Looking for the cause of a bad shudder ?

[Ron41]

Hi all, at about 80 - 85 klm an hour i get a bad shudder whilst driving on petrol, the car is duel fuel but doesn't do it when running on gas, only does it on petrol, if i accelerate up to 90 and over the shudder goes away.
As far as i know it can't be the trans as it would do it on both fuels, nor the electrical system as i believe gas depends on better spark than petrol.
So the problem must be the petrol system somewere but were would you start looking ?

Appreciate any advise
thanks

[Vs-Stato]

Try some injecter cleaner. Might not be getting enough fuel through. Im not saying that is definatly the problem but its worth a shot.

[Vs-Stato]

Or maybe a wheel balance is needed???

[Ron41]

Thanks mate, I will get some of that injector clean and try that first anyway, couldn't be a wheel balance issue though because it only happens on petrol not both fuels.

[Vs-Stato]

Ahh. Yeah didnt think of that haha.... Hopefully the injecter cleaner will work...

[Ron41]

Well still got that shudder after using that injector cleaning stuff, i had mixed about 30 bucks worth of petrol with that injector clean, it has made no differance, should i buy some more injector clean ? or start looking at other reasons ?
thanks for any help.

I did a code check a couple weeks ago, by memory it read code 57 & 76.

[Ron41]

Just double checked those codes and it was right.
going by my gregories - code 57 - injector power supply [ voltage variation, terminal B12 ]
code 76 - air/ fuel ratio [ variation between left and right banks ]


I have changed the oxygen sensors about 12 months ago, could the injectors need cleaning by a mechanic or who ever does them ?

[rambunctious]

A 350ml bottle of Wynns Injector Cleaner should be used over 2 tanks of fuel ie approx 120 to 140 litres of fuel.
When you have run 2 tanks of fuel through your car with the cleaner added, only then can you say if it worked or not.

I have been using Wynns for over 15 years and it works. It made a hell of a difference on a VN many years ago.

[hako]

I've never used injector cleaner - just lucky. From what I've read, premium fuel include injector cleaners so some people recommend using a tankfull every year or so if you're a tight ass like me.
I'd check the O2 connectors to see if they're tight and also check the battery terminals....also do a ECU reset by disconnecting the battery. But it does seem to point to injectors - be a bit wary of what or who does an injector clean as I've heard plenty of bad stories from both sides of the fence.
Torque converter is still locking up above 80Kph OK?

[fjwb]

Check the wires on the injector plugs, I've seen a few of them back out of the plugs losing contact with the injector. Your gas system will also tap into each bank of injectors somewhere on the engine harness, should be able to see where the non factory wires are by following the harness from the gas system. Check the integrity of those connections too.

[Ron41]

Thanks for your replies, trust me to have it arse up, i thought the less fuel would make the cleaner more potent, i will get some more cleaner and fill it up with premiun fuel, also check the wires.

hako - I have had the auto checked by 2 auto shops, both say there is nothing wrong there, thank god, i only get this shudder on petrol, runs fine on lpg.

Again thanks for your help, much appreciated.

[md22853]

yes my vr shudders when i start it up rev it higher ,as i drive off and it gets louder with speed and shakes my steering wheel to blazes you would enjoy this car if you wanted a cheap thrill but i just want to find out whats up with it.