engine dies when i pull out dipstick

[IdahoKidd]

Not in old school American V8s and apparently not Korean cars. My teenage daughter, bless her non mechanically inclined heart, checked the oil in her Kia Sportage and then tossed the dipstick in the trash can at the gas station. Drove it for a month. I open the hood and there is oil residue everywhere. This car makes a tremendous amount of positive crank pressure. Still ran like it always did though. (aka, slow, no power, etc :sick:)

[conedodger]

nope. aside from a 20 over rebore and a replacement identical head, i haven't changed anything. it ran much rougher before the rebuild, in a different way. now it kind of misses and lopes a little, but never dies like it did before. i keep finding vacuum leaks and fixing them, such as the injector seals, and it improves incrementally with every leak i find. this could be just another one.

my dad has worked mostly on german cars in the past. is the engine dying when the dipstick removed something that doesn't occur in german cars?

Each car is individual although you will find that many of the early efi systems were made by Bosch and you will find many of the same characteristic patterns in these cars that used LJet, DJet etc... As an example, when my 914 was DJet, if I pulled a vacuum line to create a vacuum leak the engine would surge to 3000 RPM. My 911 which is a much later derivative of LJet than your 280Z is completely unaffected by removing the oil cap. By the way, you should also find the car kills when you remove the oil cap.

The idle you posted is not really indicative of a vacuum leak. There is a procedure for testing individual efi components. It can be found in the FSM. You might consider running these tests. I had a situation not unlike yours and I checked the CHT resistance and found it to be higher than spec. Replacing it cleaned up the way the car ran in more than one way. Hydrocarbons down, driveability up. Because of that higher resistance the efi brain has to assume that the CHT is high and to protect the engine it increases injector pulse time.

Pop the caps on your TPS and AFM. Each has a set of copper strips which can get gunked up with corrosion after years of use. Use a very soft pencil eracer to gently clean this off then replace the cover. Most efi components in the LJet system send resistance signals to the brain which controls pulse time on the batch fired injectors. If things get gunked up resistance can increase, sometimes to infinity.

Edited January 13, 2010 by conedodger

[tlorber]

I don't think it is a great idea to pull the dipstick while the engine is running. I remember doing it once on a car (I think it was a 1200 in college). A lobe on the crankshaft launched the dipstick into the air and it landed in the dirt. Luckily those cars thrive on abuse.