Diagnostic help!

[Boris]

Hi Guys,
I've a stock 82 JA with a few hickups and am wondering if it may be a common Starion problem you can help me diagnose.
Symptoms:-
1) Runs sweetly at low power :) but at wide open throttle the boost guage only just makes it into the green. :(
2) On backing off from wide open throtle there is a sudden total loss of power for say half a second then it comes back with a drive train wrenching bang.
3) When thoroughly warm, after about an hour, the engine gets 'fluffie' past a certain throttle setting (about 2/3rds) and looses power till the throttle is reduced below the cutoff.
-------
I've tried new coil and leads, and maybe thet seemed to help for about an hour - not sure. Ive tried fuel filter - no difference.
Any suggestions?
Thanks
Boris

[merlin]

is this a stock engine, or a modified setup?

[Boris]

Yeh it's stock - ie standard - ie original - as in unaltered and untouched. cheers
Brian

[merlin]

there may be more than 1 problem here.

1. check that the waste gate flap lever is attached to the waste gate canister rod (on the side of the turbo). this may explain the lack of boost.

2. check the throttle position sensor and wires, these are prone to failure at this age.

[Junkers]

In regards to the boost gauge only making it into the green.. after time the actuator spring becomes worn and moves easily which means all the exhuast gas get bypassed via the wastegate rather than the turbo, this results in your low boost.

Anyhow you can solve this with a boost controller, they cost around $50 dollars and allow you to set the boost at whatever you like, although since your spring is warn adjusting it can be a very touchy situation.. you get there though :)

[Entaran]

Plugs and leads might fix #3.

[Boris]

Hi again,
Thanks for the help Merlin, Big Boy and Entaran. I have checked the throttle sensor against the manual and it is out of specs at 3 k ohm instead of 4-6 so that is a start. Have to grow a few extra hands to complete the test :-) Holding the multi meter on hte pins while moveing the throttle is a challenge! The wires look good.
The waste gate actuator rod is definitely attached and is very solid. It is normal to be able to move it by hand?
Cheers
Boris

[WidebodyWoody]

You shouldn't be able to move it by hand, because it should need atleast 7 pounds of pressure to move it. That would be a bit problem with not being able to get any boost

[AB]

On every turbo I've tried I've been able to move the wastegate actuator arm, and they've all been able to boost up to 12psi without problems. It needs quite a bit of a pull, but it does move. Maybe you weren't pulling hard enough?

[Boris]

Well, after buying a new multi meter I discover the throttle sensor and variable resistor are meeting specs so I am off to check on the waste gate. While playing with the throttle sensor I found a split vacuum hose so I did a temporary fix on that an will buy a new hose tomorrow. Fingers crossed.
Thanks for all the suggestions.
Cheers
Boris

[flav]

Remove your dist. cap and have a look at the wires going into it, see if they are burnt out. This will lead to all kinds of trouble. Have a look at the map sensor vac line for a split also.

[Boris]

Hi Flav!
Thanks for the suggestion. The disy cap looks prestine inside, but the rotor looks a bit ratty so I might replace it.

Sorry for my ignorance but can you translate the "where and what" of "MAP"? I found "MAS" and "SAS" in the manual but "MAP" illudes me at the moment.

I have some good news in that the line that I found to be split was the one from the manifold to the boost sensor and consequently, having done a temporary fix, my guage now spins happily into the red again. :) :)

The bad news is that the waste gate appear to be stuck. I removed the actuator rod and the lever to which it attaches is imovable. :(

Has anyone heard of waste gates jamming? Any suggestions on a proceedure to free it up? :?

Cheers and heaps of thanks. It is great to be able to talk Starion with people who know! :D
Boris.

[WidebodyWoody]

On a JA there is a MAP sensor on the firewall located just above the power steering and they can stuff up and make the car run really bad. The map sensor if it is playing up can cause the car to do everything that you have described. I had the same problem with my JA, I got another one for $150 from a wreckers that did the trick. I still have my old one and I know whats wrong with it but I myself can't fix it. The pin itself has crap in it that distorts the signal.

[flav]

The rattle is the weights behind the rotor. This in normal.
The problem with the MAP and Distributors begins to happen when you wind up the boost. The vac advance/boost retard cops a beating and eventually the diapragm fails and lets boost pressure past it and into the distributor, this pressure has fuel vapour in it, you get little explosions happening in the dist. body and thus melts the wires and tiny module windings. This creates havoc.... all kinds os stalling, jumping, (power on and off like a switch) and more. The MAP gets the same treatment but this affects the 'O' rings and sometimes the circuit board as well.
If you have any kinds of problems with a Starion its usually one of these or injector wiring/conectors.

[Boris]

So is this the "MAP"?

As near as I can tell this is what the manual refers to as the "boost sensor". Does "MAP" stand for anything?
The power steering pump in my car is at the front of the engine bay and not near the firewall, so I was not quite sure about WidebodyWoody's description. :?
cheers
Boris