Engine Surging When Warm. Idle And Whilst Driving

delbhoy · March 13, 2013

Hi folks, I'm a newbie here. Over the last few weeks my IS200 has started revving up in a rythmic motion. It idles at about 800 RPM and surges up to about 1500RPM and back down again. I took it to the garage and they plugged it into the diagnostics. It showed a P1306 code which was the camshaft position sensor. I've since had that replaced and the problem persists. It happens every time I drive the car. I can also feel it surging a little while I'm driving it. After extensive research, I've come up with all sorts of problems. Some say Idle control valve, some say PCV, some say throttle body and some say vacuum leak! Please help as one of the things I seen was a head gasket! I really don't want it to be that!!

Any help would be greatly appreciated folks. Thanks

steve2006 · March 13, 2013

I would start with the easy things you can do yourself for little cost i.e. clean the throttle body and the IACV.

It could also be the AFM so I would unplug it and start the engine and see if the idle speed stabilises without it.

To check for a vacuum leak buy an automobile stethoscope for a few pounds to probe and listen for air leaks.

Interesting article below regarding the VVTI causes erratic idle.

http://www.aecs.net/techniek2011/Oct%20Lexus%20.pdf

delbhoy · March 13, 2013

Got it booked in in a couple of days at a mates garage so we will go through these things step by step. When he put the diagnostics onto it, it read a P1306 (I think!) which was the camshaft position sensor. I subsequently got a new one and had it fitted that day. Drove out of the garage and it started doing the same bloody thing. So, the engine management light has come back on again and it's reading the same again! I may have to get in touch with the seller of the part incase it was a dud. Anyway, hopefully it won't be too serious.

Thanks again.

delbhoy · March 13, 2013

Also, that article was interesting. Thing is, mine isn't revving up that high. It was idling at around 8-900 RPM, and surging up only by about 500 revs to 13-1400. Today the throttle body was cleaned, and was a little stiff. Now it sits at around 1500 and surges up to about 2000! I reckon it'll just need the ICV altered now. My mate was in a hurry today so couldn't do that.That'll take the revs back down but I doubt it'll solve the problem. It's annoying because the regularity of the surges has been increasing. A few weeks ago when it started, it was only about every ten seconds. Now it's every two or three. Hey ho.

dandydons · March 13, 2013

Maybe a longshot but worth checking your coolant level - I had the same issue many years ago on a corolla gti - and was a simple fix of topping up coolant level . That was after going round a few garages who failed to diagnose .

delbhoy · March 14, 2013

I'll check that in the morning. Thanks

delbhoy · March 14, 2013

Checked the cooland, and I'm glad I did! It was way down. Topped it up and took it out for a run and it's still doing it I'm afraid. Cheers for saving me some other problems though!

dandydons · March 14, 2013

Checked the cooland, and I'm glad I did! It was way down. Topped it up and took it out for a run and it's still doing it I'm afraid. Cheers for saving me some other problems though!

it was a bit of a longshot - thinking back I think the corolla did it more from cold compared to your problem but no harm done with topping it up.. hope you get to the bottom of it.

delbhoy · March 16, 2013

Right, a little update folks. I've bled the coolant system and the problem continues. Just to be a bit more concise - when the engine warms up, the problem starts. What I have noticed is when it's idling, it stops for a minute before the fan comes on. Then the fan goes off, and it starts doing it again! Pulling my hair out with it TBH. Any ideas based on the new info I've given?

Thanks for the help guys.

delbhoy · April 3, 2013

Final update on the situation folks. I had it in the garage and the mechanic called me to say he hadn't seen anything like it! The timing belt was shredded with handfuls of shredded rubber in the timing belt case! And it had jumped 3 teeth! The guy wouldn't even start it up to move it, he was that worried about it going. Anyway, got a new kit and had it replaced. Everything is going like a dream.

Thanks for the input guys.