potent951turbo

I just bought the 951 that I have been planning on buying since the day I saw it several years ago this past Sunday. I bought the car not running although we did get it running enough for me to know the engine was still strong etc. (it was a friends car). But I bought the car knowing it would need some fine tuning to get it back up to par. Anyways I have been tinkering with the car the past two days trying to get it to start and I have only had success twice now getting it to start and both times it ran very strong, but as soon as I cut it off it refuses to start. Most of the time the engine is just turning over with intermittent times when it will fire and try to start but doesn't quite get there. I have drained all the gas in the car and put brand new fresh gas in it, changed the plugs, cleaned the contact points on the distributor cap and the car just got new intake manifold gaskets, rebuilt turbo and several other things. But like I said I have only gotten it to start twice and both times were luck because I just kept trying to start it and didn't change anything and it just happened to get enough to kick in it to fire up. A few times it has tried to start it will cough up on itself and have a little smoke come out of the aircleaner. I also changed the reference sensors off of it with my other 951 just to see if that was a problem and still I just cant get it to start without just getting lucky. Does anyone have any ideas at all, I really want to get this thing running.
BTW- It also has an apexi AVCR in it, maybe this could interfere with it running properly. It also has a set of chips, and an sfr 3 inch exhaust.

testarossa_td

DME relay?
O2 sensor?
Fuel Pump?
Fuel Filter?
TPS?

Mike Murcia

Check out the passenger footwell where the AVC-r was wired in and look for any signs of bad wiring to the DME and KLR.

ibkevin

In addition to ^^^^^, gaping vacuum leak, TPS disconnected?

How agressively did you clean the contscts in the dist cap? Did you swapout excessive clearance for carbon build up?

dlgranison

I just had a similar problem. The metal fitting in the intake manifold that connects to the idle stabilizer came out of the intake manifold. HUGE vaccum leak

potent951turbo

Alright, I decided to take out the avc-r mainly because I had planned to already and I think I need to get down to the basics with this problem. I have gotten it to start twice since taking it out and it seemed to idle better without the avc-r. I am still having an up and down idle which makes me think that there was a vacuum leak, but I have checked and rechecked everything and all is well. I basically Just cleaned off the carbon inside the distributor cap, which helped me get alot more fire then before. When it is running the idle is either up and down between 1100 and 1500 or constant at about 2k, which points to the tps but my instructions on adjusting it don't tell me which pins are which on the diagnostic connector to put a jumper in. Right now when I try to start it I am getting about 50 50 between just turning it over and it trying to start, and when it trys to start it kicks over a few times and just seems like it looses its momentum and dies.

Mike Murcia

This should help in setting the idle:

http://www.clarks-garage.com/shop-manual/fuel-08.htm

potent951turbo

Well after reading the idle adjustment process on clarks garage, I tried it and put the jumper in the pins and nothing seemed to happen even after playing with the adjustment screw. After that I was looking at my other 951 and realized in the diagnostic connector was a little round tool with a toggle switch with a red and green LED. I am assuming the previous owner must have left it in there or something but I have been driving that car all this time with that in place. I really have no idea how to use this little device so I am not sure what steps I should do in using it. I tried putting in my 951 that is having the running problems and with the power on the red led lights up and I can flip the toggle switch and the green led will come on, but I did get the car to start once with it in place and then the green light stays on no matter what position the toggle switch is in, and still no change with the idle screw. The only difference now is that the car seems to idle very smooth at 2k rpm's and no longer going up and down. But still there is something causing the car to have a really hard time starting. It sounds like it wants to start but after it runs for about two seconds it dies off and I have to continue turning it over to try and start it. Any ideas??

bearone

bad gas.

87951

Mike Murcia

High idle and difficulty starting sounds like a vac leak somewhere. It could also be that yout throttle is not closing all the way. A more thorough procedure for setting the idle is here: (taken from an old post)

Setting the Idle on the 944 Turbo:

To do it correctly and throughly, it is a four step process.

