 2008 9:58 am
by Shug
Just to add - when you do the MEMS reset - don't use throttle to start it, or you'll forever have to (until you re-set again)...

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Thu Jul 17, 2008 10:00 am
by mac
S2 Rich, doesn't have a MEM's and doesn't accept a reset in the conventional way (I think it learns setting's more)


I would test the TPS - get the car running and unplug it - it should start to faulter and die, if it doesn't then it's not working.


Mac

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Thu Jul 17, 2008 11:59 am
by Rich H
Oh, ok.
I thought that you reset its learning in the same way??

I'd still lookk at the IACV though.

Re: Momentary shuddering throttle at low revs... Fuel issue??

Posted: Thu Jul 17, 2008 12:04 pm
by mac
Apparently it's always learning (or so I've been told) - I have been able to force a reset - but that involved removing the battery and the ECU - not something I would recommend as you can kill the ECU if you don't put the protective shroud back on properly (been there, done that)