Well the car is back at my house for now.

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Here's a quick video of how the car sounds now, for those who are curious. I start the car, and then just let it die the first time. The second time, I try my best to keep the car idling, with slight throttle application(s). This is where you can see it is surging. Third start I do rev it up a bit, and you can see there is pretty poor throttle response, and hear some of the spitting back and backfiring that we are getting.

I'll be attempting to find any vacuum leaks and checking over the intake system and throttle linkages in more detail than I have before this afternoon/evening.

http://www.youtube.com/watch?v=IZH29...ature=youtu.be

 

Have you kept it running long enough to get the engine closer to operating temp, and if so, did the behavior change?

 

I have run it for 5+ minutes, and yes, the idle does start smoothing out. I'm going to do this again today as well. I'd like to get the oil temperature gauge working properly first though...

 

LOL, gee, why?

Cool project- best of luck with it!

 

OK! Afternoon projects:

1. Check throttle linkage. It was very good, both left and right banks were in good shape. I tweaked the right side, closing one of the ball ends a turn to make it ever-so-slightly tighter (and thus more closed) at rest. But I don't think it really needed it.

2. Check for vacuum leaks. I didn't find any. The fuel pressure regulator appears to be the only thing requiring vacuum from the throttle bodies, and it is taking off from cylinders 3 and 2 which are Y'd together.

3. I haven't checked the Throttle Position Sensor yet, that will be next.

While inspecting everything and cleaning the engine bay (a little dirt is fine but we had some pretty good grime going), I tried to take pictures of all the disconnected bits of the wiring harness. I know many of these are unhooked due to the conversion to individual throttle bodies, but can someone with better knowledge of 964 motors help identify which connectors are which? It would be good to make sure nothing is disconnected that is supposed to be connected.



The above is a 2 pin quick disconnect connector, which also has two other female blade connectors coming out of the same section of the harness. The colors of the wires for the blade connectors are Green/Yellow and Black/Yellow.



Also on the left side of the engine bay, a 2 pin quick disconnect connector, wire colors are Red/White and Green/Yellow.



Also on the left side of the engine bay, a 2 pin connector that looks like a press-fit with two little "arms" on either side to hold the connection, wires are two Green/Yellow wires leading to one pin, and a Brown (ground I assume) one going to the other pin. Related to the first two pictures?



Took this picture near the throttle linkage/triangle of death (as we affectionately refer to it on earlier motors due to the multitude of potential leaks in this area). Maybe we have found the source of the temp gauge not working -- The wire hooked up to the temp sensor is Green/Black, but there is a Green/White wire that is simply taped off that comes out of the same part of the harness. If that isn't temperature, what is it? Also, anyone have better ideas on where to put the return spring? Maybe fab up a vertical bracket and then attach it to one of the bolts holding the throttle cable? As mentioned earlier, it is currently totally screwy and is zip-tied to the fuel rail on the left side.



Last but not least, we have this 2 prong quick disconnect right near the distributors. It is Yellow/Brown and Green/White. There is another plug of the exact same type that is plugged into Distributor #1.

Thanks for any help guys. We'll get to the bottom of this.

 

The two first pics is the inlet temp sensor and to the resistor terminals.
They are located on the tube from the egine bay fan to the heatexchangers.

The third pic is the conector to the fan.

The last pic is the conector to the fan belt tension switch, that will iluminate
a warning on the clock.

I´m at work and dont have the wiring diagram here...


Best regards
Marcus

 

OK we can definitely live without those. So that leaves just the temperature sender wire. Should we be using the Green/Black or the Green/White wire? And what does the "other" one operate? Could it be an (unhooked) oil pressure switch?

Edit: jogged my memory, and SCs and Carreras use a Green/Black wire for the temp sender (which is what is hooked up on mine). So that likely isn't the temperature sender issue. Still want to know what the Green/White wire is for.

Thanks very much for the input Marcus.

 

On a slightly different note (non-engine related), I've got some other questions about the car.

1. To go back to 964-style front end, do you think I could fit regular 930 turbo-style front fender flares, without the screw-on extensions? That plus the DP bumper pictured earlier in the thread, and new side skirts? Or are these front wheels too wide for a 930 flare?

2. I think I need some replacement heat shielding material to line the bumper with. What's currently there is corrugated aluminum stuff, fairly stiff, it has a Porsche 993 part number. This "muffler" gets HOT when I've had the bumper off and the motor running, so good heat shielding is a must. I don't care if it is aftermarket stuff I have to fab up, just point me towards something good.

 

I really enjoyed reading this thread so far, I hope you get the issue tracked down and fixed soon.

 

I would PM "Geoffrey" here on RL. He has a 964 RSR look car and I am sure could steer you in the right direction. The website for his shop is www.racetek-engineering.com

 

We had a 993 Cup car that was the original Motronic system with just the single throttle body. It was horrible running when cold, until you got it warmed up. Very typical. Finally fixed all the issues when we went with Motec and individual throttle bodies.

 

Might this be something to do with the ECU needing to "re-adapt" idle every time it loses power?

Being a racecar, I'm constantly cutting off all power to the car with the battery cut-off switch.

 

So the car does idle once it is up to temperature. Up to temperature meaning I got the oil temp gauge to climb to the second bar by running the car at 2K RPMs manually. And with the rear bumper off everything is EXTREMELY hot. I will need to fabricate up some new heat shielding as I'm nearly melting my center panel and taillights with things as they are. In fact, I had to pull off the center section as the little rubber weatherstrip on the bottom of it started falling off and then caught on fire on the exhaust.

Here is a (dark and blurry) video of things idling and a view of the gauges. Everything appears to be working now. The sunroof switch is wired up to the oil temperature gauge and I assume you should be able to get a post-oil-cooler reading when it is in one position, but that position isn't working. However, the other one is, and I'm assuming I think fairly safely that this is the engine oil temp.

Things are still way too lean at idle. Between 16.8 and 17 AFR. Am I at danger of hurting the motor if I let it idle so lean?

http://youtu.be/VAwEkoiPH_g

 

Maybe the idle air bleed screws are backed too far out and I should turn them all in evenly and see if that riches up the idle? I do have a synchro meter for synching my carb'd 356 so I can make sure they stay balanced.

 

Cool car. I remember seeing this on Pelican & was tempted.. would love to find a similar project when time / space permit.

re: rough running, noticed you're in NC but the car was previously run in Colorado. The ECU is likely set-up for alpha-N operation (no MAFS, I don't see any vacuum lines connecting to a MAP nor any O2 sensors to allow adaptation). You'll probably need to re-map for your elevation to fix it the 'right' way.

Alternately, you can try increasing the fuel pressure to compensate. Assuming the car was calibrated for Denver altitude, you need approx. 16% more fuel (baro = ~25inHg there vs. ~29 in NC). Increasing rail pressure by 35% should get you close.

Another idea would be to adjust the throttle position sensor to read ~16% 'more open' for the same absolute throttle position but this might cause other problems with idle.

Don't mess w/ the throttles until it can idle on its own.

edit: if it has a stock 3.5bar regulator, a 5bar will get you close. can you put a gauge on it to check?