Previously in another thread I responded to this problem and finally cleaned both the IACV and FITV and both checked ok. No check engine light every came on. Replaced fuel filter, spark plugs and wires and rotor cap. Drove it for maybe 100 miles. Assume the fuel pump is ok as I can drive the car at speeds above idle and it seems to run fine except not quite as responsive.
At Idle when in neural at times it kinda will miss or pulsate and if I put it in gear (automatic trans) the idle will drop and it will then run somewhat rough and would stay running at times and then idle would increase. If during this time if I slighty push the throttle it may stumble and sometimes will shut off. If I pad the throttle it will stay running. I will also point out that when the engine is cold the hesitasion is almost minal. After it reaches normal temp it begins this hesitation.
Today I removed the plugs (that I replaced 100 miles ago) and found the electrodes to be completely brand new looking with no evidence of any change of color…just brite white! I then reinstalled them started engine and checked timing and it was right on. So maybe, just maybe the fuel is the issue since the plugs seem to be burning way lean? Back when I replaced the fuel filter it had small particles of rust in it. Could it be the injectors (all of them) be partially plugged due to bad gas or particles entered injectors? All the plugs had the same condition like they had never been out of the box. I have a fuel gage but that small bolt on top of the fuel line at the filter hole size does not fit the 1/8" gage fitting so I am unable to check fuel pressure. Could it be the pump is ok and the internal intake mess sock is somewhat plugged and restricting fuel to the engine at times? If this was so the engine at high RPMs would die or bogg and it does not do that. At hot idle could it be all of the injectors are not delivering enough fuel for idle air requirements due to be partially blocked? I guess maybe when I throttle down on it they deliver enough fuel to not starve the engine on a demand basis.
Any suggestions, Thanks…frustrated :tapfing:
def. sounds like a fuel issue to me…
check for vacuum leaks? use starter fluid
Have you checked to make sure your coil and ignitor unit in the distributor are within spec
In my experience, missing and hessitation is usualy distributor/spark related
Since the plugs have no color on electrodes would not be a spark related? The plug electrodes are just like new, bright white, if it was lacking spark wouldnt the plugs be fouled or show signs of fuel not burnt since it would be lacvking spark to burn “all” of the fuel properly? thanks
Not exactly, Fuel is a good solvent and evaporates fairly fast when not under pressure. In the long term, yes it would show signs of fouling with lack of spark.
Did you pull the plugs after the car was resting? or immediately after running the car?
yep. checked them both ways
Well problem is the iacv. I cleaned it previously weeks ago. This evidently has been slowly going out for sometime with an intermittent miss (only at idle) at first and steadily got worse. Sure acted like a case of bad gas with the missing. It finally showed itself by “starting to rev up and down” which it has never done before and really started to miss badly and die out now.
Question, is this iacv (two wire) specific to model/year of the 1990 Ls B18 or is there another later model replacement. thanks
BTW thanks for the replies