rough idle/stalling at cold startup? LS B18A

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. :confused:

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.

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

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..

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

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

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.

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

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.

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.

TDC = Top Dead Center

relates to the position of the piston in each cylinder

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?

would like to know 2!!! mines got the same problem as mentioned before!!!

throttle position sensor?
i had the same problem, just replaced the throttle body.
lol

how much does a throttle body cost. or how about a new choke valve. the mechanic told me about $100 for a second hand choke valve from a honda wrecker in melbourne. thats if thats the actual problem though.

i assume you mean the fast idle valve;when it is cold and playing up remove the intake tube off the throttlebody, there should be 2 holes in the throttlebody(firewall side)from memory top 1 is for the fast idle and bottom is for the EACV. Put your finger over 1 hole at a time to restrict the the air flow, if it idles better match the component and thats most likley your problem. Also check your base idle screw as a rule of thumb it should be wound out about 3/4 turn

thanks. I'll defnitely look into that. Im pretty sure its somethign to do with IACV/ FITV. a guy whos an apprentice at honda said it could be the spark timing. I have no idea what that is though. does someone think that could be the problem? Because the timing belt has just been done it would make more sense. But the mechanic says his checked the timing and its fine. At the moment at cold startup the FITV will kick in if i give it some acceleration. if i dont it will usually just stay around 600rpm and is extremely rough. I know i have to check those things mentioned above but i cant do it myself so im just waiting now. I dont really want to go back to the same mechanic.

Did the mechanic check to ignition timing or belt timing when you took it back? Maybe he check ignition therefore the exhaust cam timing could still be out. Take it somewhere esle and if it is a problem with his work go back and ask for some compensation.

so a little update on this problem for anyone having similar problems. While the problem is not fixed yet. Everything has been checked/cleaned including TB IAVC and FITV, and the car is running a whole lot better for it. But finally last nite we found a tiny crack in the distributor cap that connects to the leads(i think) so the electricity is not earthed properly. So new cap on its way and some new leads and also found a tiny coolant leak from one of the little hoses during cold startup which ceases when the engine is warm. So a new one of those and hopefully and finally the problem will go away. :)

problem still not fixed. it's so annoying. things i have had done since my timing belt got replaced and the problem started occuring.... cleaned throttle body, IACV. FITV cleaned/checked(but not replaced). The problem was thought to be that it was sticking but it sucks air very strongly at startup. Distributor cap replaced because of little crack. New hose where there was a slight coolant leak at startup. Engine oil flush, oil change... added injector cleaner to my last tank.
All of this has helped slightly but problem is still there. Basically the Fast idle will not engage by itself at cold startup. it will only start to engage after given some revs. The engine sounds rough and hunts up and down, until FITV engages and there is lots of fumes i believe from petrol being injected but not being burnt. Once everythign gets going the car is like normal. Im really stumped. i want to go back to the mechanic and ask wtf he did to my car when he did the timing belt but I know he will just tell me the timing is fine and that it wasnt anything he did and that he will look further into it which means $$$$. i suppose its my only option. sorry if i keep repeating myself.....:p

This sounds just like problem im having. My car has pretty much exact same problems as this. Just had a new distributor put in as i kept getting CEL from problems with it. But my rough idle has been there for awhile. My timing belt was replaced about 2-3 months ago which is about the time i started to notice the problem. I have cleaned TB, IACV and checked strong suction from FITV at startup but still most times it starts with a really low rough idle. Any ideas anyone, its really quite annoying.

Hey, i've mentioned before that my LS did a similar thing, it was the main relay that had a problem. i didn't even think of it before, because i'd just bought the car when it started, but it was after i had the timing belts replaced...

Not saying it is the main relay but its worth a look if your stumped.

anyone got a fix for this problem i might have a similar problem?? old thread brought back to life