new to z need some help with experience z owners! please

[Zed Head]

It's a 280Z with EFI. Running rich is a typical problem, usually caused by corroded sensor connections, or bad fuel pressure regulators or AFM adjustments or leaking cold start valve. If you use the search box and look for "running rich" or "fouled plugs" or "bad gas mileage" or similar you'll find a bunch of threads dealing with tuning up the 280Z EFI system. It seems like any 280Z that sits for a year or more develops a "running rich" problem. Gas in the oil often comes from excess gas in the cylinders leaking past the rings.

125 psi is not that low. There's a lot of variability in the gauges that are out there. Consistency between cylinders is what's important, and your numbers look pretty good. You should spend some time fixing the small stuff to get it running right before diving in to head gaskets. The EFI systems seem to go downhill pretty fast if they're been sitting for a while.

Tune it up and put some miles on it. If the gas in the oil is a small quantity, the PCV system will clear it out if it's working right (hopefully a PO hasn't disconnected it). A poorly working PCV system could actually be the source of the gas-in-oil smell.

[FastWoman]

^^^ What Zed said. Especially check out the coolant temp sensor connections. The CTS is the smaller of the two items screwed into the thermostat housing and having a 2-conductor Bosch-style connector on it. Those connectors at the front of the engine are exposed to pretty harsh conditions and can rot and corrode pretty badly. The CTS, BTW, is "THE" most important influence on fuel/air mixture, other than the AFM, and a weak connection in that circuit will have your engine running quite rich.

[mn91]

OK thanks guys you guys made me feel a lot better I will try the wet comp test and let you guys know what's the deal. Then I'll have to look up how to do a valve adjustment... Is it hard? Sounds hard never done one before.. I'll look up All the running rich stuff and post back on what I encounter. Thanks again

[mn91]

ok so i did a wet comp test on cylinder 1-3 bc thats all the oil i had for it. i warmed up the car made sure it i had it at wot and put a few drops of oil in and comp only raised about 10 psi on each cylinder. my compression was 125 120 130 125 125 125. with wet i had 135 130 140 on the first 3. so what you guys think? bad? or not to bad? thanks in advance

[mn91]

bump! anyone know?

[240260280z]

ok so i did a wet comp test on cylinder 1-3 bc thats all the oil i had for it. i warmed up the car made sure it i had it at wot and put a few drops of oil in and comp only raised about 10 psi on each cylinder. my compression was 125 120 130 125 125 125. with wet i had 135 130 140 on the first 3. so what you guys think? bad? or not to bad? thanks in advance

My Z had similar numbers when I got it and ran "ok".

Adjusting the valves, and de-carboning the chambers may help bump up compression an additional ~10-15psi.

If you are not losing rad fluid, if the plugs look ok, if the oil looks ok, and there are no unusual sounds then you should be good.

FYI white smoke at start-up is usually 3 things:

1. overnight condensation in your exhaust system evaporating

2. water vapor from the combustion process condensing due to the cold exhaust system.

3. water vapor from the combustion process condensing due to the cold ambient air (more pronounced on cold mornings (especially in winter)).

Once the exhaust system comes up to temperature, the white smoke decreases.

Unless you see white smoke all the time and are losing radiator fluid, don't worry.

Edited November 25, 2011 by Blue

[mn91]

Thanks for the reply. But the problem is my plugs are foul and my oil smells like gas. Been trouble shooting for a few days now. So I'm just trying to make it run less rich at the moment. But I've been searching up all of the suggestions from everybody and trouble shooting it. Thanks people

[Zed Head]

If you post more results from your tests, you'll get more feedback. So far you've only shown cylinder pressure numbers (which looked pretty good to me). Have you been driving the car, or has it been sitting in the garage since 3 days ago when you noticed the white smoke and the gassy oil smell??

[mn91]

Yeah ive driven the car forprobably another 50 miles. I've been busy with the holiday and all that but I will post back tommorrow when I start troubleshooting some more. I spent most my time reasearching and reading the fsm

[240260280z]

On 280z's, a common problem are the electrical connections in the EFI system. The main culprit for fuel fouled plugs is the pigtail to the temperature sensor at the thermostat housing.

Read these two links and you will understand better.

http://atlanticz.ca/zclub/techtips/runningrich/index.html (read the stuff below the dyno graph)

http://atlanticz.ca/zclub/techtips/electricalconnections/index.html

You should also use NGK plugs.

Edited November 26, 2011 by Blue

[mn91]

ok so when i was checking my sensors and taking things apart my and the ground wire on my temp switch (the sensor with 2 wires coming out of it one is ground) broke off.. the car runs and drives fine without it but is it crucial? and when taking things apart i noticed that there were a wall of oil in my throttle body so i ran seafoam through it and now it does not hesistate or stumble anymore! but im sure it will come back soon.. just a guy feeling. and also should i run the seafoam through my oil? the only thing is i dont want it to unstick things that shouldnt be unstick and it might mess up the motor.. just stories ive read online..

also my afm the black cover will not come off! there isnt a screw or anything to take it off. it looks like someone glued it on. and it also looks really really new.. what you guys think?

[240260280z]

No need to mess with the AFM idle bypass (black cap) at this time. Its purpose is for emissions at idle.

If you have a multimeter, you can measure the resistance of the temp sensor at the thermostat then measure it where it connects to the ECU at the driver kick panel. The resistance should be similar.