Problem Previa Plz Help

[codhead]

hi peeps,

I have a n reg previa 2.4 petrol rear wheel drive and she's manual box.

I have just had her in for m.o.t. and she needed a new cat, which i got the garage to do and she all passed, when i picked her up i had a advice note saying i had coolant leak. And sure enough, i stopped on way home from garage at shop and when i got back she had a pool of water around her :~( so i had her towed home to investigate. thought it was gonna be a blown hose or rad, or may be something along them line but when i opened the bonnet the header tank was still full of water. so next day stripped down cooling system and flushed water bottle was completely blocked up, it was moor water tight than a ducks a**!!!!!!!!!!!!! also found some origanle hose clips that were beond best!!!!! so replaced all of them!!!!!! put her back together with a new double layer rad in :~) filled her up with coolent and ran with expantion tank cap off till she was hot and thermostat openned, topping up as nessercery. turned her off alowed her to cool and topped up again. right thats the history now for the problem............. once i was relativly happy with myself for sorting the cooling isue took her out for a run....... she is fine when cold and she walms up just fine just like she always has, the problem start when she upto temp (you know just when the revs drop down ) if i have to compleatly remove foot off accelerator res drop BIG time and bounce be tween probs 100-500 rpm and she sounds like she wants to stall out. now she not stalled yet just sounds like she wants to and she's running fine if i dont stop ( which i wouldn't if i was in a ideal world but i live in town so stopping nessasery!!!!! )

so just wanted to know if anyone had any ideas PLZ included the whole story incase i done some thing wrong with the flushing stuff. many that for any help you can give!!!!!!!!!!!!!

[codhead]

OK just couple more points that may help......... firstly the problem will happen while not on breaks/as soon as i take foot off of accelerator ( though about adjusting throttle cable??? ) also not sure if they fitted cat properly, noticed, while bleeding coolant from engine, that no gasket been used on cat just exhaust sealant and that don't seem to be sealed all way round??

[propnut]

Idle speed is controlled via the ECU and actioned by the ISCV (idle speed control valve). The throttle bodies on these cars get horribly gummed up and it is worth taking it off and giving it a damn good clean with carb cleaner. Does sound a bit odd that it was fine before the new cat was fitted though. The ECY does take input from the lambda sensors but only as far as how rich or how lean to make the mixture.

There is one other possibility however and this is based on the fact you have worked on the cooling system. Under the drivers seat inspection bay there are two sensors. The coolant temp sensor and the cold start injector time switch. The coolant sensor has a green top and if you have an air block in this region it could play havoc with your system. The is a bleed bolt in that housing, may be an idea to loosen it and ensure there is no trapped air.

Also air in that area will stop the cold start injector time switch operating and could see your cold start injector opening unnecessarily.

[codhead]

Many thanks propnut you is a star.

I'll check for air then and clean up throttle body. more time with me Haynes and spanners then great fun :~)

although why don't Haynes tell you there is more bleed bolts i only got the ones on rad and by the water pump............ hayhoe. I think am gonna have cat off and fit properly too there must be a gasket for it rarther than that gunge they have used!!!!!!

Many thanks again pal !!!!!!!!!!

[propnut]

The flanges should be sealed with a circular copper ring or asbestos gasket. Only a muppet would use gun gum. Also note that if any of the gungum they used has found its way to the sensors then it will render them useless and could also very well be why you are seeing the problems you are as the ECU is getting erroneous feedback.