Setting the hard stop. Car is not running. The purpose of the hard stop adjustment is to keep the throttle plate for binding or landing in the throttle body bore to hard. It's purpose is "not" to set the idle. Loosen the jam nut (8mm). Loosen the screw with a small straight blade screwdriver slowly and carefully until the screw turns loose. With a gentle touch, slowly turn the screw back in until you can feel it touch the stop. From there, turn it another 1/8 turn. Tighten the lock nut back down. If you have the intercooler pipe off, you would barely be able to detect that the throttle plate moved.

Setting the Throttle Position Sensor (TPS). Car is not running. A correctly adjusted throttle position sensor will make a clicking sound when you just roll the throttle off the stop. Place you fingers on the throttle cam and rotate the throttle open off idle. If it does not click, it's not adjusted properly. If it rotates several degrees before clicking, it's not adjusted properly. Loosen the two phillip screws on the TPS just enough to allow you to rotate it with a slight effort. Rotate the TPS to where when you rotate the throttle cam, it clicks when your just off the stop or about 1 degree of rotation. Then tighten the two TPS screws back down.

Jumping the Idle Stabilizer. Car is not running. You will need a short piece or wire (3-4") with both ends stripped bare. Place the ends of the wire in the terminals "B" and "C" pictured below. This will put the Idle Stabilizer in a central position of it's movement when the car is running.


Adjusting the idle RPM. With the previous three steps completed, you will be setting the idle RPM. With the car in neutral and the emergency brake on, start the car. Turn off the A/C if on. Let the car come up to normal operating temperature. The idle RPM is adjusted by turning the idle screw located on the top of the throttle body. Normally it will be approximately 1/2 turn open from fully seated down (clockwise). Idle should be 840+/-20 RPM.



I'd take a few minutes to set the idle before chasing down a vac leak because they can be hard to find without pressurizing the intake.

potent951turbo

Bearone- I drained every bit of gas out of my tank and replenished it with new gas, so thats not my problem.

Mike Murcia- Thanks for all this info and help. I will be back on it tomorrow afternoon, and I will try and get that idle taken care of first. Any idea on how to use the little tool I found with the green and red led's?

Dal Heger

Either a huge vacuum leak, or your TPS is bad. The car should idle at 850+/-50 rpm.

The little tool is a flash code reader. Take the car out and drive it, then before turning it off (turning it off clears the stored codes) use the reader - plug it in and read the flashes. The green LED and switch is just there to test for power. The red LED is the one that will flash if there are stored codes. Check out http://www.lindseyracing.com/Merchan...ode=TECHGARAGE for a start.

Dal.

roadrunner

not that this would be the same problem on your car, just adding information that might help because it started out in a similar way...

Check the plugs to make sure they are not wet (mine were soaked). The fuel dampener on my car failed with a hole in the diaphragm, and this caused fuel to be pumped directly into the intake manifold. After replacement, the car ran fine until I really got on it, then it would stumble until it shut off. It would have trouble restarting sometimes, then it would run fine until I got on it again. It turned out the fuel pressure regulator was bad, stuck closed so it overpressurized the fuel system and flooded the engine. I found this out too late, after a fuel lock during cranking and subsequent siezed engine.

potent951turbo

Alright today I changed my distributor cap and rotor with almost brand new items off of my other 951 and still no difference. I am getting fire and moments where it kicks on its own for a second but it just dies off. I have the TPS adjusted properly now, and it is almost brand new so I don't think thats the problem. I want to say its a vacuum leak but when it is running I hear no leaks and it runs pretty well, but does have a stumble when you rev the engine up some and an occasional backfire or two. I have checked and rechecked vacuum lines with no luck and finding anything suspect. What else could it be?

lart951

go to www.951forums.com and post your question in their technical forum, most of the old timers rennlist gurus/specialist hang over there.