Saabscene Saab Forum - Saab Technical Information Resource banner
1 - 12 of 12 Posts

·
Registered
Joined
·
50 Posts
Discussion Starter · #1 ·
really bizaar one now, all running fine until yesterday. Under hard acceloration engine looses power a couple times per second.
It makes it look like I'm running on kangaroo petrol! (if you know what I mean!) It runs sweet rest of the time. only does it when accelorator is more than 1/2 pressed. could it be throttle position sensor, or boost pressure sensor fault,
its a 2.3 LTP auto, so its definately not my clutch control!
 

·
Registered
Joined
·
50 Posts
Discussion Starter · #3 ·
changed the plugs a couple months ago, it was running fine. It doesn't appear to be related to revs, merely how much load is on the engine, ie pulling away, overtaking, accelerating up hill!

ii's really frustrating. It runs perfectly under normal use!
 

·
Registered
Joined
·
127 Posts
I had this until recently and was told that adding a petrol additive,the ones you do every 6000 limes or so would help and it has to a good effect.I now accelerate hard just to check when oils warmed up and problem gone.
I can't remember the make but it cleans the injectors etc.got it from Halfords and you apply one bottle to one tank every 6000 miles
 

·
Registered
Joined
·
8,216 Posts
Originally posted by lurky:
[qb]I know there is some debate about using some types with the DI unit, but it has been woring absolutely fine for the last couple of months![/qb][/b]
There is no debate. The only plugs that will work consistently are the specified NGKs. People who try other plugs (Bosch Platinum seem to be a popular "upgrade", for instance) often report that they run fine and tell us we don't know what we're talking about. Then a couple of months later, they're back here asking about running problems. Can't be the plugs - they're brand new

If you're not sure which plugs you have in there, check them. If they're not NGK BCPR7ES or BCPR7ES-11 (the pre-gapped version), then change them for the proper ones and if that doesn't fix it you've at least eliminated one potential cause.
 

·
Registered
Joined
·
11,343 Posts
OK, here it is again, important info as to why should use the specified NGK spark plugs:

Guide for Direct Ignition cassette and spark plug service - all DI-equipped vehicles

Using non-resistor spark plugs could cause several different types of fault symptoms and driveability problems in the car. The DI uses the spark plugs are used to monitor the combustion process.

An incorrect spark plug gap (excessive wear) can also lead to driveability problems. Use of non-resistor spark plugs could also destroy the DI cassette.

! - Spark plug burn-off - !
Automatic spark plug burn-off is carried out with a burst of sparks each time the engine is switched off. Burn-off is carried out in all cylinders simultaneously and lasts for 5 seconds at a rate of 210 sparks per second.

! -This Is Lethal Current Use Extreme Caution- !

Therefore, it is very important to adhere to the following guidelines :

When replacing the spark plugs it's important to check following:

- First Allow 30 seconds for the module to power down then remove the electrical plug to ensure your safety.
- Always use resistor type NGK spark plugs. All Saabs equipped with DI cassettes have been specified with resistor type NGK plugs
- Verify the correct gap at the electrode (1.0mm -1.1mm)
- Check For oil leakage from coil assemblies. This would indicate a failed DI assembly.

Before installation of the DI cassette:

Coat the rubber boots on the cassette with Krytox (P/N 30 19 312) or a name brand dielectric grease.
Check to be sure that the contact springs can be seen inside the coil towers and replace them if they are damaged or missing ( P/N 91 67 032)
Coat the thread of the spark plugs with Molycote 1000 (P/N 30 20 271) or high temperature anti-sieze.

Torque:

Install and torque the Spark plugs to 21 lbf ft
Fit the Cassette to the valve cover and torque to 8.1 lbf ft

Spark plug considerations

"7" series spark plugs have a colder heat range than "6" series and are, therefore, commonly used as an alternative plug on cars consistently run at high speeds or under heavy loads.

"R" in the NGK plug designation signifies resistor type.
 

·
Registered
Joined
·
8,216 Posts
Excellent, /john. Where is that from?

Just to elaborate on the reason for using NGK only, since most people have a hard time believing that a car can be so sensitive to the type of plug:

The Saab DI system uses ionisation across the plugs to sense various conditions within the engine, e.g. compression stroke, knock, etc. This uses properties of the plugs that are not normally specified by plug manufacturers, and not normally considered during design. The DI system was developed using the NGK plugs, in which these properties are guaranteed to be consistent. Any other manufacturer who offers "equivalent" plugs to the NGK should not claim them to be equivalent in a DI application unless they specify all of the properties of the plug that are important for correct operation of the DI system. To my knowledge, most if not all other manufacturers don't. That doesn't stop them from listing plugs for DI engines, though.
 
1 - 12 of 12 Posts
Top