Help me diagnose whats wrong?

[frapjap]

I am thinking about picking up this car and joining the Z crew, but I don't know a whole hell of a lot about VG's or the 300zx temperments in general. Here is the guy's local ad.

Quote »i have a 1990 300zx twin turbo 96500 miles black with dark gray leather int. The car has some type of engine problem the car does run, but won't stay running when it warms up. Might need engine rebuild because car also smokes when you are driving and the rpm's are under 3000. The car might need some type of sensor like mass air flow meter, iac, valve coolant temp, not sure. Also changed 2 bad injectors and runs better than it did before but still has issues.

Modifications done about 100 miles ago

JDM transmission......................................$500.00 Southbend DXD 6 puck sprung clutch....................$400.00 Fidanza 9.5LB flywheel................................$350.00 Megan racing down pipes 2 1/2 in......................$150.00

other modifications

pop charger/intake greedy mufflers Eibac springs Tokico adustable shocks[/quote]I'd really like to get a hold of this car, but I don't want a massive headache and take a loss on it if I do purchase it...Personally, I think there is something wrong with a Coolant Temp sensor or fuel related, but I don't know for sure. I'm fairly mechanically inclined, I do think I could manage working on the car- even though it is very compact in the engine bay!

Modified by frapjap at 2:42 PM 1/24/2007
Modified by frapjap at 2:51 PM 1/24/2007

[gpelite]

How much is he asking?

Could be any multitude of stuff, there is not much there to go on. Could be as simple as a MAF or as extensive as inejectors and burnt plugs and dentonation from such an imbalance neglected over time. Can you tell if its burning oil? How are the oil levels and pressure?

who knows, just get it cheap because of it

[frapjap]

He is asking 5000. Its in really, really nice shape. Its a stock body in black.

Here are some pictures. It looks well taken care of- not in need of a bath, rims arent covered in brake dust, etc.









The ad says flexible on price. I figure I'll go and test drive it and keep chewing him down until I get it for 2000-3000 and then I can spend that extra cash fixing it/getting help from the forum...if you all don't mind that is.

[evildky]

I doubt at 96k it's anything serious, if ti runs fine till it warms up it's the chts, a pain to get to but easy fix, depending on how the problem presents could also be the knock sensor, at any rate for 5k sounds like a pretty sweet deal for a clean chassis

[frapjap]

What might be causing the knock sensor to react?

*This will be the first time I've ever had to deal with a knock sensor so I'm not all to familiar with it...

[mark1212]

the knock sensor is known to have all kinds of problems, the ecu actually doesnt recognize that its there b/c the sensor goes bad, so the ecu kinda goes into 'safety' mode and retards the ignition timing by 5 or 6 degrees. read the codes the ecu stores to see if that really is the problem first tho if the guy will let you. go to this website,

http://zhome.com/ZCMnL/PICS/ecu/ecu.html it has a step by step instructions on how to read the ecu for codes about halfway down the page. this should be done before you buy the car if possible. let us know what codes you get if any.

[frapjap]

You got it! Thanks a hell of a lot guys!