What are the signs of bad turbo???

[danman]

I took my friend for a little spin in my new car, a 1974 260Z with 280zxt swap done by previous owners (not the one I bought it from). Car sat in a garage for 4 years because couldn't find shop to do illegal smog anymore, when 2003 rolled around it was exempted in California (not bad emissions, just no cat or other smog equip. Lucky for me car is exempt now).

 

Friend said that my blow off valve sounded strange and the turbo might be going bad. Previous owner was running 17psi boost intercooled and upgraded injectors with Jim Wolf computer controlling things. The blow off sounds a little like the three stooges (whoop, whoop, whoop in higher pitch) it is not an even and smooth sound. This is first car I have owned with Turbo so I don't have car to compare with.

 

The car also seems to loose power somethimes when at mid throtle. When pushed hard though it is scary fast almost like it is set up to run hard and not cruise. Car runs rich. Car idles high about 1,300 RPM and will sometimes fluctuate. Stock should be around 800 RPM, don't want to mess with idle speed until I can consult with shop that did orig. transplant, but they couldn't get me an appointment until Jan 5th. I don't want to screw anything up, so until I know what was done I won't change idle speed, might have cam swap and who knows what the Jim Wolf computer is programmed to do. I will request copy of paperwork from original shop. I will check timing on Monday at friend's shop, also all hoses will be swapped many are hard or cracking. Plus I am doing other basic tune-up items and draining flushing and refilling all fluids, going to change some of the fuel line and all filters. Car is running two fuel pumps and fuel line doesn't look stock. Not braided steel, just large. Maybe these items will fix.

 

How can I tell if turbo is bad or is my friend talking out of his arse? Shop may tell me turbo is bad. Can't vouch for reputation of shop yet, although install work looks good. With me mechanics have to earn trust, seen too many shaddy ones over the years, even at dealerships. I don't want to get hosed and be told something is broke that isn't. Guys sound good and honest over the phone. They were glad to hear the car was coming back to their shop, they hadn't seen it in many years. He said it was incredible car when tuned properly ( at low boost it was running 5 sec. 0-60 with mid 13's 1/4 mile time according to shop). It has seen a few years of neglect recently. The owner I bought it from didn't seem to care for car very much anymore. It had been sitting for weeks when I came to see it, needed to be jumped to start. Since then starts right up every time. Guy was rich and had gotten tired of his toy. Lucky for me.

[240hoke]

The "whoop whoop" you are hearing is compressor surging more than likly, sounds linda like there is a bird under your hood when you let off the gas? This is caused by the boost slowing the turbo down when the throttle plate is shut. I would suggest to check you vaccum line to the BOV.

 

As far as checking to see if the turbo is good or not, there are a couple things to do. Take off the air inlet to the turbo and check to make sure the impeller turns freely and smoothly, also wiggly it back and forth to check for play. Play shoud be nonexistent. Chances are if the turbo doesnt have much play then it's OK. Next take off the outlet pipe from the compressor and check for excessive oil, if the turbo bearing is shot you will see oil here. If all that checks out fine you should be good to go!

 

Sounds like a nice find, good luck with the car.

 

Oh and get us some pictures!

 

-Austin

[danman]

Thanks for the info. I have changed all the vac. lines, (including one that runs to BOV) that I could do without going behind the dash. Two lines run through firewall to dash. I am taking car to original shop that built her on Jan. 5th. I will try and check these items you list before the shop sees it. I don't wan't to be sold something I don't need. I confirmed that they are decent shop through local Performance shop owner. I trust this guy and he vouches for the shop, but at $90 per hour I do as much work myself as possible.

 

The idle runs at about 1000 RPM's now that I changed vac. lines. (It used to run around 1500RPM) It still will surge plus or minus 100 RPM. Also the power seems to cut out when cruising and then give gas, I have to shift to bring her around. Car is running Jim Wolf computer. The whole car sat for 4yrs. I don't know how much care was taken when put in storage. I am doing all the standard care items, drain and flush all fluids, replace fuel line, all hoses and belt, new spark plugs and wires, fuel filters, PCV valve, etc. I have a feeling that the fuel injectors might be clogged too, is there good way to test, I believe they are upgraded units. I need to check TPS, that can cause strange things to happen also.(what is procedure to test TPS, enigine should be from 280ZXT, not sure which year think available 81-83, head says P90, can't see block, but must be F54)

Any thoughts on idle issue and power loss when cruise an give gas???

 

Will post pics when my fuel line is done and car is safe again.

[Lockjaw]

You should clean all your connections to the electrical components with brake clean, specifically, the ecu, the TPS, and the MAF, since it is a JWT ECU you should be running either the Mustang Cobra maf or one from a 300ZX. You may want to check the 300 ZX one to make sure someone hasn't removed all the screens.

 

I would also run some fuel injector cleaner thru it since it has sat for so long.

 

Also, the MAF should be 18 inches away from the inlet of the turbo.