Previa Idle Problem

[PeteH]

I have a 1996 Previa 2.4 GS Auto (60k miles) which has recently started juddering at junctions with a very slow idle. It does not stall but is dangerous as there is no power as I pull away.

The power then kicks in and it drives great.

Unfortunatley I cant get at the leads / plugs to check but wondered if there is a known common problem before I let a garage rip me off ?

I believe HT leads cost around £90 !

cheers Pete

[cbauto]

Hi Pete

I would be very interested to hear if you get this problem sorted. I have a 1997 automatic which has a similar problem,it does cut out occasionally. As I speak it is in the garage being investigated.I am not optimistic as it has been checked out before and no joy!!

[cbauto]

Hi Pete

I would be very interested to hear if you get this problem sorted. I have a 1997 automatic which has a similar problem,it does cut out occasionally. As I speak it is in the garage being investigated.I am not optimistic as it has been checked out before and no joy!!

[PeteH]

No probs - I will let you know how I get on but like you I am not hopeful - I may ask a garage to diagnose it and do the fix myself if its not too awkward

cheers

Pete

[nick007]

the previa had two known problems with erratic idle and engine hesitation first hesitation was either air pipi from air box split or wiring from throttle position sensor broken or idle problem was oil was sucked up the inlet manifold into map sensor/pim sensor causing wrong air pressure in map sensor the real way to fix is replace all valves and sensor and reroute new piping which will cost you a nice sum of around £400 from main dealer or take all pipes and valves off and try and clean out good luck

[PeteH]

Thanks alot for that Nick, that gives me something to go one before passing to a garage

-Pete

[Biker Baz]

Hi Pete,

Just as further options check hte strings I posted by searching on "previa idle".

The way I see it is anythings better than paying a toyota dealer £100 per hour!

Hope it helps.

I have a 1996 Previa 2.4 GS Auto (60k miles) which has recently started juddering at junctions with a very slow idle. It does not stall but is dangerous as there is no power as I pull away.

The power then kicks in and it drives great.

Unfortunatley I cant get at the leads / plugs to check but wondered if there is a known common problem before I let a garage rip me off ?

I believe HT leads cost around £90 !

cheers Pete

←

[shutty]

Toyota issued modified vaccuum pipes to rectify this, its a while ago but any good dealer will know the problem

[miti-babe]

Toyota issued modified vaccuum pipes to rectify this, its a while ago but any good dealer will know the problem

←

This is quite a well-known problem and I think that 60k miles is just about right for it to strike...

I've had this problem myself on my '91 2.4GL Auto, but I think that all the 2.4 petrol variants are susceptable to the same problem here...

I think it's down to emulsified oil vapour blocking the airways in the throttle body...

This is caused by the evaporative emission control valve, which allows oil vapours to recirculate into the inlet via a 0.5" bore tube that runs from the top of the rocker cover (where the valve is situated), across the inlet manifold and into the flexible inlet tract, about 8" down from the throttle body...

The cure (100% successful for me by the way) is to remove the throttle body as detailed in my Haynes manual (Haynes Manual No 2048 covers the USA Previas from 91 to 95... it was superb for me on this... actually outlined the problem in the text of the manual! ).

This also includes removal of the flexible inlet tract - not an easy job at this time of year... :ffs:

Next is to give the Throttle body and inlet tract a damn good clean - petrol or paraffin are favourite to start off with... the Haynes said to use carburettor cleaner, but I'd have used a whole case of the stuff... the throttle body will be covered in emulsified oil, carbon deposits and all sorts of vehicular gunk.. These will probably need to be mechanically removed (paraffin cleans off the wet stuff and softens the harder stuff) prior to final cleaning with carburettor cleaner (Xylene based these days... don't use this stuff in confined places!

As the Haynes says... replacement is the reverse of removal and if it works on yours as it did on mine, you'll think that someone changed your engine... :hokus-pokus:

Why 60k miles.? Well, the Haynes says that this known affliction shouldn't give any trouble, providing the throttle body is cleaned at every major service... Toyota recommend them every 60k miles... simple really...

Additionally... this problem will occur earlier where the car is used on regular, short hop journeys or in cooler climates as the evaporative emissions will be cooler and more likely to contain emulsified oil by-products... Such use also increases the combustion by-products in the oil and this will also add to the muck being flung at the throttle body...

Good luck B)

Jeff

[pondus]

I've had a similar problem. My mechanic found out the Lambda sensors was not working properly. After he replaced them and adjusted the ECU its spinning like at cat. I presume it didn't made it worse that I change the airfilter to a K&N-filter.

Pondus

Toyota issued modified vaccuum pipes to rectify this, its a while ago but any good dealer will know the problem

←

This is quite a well-known problem and I think that 60k miles is just about right for it to strike...

I've had this problem myself on my '91 2.4GL Auto, but I think that all the 2.4 petrol variants are susceptable to the same problem here...

I think it's down to emulsified oil vapour blocking the airways in the throttle body...

