On Saturday I took my 1990 DA into the shop to have some work done including:
-new timing belt
-new water pump
-new GReddy header
-new 02 sensor
Upon the completion of the installation of these I am now getting a fluctuating idle. My car will now try to stall at idle at which time it will rev itself up to about 1500 rpm and it continues to do this. It seems to only do this while the car is warm and not during warmup where it seems to idle fine. Sometimes it will actually succeed in stalling itself. Other times it will stabilize at regular idle speed. It also makes an odd noise through the intake that sounds like a popping noise before it revs up. That might be normal but I had never noticed it before.
We did have a problem with my car wanting to overheat after pouring coolant into it when I was about to leave the shop. I turned out to be an air pocket in my radiator. After bleeding the coolant it seems to work fine. I don’t think this has anything to do with it but I thought that I may as well mention it.
Is it possible that my timing may be off? I asked the guy who put the belt on and he said that it is impossible saying my car wouldn’t run at all; which is contradicted by some of the posts I’ve read while searching.
I don’t know if it would have anything to do with the installation of the new header and 02 sensor even though I would think that it shouldn’t.
I have searched this topic incessantly and I have no idea what it could be other than the timing. I had a problem like this before and it turned out to be my FITV. So I know all about that. I have already replaced my IACV as well. And yes I have reset my ECU several times now too.
Just two days ago I installed a new water pump, timing belt, and tensionor. After everything was installed, the car had a rough idle. I knew right away that it was my cam timing. I redid it again, and it was off again. The third time was a charm, got the cams and crank aligned in perfect order.
Now the car has the best idle that I have experienced since owning the car. When I am on the road and I come to a stop, the idle drops to 800 rpms and is ROCK solid. It used to jump around, lope, and stall on occasion. I can’t believe how well it is running and idleing with 290K miles on the clock.
My advice to you is to pull the valve cover, take a 19 mm socket and turn your crank counterclockwise until the up marks on the cams are pointing straight up. Next, take a strong light and look down at the crank pulley. There will be a single white mark to the right of 3 other marks. Check to see if the single white mark is located directly under the pointer on the lower cover. If the cams don’t line up with the up marks straight up and the crank pulley’s white mark line up with the lower pointer, you car is out of time.
I bet half of the tegs out there that have bad idle problems are a result of either one of the cams being a tooth off or the crank being a tooth off in relation to the cams. I have had my car for going on 3 years, and now that it is timed perfectly, it runs really strong and idles like new, never dropping. Good luck to you.
PS–an air bubble in your head can make the car idle funny, so if that is the case, sorry I made you read all that.