Juddering Update

[redmaestro]

Hi All,
As promised, here's the update:

My new ECU arrived this morning (yay!), so I quicking installed it. I've been driving around today since, and it is still juddering!! :banghead:

Any other ideas?

Thanks

[threelitre]

Have you tried to clean the crank angle sensor? If this is not working properly then the ignition might play up.

Alexander

[G Force]

Hi if the problem is still the same ie. not reving over 2000rpm and surging at this point intermittantly whilst other times it can run perfect . I still think it could be related to the throttle potentiometer. It is a pitty that you cant check the voltage output with the multimeter as this may show a problem with the throttle pot. Another thing to check would be to make sure the fuel ecu is dry and not getting damp due to water leaking into the footwell.

Check the fuel ecu plug is Ok. Check the throttle pot harness plug connector is clean & dry.

As you realise there are many things that could be faulty. A faulty throttle pot or wiring could cause your problem, A faulty fuel ecu or wiring could cause your problem or a faulty crank sensor or wiring.

Cheers

[Chris Y]

Another vote here for the throttle pot.

Had this once on my Mini. The injection Minis have a little switch just under the throttle pedal that activates when the throttle is fully closed. These occasionally stick, tricking the ECU into thinking the throttle pedal is not being pressed, and it simply refuses to rev above a certain amount. The same symptoms can happen with the ECU not being able to read the throttle pot input, and again 'defaulting' to a certain value.

The same thing could be happening with your Maestro - the pot sensor anyway, not the pedal switch, as I don't think there is on on the Maestros.

[redmaestro]

I may be 'speaking too soon', but so far this week, she hasnt juddered since sunday.

I started tinkering under the bonnet on Sunday afternoon, checking connections and cleaning & WD'ing them. I even tried to clean up the crank sensor thingy. I also made a small discovery. The plastic 'boot' that connects a wire from the ECU to the throttle assembly was cracked and letting in air. When the engine was running, you could hear a loudish sucking noise. After a quick bodged repair with some insulating tape, I have sealed up the crack.

Whether or not this is the reason for my problems, i dont know. All I can say is that I have driven about 60 miles or so without missing a beat. I'll keep you posted..........

Keep your fingers crossed . . . . :rolleyes:

[G51 NAV]

yes that's a vaccuum pipe. It could well have been that leak which has been causing your problems all along. Try pulling it off at one end and see if you get the same old symptoms

[redmaestro]

I did try it while I was tinkering, and the engine ran rough but still revved over 2000rpm. Perhaps there are other factors which may effect it like engine temp etc?

Anyways, still no signs of it playing up, so I live in hope. Ideally I should replace that plastic connector if I can find one.

[BikerGran]

If you're having problems with one vacuum pipe, it's prolly worth checking all the pipes - I had continual problems till me mechanic fixed it - he said he sealed all the pipes - sure enough you can see that something has been used, I forgot to ask what, but it certainly made a big difference.

BTW you can get vacuum pipe bend and connecters in a little packet from auto shop for about £2. Or you can make them up with L and T connecters meant for windscreen washers, which is what I did follwing instructions that are on the site her somewhere (I think).

[G Force]

checking connections and cleaning & WD'ing them. I even tried to clean up the crank sensor thingy. I also made a small discovery. The plastic 'boot' that connects a wire from the ECU to the throttle assembly was cracked and letting in air.


Hi I doubt if the vacuum connection was the cause of the main running problem but it certainly would not help overall.

The connections however could easily be the real problem and hopefully fingers crossed you have effected a permenent cure, well done:)

[dave-mg]

lol i think you have the same problem as im haveing with my mg.
ive tried lots of things and the problem's still there.
i also found a split vacum pipe and have now replaced them all along with a fuel ecu,ignition ecu(also added an oil trap in the vacum line as the mg's never had them and i notice some oil in the line)
ive completly changed all the breather pipes as well as well as done all the basics plugs,leads,cap and arm.
what i have found is the car is ok till it reaches temp and thats when it starts. up to 2 and a half thousand revs it judders but after that its ok(mainly)
its impossable to drive in 4th at 30 mph(5th is just a no go as it jumps like hell)so i leave it in 3rd.
ive had my car over a year now and to say its annoying is an understament.
when i first got it it had 3 broken studs in the head(the exhaust was blowing at the manifold due to the broken studs) so i had the head done (skimmed and the studs removed)i reground the valves and fitted new stem seals.
im at the stage now theres not much left i can do.
i was wondering about the throttle pot also the other thing on the manifold(dunno what its called or what it does)either that or im wondering if the servo might be the problem, i know the brakes were never great but i really got to stand on the pedal(ive replaced the master cylinder and front calipers with new ones and replaced virtualy every brake pipe)
ive went past the stage of giveing up and i sold the car,but i missed it after 2 weeks and got it back again(it looks good in the driveway lol)
i dont use it that often mainly due to this problem
i dont know if theres something ive tried you havent,but as neither of us have done the throttle pot or that other thing it might be worth a try hopefully it might fix the problem.

[G Force]

Hi juddering on light thottle could be glazed injectors, or the throttle pot setting, valve clearances too narrow, but one thing I would recomend you double check is that the plugs are gapped at 0.040in 1mm as plugs gapped too narrow will cause a misfire at light throttle.

Gary

[E_T_V]

i was wondering about the throttle pot also the other thing on the manifold(dunno what its called or what it does)either that or im wondering if the servo might be the problem, i know the brakes were never great but i really got to stand on the pedal(ive replaced the master cylinder and front calipers with new ones and replaced virtualy every brake pipe)

You could be on to something with the brake servo. If it is leaking then it'll be admitting air into the air inlet even though the throttle is closed. The ECU then may get very confused. You could temporarily try unplugging the brake servo pipe and blocking the port on the inlet. Obviously then you'll have no power assistance on the brakes so you'll have to stamp on them hard. If you notice little brake difference then the servo is definatly duff. If the running problem is solved then you might have killed two birds with one stone :D