This is caused by the evaporative emission control valve, which allows oil vapours to recirculate into the inlet via a 0.5" bore tube that runs from the top of the rocker cover (where the valve is situated), across the inlet manifold and into the flexible inlet tract, about 8" down from the throttle body...

The cure (100% successful for me by the way) is to remove the throttle body as detailed in my Haynes manual (Haynes Manual No 2048 covers the USA Previas from 91 to 95... it was superb for me on this... actually outlined the problem in the text of the manual! ).

This also includes removal of the flexible inlet tract - not an easy job at this time of year... :ffs:

Next is to give the Throttle body and inlet tract a damn good clean - petrol or paraffin are favourite to start off with... the Haynes said to use carburettor cleaner, but I'd have used a whole case of the stuff... the throttle body will be covered in emulsified oil, carbon deposits and all sorts of vehicular gunk.. These will probably need to be mechanically removed (paraffin cleans off the wet stuff and softens the harder stuff) prior to final cleaning with carburettor cleaner (Xylene based these days... don't use this stuff in confined places!

As the Haynes says... replacement is the reverse of removal and if it works on yours as it did on mine, you'll think that someone changed your engine... :hokus-pokus:

Why 60k miles.? Well, the Haynes says that this known affliction shouldn't give any trouble, providing the throttle body is cleaned at every major service... Toyota recommend them every 60k miles... simple really...

Additionally... this problem will occur earlier where the car is used on regular, short hop journeys or in cooler climates as the evaporative emissions will be cooler and more likely to contain emulsified oil by-products... Such use also increases the combustion by-products in the oil and this will also add to the muck being flung at the throttle body...

Good luck B)

Jeff

←

[proteus1959]

I have a 1996 Previa 2.4 GS Auto (60k miles) which has recently started juddering at junctions with a very slow idle. It does not stall but is dangerous as there is no power as I pull away.

The power then kicks in and it drives great.

Unfortunatley I cant get at the leads / plugs to check but wondered if there is a known common problem before I let a garage rip me off ?

I believe HT leads cost around £90 !

cheers Pete

←

This is a well known problem on older 60k + mileage previas, and can be fixed one of three ways

the problem is caused by oil getting into the PIM switch from the manifold

1: take it to a Toyota delaer and they will charge you £400+ for fixing it

2: Lift the passenger seat, undo the engine cover and look just to the right of the manifold, there is a light green plug with a vacuum tunbe running from it, about 4 inches up the tube there is a filter again light green, follow this tube till you come to a black box ( the pim sensor) which is bolted onto the floor pan

remove the hose and filter from either end, although I use this method, I suggest you fdont unless you are safe around petrol, I use a syringe and wash the hose and filter out with petrol, or carb cleaner, i then remove the Pim sensor ( its held on with one bolt to the floor pan) and spray carb cleaner into it... BE CAREFUL, do NOT stick any object into the PIM, just spray into the nozzle with a short spray, and leave it to evaporate! re assamble to the lot and bobs your uncle it should be good for three to four months. ( again be careful with the pim, a replacement costs £177+vat)

Methos 3: a permanent fix for less that £20. follow 2 above, but you will also need two 3 way vacuum hose adaptors ( fish tank air hose adaptors are great for this) and about 18 inches of vacuum hose.

Where the filter fitted originally, replace this with a 3 way connector and about 4 inches of vacuum hose, then put the filter in, then connect the reamining house ( you will need to take the drivers seat out for the next bit, as you need access to the other side of the engine)

then run the hose towards the PCV sensor, next to the PCV tubing are two more vacuum hoses, now the hose you want is usually on the right ( but not always) splice into it, add the last three way connector, and connect the remaining house

Viola problem solved, what you are actually doing is using vacuum to suck the oil away from the pim sensor, so it never gets clogged again, its easy to do, takes about an hour, and is the fix suggested by toyota, but at around £20 instead of £400

[Phill70]

2: Lift the passenger seat, undo the engine cover and look just to the right of the manifold, there is a light green plug with a vacuum tunbe running from it, about 4 inches up the tube there is a filter again light green, follow this tube till you come to a black box ( the pim sensor) which is bolted onto the floor pan

remove the hose and filter from either end, although I use this method, I suggest you fdont unless you are safe around petrol, I use a syringe and wash the hose and filter out with petrol, or carb cleaner, i then remove the Pim sensor ( its held on with one bolt to the floor pan) and spray carb cleaner into it... BE CAREFUL, do NOT stick any object into the PIM, just spray into the nozzle with a short spray, and leave it to evaporate! re assamble to the lot and bobs your uncle it should be good for three to four months. ( again be careful with the pim, a replacement costs £177+vat)

Just done the above, worked a treat, cheers

does it matter which way round the filter goes back ?

Glyn

[martin bravo]

anyone knows why my techometer is not working. after a long run it gives some indication.

 it happened when i replaced the dash board bulbs.

i have 2.4 previa automatic 1995 model. LHD.

now speedometer is giving 20kph less.