Low Speed Juddering

Calum122

Member +
Hello,

So the other day I gave the engine bay a much needed jet wash...uhh didn't clean anything at all.

I then let it sit for about a week before I drove it next, it was just Sunday and I don't drive it during the week.

I noticed on the following Friday that below 2K the car is now undriveable, has low speed juddering and if you increase the throttle, nothing happens. After a few moments, the car lurches into boost a bit unexpectedly.

At first I thought it was just water got into somewhere it shouldn't, then I figured I must have blown a vacuum line off somewhere. But after a fair few weeks, and a good mooch around the engine bay, I can't seem to pin point the source of the fault.

To clarify, anything about 2K, 2.5K or 3K (One of them definitely 3K) the car drives and pulls hard. No hesitation in the upper rev range. I suspect it's a boost leak, and now I'm just working the turbo harder than necessary to overcome the leak.

Is there any other common thing that would cause this?

I was thinking, maybe the igniter, dizzy or leads are just getting old and new renewing. The spark plugs are like 5 years old as well, never changed the fuel filter. Air filter is 5 years old.

I'm reluctant to spend any money on this car at this moment in time, having spent thousands on it, and just in the process of buying a house. It only needs to last a few months then I'll pull the motor and give it a proper refresh.

But any ideas?

Cheers,

Calum
 

SKINY

Lifer
mine started doing something similar in heavy rain, Jay advised to to check spark plug leads where sealed on the rocker, wee bit of Vaseline later and all was good :)
also had a slight misfire when i had it on the dyno, king lead, cap and arm all got replaced for new and cured it. I couldn't tell driving it about but the dyno boy Gavin @g-sport spotted it, you can see on the graph too where it missed. Still made a good healthy 148 HP :)
 

Calum122

Member +
It had a new genuine king lead, and HT leads are magnecore aftermarket, done probably long long ago. Dizzy condition unknown, will be looking to replace that sometime in the future, can these be had new? Price reasonable.

I wouldn't mind replacing the ignitor for refreshments sake.

I took the plugs out, they're not golden brown like they were way back when I got the car. A little grey at the tips, slightly running lean. More black to be fair.

The spark plugs were dry, I sprayed a little electrical contact cleaner, but this did not remedy the problem.

Once everything is up to temperature, car idles at around 600RPM. Used to idle spot on before I jet washed the bay. I'm adamant it's a vacuum leak.

It seems below 2K RPM, no matter what gear, the car has a really hard time, then jumps into boost.

Car seems a little down on power, but still revs out.

Such a fantastic, reliable car though. Despite the endless mistakes I've made and problems I've had. The fact it's still boosting is just testament to Toyota really.
 

Calum122

Member +
No I didn't

You think they got some corrosion on them?

You would have thought the problem would persist at high RPM as well though.
 

SKINY

Lifer
its possible they are bud or maybe got water in it, in my cap the wee nipple was gone and 2 terminals where fecked but car still ran that well i never noticed till it was pointed out.
 

Calum122

Member +
So I pulled the dizzy, pulled the leads and gave them all a good bath in some GT85.

The king lead had a fair amount of corrosion on the inside, I replaced with OEM quite recently.

Anyway, wow, what a difference that makes. The car was massively down on power. Just went back out in it now, and even in the wet, with tyres that just light up, the power restored was mental.

So yeah, ignition system was at fault. Cheap easy fix, car is back to running like a dream :D

Cheers for the input lads.
 
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