rough idle/stalling at cold startup? LS B18A

**max06** · 20-10-2006 03:06 PM

hi guys, im new but I have been reading these forums for a while. i know there are many similar cases but i havent read one like mine yet. sorry if this has been covered. I just had my timing belt and water pump replaced and when i picked up the car and started it up it kept stalling on me. I got it home though. Now, every time i start the car, instead of the choking system kicking in, first the revs go up for a second then down until it stalls. Sometimes it only almost stalls but picks itself up at the last second. The problem is alot worse at cold startup. It is idling at about 600-700 rpm and its rougher than usual. It makes alot more smell at startup than usual. before i never had any of these problems. went back to the mechanic, he says all the timing is perfect and it couldnt have anythign to do with what he has replaced. His offered to look at it again but i thought i would ask on here anyway. I dont think its a leaking vacuum. Ive read about people cleaning out the IACV and throttle body. Is this a good idea in my case? At the moment the only way i can stop is stalling at cold startup is obviously to rev it, but i dont think its a coincidence that the car was always idling fine and now just after timing belt is replaced its like this.

**JasonGilholme** · 20-10-2006 03:21 PM

Dude don't waste your time. Take it back to the guy.

Your car was perfect before you gave it to him and now it doesn't work. its his fault let him fix it.

Don't let him charge you anythin either. Its his job to give you your car back in the same condition that he received it in.

**FEL12X** · 20-10-2006 03:25 PM

my LS has this problem before

it was the head gasket...coolant got into the head so make it rough idling

hope urs not like that

**max06** · 20-10-2006 05:04 PM

i'll mention the head gasket and coolant. I know for sure that the coolant was replaced, but how could this get on the head gasket?. if it was a build up of carbon or dirty something in the fuel injection or throttle body, it wouldnt have just happened over night would it? wouldnt it have been more gradual?. it just makes no sense that this would happen after a timing belt is replaced. yeh im definitely going back to the guy, i already did go back today and he said what his done with the timing belt is all perfect and the timing is perfect and that this problem couldnt have been caused by something he has done. But he was not sure either. its strange. any other ideas? anyone..

**JasonGilholme** · 20-10-2006 05:11 PM

Get him to redo it. it could be out by a tooth or two.

**Edgeauto** · 22-10-2006 10:16 PM

Does it drive allright or does it seem sluggish? If it drives ok prob nothing to do with the belt timing

**max06** · 23-10-2006 09:35 AM

hi, yeh once the engine is warm and the car has been driving then it all seems pretty normal, maybe a little rougher on idle at the lights, but not much. Its really just at startup that there is a problem. I am not driving it at the moment before i go back to the mechanic but i started it up the other day on a cold morning and it was even worse. There was no consistency at all in the revs and it would have stalled. I believe the mechanic, that it has nothign to do with the timing belt. Because it sounds more like a fuel sort of problem and that section of the engine is not anywhere near the timing belt. Its possible that the problem just happenned while the car was in his care, but thats pretty dodgy. What could he have done to my car to cause a problem like that? I know he did drive it around a bit. i will know in a couple of days.

**TRU32U** · 24-10-2006 09:47 AM

sounds like timings out like when was replaced was it taken to TDC??

**EGB18CT** · 24-10-2006 09:58 AM

mine does the same sort of thing too, only on cold start but mine idles around 2000 then slowly drops once the car warms up then fluctuates between 1000-1100rpm. Now i hve cleaned out the IACV valve and the throttle body out twice but it still does this. NOw i changed my timing belt a few months ago when i did my engine conversion and checked the timing with a timing light and it was spot on. Its just getting worse.

Now i know i have a rooted brake master cylinder so my brake pedal creeps to the floor then i use brakes, could this be the problem??? just a thought.

Got similar problems to u dude.

**max06** · 24-10-2006 10:09 AM

What is TDC sorry? The mechanic has checked the timing. he says its perfect. But im taking the car in later today. If the timing is out wouldnt it effect the car the whole time and not just at startup? What the mechanic did say is the old timing belt around the exhaust camshaft (i hope im making sense) was out a tooth or had skipped a tooth and thats why it had less power. I noticed my car does now have alot more pickup now which is one good thing that came out of this i suppose.

**dudeling7** · 24-10-2006 10:27 AM

TDC = Top Dead Center

relates to the position of the piston in each cylinder

**max06** · 26-10-2006 09:23 AM

ok so an update on this problem. Throttle body was cleaned out. Picked it up form the mechanic and the car worked nicely, idled normally. This morning at cold startup, same problem just not as bad, but still evidently there. When the engine is warm theres no problem at all at startup and obviously the mechanic didnt check this because the engine was never cold. Does anyone else have any idea what it could be. I thought it may be the automatic choke playing up, sometimes it works sometimes it doesnt. What does the IACV do and could this be the problem?