Phil Brennan, 91 Saab 900 Turbo 16S

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Phil Brennan, 91 Saab 900 Turbo 16S

Post by reckless » Wed Jul 02, 2008 7:13 am

'91 Saab 900 T16S 3 door in scarabe green.

Motivations for the project:
1) Add mapped ignition, to replace crude stock system
2) Add mapped fuel to allow tuning to suit future modifications
3) Learn about engine management ( well, this is why I chose megasquirt )
4) possibly run on e85

Bought box from daxtojeiro ( phil@extraefi ) since I wanted the project to get off the ground.
MS1-extra v3 board with 029y4 firmware.
Ran with ignition control since last october, very simple using standard dizzy hall sensor, stock bosch ignition module.
Used keithg's instructions to get it up and running. Still running time based cranking but it starts quick enough for me. Faster than stock when using MS for fuel instead of stock system :)
Looked at a few spark maps from other saabs, including 9000 with DI, and other MS'ers maps. Its somewhere in between the DI map and Saab-Daniels map for T16.
Compared to stock, I've added a lot more advance off boost, and at low boost levels.
Because of limitations of standard intake/exhaust, still limited to around stock advance on full boost, but its nice to have the control!
This change really transformed the car off boost, throttle response is much improved from stock.
This year, decided to move up to full control, still using as many stock components as possible.
Fitted innovate wideband and got it monitoring standard lucas cu14 fuel ecu AFR's, and also feeding it a narrowband signal.
Used spare lucas ecu to make adapter to standard saab loom - this makes it much easier and neater. Since the car is my daily driver I had to be able to switch back to lucas if necessary
during the transition. I'm now at the stage where I can remove the stock air mass meter and ecu.

Sensors used: stock (bosch) CLT, IAT is from saab 9-5, also bosch. Simply screwed it into the IC-TB delivery pipe, with o-rings either side and a nut on the inside holding it on.
Stock lucas TPS is used, stock APC turbo boost control solenoid.
Injectors are stock lucas 270cc, low impedence.

So currently MS is controlling spark, fuel and boost. Idle control is to be added, along with knock detection ( signal is available from saab apc )
The ecu has switcheable maps, this was to allow running on e85. I've created a rough map for e85, and may give it a shot shortly. Really I'll need to fit my new 440cc injectors first.
Car is driving well now, but I am finding the AE tuning tough going, it really is a fine art.

Now running MS2-Extra 2.01. Transition was very easy, but I still have a problem with an intermittent misfire at low rpm. Have replaced almost all ignition components except dizzy and coil - will swap out coil this evening, and distributor at the weekend if that does not fix it. Have tried every conceivable setting in megasquirt.

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Re: Phil Brennan, 91 Saab 900 Turbo 16S

Post by HAkentt » Wed Jul 02, 2008 1:58 pm

It is not the coil. Coils are like light bulbs when it goes bad it will never lit. coil will not spark one day and not spark the other day. Distributor hall sensor is your problem, it is not acurate location, little lose timing chain and timing will be all over the place. You need crank sensor from EZK 90-93 models. I don't think they had those in UK.

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Re: Phil Brennan, 91 Saab 900 Turbo 16S

Post by reckless » Tue Aug 12, 2008 12:55 pm

Think about it, if the stock distributor does not misfire at low rpm with stock ignition and stock fuel ecu, why should it do so with megasquirt? The sensors are known to fail though, so I did try swapping in a spare dizzy. In the end I traced the problem to some bad connections at the ignition module. Sorted it out, am now running best distributor MS2/Extra on the nets. Perfectly smooth to 6200rpm now, no point in revving it higher. I'm aware that the stock dizzy gives timing jitter, I will be moving to EDIS shortly, but I do have other projects.

Now running:
- IAT from Saab 9000
- 440 cc Lucas injectors
- Cone air filter in fender and 3" intake.

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