OverBoosted28

Your very first sentence "they don't know what they're doing", is your first step. Get that thing outta there and get it to someone than can and will fix it.

ferraribuyer

Yes AEM "expert" came into look at the car and he said there is no way this can tune without a cam position sensor. The thing is the ECU is picking up a cam and crank reading from the crank wheel. The crank wheel has all of its teeth and another 911 guy said that it should have 2 teeth missing for readings. I don't think the shop knows how the ignition timing works in this car at all. Now I get to bring it to a 911 guy who actually does know the cars well but I don't want to pay him to go over the same crap the other shop did. I don't know if protomotive could figure this thing out?

ferraribuyer

Ryan,
We finally got AEM out here to take a look at the car. I'll try and break this down to make sense.

The way that the car is currently set up will not work with the AEM or any other stand-alone computer out there. This was the word of AEM. There is no way for an ECU to decipher between a cam signal and a crank signal.

Devin, from AEM is trying to get a hold of a company in the UK that he had heard of that supposedly makes a cam trigger for this car. He is hoping to hear back today? This would be the only hope of getting any ECU to work firing sequentially.

If that does not come about or work then the last option that Devin has is to get a new 24 tooth or 36 tooth crank trigger wheel and modify it to lose one tooth and run the car in a batch fire configuration. From what we can tell this will require dropping the engine, changing out the crank trigger and making something work that way.

I have no clue yet to the cost of doing either of these options nor can I guarantee the outcome.

We are currently sitting at approximately $3700.00 into this at this very moment. That is accounting for parts and only about half of the time that we actually have into the car up to this point.

I need you to advise where you want us to go at this point. I will not know anything more until I hear back from Devin from AEM on the potential fixes.

chsu74

Diary of taking the road less traveled in tuning a 993TT.

tacker

the factory motronic uses pin 21 "dist hall sensor" that your ccam sync.you must have both to run in 720 sync.At least with the ecu I'm using

JDHertz11

I think I'd look for alternatives at this point. If this system is untunable then there must be something on the market that is. Unfortunately, this is most likely the reason that the last owner sold it. There have been a few guys here that have had trouble with aftermarket setups on these cars.

ferraribuyer

Well Im not going to take off the AEM ecu. This car has gone through 4 different ECUs. There has to be a reason and thats what I need to find out because everything else is fine on the car. The last owner spent a fortune because one shop said it can't be tuned you need another kind of ECU that they sell. It was a risk I was willing to take knowing the tune was going to be an issue.

OverBoosted28

I'm no electrical engineer, but couldn't the program be written to ignore the cam position sensor that's not there. The Hall sensor is really the only CPS on these cars. It's sounds like a real headache. Howabout we just trade straight across. My car car is only 520HP, but the tuning works perfectly. Just thought I'd throw it out there to a friend in need :-)

tacker

OMG, there's 2 wires coming out of your distributor. Wires to pin 20 and 21 on the factory ECU. This is the cam sensor. Then the engine speed sensor is your crank position sensor Pin 78 and 20.
it's all there.
Do the people doing the work have the factory schematic?

Tacet-Conundrum

I stopped at the 3rd page, 5 pages so far, but all I have heard so far is engine this and engine that... has anything been done to stop this monster(?) and get the power to the front wheels?

ferraribuyer

Well I just got back from the shop and learned a few things. I DO NOT have a distributer. It has a clewett plug in the spot the distributer would be. So no cam sensor from that. So I called clewett and they have a cps that goes on the end of the cam for $190. So I think i will get that. Now do you guys use the crank pulley to get crank position or do you use the flywheel and hall sensor to get crank position? I think Im going to have to use the flywheel because PO hacked up the crank pulley to only 12 teeth and its not missing any in between. So ECU can't read the crank position for TDC. I could buy a new crank pulley like a 36-1 or something but I don't know whats supposed to be on this car factory? Any Help?

sfl993t4

I think that fitting the clewett cam position sensor is going to be an engine out job (it needs drilling into the end of the cam, and on a 993tt the hole in the tinware enlarged a little so that the new sensor seal fits).

You'd probably be much better just removing the clewett plug and putting a distributor back in and using the hall sender from that (as tacker suggested) even if the distributor is only functioning as a cam position sensor.

Steve

OverBoosted28

After all of this your "twin plug" doesn't even have a dual dist? There's plenty of guys on here that are running monsters with dual dist/ twin plugs, that apparently are getting enough juice. Instead of continuously beating your head against a wall, on an unknown, go with something proven. The simplicity will lessen any future headaches.

Al Pettee

I repeat, stop what you are doing now and send the car to Protomotive....

Spartan

Guys have been running cam sensors for a long time. You have to either modify your existing cam or install a custom cam that has the provision to put a trigger in it. Drivers side where the old scavenge pump for 930/965's used to be. My motec conversion on the 964 turbo has this and so will my 993tt motec conversion.

Find some 911 guys that have done a bunch of these conversions. Turbokraft, pat williams, Etc